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The significance of snow and arboreal lichen in the winter ecology of mountain caribou (Rangifer tarandus… Antifeau, Theodore Danial 1987

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THE SIGNIFICANCE OF SNOW AND ARBOREAL LICHEN IN THE WINTER ECOLOGY OF MOUNTAIN CARIBOU (Rangifer tarandus caribou) IN THE NORTH THOMPSON WATERSHED OF BRITISH COLUMBIA. By THEODORE DANIAL ANTIFEAU B . S c , Simon Fraser U n i v e r s i t y , 1976. A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Animal Science) We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 1987 (c) w Theodore Dan i a l A n t i f e a u , 1987 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Animal Science The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date 30 Apr i l 1987  DE-6(3/81) i i A b s t r a c t The w i n t e r ecology of mountain c a r i b o u (Rangi fer tarandus ca r ibou ) i n the North Thompson watershed of B r i t i s h Columbia was i n v e s t i g a t e d over w i n t e r s 1978-79 and 1979-80. The main o b j e c t i v e of the study was t o eva lua te c a r i b o u movements and h a b i t a t use i n r e l a t i o n t o i n d i c e s of energy c o s t of locomot ion i n snow and to forage a v a i l a b i l i t y , e s p e c i a l l y a r b o r e a l l i c h e n s . These d a t a were c o l l e c t e d i n h a b i t a t s from v a l l e y bottom to a l p i n e throughout w i n t e r . L a r g e l y because of t h e i r h igh a r b o r e a l l i c h e n p r o d u c t i v i t y , mature f o r e s t s a re regarded by w i l d l i f e managers as e s s e n t i a l w i n t e r h a b i t a t of c a r i b o u , l e a d i n g t o c o n f l i c t s w i t h f o r e s t h a r v e s t i n g . Data were compared between mature f o r e s t s and other h a b i t a t t y p e s , to eva lua te t h e i r importance to c a r i b o u . An index of c a r i b o u locomot ion cos t i n snow was c a r i b o u t r a c k depth i n snow. A s i g n i f i c a n t r e g r e s s i o n between c a r i b o u t r a c k depth and human s i n k i n g depth i n snow p e r m i t t e d an es t imate of c a r i b o u locomot ion c o s t s i n a l l h a b i t a t s . Locomotion c o s t s o f t e n were g reate r i n cu tove rs than i n mature f o r e s t s , and b r o a d l y i n c r e a s e d w i t h e l e v a t i o n ; w h i l e temporal t rends were c y c l i c a l , due to a l t e r n a t i n g accumulat ions of f r e s h , s o f t snow f o l l o w e d by set t lement and maturat ion of the su r face snow. A n a l y s i s of f e c a l and rumen samples, and f e e d i n g - s i t e i n s p e c t i o n s were used to determine c a r i b o u w in te r food h a b i t s . A r b o r e a l l i c h e n s ( A l e c t o r i a sp . and B r y o r i a spp. ) dominated the d i e t by mid w i n t e r because t e r r e s t r i a l fo rage a v a i l a b i l i t y d e c l i n e d due to deep and c r u s t e d snowpacks. For each h a b i t a t , the a b s o l u t e abundance of a r b o r e a l l i c h e n was i n v e n t o r i e d , and then t h i s data together w i t h snowpack measurements were used t o es t imate the r e l a t i v e a v a i l a b i l i t y of a r b o r e a l l i c h e n over w i n t e r . A r b o r e a l l i c h e n a v a i l a b i l i t y was g r e a t e s t i n mature f o r e s t s , and g e n e r a l l y i n c r e a s e d w i t h e l e v a t i o n ; i t a l s o i n c r e a s e d w i t h i n h a b i t a t s as snow deepened and e leva ted i i i c a r i b o u t o h igher f o r e s t canopy l e v e l s where g reater q u a n t i t i e s of l i c h e n o c c u r r e d . For the f i r s t t ime , r a d i o te lemet ry was used to determine mountain c a r i b o u movements and h a b i t a t use . Observat ions of n o n - r a d i o c o l l a r e d c a r i b o u were a l s o used i n some a n a l y s e s . In both used and unused h a b i t a t s , es t imated energy c o s t s of locomot ion and the a v a i l a b i l i t y of a r b o r e a l l i c h e n were t r e a t e d as i n d i c e s of energy expend i tu re and of energy i n t a k e of f o r a g i n g . These i n d i c e s were q u a l i t a t i v e l y i n t e g r a t e d i n a net energy ba lance r e l a t i o n s h i p to eva lua te c a r i b o u movements and h a b i t a t use . Car ibou appeared to f o l l o w a genera l o p t i m i z i n g s t r a t e g y , b a l a n c i n g t h e i r energy expend i tu re f o r locomot ion i n snow aga ins t the energy a v a i l a b l e from f o r a g e , when both t e r r e s t r i a l and a r b o r e a l forages a re c o n s i d e r e d . Throughout w i n t e r , c a r i b o u p r e f e r a b l y used mature f o r e s t s , which o f f e r e d much g reate r e n e r g e t i c b e n e f i t s than cutovers and immature f o r e s t s . As snow i n suba lp ine (Engelmann Spruce - Suba lp ine F i r Zone) and a l p i n e summer h a b i t a t s deepened over e a r l y w i n t e r , c a r i b o u migrated to lower suba lp ine and lower s lope and v a l l e y ( I n t e r i o r Cedar - Hemlock Zone), mature f o r e s t h a b i t a t s . Car ibou locomot ion c o n d i t i o n s and fo rage a v a i l a b i l i t y , p r i m a r i l y of t e r r e s t r i a l f o rages , were most f a v o u r a b l e a t these lower e l e v a t i o n s , d e s p i t e lower a r b o r e a l l i c h e n a v a i l a b i l i t y , because of s n o w f a l l i n t e r c e p t i o n by the f o r e s t canopy and lower s n o w f a l l . F i r m e r , m id -w in te r snowpack c o n d i t i o n s a l l owed c a r i b o u to reascend to l a t e w i n t e r range i n h igher e l e v a t i o n suba lp ine f o r e s t s , wh ich , because of g r e a t e r a r b o r e a l l i c h e n a v a i l a b i l i t i e s combined w i t h moderated locomot ion c o n d i t i o n s , became the most f avou rab le h a b i t a t s . Minor e l e v a t i o n a l s h i f t s d u r i n g t h i s p e r i o d occur red i n response to f l u c t u a t i o n s i n locomot ion c o n d i t i o n s caused by c y c l e s of snow accumulat ion and snow se t t l ement . iv This study confirmed that mature forests are required habitat for caribou throughout winter, by providing c r i t i c a l arboreal lichen forage, and compared to cutovers, having lower locomotion costs and greater availability of t e r r e s t r i a l forage. Proposed forest reserves above 1680 m elevation in the upper subalpine are insufficient therefore to ensure essential caribou winter habitat. Mature forests from valley bottoms to the lower subalpine must also be reserved. V Tab le of Contents A b s t r a c t i i L i s t of Tables v i i i L i s t of F i g u r e s i x Acknowledgements x i I . INTRODUCTION 1 I I . STUDY AREA AND STUDY PERIOD 6 L o c a t i o n 6 Physiography 6 C l i m a t e 8 B i o g e o c l i m a t i c Zones 8 Land Use 9 H a b i t a t C l a s s i f i c a t i o n 9 Study P e r i o d 12 I I I . SNOW CONDITIONS AND CARIBOU LOCOMOTION 13 I n t r o d u c t i o n 13 Methods 13 C l i m a t i c Data 13 Design and sampling of snow courses 13 Comparison of snow and genera l weather c o n d i t i o n s between w i n t e r s 15 Winter i n t e r v a l s 16 Car ibou Locomotion C o n d i t i o n s i n Snow 16 Chest he ight 16 P r e d i c t i n g c a r i b o u t r a c k depths 17 Energy c o s t s of locomot ion i n snow 17 R e s u l t s 18 T o t a l Snow Depths 18 Car ibou Locomotion C o n d i t i o n s i n Snow 21 P r e d i c t i n g c a r i b o u t r a c k depths 21 Car ibou t r a c k depths i n r e l a t i o n to h a b i t a t c l a s s i f i c a t i o n f a c t o r s 21 Locomotion c o n d i t i o n s i n r e l a t i o n t o snowpack c r u s t i n g and weather 27 Locomotion c o n d i t i o n s i n the L ichen Reserve 31 Representat iveness of c a r i b o u locomot ion c o n d i t i o n s over the 1979-80 w i n t e r 32 D i s c u s s i o n 36 P r e d i c t i n g Car ibou Track Depth 36 Ind ices to Locomotion C o n d i t i o n s i n Snow 36 F a c t o r s A f f e c t i n g Locomotion C o n d i t i o n s 37 Temporal Trend i n Locomotion C o n t i t i o n s and C l i m a t e 38 IV . UTILIZATION AND AVAILABILITY OF WINTER FORAGE 40 I n t r o d u c t i o n 40 Methods 40 Food Hab i t s 40 v i Chemical Composit ion and D i g e s t i b i l i t y of A l e c t o r i o i d L i c h e n . . . 42 A v a i l a b i l i t y of Winter Forages 42 T e r r e s t r i a l forages 42 A r b o r e a l a l e c t o r i o i d l i c h e n s 44 1. L ichen i n v e n t o r y 44 2 . A v a i l a b i l i t y of a r b o r e a l l i c h e n 47 R e s u l t s 48 Food H a b i t s 48 N u t r i t i v e Q u a l i t y of A l e c t o r i o i d L ichens 51 T e r r e s t r i a l Forage A v a i l a b i l i t y 53 A r b o r e a l A l e c t o r i o i d L ichen Abundance and A v a i l a b i l i t y 57 R e l i a b i l i t y of l i c h e n abundance est imates 57 Abundance of a r b o r e a l l i c h e n 57 1. W i th in and between h a b i t a t types 57 2 . Abundance of a l e c t o r i o i d l i c h e n by genera 60 3 . A r b o r e a l l i c h e n l i t t e r 62 A v a i l a b i l i t y of a r b o r e a l l i c h e n over w in te r 62 D i s c u s s i o n 68 Winter D i e t 68 N u t r i t i o n a l Value of A l e c t o r i o i d L ichens 70 Abundance and A v a i l a b i l i t y of A r b o r e a l A l e c t o r i o i d L ichens . . . . 71 V. SEASONAL DISTRIBUTION OF CARIBOU 74 I n t r o d u c t i o n 74 Methods 74 Capture and R a d i o t r a c k i n g 74 A e r i a l Surveys 75 R e s u l t s 77 Group Dynamics of R a d i o c o l l a r e d Car ibou 77 Home Ranges 79 Comparison of R a d i o c o l l a r e d and N o n - r a d i o c o l l a r e d Car ibou D i s t r i b u t i o n s 79 A l t i t u d i n a l M i g r a t i o n 82 D i s c u s s i o n 85 V I . CARIBOU WINTER DISTRIBUTION IN RELATION TO LOCOMOTION CONDITIONS IN SNOW AND ARBOREAL LICHEN AVAILABILITY 86 I n t r o d u c t i o n 86 A. I n d i v i d u a l E f f e c t s of Energy Cost of Locomotion and A r b o r e a l L ichen A v a i l a b i l i t y on Car ibou Hab i ta t Use 87 Data C o n s i d e r a t i o n s and B i v a r i a t e C o r r e l a t i o n a l A n a l y s e s . . . . 87 R e s u l t s 88 1. Car ibou H a b i t a t Use and Energy Cost of L o c o m o t i o n . . . . 88 2 . Car ibou Hab i ta t Use and A r b o r e a l L i c h e n A v a i l a b i l i t y 94 B. Combined E f f e c t s of Energy Cost of Locomotion and A r b o r e a l L ichen A v a i l a b i l i t y on Car ibou Hab i ta t Use 96 Data C o n s i d e r a t i o n s and D e s c r i p t i v e M u l t i v a r i a t e A n a l y s e s . . . 96 R e s u l t s 100 v i i C. Genera l Car ibou Responses t o Locomotion C o n d i t i o n s i n S n o w . . . . 102 1. E l e v a t i o n a l D i s t r i b u t i o n 103 Data C o n s i d e r a t i o n s and Analyses 103 R e s u l t s 104 2 . H a b i t a t D i s t r i b u t i o n 104 Data C o n s i d e r a t i o n s and Analyses 104 R e s u l t s 106 3 . A e r i a l Survey Observat ions 109 V I I . SUMMARY DISCUSSION 110 Net Energy Model 110 E a r l y Winter I l l Net energy framework I l l G rad ient i n a l t i t u d i n a l m i g r a t i o n i n e a r l y w i n t e r 114 I n f l u e n c e of a r b o r e a l l i c h e n a t l ogg ing o p e r a t i o n s i n e a r l y w in te r 115 Late Winter 116 Car ibou movements between low and h igh e l e v a t i o n ranges 116 Car ibou h a b i t a t use w i t h i n h i g h e l e v a t i o n ranges 118 Adequacy of A r b o r e a l L ichen Range 120 Car ibou Locomotion Thresholds 123 Comparison of Snow and Locomotion C o n d i t i o n s Between Winters 124 Management and Research I m p l i c a t i o n s 125 V I I I . LITERATURE CITED 129 IX. APPENDICES 140 A. Snow water e q u i v a l e n t s recorded by the Mount S a i n t Anne snowpi l low, w i n t e r 1979-80, North Thompson 140 B. Forage p l a n t s used by mountain c a r i b o u i n l a t e f a l l and w i n t e r , 1978 to 1980, Nor th Thompson 141 v i i i L i s t of Tables 1. Hab i ta t c l a s s i f i c a t i o n des ign used t o s t r a t i f y the b i o p h y s i c a l environment of the North Thompson study a rea 10 2 . Spearman's rank c o r r e l a t i o n c o e f f i c i e n t s between e l e v a t i o n - c l a s s and mean p r e d i c t e d c a r i b o u t r a c k depth of h a b i t a t - c e l l s , w i n t e r 1979-80, North Thompson 26 3 . I nd ices t o the occurrence and i n t e n s i t y of c r u s t i n g i n the upper 70 cm of snowpacks, w in te r 1979-80, North Thompson 28 4 . Composi t ion of p l a n t types i n w i n t e r , 1979-80, f e c a l samples of North Thompson c a r i b o u determined by m i c r o h i s t o l o g i c a l a n a l y s i s 49 5 . Use of both forage types and v a r i o u s sources of a r b o r e a l l i c h e n s , observed a t c a r i b o u f eed ing s i t e s i n f a l l , e a r l y w i n t e r and l a t e w in te r o f 1978-79 and 1979-80 combined 50 6. N u t r i e n t compos i t ion and i n v i t r o d ry matter d i g e s t i b i l i t y of a r b o r e a l a l e c t o r i o i d l i c h e n s from low and h i g h e l e v a t i o n , mature f o r e s t s i t e s , North Thompson c a r i b o u w in te r range 52 7. L o c a t i o n s , s i t e and stand c h a r a c t e r i s t i c s , and a r b o r e a l a l e c t o r i o i d l i c h e n abundance est imates f o r the 0 to 6 m canopy stratum of f o r e s t stands 58 8. R a d i o c o l l a r e d c a r i b o u , o b s e r v a t i o n p e r i o d s , home range s i z e s , and comments on t h e i r a s s o c i a t i o n s w i t h o ther c a r i b o u 78 9. Spearman's rank c o r r e l a t i o n c o e f f i c i e n t s between the number of c a r i b o u r a d i o l o c a t i o n s i n h a b i t a t - c e l l s , and 1) the r e l a t i v e energy cos t of locomot ion i n snow, and 2) the a r b o r e a l l i c h e n a v a i l a b i l i t y , of h a b i t a t - c e l l s , over w in te r 1979-80 89 10. Two-way mat r i ces showing percentage of r a d i o c o l l a r e d c a r i b o u o b s e r v a t i o n s by ordered combinat ions of r e l a t i v e energy c o s t of locomot ion i n snow, and a v a i l a b l e a r b o r e a l l i c h e n , f o r w i n t e r p e r i o d s over w in te r 1979-80 97 11. S e q u e n t i a l comparisons between d i r e c t i o n s of change i n c a r i b o u use of suba lp ine h a b i t a t s and i n c a r i b o u locomot ion c o n d i t i o n s i n snow i n the suba lp ine , w i n t e r 1979-80 107 i x L i s t of F i g u r e s 1. Nor th Thompson study a rea and l o c a t i o n s of snow course (S) and a r b o r e a l l i c h e n i n v e n t o r y (L) s i t e s 7 2 . Snowpack depths i n d i f f e r e n t h a b i t a t s , s t r a t i f i e d t o (a) mature and (b) immature s e r a i t ypes , w i n t e r 1979-80, North Thompson 19 3 . D e v i a t i o n from long - te rm monthly averages i n snowpack depths and d e n s i t i e s over w in te rs 1978-79 and 1979-80; and comparison of average d a i l y a i r temperatures between w i n t e r s 1978-79 and 1979-80 . . . 20 4. R e l a t i o n s h i p between c a r i b o u t r a c k depth i n snow and human s i n k i n g depth i n snow, w in te r 1979-80, Nor th Thompson 22 5 . P r e d i c t e d mean c a r i b o u t r a c k depth per h a b i t a t - c e l l , over w i n t e r 1979-80, North Thompson 23 6. Index of energy c o s t s of c a r i b o u locomot ion i n snow, over w i n t e r 1979-80 30 7. Comparison of est imated energy c o s t s of c a r i b o u locomot ion i n snow between mature h a b i t a t - c e l l s of the L i c h e n Reserve, ESSF- low, and ICH h a b i t a t s , w in te r 1979-80, Nor th Thompson 33 8. Comparison of c a r i b o u locomot ion c o n d i t i o n s i n snow between w i n t e r s 1978-79 and 1979-80, North Thompson 34 9. Net Shrub A v a i l a b i l i t y index i n mature and immature s e r a i types of h a b i t a t t y p e s , w in te r 1979-80, Nor th Thompson 54 10. I nd ices of c o n d i t i o n s f o r c a r i b o u f o r a g i n g i n the shrub and herb v e g e t a t i v e s t r a t a i n ICH Zone h a b i t a t t y p e s , w inter 1979-80, North Thompson 55 11 . R e l a t i v e abundance (%) of B r y o r i a spp. and A l e c t o r i a sp . i n the 0 t o 6 in f o r e s t canopy s t ratum, by h a b i t a t t ype , North Thompson 61 12. A r b o r e a l a l e c t o r i o i d l i c h e n l i t t e r f a l l abundance, f o r mature s e r a i types of h a b i t a t types ' 63 X 13. D i s t r i b u t i o n of a r b o r e a l a l e c t o r i o i d l i c h e n abundance by 0.5 m he ight i n t e r v a l s i n the 0 to 6 m f o r e s t canopy stratum of mature f o r e s t s , by h a b i t a t type 64 14. R e l a t i o n s h i p between instantaneous es t imates of a r b o r e a l a l e c t o r i o i d l i c h e n a v a i l a b l e to c a r i b o u and g r a z i n g base l e v e l above ground l e v e l i n mature s e r a i types of h a b i t a t types 65 15. Instantaneous est imates of a r b o r e a l a l e c t o r i o i d l i c h e n a v a i l a b l e to c a r i b o u i n mature s e r a i types of h a b i t a t t ypes , w i n t e r 1979-80, North Thompson 66 16. Winter a e r i a l survey r o u t e s , i n the North Thompson study a r e a 76 17. Y e a r - l o n g home ranges of r a d i o c o l l a r e d c a r i b o u i n the North Thompson .'. 80 18. Average e l e v a t i o n - c l a s s of a e r i a l survey obse rva t i ons of (A) r a d i o c o l l a r e d and (B) n o n - r a d i o c o l l a r e d c a r i b o u groups, September 1979 to August 1980, Nor th Thompson 81 19. Mean e l e v a t i o n s of r a d i o c o l l a r e d c a r i b o u i n the Nor th Thompson 83 20. R a d i o c o l l a r e d c a r i b o u o b s e r v a t i o n s , and est imates of r e l a t i v e energy cos t of locomot ion i n snow and a r b o r e a l a l e c t o r i o i d l i c h e n a v a i l a b i l i t y by h a b i t a t t y p e s , over w i n t e r 1979-80 90 2 1 . Comparison of t rend between mean e l e v a t i o n s of r a d i o c o l l a r e d c a r i b o u and an index of c a r i b o u locomot ion c o n d i t i o n s i n snow, w i n t e r 1979-80, North Thompson 105 22 . Car ibou h a b i t a t use compared to averages of r e l a t i v e i n c r e a s e s i n the net cos t of locomot ion i n snow f o r h a b i t a t type g roup ings , w i n t e r 1979-80, North Thompson 108 x i Acknowledgements The major f i e l d work f o r t h i s study was conducted w h i l e I was employed by the F i s h and W i l d l i f e Branch, B r i t i s h Columbia M i n i s t r y of Environment. I am g r a t e f u l to R.W. R i t c e y , Reg iona l W i l d l i f e B i o l o g i s t , and G .E . S t r i n g e r , Reg iona l Manager ( r e t i r e d ) , F i s h and W i l d l i f e Branch, Thompson Reg ion , f o r t h e i r support and encouragement d u r i n g t h i s c r i t i c a l f i e l d work phase. S p e c i a l thanks go to Dr. D.M. S h a c k l e t o n , my graduate s u p e r v i s o r , R.W. R i t c e y , and D rs . F . L . B u n n e l l , D.S. Eastman and A . S . Harestad f o r t h e i r adv ice and d i r e c t i o n as members of my a d v i s o r y committee. Thanks a l s o to R.M. E l l i s , D . J . Low and S . K . Stevenson f o r t h e i r a d v i c e and a s s i s t a n c e . P r i n c i p a l f i n a n c i a l and l o g i s t i c support and equipment f o r t h i s study were p rov ided by the F i s h and W i l d l i f e Branch and the Environment and Land Use Committee S e c r e t a r i a t , both of the B .C . M i n i s t r y of Environment, the Research Branch, B .C . M i n i s t r y of F o r e s t s , and the Department of Animal S c i e n c e , U n i v e r s i t y of B r i t i s h Columbia. F i n a n c i a l a s s i s t a n c e was a l s o r e c e i v e d from the Canadian W i l d l i f e S e r v i c e ( W i l d l i f e B i o l o g y S c h o l a r s h i p ) , the Canadian W i l d l i f e Foundat ion ( O r v i l l e E r i c k s o n Memorial S c h o l a r s h i p Fund), the Sc ience C o u n c i l of B r i t i s h Columbia (grant t o F . L . B u n n e l l , F a c u l t y of F o r e s t r y , U . B . C ) , and the U n i v e r s i t y of B r i t i s h Columbia ( U n i v e r s i t y Graduate F e l l o w s h i p Award). T e c h n i c a l a s s i s t a n c e and equipment were a l s o p rov ided by the A i r S tud ies Branch (meteorology) and the Water Management Branch (snow sampl ing ) , both of the B .C . M i n i s t r y of Environment; the Communications and P r o t e c t i o n D i v i s i o n , B .C . M i n i s t r y of Fo res ts ( r a d i o equipment) ; and Ba lco I n d u s t r i e s L t d . , C learwater Timber L t d . , and Weyerhaeuser (Canada) L t d . ( r a d i o equipment f o r l o g g i n g roads , and maps). N e a r l y a l l a e r i a l r a d i o - t r a c k i n g was done from a B .C . M i n i s t r y of T r a n s p o r t a t i o n and Highways a i r c r a f t capably p i l o t e d by Lou I v e r s o n . Accomodation f o r both w in te rs was p rov ided by the M i n i s t r y of x i i F o r e s t s through the c o u r t e s y of Gordon P r e s t , Ranger a t B lue R i v e r . Chuck K a l n i n , of the Range Research S t a t i o n , A g r i c u l t u r e Canada, Kamloops, B . C . , k i n d l y arranged f o r the n u t r i e n t compos i t ion and d i g e s t i b i l i t y ana lyses of a r b o r e a l l i c h e n s . Jack Bone, Bob Lay, D a r y l l Hebert , Doug Janz and Dave Low, a l l of the B .C . F i s h and W i l d l i f e Branch, and A l t o n Harestad g r a t e f u l l y l e n t equipment and /o r p rov ided v a l u a b l e a d v i c e rega rd ing i m m o b i l i z a t i o n and r a d i o c o l l a r i n g of u n g u l a t e s . I a l s o thank Hebert , Janz and Low, a long w i t h Ralph R i t c e y , Geoff Swannel l and S c o t t Wi lson f o r a s s i s t a n c e i n c a p t u r i n g c a r i b o u . A s s i s t a n c e i n f i e l d work and d a t a p r o c e s s i n g was a b l y p r o v i d e d by Kat Palmer and S c o t t W i l s o n . F rase r R u s s e l l , Dennis L l o y d and Bob M i t c h e l l , Research Branch, B .C . M i n i s t r y of F o r e s t s , Kamloops, p rov ided v a l u a b l e a d v i c e i n many aspects of f o r e s t ecology and sampl ing . L ichens were i d e n t i f i e d by Trevor Goward, T e r r y Mc in tosh and Kat Palmer. F i n a l l y , I thank my w i f e E l i s a f o r h e l p i n g b r e a k - t r a i l through some of the most d i f f i c u l t c o n d i t i o n s . 1 I. INTRODUCTION The sub ject of t h i s study i s the w in te r ecology of mountain c a r i b o u (Rang i fe r tarandus c a r i b o u Gmel in ) . I t s purpose i s to determine the movement and h a b i t a t use p a t t e r n s of mountain c a r i b o u i n w i n t e r , and t o i n v e s t i g a t e and i n t e g r a t e the i n f l u e n c e of locomot ion c o n d i t i o n s i n snow and fo rage a v a i l a b i l i t y , e s p e c i a l l y a r b o r e a l l i c h e n s , upon these p a t t e r n s . Mountain c a r i b o u belong t o the woodland subspecies of c a r i b o u ( B a n f i e l d 1961), and i n h a b i t a l p i n e tundra and c o n i f e r o u s f o r e s t s of the mountains of southern B r i t i s h Columbia (Cowan and Guiguet 1965) and ad jacent areas of the northwestern U n i t e d S ta tes (Freddy 1974, Layser 1974). Winter h a b i t a t s used by mountain c a r i b o u a re c h a r a c t e r i z e d by deep snowpacks. C o i n c i d i n g w i t h such snow c o n d i t i o n s , a r b o r e a l l i c h e n s of the genera A l e c t o r i a and B r y o r i a ( a l e c t o r i o i d l i c h e n s ) (Brodo and Hawksworth 1977) a re a major w in te r f o r a g e . These l i c h e n s dominate the d i e t as w i n t e r p rogresses because t e r r e s t r i a l forages d e c l i n e i n a v a i l a b i l i t y due t o deepening snowpacks ( B l o o m f i e l d 1979, Edwards and R i t c e y 1960, Freddy 1974). A r b o r e a l l i c h e n s a re cons idered an e s s e n t i a l resource i n ensur ing o v e r - w i n t e r s u r v i v a l of mountain c a r i b o u , and t h e i r p r o v i s i o n has consequent ly r e c e i v e d c o n s i d e r a b l e a t t e n t i o n i n c a r i b o u w in te r range management. Broad q u a l i t a t i v e aspects of the w i n t e r eco logy and d i s t r i b u t i o n of mountain c a r i b o u have been cons idered f o r some t i m e . The dominant envi ronmental f a c t o r s a f f e c t i n g c a r i b o u w i n t e r movements and h a b i t a t use, such as locomot ion c o n d i t i o n s and forage a v a i l a b i l i t y , both i n f l u e n c e d by snowpack c o n d i t i o n s , were recogn ized by p r e v i o u s resea rchers f o r c a r i b o u i n genera l (Bergerud 1974a, 1974b, Henshaw 1968, L a P e r r i e r e and Lent 1977, M i l l e r 1974, 1976, P r u i t t 1959, 1979, Skogland 1978, Stardom 1975), and mountain c a r i b o u i n p a r t i c u l a r ( B l o o m f i e l d 1979, Edwards and R i t c e y 1959, 1960, Edwards et a l . 1960, Freddy 1974, R i t c e y 1974, 1976). Other authors 2 have a l s o suggested that p r e d a t o r s , p r i m a r i l y wolves (Can is l u p u s ) , may i n f l u e n c e c a r i b o u w in te r d i s t r i b u t i o n s (Bergerud 1974b, M i l l e r 1976). P rev ious mountain c a r i b o u d i s t r i b u t i o n a l i n f o r m a t i o n was based i n most cases on d i s c o n t i n u o u s f i e l d s t u d i e s , u s u a l l y w i t h s m a l l samples, and i n a l l cases on o b s e r v a t i o n s of unmarked a n i m a l s . Furthermore, no comprehensive i n v e s t i g a t i o n s of the snow environment, fo rage a v a i l a b i l i t y , o r t h e i r i n t e r a c t i o n s , have been conducted w i t h respec t to mountain c a r i b o u , w i t h p rev ious i n f o r m a t i o n be ing q u a l i t a t i v e ( B l o o m f i e l d 1979, Edwards and R i t c e y 1959, 1960, Freddy 1974), or q u a n t i t a t i v e but p r e l i m i n a r y and o n l y i n d i r e c t l y a p p l i c a b l e to w i n t e r ( A h t i 1962, Edwards et a l . 1960, Stevenson 1979). Among the genera l e c o l o g i c a l r e l a t i o n s h i p s tha t d i d emerge from these e a r l i e r s t u d i e s , c o n i f e r o u s f o r e s t s , e s p e c i a l l y mature and l a t e s e r a i s tages , i . e . , o l d - g r o w t h f o r e s t s , from v a l l e y s t o t i m b e r l i n e were important w in te r h a b i t a t f o r mountain c a r i b o u . T h i s w in te r h a b i t a t was used f o r two main reasons . F i r s t , f o r e s t canopies i n t e r c e p t s n o w f a l l , r e s u l t i n g i n sha l lower snow accumulat ions on the ground compared t o n o n - f o r e s t s i t e s . F o r e s t s , t h e r e f o r e , appeared to p rov ide g rea te r r e l a t i v e a v a i l a b i l i t i e s of t e r r e s t r i a l f o r a g e s , and t o f a c i l i t a t e movements, rang ing from l o c a l f o r a g i n g movements t o seasonal m i g r a t i o n s ( B l o o m f i e l d 1979, Edwards and R i t c e y 1959, R i t c e y 1974, 1976). Second, f o r e s t s p rov ide c a r i b o u w i t h a r b o r e a l l i c h e n s , a p r i n c i p a l , a v a i l a b l e w in te r f o r a g e . And i m p o r t a n t l y , a r b o r e a l l i c h e n s were cons ide red to be most p r o d u c t i v e i n o l d - g r o w t h f o r e s t s , w h i l e t h e i r abundance was cons ide red n e g l i g i b l e or low i n f o r e s t s younger than 100 t o 150 years ( A h t i 1962, Edwards et a l . 1960, R i t c e y 1974, 1976). T h e r e f o r e , l o g g i n g , which was o c c u r r i n g from v a l l e y to suba lp ine f o r e s t s i n many reg ions of mountain c a r i b o u d i s t r i b u t i o n , as w e l l as w i l d f i r e s and escap ing s l a s h f i r e s , were p e r c e i v e d as p o t e n t i a l t h r e a t s to c r u c i a l w i n t e r h a b i t a t s r e q u i r e d by c a r i b o u ( R i t c e y 1974, 1976). 3 Independent of the moderating e f f e c t of f o r e s t cove r , weather a f f e c t e d snow c o n d i t i o n s and had a marked i n f l u e n c e on locomot ion and a l t i t u d i n a l m i g r a t i o n p a t t e r n s of c a r i b o u i n w in te r ( B l o o m f i e l d 1979, Edwards and R i t c e y 1959). For example, from an e a r l y w in te r d i s t r i b u t i o n a t lower e l e v a t i o n s i n v a l l e y s and lower s l o p e s , c a r i b o u norma l l y migra ted to suba lp ine areas f o r the l a t e w i n t e r . These ascents a p p a r e n t l y were dependent on m i d - w i n t e r thaws and subsequent f r e e z i n g which s e t t l e d and c o n s o l i d a t e d the s o f t , e a r l y w in te r snow accumula t ions , improving o v e r a l l t r a v e l c o n d i t i o n s . Snow cover was a l s o thought to a f f e c t a r b o r e a l l i c h e n a v a i l a b i l i t y and a c c e s s i b i l i t y (Edwards and R i t c e y 1959, Edwards et a l . 1960). Greater q u a n t i t i e s of a r b o r e a l l i c h e n were a v a i l a b l e i n suba lp ine f o r e s t s than i n lower e l e v a t i o n f o r e s t s , and t h i s d i f f e r e n t i a l i n forage resource was b e l i e v e d a c o m p e l l i n g f a c t o r i n the m i d - w i n t e r , ascending m i g r a t i o n . Combined w i t h measures of the abso lu te abundance and the d i s t r i b u t i o n of l i c h e n i n the f o r e s t canopy, Edwards et a l . (1960) cons idered the depth and s u p p o r t a b i l i t y of snowpacks t o be c r i t i c a l f a c t o r s determin ing the q u a l i t y of f o r e s t s as a r b o r e a l l i c h e n w i n t e r range. These l a t t e r two f a c t o r s c o n t r o l the amount of l i c h e n a c t u a l l y a v a i l a b l e by de te rm in ing the v e r t i c a l p o s i t i o n of c a r i b o u w i t h i n the f o r e s t canopy, and a l s o i n f l u e n c e the a c c e s s i b i l i t y of l i c h e n by a f f e c t i n g c a r i b o u m o b i l i t y . P rev ious mountain c a r i b o u r e s e a r c h e r s have g e n e r a l l y concluded tha t mature c o n i f e r o u s f o r e s t s a re e s s e n t i a l w i n t e r h a b i t a t s , a l though t h i s has been quest ioned by Bergerud (1974c, 1978a). Consequent ly , based on the r e c o g n i t i o n t h a t a r b o r e a l l i c h e n s are most l i k e l y the c r i t i c a l w i n t e r fo rage , mountain c a r i b o u w in te r range management has been dominated by p r o p o s a l s to rese rve from harvest s u b s t a n t i a l areas of o l d - g r o w t h , suba lp ine c o n i f e r o u s f o r e s t s as a r b o r e a l l i c h e n range r e s e r v e s , r e s u l t i n g i n i n t e n s e c o n f l i c t w i t h the f o r e s t i n d u s t r y ( R i t c e y 1974, 1976, 1978, 1979) . 4 The genera l o b j e c t i v e of my study was to examine more c l o s e l y the p r e v i o u s l y observed h a b i t a t use p a t t e r n s and proposed e c o l o g i c a l r e l a t i o n s h i p s of mountain c a r i b o u i n w i n t e r , and i m p l i c a t i o n s t o management of f o r e s t r e s o u r c e s . As f o r e s t harvest and other human-induced a l t e r a t i o n s t o h a b i t a t i n c r e a s e w i t h i n mountain c a r i b o u range, more d e t a i l e d i n f o r m a t i o n concern ing c a r i b o u ecology and the r o l e of f o r e s t s as w in te r h a b i t a t s i s necessary to manage both f o r e s t s and c a r i b o u . In w i n t e r , c a r i b o u and o ther no r the rn ungulates u s u a l l y exper ience nega t i ve energy ba lance (Dauphine 1976, McEwan and Whitehead 1970, Mautz 1978), and t h e r e f o r e a c o n s e r v a t i o n of energy i n t h i s season of h i g h e n e r g e t i c s t r e s s would appear t o be a most prudent s t r a t e g y towards the o v e r -w in te r c o n d i t i o n , or even s u r v i v a l , of a n i m a l s . T r a d e - o f f s t o m a i n t a i n the most f avou rab le or optimum net ba lance between the energy expend i tu re f o r f o r a g i n g movements i n snow and the energy r e t u r n from forage i n g e s t e d , has been proposed as a necessary component of energy c o n s e r v a t i o n adapta t ions f o r s u r v i v a l by w h i t e - t a i l e d deer (Odocoi leus v i r g i n i a n u s ) i n w in te r (Moen 1976, 1978). S i m i l a r net energy ba lance frameworks have been proposed by o the rs i n v e s t i g a t i n g w i n t e r eco logy and h a b i t a t u t i l i z a t i o n s t r a t e g i e s of n o r t h e r n ungulates i n reg ions of deep seasonal snowcover (Harestad and B u n n e l l 1979, M a t t f e l d 1974). A foundat ion f o r these net energy r e l a t i o n s h i p s cou ld be found i n o p t i m a l f o r a g i n g theory , which contends that an imals tend t o maximize t h e i r net r a t e of n u t r i e n t i n t a k e , w i t h the c r i t i c a l n u t r i e n t u s u a l l y assumed t o be energy (Krebs 1978, Pyke et a l . 1977). A net energy balance r e l a t i o n s h i p , a long s i m i l a r l i n e s tha t Moen (1976, 1978) and o the rs have cons ide red f o r o ther ungulate s p e c i e s , i s a u s e f u l conceptua l framework by which to eva lua te the movements and h a b i t a t use of mountain c a r i b o u i n w i n t e r . Such a net energy f u n c t i o n f o r m a l l y o r i e n t s and i n t e g r a t e s the v a r i a b l e s recogn ized by e a r l i e r r e s e a r c h e r s as the main 5 environmental factors in mountain caribou winter ecology: forage availability (energy input) and movement conditions (energy cost), both influenced by snow. My specific objectives were to: 1) in representative habitats throughout the winter obtain simultaneous measures or indices of, - energy costs of locomotion in snow, - forage utilization, - forage availability, concentrating on arboreal alectorioid lichens, - caribou habitat u t i l i z a t i o n , using radio telemetry for the f i r s t time i n mountain caribou studies. 2) evaluate the relative importance and interaction of locomotion conditions and arboreal lichen a v a i l a b i l i t y in the winter movements and habitat use of caribou. 3) evaluate the role and importance of the proposed subalpine arboreal lichen reserves in the winter ecology of the caribou population. This would assist management of caribou and contribute towards resolving caribou-forestry conflicts. 6 I I . STUDY AREA AND STUDY PERIOD L o c a t i o n The study a rea was l o c a t e d i n southeastern B r i t i s h Columbia, cent red o o 2 approx imate ly a t 52 N, 119 25' W, and covered approx imate ly 3000 km p r i m a r i l y w i t h i n the dra inage b a s i n of the upper h a l f of the North Thompson R i v e r (F igu re 1 ) . The study a r e a , r e f e r r e d to as the Nor th Thompson, i s predominant ly crown land ad jacent t o the south and east boundar ies of We l ls Gray P r o v i n c i a l Park . I t i s conta ined w i t h i n the North Thompson, R a f t , and Adams P u b l i c Sus ta ined Y i e l d U n i t s . P o r t i o n s of We l ls Gray Park a long i t s south and east boundar ies , ma in ly w i t h i n the M u r t l e Lake Nature Conservancy A rea , were a l s o i n c l u d e d . Physiography The a rea i n c l u d e s p o r t i o n s of two phys iog raph ic r e g i o n s (Ho l land 1976): the I n t e r i o r P l a t e a u t o the south and west , represented by the Shuswap High land p h y s i o g r a p h i c s u b d i v i s i o n ; and the Columbia Mountains and Southern R o c k i e s , rep resented by the two p h y s i o g r a p h i c s u b d i v i s i o n s of the Car iboo Mountains t o the n o r t h and the Monashee Mountains t o the e a s t . The t e r r a i n i s mountainous and d i s s e c t e d by deep ly i n c i s e d d ra inage systems. There i s a genera l t r a n s i t i o n from southwest t o no r theas t ( i . e . , a l ong the North Thompson R i v e r v a l l e y ) of i n c r e a s i n g l y rugged r e l i e f , w i t h a cor respond ing g rad ien t i n c l i m a t e and a s s o c i a t e d v e g e t a t i o n . Southern and western a r e a s , be ing pa r t of the Shuswap H igh lands , a re g e n e r a l l y e l e v a t e d , r o l l i n g f o o t h i l l and h i g h p l a t e a u t e r r a i n w i t h some i s o l a t e d peaks, where maximum e l e v a t i o n s g e n e r a l l y range from 1500 to 2000 m. To the no r th and e a s t , the t e r r a i n grades towards the more rugged Car iboo and Monashee Mountains , where maximum e l e v a t i o n s range from 2500 to over 3000 m. Summits above 2000 to 2500 m are o f t e n p r e c i p i t o u s and i r r e g u l a r , w h i l e lower r i dges and summits a re more subdued and rounded, s i m i l a r to the t e r r a i n of the Shuswap H igh lands . 7 F i g u r e 1. Nor th Thompson study a rea ( d e l i n e a t e d by broken l i n e ) , and l o c a t i o n s of snow course (S) and a r b o r e a l l i c h e n i n v e n t o r y (L) s i t e s . S I , Spahats Creek (winter 1978-79) ; S2, Mount S a i n t Anne (winter 1979-80) ; L I , A v o l a R idge ; L2 , Ground Hog Mountain ; L3 , B lue R i v e r ; L4, Mi ledge Creek. A l s o shown a re the moist and wet c l i m a t i c reg ions (L loyd 1983) (separated by broken l i n e and d o t s ) , and the boundary of We l ls Gray Park ( s o l i d l i n e ) . 8 C l i m a t e P r e c i p i t a t i o n , i n c l u d i n g s n o w f a l l , i n c r e a s e s northward and eastward w i t h i n the study a rea (Goward 1981) . R e f l e c t i n g t h i s broad p r e c i p i t a t i o n p a t t e r n , a moist c l i m a t i c r e g i o n and a wet c l i m a t i c r e g i o n have been i d e n t i f i e d w i t h i n the study a rea (L loyd 1983; F i g u r e 1 ) . However, the study a rea occurs ma in ly w i t h i n the I n t e r i o r Wet B e l t r e g i o n of B r i t i s h Columbia (Rowe 1972), c h a r a c t e r i z e d by m o i s t , warm summers and c o l d w i n t e r s w i t h heavy s n o w f a l l (Clement 1979). Depending upon B i o p h y s i c a l Zone or e l e v a t i o n w i t h i n t h i s r e g i o n , annual p r e c i p i t a t i o n v a r i e s from 560 mm t o 2800 mm, and the percentage as snow ranges from 53% to 74% (Clement 1979). B i o g e o c l i m a t i c Zones Four B i o g e o c l i m a t i c Zones ( K r a j i n a 1965) occur i n the study a rea (L loyd 1983). In order of i n c r e a s i n g e l e v a t i o n , they a r e : 1) The I n t e r i o r Douglas F i r (IDF) Zone comprises a very minor p r o p o r t i o n , r e s t r i c t e d t o the r e l a t i v e l y d r y southwestern s e c t i o n , where i t occurs i n the lower s lopes and v a l l e y bottoms. Car ibou d i d not use t h i s Zone, and i t i s not cons ide red i n t h i s s tudy . 2) The I n t e r i o r Cedar - Hemlock (ICH) Zone occup ies the lower e l e v a t i o n s of most of the study a r e a . The c l i m a x v e g e t a t i o n i s a dense, cont inuous o v e r s t o r y of western hemlock (Tsuga h e t e r o p h y l l a ) and western red cedar (Thuja p l i c a t a ) , w i t h v a r i a b l e but o f t e n sparse shrub, v a r i a b l e herb and w e l l developed moss s t r a t a . A s s o c i a t e d s e r a i t r e e spec ies i n c l u d e lodgepo le p ine (P inus c o n t o r t a ) , whi te p i n e (P . m o n t i c o l a ) , Douglas f i r (Pseudotsuga  m e n z i e s i i ) and aspen (Populus t remu lo ides ) (L loyd 1983). 3) The Engelmann Spruce -Suba lp ine F i r (ESSF) Zone occup ies the f o r e s t e d upper e l e v a t i o n s (> 1300 t o 1400 m) throughout the study a r e a . The c l imax v e g e t a t i o n i s a v a r i a b l y cont inuous t o open o v e r s t o r y of Engelmann spruce ( P i c e a engelmanni i ) and suba lp ine f i r (Abies l a s i o c a r p a ) , w i t h o f t e n dense 9 and w e l l developed shrub, herb and moss s t r a t a . Lodgepole p i n e i s an a s s o c i a t e d s e r a i t r e e s p e c i e s i n t h i s Zone. 4) The A l p i n e Tundra (AT) Zone occurs above the ESSF Zone (> 1900 t o 2000 m). Cl imax v e g e t a t i o n v a r i e s from cont inuous to sparse low shrubs, herbs and gramino ids , w i t h the o c c a s i o n a l occur rence a t the lowest e l e v a t i o n s of krummholz forms of Engelmann spruce , suba lp ine f i r , whi tebark p i n e (P inus  a l b i c a u l i s ) and lodgepo le p i n e . Land Use The pr imary land use w i t h i n the study a rea has been, and cont inues t o be, f o r e s t h a r v e s t i n g , which i s p r a c t i s e d i n a l l f o r e s t e d B i o g e o c l i m a t i c Zones (IDF, ICH and ESSF) . F o r e s t harvest and w i l d f i r e have been the major causes of e a r l y s e r a i stages ( i . e . , a r b i t r a r i l y f o r e s t s < 140 years o l d ) , a l though mature f o r e s t s have been c l e a r e d f o r se t t lements and some a g r i c u l t u r e i n lower s lopes and v a l l e y s , e s p e c i a l l y between C learwater and B lue R i v e r . E a r l y s e r a i stages a re more or l e s s p r e v a l e n t throughout the study a r e a , but more o f t e n ad jacent to We l l s Gray P r o v i n c i a l Park , i n the moist c l i m a t i c r e g i o n , and a t lower e l e v a t i o n s (IDF and ICH Zones) . Hab i ta t C l a s s i f i c a t i o n The h a b i t a t c l a s s i f i c a t i o n scheme was developed from a t w o - l e v e l h i e r a r c h y . At the pr imary l e v e l , the study a rea was s t r a t i f i e d i n t o s i x h a b i t a t types d e f i n e d by B i o g e o c l i m a t i c Zone, e l e v a t i o n , and a proposed a r b o r e a l l i c h e n rese rve (L ichen Reserve) of o l d growth suba lp ine f o r e s t exempted from l o g g i n g f o r c a r i b o u w in te r range ( R i t c e y 1978, 1979) . The L ichen Reserve i s e s s e n t i a l l y e q u i v a l e n t to A h t i ' s (1962) Upper Suba lp ine and H a m e t - A h t i 1 s (1965) Orohemia rc t ic Zone (mountain f o r e s t - a l p i n e tundra ecotone ) , and l i e s above 1680 m (5500 f t ) , rep resented by the upper s e c t i o n of the ESSF-Forested Subzone and by the e n t i r e ESSF -Park land Subzone (Table 1 ) . At the secondary l e v e l of c l a s s i f i c a t i o n , most h a b i t a t types were Table 1. Habitat classification design used to stratify the biophysical environment of the North Thompson study area. BIOGEOCLIMATIC ZONE BIOGEOCLIMATIC SUBZONE TIMBER HABITAT ELEVATION MERCHANT- ASPECT TYPE RANGE (m) ABILITY CLASSES* No. Of SERAL HABITAT TYPE CELLS FOREST COVER CHARACTERISTICS Alpine Tundra (AT) AT ALPINE > 1950 N i l MAT Vegetated and non-vegetated Alpine (A). ESSF PARKLAND PARKLAND 1800-1960 Poor N & S MAT - N i l Alpine Forest (A FOR), of Engelmann spruce (S) and subalpine f i r (B). Engelmann Spruce - Subalpine F i r (ESSF) ESSF FORESTED ESSF-high 1660-1860 Fair N & S MAT & -Poor IMMAT ESSF-low 1350-1679 Good N S> S MAT & 4 -Fair IMMAT S and/or B as dominant or codominant i n mixed or pure forest typings. Also includes cedar (C) as minor species, or lodgepole pine (PI) as dominant or minor species. Interior Cedar Hemlock (ICH) ICH ICH-high 1000-1349 Good N & S MAT & IMMAT - C and/or hemlock (H) as dominants or codominants i n mixed or pure forest typings. - S could be a dominant or minor sp. ICH-low 650-999 Good N & S MAT (, IMMAT - Also includes PI, Douglas f i r , aspen, or white pine. N = North » 315°-0° and 0°-135°; S = South = 135°-315°. TOTAL=19 MAT = Mature; IMMAT = Immature (see text). 11 f u r t h e r subd iv ided i n t o h a b i t a t - c e l l s , by s e r a i type and a s p e c t . H a b i t a t Types: The s i x h a b i t a t types i d e n t i f i e d a re presented i n Tab le 1. A long an i n c r e a s i n g e l e v a t i o n a l g rad ien t i n the ESSF Zone, the f o r e s t changes from a r e l a t i v e l y c l o s e d canop ied , cont inuous f o r e s t , t o an open f o r e s t - s u b a l p i n e meadow mosaic . The upper s e c t i o n of the ESSF Zone i n B r i t i s h Columbia has been c l a s s i f i e d as a Park land Subzone ( K r a j i n a 1969). A l though ecosystem c l a s s i f i c a t i o n and mapping of the North Thompson were not a v a i l a b l e , an attempt was made t o i d e n t i f y an approx imat ion of the ESSF -Park land Subzone f o l l o w i n g Brooke et a l . (1970). Th is was because, a l though the proposed L ichen Reserve between 1680 m and the A l p i n e c o u l d f u n c t i o n a l l y be viewed as one h a b i t a t u n i t ( the upper s u b a l p i n e , A h t i 1962), there i s s t i l l a n o t i c e a b l e g r a d i e n t i n f o r e s t physiognomy and m e r c h a n t a b i l i t y w i t h i n t h i s upper ESSF r e g i o n . I thought tha t these d i f f e r e n t c o n d i t i o n s may c o r r e l a t e to important v a r i a t i o n s i n snow c o n d i t i o n and a r b o r e a l l i c h e n a v a i l a b i l i t y . T h e r e f o r e , the L ichen Reserve was subd iv ided i n t o two h a b i t a t t y p e s , cor respond ing t o the two Subzones of the ESSF Zone rep resen ted : ESSF-h igh (upper s e c t i o n of ESSF-Forested Subzone) and Park land (ESSF-Park land Subzone) (Table 1 ) . H a b i t a t s were c l a s s i f i e d us ing f o r e s t cover i n v e n t o r y maps (B .C . M i n i s t r y of F o r e s t s 1967), when a v a i l a b l e , and 1:50,000 s c a l e topograph ic maps and b l a c k and whi te a e r i a l photographs. The A l p i n e Fo res t (AF) type on f o r e s t cover maps i s not n e c e s s a r i l y d i r e c t l y equ iva len t t o the ESSF -Park land Subzone (D.A. L l o y d p e r s . comm. 1978), but t h i s cover type o c c u r r i n g above 1800 m was a reasonable approx imat ion (Table 1 ) . H a b i t a t - c e l l s : W i t h i n most h a b i t a t t ypes , the f a c t o r s of s e r a i type (immature; mature) and aspect ( n o r t h ; south) were a l s o i n c o r p o r a t e d i n t o a f i n a l c l a s s i f i c a t i o n 12 u n i t - the h a b i t a t - c e l l , of which 19 were recogn ized (Table 1 ) . The two s e r a i types chosen a p r i o r i were: 1) an immature c l a s s , i n c l u d i n g n o n - f o r e s t and non -p roduct i ve f o r e s t c l a s s i f i c a t i o n s (except the A l p i n e and A l p i n e Fores t cover t y p e s , Table 1 ) , d i s t u r b e d stands ( logged or burned s i t e s ) , and f o r e s t s l e s s than 140 years o l d ; 2) a mature c l a s s c o n s i s t i n g of f o r e s t stands g r e a t e r than 140 years o l d (B .C . M i n i s t r y of Fo res ts 1967). These mature or " o l d - g r o w t h " f o r e s t s were separated from a l l other f o r e s t cover map c l a s s i f i c a t i o n s because of the heavy w in te r use of the former areas by mountain c a r i b o u p r e v i o u s l y observed w i t h i n the study a rea (Edwards 1954, Edwards and R i t c e y 1959, R i t c e y 1974, 1976), and i n o ther areas of t h e i r range i n B r i t i s h Columbia ( B l o o m f i e l d 1979) and Idaho (Evans 1964, Freddy 1974) . In f o l l o w i n g c h a p t e r s , the term " p a i r e d s i t e s " r e f e r s t o two h a b i t a t -c e l l s e q u i v a l e n t on a l l h a b i t a t c l a s s i f i c a t i o n f a c t o r s but one. Assessments of snow c o n d i t i o n s and a r b o r e a l l i c h e n a v a i l a b i l i t i e s were conducted a t , and c a r i b o u r a d i o l o c a t i o n s and o ther observa t ions were recorded at l e a s t t o , the l e v e l of the h a b i t a t - c e l l . Study p e r i o d F i e l d work commenced i n June 1978 and cont inued through to August 1980, but concent ra ted on the w in te r p e r i o d s . The i n t e n s i v e study p e r i o d was the w in te r of 1979-80 (November 1979 t o A p r i l 1980), when four r a d i o c o l l a r e d c a r i b o u and t h e i r groups were a v a i l a b l e f o r s tudy . Formal h a b i t a t assessments, p r i m a r i l y the a r b o r e a l l i c h e n i n v e n t o r y , were conducted ma in ly between June t o August 1978 and May to August 1980. 13 I I I . SNOW CONDITIONS AND CARIBOU LOCOMOTION INTRODUCTION The o b j e c t i v e s of t h i s s e c t i o n a re to determine the s p a t i a l and temporal p a t t e r n s of snow depth and c o n d i t i o n , and t o develop an index of the energy c o s t s of c a r i b o u locomot ion i n snow, d u r i n g the i n t e n s i v e s t u d y - w i n t e r of 1979-80. Both snowpack depths and locomot ion c o n d i t i o n s i n snow (ease of c a r i b o u movement i n snow, based on the combined e f f e c t of snowpack depth and l o a d - b e a r i n g support , i . e . , c a r i b o u t r a c k depths or r e l a t e d energy c o s t s of locomot ion i n snow; M a t t f e l d 1974, Parker e t a l . 1984) a re examined i n r e l a t i o n t o the h a b i t a t c l a s s i f i c a t i o n f a c t o r s of e l e v a t i o n - c l a s s , s e r a i type and a s p e c t . Some f a c t o r s a f f e c t i n g locomot ion c o n d i t i o n s i n snow and how they a c t e d a re a l s o i n v e s t i g a t e d and d i s c u s s e d . F i n a l l y , the r e p r e s e n t a t i v e n e s s of genera l weather c o n d i t i o n s , snow cover c h a r a c t e r i s t i c s , and locomot ion c o n d i t i o n s i n snow over t h i s w in te r a re e v a l u a t e d . T o t a l snowpack depths were measured f o r e s t i m a t i n g the a v a i l a b i l i t y of fo rages i n w i n t e r (Chapter I V ) . Locomotion c o n d i t i o n s i n snow were est imated t o e v a l u a t e t h e i r i n f l u e n c e on movements and h a b i t a t use of c a r i b o u i n w in te r (Chapter V I ) . METHODS C l i m a t i c Data Design and sampl ing of snow courses The d e s i g n and sampling of snow courses were adapted from the procedures of Environment Canada (1973) and the Water I n v e s t i g a t i o n Branch (1977). Where p o s s i b l e , snow courses were l o c a t e d on r e l a t i v e l y l e v e l s i t e s , w i t h most c o n s i s t i n g of a l i n e a r t r a n s e c t of 10 sample p o i n t s 10 m a p a r t . Sampling p o i n t s were p o s i t i o n e d t o a v o i d rock or w i n d f a l l s , then c l e a r e d of d e b r i s , l e v e l l e d , and permanently marked. In 1979-80, two sample p o i n t s per 14 snow course , a t l e a s t 30 m apar t and p o s i t i o n e d i n r e l a t i v e l y l a r g e and l e v e l s i t e s , were des ignated as snowpack p r o f i l e i n v e s t i g a t i o n s t a t i o n s . Dur ing the w in te r of 1978-79, e i g h t snow courses were e s t a b l i s h e d a long the Spahats Creek w i n t e r - l o g g i n g road , running between R a f t and Trophy Mountains i n the southwest corner of the study area (F igu re 1 ) . The courses were i n p a i r e d mature f o r e s t and n o n - f o r e s t s i t e s on s o u t h e r l y exposures , i n ICH- low, ICH-h igh , ESSF- low, and ESSF-h igh h a b i t a t t y p e s . In the w in te r of 1979-80, 19 snow c o u r s e s , r e p r e s e n t i n g the 19 h a b i t a t - c e l l s (Table 1) and r e p l a c i n g the p rev ious w i n t e r ' s snow c o u r s e s , were e s t a b l i s h e d i n the c e n t r a l p o r t i o n of the study a rea a l o n g , or near , the Mount S a i n t Anne microwave tower r i d g e (F igu re 1 ) . N o n - f o r e s t e d (open) s i t e s were chosen to represent the immature h a b i t a t -c e l l s , because s u i t a b l e second-growth f o r e s t e d s i t e s were not r e a d i l y a v a i l a b l e i n the survey l o c a t i o n s of e i t h e r w i n t e r . The open s i t e s were u s u a l l y r e c e n t l y logged a r e a s , except i n ESSF-h igh where e i t h e r l a r g e road s ide c l e a r i n g s or l a r g e n a t u r a l meadows were used . The snow courses were l o c a t e d as c l o s e as p o s s i b l e to the midd le of the e l e v a t i o n a l range d e f i n i n g each h a b i t a t type (Table 1 ) . South aspect snow courses were between 160° and 230°, w h i l e no r th aspect courses were between 325° to 0° and 0° to 110°. S t a r t i n g i n e a r l y November, the snow courses were sampled a t approx imate ly two week i n t e r v a l s , u n t i l the end of March i n 1979-80 and e a r l y A p r i l i n 1978-79. Dur ing both w i n t e r s , t o t a l snowpack depth and my s i n k i n g depth (see l a t e r ) were measured once a t each snow course sampl ing p o i n t per sampling s e s s i o n . A p r i l and May 1980 snowpack depths were es t imated from data p rov ided by the Inventory and Eng inee r ing Branch (1980) or from observa t ions of Steve Quinn (pers . comm. 1980) . To eva lua te the snowpack c o n d i t i o n s i n 1979-80 f o r t r a v e l l i n g and c r a t e r i n g by c a r i b o u , snow hardness and c r u s t c h a r a c t e r i s t i c s were measured 15 a t the two snow p r o f i l e s t a t i o n s of each snow c o u r s e . A s p r i n g penetrometer 2 (Eastman 1978:339) was used to measure the v e r t i c a l hardness (g/cm ; the 2 i n s t r u m e n t ' s maximum read ing was 1000 g/cm ) of s p e c i f i c snow l a y e r s . Data c o l l e c t e d i n c l u d e d the hardness of the hardest d i s c e r n a b l e l a y e r i n the top 10 cm s e c t i o n of the snowpack; as w e l l as the number, depth from the su r face (cm), t h i c k n e s s (cm), and hardness of d i s c e r n a b l e c r u s t s or i c e l a y e r s , to a depth equal t o the average chest he ight of an a d u l t c a r i b o u (70 cm; see l a t e r ) . At each snow p r o f i l e s t a t i o n , f i v e hardness measurements per snow l a y e r ( s u r f a c e 10 cm, and subsurface c r u s t s ) were made. I n d i c e s of the i n t e n s i t y of c r u s t i n g i n c l u d e d the combined (summated) t h i c k n e s s e s of a l l i c e and c r u s t l a y e r s ( a f t e r M i l l e r et a l . 1982), and the t o t a l number of these l a y e r s , w i t h i n the upper 70 cm p r o f i l e of snowpacks. Comparison of snow and genera l weather c o n d i t i o n s between w i n t e r s Snowpack depths and d e n s i t i e s i n the two w i n t e r s of study i n r e l a t i o n t o . l ong - te rm averages were compared w i t h da ta from f i v e permanent snow courses sampled by the Inventory and Eng ineer ing Branch (1980, and unpub l i shed ) . The snow courses were l o c a t e d i n the c e n t r a l and no r the rn s e c t i o n s of the study a r e a , near my 1979-80 snow c o u r s e s , a t B lue R i v e r Town (670 m), Cook Forks (1390 m), Mount Cook (1580 m), Mount S a i n t Anne (1770 m) and Mount A l b r e d a (1920 m), and represented snow c o n d i t i o n s from v a l l e y bottom to s u b a l p i n e . They were sampled on the f i r s t of each month, u s u a l l y from 1 February t o 1 May, but some as e a r l y as 1 December. The l ong - te rm monthly averages of snowpack depth and d e n s i t y were computed f o r each of the permanent snow courses from data c o l l e c t e d between 1967-68 to 1979-80. W i t h i n each of the two study w i n t e r s , the monthly percentage d e v i a t i o n s i n t o t a l snowpack depth and d e n s i t y from t h e i r l o n g -term averages were determined f o r each snow course , and averaged across snow c o u r s e s . These average monthly d e v i a t i o n s p rov ided an index f o r comparing 16 snowpack c o n d i t i o n s and predominant weather c o n d i t i o n s d u r i n g the s tudy . A i r temperatures between the study w i n t e r s were compared by monthly averages i n mean d a i l y temperatures ob ta ined from the 1770 m, Mount S a i n t Anne snow course ( Inventory and Eng ineer ing Branch, unpub l ished d a t a ) . Winter i n t e r v a l s The i n t e n s i v e - s t u d y w in te r of 1979-80 was a r b i t r a r i l y d i v i d e d i n t o 11 i n t e r v a l s cent red about the dates of snow course measurements (see Appendix A ) . These i n t e r v a l s v a r i e d from 10 t o 16 days i n l e n g t h , except the f i r s t i n t e r v a l which was 23 days i n l eng th because of b a c k - d a t i n g t o the f i r s t recorded snow accumu la t ion . The f i r s t i n t e r v a l began on 23 October , when the f i r s t p e r s i s t i n g snow accumulat ions were recorded by the Mount S a i n t Anne snowpi l low (Appendix A ) . The l a s t i n t e r v a l te rminated on 2 A p r i l , f o l l o w i n g the l a s t snow course i n v e n t o r y . Snow measurements were assumed t o represent snowpack c o n d i t i o n s over the i n t e r v a l s . Car ibou Locomotion C o n d i t i o n s i n Snow  Chest h e i g h t s Car ibou chest h e i g h t , r e q u i r e d t o compute the r e l a t i v e energy c o s t s of locomot ion i n snow (Parker et a l . 1984), i s r a r e l y r e p o r t e d , but shoulder he ight i s . The re fo re , an i n d i r e c t es t imate of chest he ight was c a l c u l a t e d . Photographs of s tand ing mountain c a r i b o u i n summer pe lage were used t o d e r i v e an average a d u l t r a t i o of chest h e i g h t : s h o u l d e r he igh t of 0.56 (n=6, range of 0.52 t o 0 .58 ) , and s i n g l e r a t i o s of 0.56 and 0.57 f o r two c a l v e s . These va lues were s i m i l a r to r a t i o s of 0.51 f o r a d u l t and 0.52 f o r c a l f , domest icated r e i n d e e r c a l c u l a t e d from Thing (1977:15, and F i g u r e 12 ) . Average shoulder h e i g h t s f o r a d u l t mountain c a r i b o u c a l c u l a t e d from v a r i o u s sources were 123.0 cm f o r males (Cowan and Guiguet 1965, Demarchi 1971 c i t e d by Layser 1974, Freddy 1974, and present study) and 119.4 cm f o r a d u l t females (Cowan and Guiguet 1965), which r e s u l t e d i n a mean of 121.2 cm 17 f o r sexes combined. App ly ing the a d u l t chest he igh t to shoulder he ight r a t i o , y i e l d e d an est imate of 67.9 cm f o r average a d u l t chest h e i g h t , which f o r convenience was rounded to 70.0 cm. P r e d i c t i n g c a r i b o u t r a c k depths To p r e d i c t c a r i b o u t r a c k depths i n snow i n areas where c a r i b o u were absent , the r e l a t i o n s h i p between c a r i b o u t r a c k depth and my s i n k i n g depth was c a l c u l a t e d by r e g r e s s i o n methods. At p e r i o d i c i n t e r v a l s a long f r e s h (same day) t r a i l s of i n d i v i d u a l c a r i b o u , c l u s t e r samples o f f i v e c a r i b o u t r a c k depths and f i v e of my s i n k i n g depths without snowshoes (weight t r a n s f e r r e d t o one f o o t ) i n a d j a c e n t , und is tu rbed snow were c o l l e c t e d . Energy c o s t s of locomotion i n snow R e l a t i v e energy c o s t s of c a r i b o u wa lk ing i n snow, expressed as a percentage above the cost of wa lk ing without snow, were est imated by the equat ion developed by Parker et a l . (1984) f o r e l k (Cervus elaphus n e l s o n i ) and mule deer (0 . hemionus): R e l a t i v e Energy Cost = 0 . 7 1 (RSD) e ° - 0 1 9 1 < R S D ) f where RSD = r e l a t i v e s i n k i n g depth , and i s c a r i b o u s i n k i n g depth expressed as a percentage of chest h e i g h t . Th is r e l a t i o n s h i p was developed f o r snow cover w i t h a d e n s i t y of 0.2 3 g/cm . Leav ing t r a c k depth c o n s t a n t , the r e l a t i v e energy expend i tu re of wa lk ing i n snow i n c r e a s e s as snow d e n s i t y i n c r e a s e s (Parker et a l . 1984). But because snow d e n s i t i e s were not measured i n the present study , i t was 3 assumed that d e n s i t i e s were s i m i l a r (0 .2 g/cm ) f o r a l l c a r i b o u t r a c k depths . A l though t h i s was probab ly i n v a l i d , p a r t i c u l a r l y f o r some of the h e a v i l y c r u s t e d or wind compacted snowpacks observed, i t does p r o v i d e an a c c e p t a b l e s t a r t i n g p o i n t f o r the s t u d y ' s o b j e c t i v e s . 18 RESULTS T o t a l Snow Depths In the w in te r of 1979-80, the f i r s t p e r s i s t i n g snow accumulat ions i n the suba lp ine h a b i t a t s occur red as u s u a l i n l a t e October (Appendix A ) . The major s e r i e s of t y p i c a l l y heavy, e a r l y w i n t e r snows f e l l d u r i n g the second and t h i r d weeks of December (Appendix A, F i g u r e 2 ) . A l though these s n o w f a l l s commenced somewhat l a t e r than normal , they were f requent , and thus snow accumulated r a p i d l y t o normal l e v e l s by 1 January (F igu re 3 ) . The snowpacks cont inued to deepen but not as r a p i d l y , because of s e t t l e m e n t , r a i n or snowmelt. The snow accumulat ion p a t t e r n between 1 January and 1 A p r i l g e n e r a l l y c o i n c i d e d w i t h the l o n g - t e r m average (F igu re 3 ) . By e a r l y or mid A p r i l , a l l snowpacks began to d e c l i n e , w i t h the snowmelt p a t t e r n i n v e r s e l y c o r r e l a t e d w i t h e l e v a t i o n ( F i g u r e 2 ) . The s p r i n g snow melt was e a r l i e r than normal (F igu re 3 ) . T o t a l snowpack d e n s i t i e s over the 1979-80 w i n t e r were u s u a l l y g reate r than the long - te rm averages ( F i g u r e 3 ) , r e f l e c t i n g f requent moist to wet s n o w f a l l s , p e r i o d i c m i l d weather, and o c c a s i o n a l r a i n . For each w in te r i n t e r v a l , p a t t e r n s i n t o t a l snowpack depths i n r e l a t i o n to each of the h a b i t a t c l a s s i f i c a t i o n f a c t o r s ( e l e v a t i o n c l a s s , s e r a i type and aspect ) were eva luated by one-way ANOVA's and s i n g l e degree of freedom l i n e a r comparisons (Sokal and Roh l f 1981:520-529) . Snowpack depth i n c r e a s e d s i g n i f i c a n t l y w i t h e l e v a t i o n ( a l l p - v a l u e s < 0 .05 ) , except i n the A l p i n e (F igu re 2b) where they were o f t e n sha l lower than the nearby, but lower e l e v a t i o n Park land and ESSF-h igh s i t e s . T h i s d i f f e r e n c e was l i k e l y due to wind r e d i s t r i b u t i o n of snow from the exposed A l p i n e s i t e s . Snowpack depths i n open s i t e s ( r ep resen t i ng immature h a b i t a t - c e l l s ) c o n s i s t e n t l y exceeded those i n p a i r e d f o r e s t s i t e s ( r e p r e s e n t i n g mature h a b i t a t - c e l l s ) ( a l l p -va lues < 0 .05 ) . However, the e f f e c t of aspect was g e n e r a l l y i n c o n s i s t e n t , 19 1979 1980 F i g u r e 2 . Snowpack depths i n d i f f e r e n t h a b i t a t s , s t r a t i f i e d t o (a) mature and (b) immature ( represented by n o n - f o r e s t s i t e s ; see t e x t ) s e r a i t y p e s , w in te r 1979-80, Nor th Thompson. Depths a re grand means (ranges shown o n l y i f > + 10 cm) of mean depths f o r p a i r e d nor th and south a s p e c t s . • , A l p i n e ; • , P a r k l a n d ; E S S F - h i g h ; O, ESSF- low; A, ICH-h igh ; X, ICH - low. 20 - 20 tu Q z UJ u <r ui a. -20-•40 DEC JAN FEB MAR APR MAY I 1 I 1 1 1 S N O W P A C K D E P T H (1) 121 / Y »T 111 (51 15) 151 1(100% I z o > 111 Q Z ui <_> <r UI Q. S N O W P A C K D E N S I T Y (5) D L T .26 .27 .31 .32 .36 . U u cr < ct ui a. z Ul A I R T E M P E R A T U R E 2 0 1 1191 1171 (171 (121 (161 (221 1251 -20 J t it j* I I I I I I I NOV DEC JAN FEB MAR APR MAY F i g u r e 3 . Average (+ range) percentage d e v i a t i o n from long - te rm monthly-averages i n snowpack depths and d e n s i t i e s over w i n t e r s 1978-79 (open c i r c l e s and broken l i n e ) and 1979-80 ( s o l i d c i r c l e s and l i n e ) , f o r up to 5 permanent snow courses (va lues i n parentheses = number of snow courses) rang ing from 670 to 1920 m e l e v a t i o n i n the North Thompson. Monthly averages (+ range) of average d a i l y a i r temperatures are a l s o compared between w in te rs 1978-79 (open c i r c l e s ) and 1979-80 ( s o l i d c i r c l e s ) f o r the permanent Mount S a i n t Anne snow course (1770 m) i n the study a rea - averages are computed on l y f o r dates of mutual d a t a between the two w in te rs (values i n parentheses = number of d a y s ) . D l t , l ong - te rm average i n t o t a l snowpack d e n s i t i e s (g/cm ) . A l l d a t a from Inventory and Eng ineer ing Branch (1980, and unpub l i shed ) . 21 and was not s i g n i f i c a n t i n e i g h t of the 11 w in te r i n t e r v a l s ( i n the remain ing th ree i n t e r v a l s , snowpack depths were g r e a t e r on p a i r e d no r th a s p e c t s ) . Car ibou Locomotion C o n d i t i o n s i n Snow  P r e d i c t i n g c a r i b o u t r a c k depths The s imple l i n e a r r e g r e s s i o n computed w i t h c l u s t e r means of f r e s h c a r i b o u t r a c k depth aga ins t my s i n k i n g depth was h i g h l y s i g n i f i c a n t and p r e c i s e (F igu re 4 ) , p e r m i t t i n g the use of my s i n k i n g depth i n snow as a v a l i d p r e d i c t o r of c a r i b o u t r a c k depth i n snow. In f i e l d - c l o t h i n g , my weight was 2 91 k g , and my f o o t - l o a d i n g w i t h weight t r a n s f e r r e d t o one foo t was 303 g/cm . Car ibou t r a c k depths i n r e l a t i o n t o h a b i t a t c l a s s i f i c a t i o n f a c t o r s For each snow course , i n the w i n t e r of 1979-80, my mean s i n k i n g depth was t ransformed by the r e g r e s s i o n equat ion (F igu re 4) t o a p r e d i c t e d mean c a r i b o u t r a c k depth (F igure 5 ) . The v a r i a n c e s i n my mean s i n k i n g depths c o u l d not be s t a b i l i z e d , t h e r e f o r e nonparametr ic s t a t i s t i c a l procedures were used to compare p r e d i c t e d mean c a r i b o u t r a c k depths (which were o r d e r -p r e s e r v i n g t rans fo rmat ions of my mean s i n k i n g depths) among h a b i t a t - c e l l s i n r e l a t i o n to a s p e c t , s e r a i type and e l e v a t i o n - c l a s s . Us ing Wi lcoxon Signed Rank t e s t s (Conover 1980:280-288) f o r a l l but w in te r i n t e r v a l 1, which had a low number of matched p a i r s (F igure 5 ) , the mean t r a c k depths d i d not d i f f e r between p a i r e d n o r t h and south aspects ( a l l p - v a l u e s > 0 . 0 5 ) ; but mean t r a c k depths were g e n e r a l l y g rea te r i n open than i n p a i r e d f o r e s t s i t e s (p < 0 .05 , i n 5 of the 10 w in te r i n t e r v a l s c o n s i d e r e d ) . A l though not c o n s i s t e n t over the e leven w in te r i n t e r v a l s , mean t r a c k depth were u s u a l l y p o s i t i v e l y c o r r e l a t e d w i t h e l e v a t i o n (Table 2 ) . Repeat ing the c o r r e l a t i o n a n a l y s i s by r e p l a c i n g e l e v a t i o n w i t h i t s i n t e r c o r r e l a t e of t o t a l snowpack depth r e s u l t e d i n e s s e n t i a l l y the same r e l a t i o n s h i p s . In summary, none of the f a c t o r s of a s p e c t , s e r a i type and e l e v a t i o n , or t o t a l snowpack depth , were s u f f i c i e n t l y c o n s i s t e n t i n 22 60n OH 1 1 1 1 1 — — i 1 O 20 40 60 MEAN HUMAN TRACK DEPTH (cm) F i g u r e 4. R e l a t i o n s h i p between c l u s t e r means of f r e s h (same day) c a r i b o u t r a c k depth i n snow and human s i n k i n g depth i n snow ( a l l c l u s t e r means based on n=5), w in te r 1979-80, North Thompson. CT = 1.6 + 0.77 HT; n=46, r =0.96, Sy.x=2.70; where CT = c a r i b o u t r a c k depth (cm) and HT = human t r a c k depth (cm). 23 60n 40-20-1 . I 23 OCT - U NOV) 1 I I 1 I I H I 1 I I 1 I I I 1 1 5 - 2 7 NOV) i •I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 6 0 1 3. (28 NOV - 12 DEC ] LO -20-SINI ISINI JSINI ISINI ISTNT IHJ II-HI H NTH! I P I A. (13 - 27 DEC) I I I S|N S Nl s N I-H IE-L| E--H ISINI HABITAT TYPE F igure 5. P r e d i c t e d mean c a r i b o u t r a c k depth per h a b i t a t - c e l l f o r w i n t e r i n t e r v a l s , w i n t e r 1979-80, North Thompson. Mean c a r i b o u t r a c k depths were p r e d i c t e d from mean human s i n k i n g depths us ing the r e g r e s s i o n e q u a t i o n shown on F igure 4 . E l e v a t i o n s of h a b i t a t types i n c r e a s e from l e f t t o r i g h t . I -L = ICH-low; I -H = I C H - h i g h ; E-L = ESSF- low; E-H = E S S F - h i g h ; P = P a r k l a n d ; A = A l p i n e ; S = South ; N = N o r t h ; • , Mature s e r a i t y p e ; O, Immature s e r a i type ( represented by n o n - f o r e s t s i t e s ) ; • , In formal Park land snow c o u r s e ; means f o r p a i r e d mature and immature h a b i t a t - c e l l s a re j o i n e d by v e r t i c a l l i n e s . 24 6 0 1 5. ( 28 DEC - 12 JAN) 40-20-601 7. 129 JAN - 13 FEB) 40-20-I-L SlNl S|N I-HI E-L 6 . (13 - 28 JAN ) 'I H I ISINI IS INj 1 I SlNl [SIN lE^Hl I P I I A 11 - ul l)>H I I ' I I 1 I I 1 I I 1 I I 8. (14 - 27 FEB) J Ii S|N S|N S|N E-L E-H P A HABITAT TYPE Figure 5. Continued. 25 CL LU Q < cr 3 O CD cr < < LU Q LU l— o Q LU cr CL 6 0 1 9. 128 FEB-9 MAR) 40H 20 H Ii T 2 j l 1 1 1 1 1 1 1 1 < 11 > 11 I 60"I 11. 122 MAR - 2 APR) 40-1 20-1 ll I .. mi LSlbLl LSiMJ |5iMJ I-L I-H E-L E-H |P 10. (10 - 21 MAR) II V 11*.: I I 1 I I 1 I I 1 I I 1 I I I HABITAT TYPE Figure 5. Continued. 26 Table 2. Spearman's rank c o r r e l a t i o n c o e f f i c i e n t s ( r s ) between e l e v a t i o n -c l a s s and mean p r e d i c t e d ca r ibou t r a c k depth of h a b i t a t - c e l l s (from F i g u r e 5 ) , w in te r 1979-80, North Thompson. ALL MATURE IMMATURE6 WINTER HABJ tTAT-CELLS HABITAT' -CELLS HABITAT -CELLS INTERVAL 3 N r s N r s N r s 1 8 • 7 4 * C 4 .45 4 .95 2 16 .89* 7 .92* 9 . 93* 3 15 .76* 8 .98* 7 .62 4 19 .27 10 .49 9 .01 5 17 .25 9 .63 8 .04 6 19 - . 3 2 10 - . 2 5 9 - . 3 7 7 17 - . 2 2 9 .46 8 - . 7 9 * 8 16 .24 8 .75* 8 0 9 19 .65* 10 .75* 9 .69* 10 19 .75* 10 .89* 9 .72* 11 17 .89* 9 .89* 8 .96* See F igu re 5 f o r d a t e s . k Sample s i z e of h a b i t a t - c e l l s . c 2 - t a i l e d p r o b a b i l i t y v a l u e ; *, p < 0 .05 . Mature f o r e s t s i t e s ; and i n c l u d e s P a r k l a n d . Represented by n o n - f o r e s t (open) s i t e s (see t e x t ) ; and i n c l u d e s A l p i n e . 27 r e l a t i o n s h i p s w i t h t r a c k depths to a l l o w p r e d i c t i n g even the rank ing of h a b i t a t - c e l l s by c a r i b o u t r a c k depths . Track depths i n the Park land and A l p i n e o f t e n were l e s s than expected g i ven e l e v a t i o n a l t rends ( F i g u r e 5 ) . The compara t i ve ly sha l l ow t r a c k depths i n these s i t e s appeared l a r g e l y due to wind compaction of snow. Al though wind compaction occur red i n o ther h a b i t a t s , p a r t i c u l a r l y i n open s i t e s , i t was g r e a t e s t i n Park land and A l p i n e because of t h e i r h i g h e l e v a t i o n and g e n e r a l l y exposed l o c a t i o n s . However, s i n k i n g depths measured a t a more s h e l t e r e d Park land s i t e were deeper than a t the nearby fo rma l Park land snow course (F igu re 5 ) , i n d i c a t i n g t h a t the i n f l u e n c e of winds can vary l o c a l l y . Locomotion c o n d i t i o n s i n r e l a t i o n to snowpack c r u s t i n g and weather C rus ts were u s u a l l y p resent i n the upper 70 cm p r o f i l e of the snowpacks, but v a r i e d i n t h i c k n e s s and f requency , w i t h marked i n c r e a s e s ev ident f i r s t i n i n t e r v a l 5 and then t o even h igher l e v e l s i n i n t e r v a l 9, be fo re d e c l i n i n g (Table 3 ) . Some of these c r u s t s d i d support me or c a r i b o u , and when one d i d n o t , i t or the c o l l e c t i v e c o n t r i b u t i o n of two or more c r u s t s c o u l d improve the s u p p o r t a b i l i t y of a snowpack. However, c r u s t s a lone cannot e x p l a i n the s p a t i a l and temporal d i s t r i b u t i o n of t r a c k depths by h a b i t a t - c e l l s (see F i g u r e 5 ) . There was no obvious and c o n s i s t e n t p a t t e r n of c r u s t c h a r a c t e r i s t i c s ( i . e . , t h i c k n e s s and ha rdness ) , numbers, or p o s i t i o n s ( i n r e l a t i o n e i t h e r to the snowpack su r face or t o other c r u s t s ) between h a b i t a t -c e l l s , nor w i t h t r a c k depths . Confounding the e f f e c t s of c r u s t s were unmeasured, but o b v i o u s l y ve ry impor tant , d i f f e r e n c e s between h a b i t a t - c e l l s i n the c o n d i t i o n of uncrusted snow l a y e r s , which a l s o c o n t r i b u t e d t o the s u p p o r t a b i l i t y of snowpacks. Crust measurements, n e v e r t h e l e s s , p r o v i d e genera l i n d i c e s to the temporal changes i n the support o f f e r e d by most snowpacks. C r u s t i n g i n d i c e s (Table 3) tend to r e f l e c t the occur rence and i n t e n s i t y of wetter snowfa l l s 28 Table 3. I nd ices to the occurrence and i n t e n s i t y of c r u s t i n g i n the upper 70 cm of snowpacks i n a l l h a b i t a t - c e l l s combined, w in te r 1979-80, K o r t h Thompson. SUM OF CRUST THICKNESSES (cm) NUMBER OF CRUSTS WINTER INTERVAL 3 Nt(Nc) X SD RANGE X SD RANGE 1 9 (8) 1.4 1.6 o - 4.0 0.6 0.5 0 - 1 2 16 (6) 0.6 0.8 0 - 2.0 0.4 0.5 0 - 1 3 15 (9) 1.4 1.5 0 - 4.0 0.7 0.7 0 - 2 4 19 (6) 1.1 2.0 0 - 6.0 0.6 1.0 0 - 3 5 17(16) 4.8 4.0 0 - 17.0 1.3 0.6 0 - 2 6 19(17) 3.5 2.5 0 - 11.0 1.6 1.1 0 - 5 7 17(12) 3.6 5.1 0 - 20.0 1.3 1.0 0 - 3 8 14(12) 3.0 2.3 0 - 6.0 1.9 1.1 0 - 3 9 19(19) 10.2 5.8 2.5 - 22.5 2.0 0.8 1 - 3 10 19(18) 8.5 5.5 0 - 18.0 1.9 1.0 0 - 3 11 17(14) 4.7 4.2 0 - 12.5 1.7 1.2 0 — 4 See F i g u r e 5 f o r da tes . Nt , number of h a b i t a t - c e l l s sampled and a l s o the sample s i z e f o r average c r u s t i n d i c e s ( i . e . , snow- f ree h a b i t a t - c e l l s e x c l u d e d ) ; Nc, number of h a b i t a t - c e l l s sampled w i th c r u s t s i n the upper 70 cm of snow. 29 and thaws, and of subsequent m e l t - f r e e z e metamorphic processes i n the snowpacks. These i n d i c e s a l s o a i d i n p o o l i n g the w i n t e r i n t e r v a l s i n t o p e r i o d s b r o a d l y d i f f e r e n t i a t e d by the r e l a t i v e i n t e n s i t i e s of snow accumula t ion , and of snow melt or s e t t l e m e n t . P r e d i c t e d mean c a r i b o u t r a c k depths (F igu re 5) were t ransformed t o r e l a t i v e energy c o s t s of l ocomot ion , and t o f a c i l i t a t e a summary of temporal t rends i n locomot ion c o n d i t i o n s , poo led i n t o B i o g e o c l i m a t i c Zones and s t r a t i f i e d by s e r a i type (F igu re 6 ) . For the few snow courses ( h a b i t a t -c e l l s ) not i n v e n t o r i e d (see F i g u r e 5 ) , the m i s s i n g t r a c k depth v a l u e s were g i ven the v a l u e s of t h e i r cor respond ing p a i r e d snow c o u r s e . The p a t t e r n s of locomot ion c o n d i t i o n s i n snow f o r B i o g e o c l i m a t i c Zones, and f o r mature and immature (open) s i t e s w i t h i n these Zones, were s i m i l a r over the 1979-80 w i n t e r ( F i g u r e 6 ) . In broad overv iew, d e s p i t e a l l h a b i t a t -c e l l s g e n e r a l l y accumulat ing f r e s h snow throughout w i n t e r (F igu re 2 ) , a net accumulat ion of f r e s h , s o f t snow, l e d to d e t e r i o r a t i n g locomot ion c o n d i t i o n s ; w h i l e a net set t lement or matu ra t ion of s u r f a c e snow, l e d to improving locomot ion c o n d i t i o n s . C o m p l i c a t i n g t h i s g e n e r a l i t y , however, o l d e r , s e t t l e d su r face snow h o r i z o n s sometimes weakened due t o thaws, r a i n or bo th . 1. E a r l y Winter (23 October to December 27 ) : The e a r l y w in te r p e r i o d from i n t e r v a l 1 t o 4 was predominant ly a snow accumulat ion phase, and est imated energy c o s t s f o r locomot ion i n c r e a s e d i n most h a b i t a t - c e l l s , peaking i n i n t e r v a l 4 ( F igu re 6) as snowpacks deepened. A l though snowpacks became d i f f e r e n t i a l l y s t r a t i f i e d between h a b i t a t - c e l l s , t h e i r upper l a y e r s were u s u a l l y s o f t and p o o r l y s u p p o r t i v e . The few c r u s t s tha t d i d develop were g e n e r a l l y t h i n (Table 3 ) , and were soon b u r i e d by f r e s h snow d e p o s i t i o n s . Due to an o v e r a l l d i r e c t a s s o c i a t i o n between t r a c k depths and snowpack depths a t t h i s t ime , t r a c k depths were g e n e r a l l y p o s i t i v e l y c o r r e l a t e d w i t h e l e v a t i o n (Table 2, F i g u r e 5 ) , and were u s u a l l y deeper i n F igu re 6. Index of energy c o s t s of ca r ibou locomotion i n snow, over w i n t e r 1979-80, Nor th Thompson. Index i s the grand mean (+ 1SE) of means f o r the r e l a t i v e i n c r e a s e i n the net c o s t of locomotion i n snow as a percentage above the cost of locomot ion w i thout snow (Parker et a l . 1984) f o r mature and immature (open) h a b i t a t - c e l l s grouped by B i o g e o c l i m a t i c Zone: ESSF, 1) Mature = ESSF- low, ESSF-high and Pa rk land , and 2) Immature = ESSF- low and E S S F - h i g h ; ICH = ICH-low and ICH-h igh , f o r both Mature and Immature; N = number of h a b i t a t - c e l l s grouped. 31 p a i r e d open s i t e s (F igu re 5 ) . 2 . La te Winter (28 December to 2 A p r i l ) : A much more tempora l l y and s p a t i a l l y v a r i a b l e complex of snow accumulat ion and snow set t lement and /o r melt occurred between i n t e r v a l s 5 and 11. Consequent ly , upper snowpack p r o f i l e c o n d i t i o n s and s t r u c t u r e s were complex, and t r a c k depths o f t e n d i d not demonstrate c l e a r r e l a t i o n s h i p s t o snowpack depths or to h a b i t a t c l a s s i f i c a t i o n f a c t o r s . Over i n t e r v a l s 5 and 6, a combinat ion of r e l a t i v e l y low i n t e n s i t y snow storms, i n t e r m i t t e n t p e r i o d s of d i u r n a l thaw- f reeze c y c l e s f o l l o w e d by days of constant s u b f r e e z i n g temperatures , and severe wind compaction a t h igher e l e v a t i o n s , l e d to an i n c r e a s e i n c r u s t i n g (Table 3) and s e t t l i n g of the s o f t , wet e a r l y w in te r snow accumu la t ions . As a r e s u l t , the support of most snowpacks improved d r a m a t i c a l l y compared t o i n t e r v a l 4 ( F igu re 6 ) . Through i n t e r v a l s 7 to 8, the weather c o n d i t i o n s became m i l d e r , resembl ing e a r l y w i n t e r , and a l l h a b i t a t s exper ienced a resumption of wetter s n o w f a l l s and o c c a s i o n a l r a i n . D i u r n a l thaw- f reeze c y c l e s were f requent , but i n t e r v e n i n g p e r i o d s of constant f r e e z i n g temperatures were b r i e f e r and not as severe as those i n i n t e r v a l s 5 and 6. Consequent ly , locomot ion c o n d i t i o n s i n most h a b i t a t - c e l l s s t e a d i l y d e t e r i o r a t e d (F igu re 6 ) , because of a net i n c r e a s e i n accumulat ions of s o f t e r snow above denser snowpack l a y e r s . By i n t e r v a l 9, the s u p p o r t a b i l i t y of a l l snowpacks improved aga in d r a m a t i c a l l y ( F igu re 6 ) , because a few days of d i u r n a l t haw - f reeze c y c l e s , f o l l o w e d by s e v e r a l days of constant s u b f r e e z i n g temperatures, r e s u l t e d i n dense snow l a y e r s and very t h i c k , hard c r u s t s i n the upper p r o f i l e of a l l snowpacks (Table 3 ) . Subsequent accumulat ions of f r e s h snow through i n t e r v a l s 10 and 11 aga in reduced the s u p p o r t a b i l i t y of most snowpacks, p a r t i c u l a r l y i n the ESSF and A l p i n e Zones (F igure 6 ) . 32 Locomotion c o n d i t i o n s i n the L ichen Reserve The upper suba lp ine h a b i t a t s of ESSF-h igh and Park land represent the proposed L ichen Reserve, in tended as l a t e w in te r range f o r c a r i b o u . I t h e r e f o r e compared c a r i b o u locomot ion c o n d i t i o n s i n mature f o r e s t h a b i t a t -c e l l s i n t h i s a rea w i t h those i n the lower suba lp ine (ESSF - low) , below the proposed r e s e r v e . Notwi thstand ing the management c o n s i d e r a t i o n f o r p o o l i n g ESSF -h igh f o r e s t and P a r k l a n d , I b e l i e v e d that average locomot ion c o s t s among these h a b i t a t - c e l l s p rov ided a good o v e r a l l index t o the o f t e n l o c a l l y heterogeneous locomot ion c o n d i t i o n s i n the h i g h e l e v a t i o n f o r e s t s , as o f f e r e d by s h e l t e r e d and /o r wind r e d e p o s i t e d snow s i t e s and by wind-exposed s i t e s . Locomotion c o n d i t i o n s i n the L ichen Reserve and the lower suba lp ine f o l l o w e d ve ry s i m i l a r temporal t rends (F igu re 7 ) , but there were some no tab le d i f f e r e n c e s i n the r e l a t i v e magnitude between them. S p e c i f i c a l l y , i n the lower suba lp ine locomot ion c o n d i t i o n s were much b e t t e r f o r a longer d u r a t i o n i n the e a r l y w i n t e r , and improved e a r l i e r i n the snowpack s t a b i l i z a t i o n p e r i o d of l a t e December t o l a t e January ( i n t e r v a l s 5 to 6, F i g u r e 7 ) . A f te rwards , locomot ion c o n d i t i o n s i n and below the L ichen Reserve were e i t h e r s i m i l a r or n o t i c e a b l y poorer i n the L ichen Reserve . Representa t i veness of c a r i b o u locomot ion c o n d i t i o n s over the 1979-80 w i n t e r Trends i n c a r i b o u locomot ion c o n d i t i o n s i n snow over w i n t e r 1979-80 (F igu re 6) appeared to r e f l e c t broad s i m i l a r i t i e s i n these c o n d i t i o n s between w i n t e r s . These s i m i l a r i t i e s a re suggested by comparing p r e d i c t e d c a r i b o u t r a c k depths between the w i n t e r s of 1978-79 and 1979-80 (F igure 8 ) . In p a r t i c u l a r , locomot ion c o n d i t i o n s s t e a d i l y worsened over the e a r l y w in te r p e r i o d of accumulat ing s o f t snow, and then improved i n the m i d - w i n t e r , deep snowpack p e r i o d due to snow set t lement ( F igu re 8 ) . Subsequent ly , t h i s c y c l e was repeated more than once, a l though not synchronously between w i n t e r s : f u r t h e r snow accumulat ions b u r i e d s e t t l e d l a y e r s and worsened locomot ion MATURE i i i i i OCT NOV DEC JAN FEB MAR WINTER INTERVALS, 1979-80 F i g u r e 7 . Comparison of est imated energy c o s t s of c a r i b o u locomotion i n snow between mature h a b i t a t - c e l l s of the L ichen Reserve (ESSF-h igh + P a r k l a n d ) , ESSF - low, and ICH h a b i t a t s ( ICH-low + ICH-h igh ) , w in te r 1979-80, North Thompson. Shown a re grand means (+ 1SE, except f o r ICH - see F igure 6 f o r these S E ' s ) of means f o r the r e l a t i v e i n c r e a s e i n the net c o s t of locomotion i n snow as a percentage above the cos t of locomotion wi thout snow ( a f t e r Parker e t a l . 1984). N = number of h a b i t a t - c e l l s grouped. 34 F igu re 8. Comparison of c a r i b o u locomotion c o n d i t i o n s i n snow between w in te rs 1978-79 (open c i r c l e s and broken l i n e ) and 1979-80 ( s o l i d c i r c l e s and l i n e ) , North Thompson. Index i s the grand mean (+ range) of the p r e d i c t e d mean c a r i b o u t r a c k depth ( p r e d i c t e d from mean human s i n k i n g depth by r e g r e s s i o n ; see F i g u r e . 4 ) f o r the four south aspect h a b i t a t - c e l l s of ESSF- low -mature and - immature and ESSF-h igh -mature and - immature. 35 c o n d i t i o n s , u n t i l s n o w f a l l subs ided and the f r e s h e r snow l a y e r s s e t t l e d or o therwise matured, l e a d i n g t o improved snowpack support ( F i g u r e 8 ) . However, the abso lu te degree of locomot ion c o s t s i n a " t y p i c a l " w in te r may be somewhat i n t e r m e d i a t e t o tha t observed between 1978-79 and 1979-80. T h i s c o n t e n t i o n i s based upon the d i f f e r e n c e between these two w in te rs i n t h e i r snowpack c h a r a c t e r i s t i c s i n r e l a t i o n to l ong - te rm averages and i n t h e i r a i r temperatures (F igu re 3 ) . Snowpack accumulat ions i n the deep snowpack p e r i o d of 1 January to 1 A p r i l i n 1979-80 were s i m i l a r t o , w h i l e i n 1978-79 they were u s u a l l y lower than , l ong - te rm averages ( F i g u r e 3 ) . However, snowpack d e n s i t i e s through w in te r i n 1979-80 were above, but i n 1978-79 were u s u a l l y below, l ong - te rm averages (F igu re 3 ) . The c o m p a r a t i v e l y c o l d e r a i r temperatures i n 1978-79 (F igu re 3) r e f l e c t e d that i n t h i s w i n t e r the lower snowpack depths were due more to lower p r e c i p i t a t i o n than t o melt of depos i ted snow; and that the lower snowpack d e n s i t i e s were due t o d r i e r and c o l d e r (low d e n s i t y ) s n o w f a l l s and to i n f r e q u e n t r a i n and t h a w - f r e e z e c y c l e s , both i n h i b i t i n g snowpack matura t ion and c r u s t i n g , u n t i l a warming t rend i n March (F igu re 3 ) . Converse ly , i n w i n t e r 1979-80, p r e c i p i t a t i o n was g e n e r a l l y moist to wet (h igh d e n s i t y ) snow, and r a i n and thaw- f reeze c y c l e s were f r e q u e n t , r e s u l t i n g i n more c r u s t i n g and i n an enhanced set t lement or c o n s o l i d a t i o n of snowpacks compared to the f i r s t w i n t e r . Such d i f f e r e n c e s between the two w i n t e r s i n dominant weather c o n d i t i o n s , r e f l e c t e d by snowpack d e n s i t i e s (F igu re 3 ) , c o r r e l a t e w i t h both the b e t t e r o v e r a l l locomot ion c o n d i t i o n s p r i o r to March, and the g r e a t e r degree of improvement i n mid w in te r locomot ion c o n d i t i o n s f o l l o w i n g the e a r l y w in te r snow accumu la t ions , i n 1979-80 (F igure 8 ) . Thus a w i n t e r w i t h average snowpack accumulat ion and d e n s i t y p a t t e r n s , and o v e r a l l weather, would l i k e l y have locomot ion c o n d i t i o n s i n t e r m e d i a t e between those observed over the two w i n t e r s of s tudy . 36 DISCUSSION P r e d i c t i n g Car ibou Track Depth The v a l i d i t y of us ing p a i r e d human s i n k i n g depth and c a r i b o u t r a c k depth i n snow t o develop a r e g r e s s i o n equat ion to p r e d i c t c a r i b o u t r a c k depths w i t h h igh p r e c i s i o n has been reproduced by Sco t t and Servheen (1984) f o r mountain c a r i b o u i n the S e l k i r k Mountains. T h i s s i m p l e , r e a d i l y performed technique i s p r e f e r r e d over d e t a i l e d and t ime consuming measurements of p h y s i c a l p r o p e r t i e s of i n d i v i d u a l snow l a y e r s , which i n any case have been found to be inadequate f o r p r e d i c t i n g ungulate t r a c k depths ( K e l s a l l and P r e s c o t t 1971, P r u i t t 1959). I n d i c e s t o Locomotion Cond i t i ons i n Snow The p r e d i c t e d c a r i b o u t r a c k depths must be cons idered o n l y as a genera l and ins tantaneous index of c a r i b o u locomot ion c o n d i t i o n s i n snow i n a dynamic system. C o n s i d e r a b l e v a r i a b i l i t y occurs i n both the s p a t i a l and temporal p a t t e r n s i n snowpack c o n d i t i o n s a f f e c t i n g t h e i r l o a d - b e a r i n g c a p a c i t y . However, i n f o r m a l obse rva t ions i n areas separated from the snow courses and i n i n t e r v e n i n g p e r i o d s between snow course i n v e n t o r y dates suggested that the genera l s p a t i a l and temporal p a t t e r n s i n c a r i b o u locomot ion c o n d i t i o n s were r e a l i s t i c and r e p r e s e n t a t i v e f o r both w i n t e r s . The r e l a t i v e energy c o s t s of locomot ion i n snow are order p r e s e r v i n g t rans fo rmat ions of p r e d i c t e d c a r i b o u t r a c k depths , and thus a re a genera l index to m o b i l i t y c o n d i t i o n s as w e l l . They do not es t imate the a c t u a l e n e r g e t i c c o s t of locomot ion by c a r i b o u , because energy expend i tu re would depend not o n l y on s i n k i n g depth but a l s o on d i s t a n c e moved, speed of t r a v e l , g a i t , body we ight , snow d e n s i t y , and whether breakab le c r u s t s or o ther d e s t a b i l i z i n g c o n d i t i o n s a re encountered ( L u i c k and White 1986, M a t t f e l d 1974, Parker et a l . 1984). The r e l a t i v e energy c o s t s a re n e v e r t h e l e s s s t i l l a more u s e f u l index to locomotion c o n d i t i o n s than t r a c k depths , because they 37 r e f l e c t that the energy r e q u i r e d to walk i n snow i n c r e a s e s e x p o n e n t i a l l y w i t h i n c r e a s i n g t r a c k depth ( M a t t f e l d 1974, Parker et a l . 1984). F a c t o r s A f f e c t i n g Locomotion C o n d i t i o n s As i n the p resent study, many i n v e s t i g a t o r s have found tha t snow accumulat ion was i n v e r s e l y r e l a t e d t o f o r e s t canopy cover , deeper i n openings than w i t h i n a f o r e s t s tand , and p o s i t i v e l y c o r r e l a t e d w i t h e l e v a t i o n ( rev iew i n McKay and Gray 1981). Such s p a t i a l p a t t e r n s would i n t u r n account ve ry g e n e r a l l y f o r the o f t e n s i m i l a r s p a t i a l p a t t e r n s i n c a r i b o u t r a c k depths , p a r t i c u l a r l y ev ident d u r i n g and soon a f t e r major snow accumulat ion phases when t r a c k depths were most c l e a r l y r e l a t e d d i r e c t l y to the depth of s o f t , f r e s h snow i n the upper p r o f i l e of snowpacks. K e l s a l l and P r e s c o t t (1971), f o r example, found that both snowpack depth and ungulate t r a c k depth were deeper o v e r a l l i n openings than i n p a i r e d f o r e s t s i t e s . The f a c t o r s of s e r a i type and e l e v a t i o n , or the i n t e r r e l a t e d f a c t o r of t o t a l snowpack depth a l o n e , were not s u f f i c i e n t , however, t o p r e d i c t r e l a t i v e t r a c k depths among h a b i t a t - c e l l s . D e t a i l e d ana lyses of weather and p h y s i c a l c h a r a c t e r i s t i c s of snowpacks were beyond the scope of the present s tudy . However, the v a r i a b l e s p a t i a l and temporal p a t t e r n s i n t r a c k depths were r e l a t e d to v a r i a b l e snowpack c h a r a c t e r i s t i c s , i n a d d i t i o n t o t o t a l depth , i n c l u d i n g the hardness, d e n s i t y and t h i c k n e s s of i n d i v i d u a l snow l a y e r s ( K e l s a l l and P r e s c o t t 1971), e s p e c i a l l y those i n the upper 70 cm p r o f i l e of snowpacks (chest he igh t of c a r i b o u ) ; and the p r o g r e s s i v e heterogeneous snowpack s t r a t i g r a p h y ev ident a f t e r e a r l y w in te r snow d e p o s i t i o n s . The dynamics of these f l u c t u a t i n g c o n d i t i o n s were dependent on the type and r a t e of s u c c e s s i v e p r e c i p i t a t i o n (dry powder t o wet snow, and r a i n ) , the degree of snow compaction or r e d i s t r i b u t i o n by wind, and weather c o n d i t i o n s , such as temperatures and t h e i r f l u c t u a t i o n s , tha t drove the metamorphosis of d e p o s i t e d snow ( K e l s a l l and P r e s c o t t 1971, Langham 1981, McKay and Gray 38 1981). In summary, p r i o r to m e l t , t he re i s a gene ra l tendency f o r snowpacks to s e t t l e , and i n c r e a s e i n d e n s i t y and l o a d - b e a r i n g c a p a c i t y . Of cou rse , newly d e p o s i t e d snow w i l l be l e s s s e t t l e d , r e s u l t i n g i n deeper t r a c k depths . Older snow l a y e r s , i n c l u d i n g those i n su r face and n e a r - s u r f a c e p o s i t i o n s , can sometimes weaken r a t h e r than s t rengthen , however, depending on the type c f metamorphic process they expe r ience , or on changes i n t h e i r temperature or wetness (Langham 1981, Prowse and Owens 1984, Schaerer 1981) . The combined i n f l u e n c e of p r e c i p i t a t i o n and other weather c o n d i t i o n s and snow metamorphic p rocesses a p p a r e n t l y a c t e d d i f f e r e n t i a l l y enough upon snowpacks d u r i n g the present study so tha t no c l e a r and c o n s i s t e n t r e l a t i o n s h i p i n l o a d - b e a r i n g c a p a c i t y among the 19 h a b i t a t - c e l l s was apparent . On a broader s c a l e , when mature f o r e s t and open s i t e s by B i o g e o c l i m a t i c Zone, or o ther groupings of a s s o c i a t e d h a b i t a t - c e l l s , a re c o n s i d e r e d , genera l p a t t e r n s i n locomot ion c o n d i t i o n s throughout the w i n t e r were r e l a t i v e l y c o n s i s t e n t ( F igu res 6 and 7 ) . Temporal Trend i n Locomotion C o n d i t i o n and C l i m a t e The c a r i b o u locomot ion c o n d i t i o n i n d i c e s demonstrated that i n both w i n t e r s of study the re was a mid w in te r p e r i o d of s e t t l e m e n t , c o n s o l i d a t i o n and i n c r e a s e d c r u s t i n g of snowpacks, r e s u l t i n g i n marked, u n i v e r s a l improvement i n t h e i r support c a p a c i t y . Th is t rend agrees w i t h the o b s e r v a t i o n s of Edwards and R i t c e y (1959) and can be cons ide red as t y p i c a l f o r the r e g i o n . C l e a r l y , t h i s p a t t e r n i n not f i x e d , as shown by v a r i a b i l i t y i n t i m i n g and magnitude of temporal changes i n locomot ion c o n d i t i o n s between 1978-79 and 1979-80. These d i f f e r e n c e s were r e l a t e d to s n o w f a l l type and other weather c o n d i t i o n s . In g e n e r a l , the o c c a s i o n a l thaws and r a i n , the s u c c e s s i v e thaw- f reeze c y c l e s and c r u s t i n g , the r e l a t i v e l y moist snow o v e r a l l , and the moderately 39 dense snowpacks, a re a l l i n d i c a t i v e of an i n l a n d - c o a s t a l snow or c l i m a t i c regime (Prowse and Owens 1984). These weather and snowpack c o n d i t i o n s , and the long - te rm monthly averages i n t o t a l snowpack d e n s i t i e s (F igu re 3) were ve ry s i m i l a r t o tha t repor ted by Prowse and Owens (1984) f o r the C r a i g i e b u r n Range, New Zea land . There fo re , the s n o w f a l l and snowpack s t r u c t u r e , and presumably the m i d - w i n t e r improvement i n snowpack s u p p o r t a b i l i t y , observed i n the present study a re t y p i c a l f o r " intermontane zones" , where both mar i t ime and c o n t i n e n t a l c l i m a t i c i n f l u e n c e s i n t e r a c t (Prowse and Owens 1984:117) . 40 IV. UTILIZATION AND AVAILABILITY OF WINTER FORAGE INTRODUCTION Th is chapter examines the w in te r f o r a g i n g c o n d i t i o n s f o r c a r i b o u , c o n s i d e r i n g the f o l l o w i n g s p e c i f i c o b j e c t i v e s : 1) To determine the w in te r food h a b i t s of c a r i b o u i n g e n e r a l , and the importance of a r b o r e a l a l e c t o r i o i d l i c h e n s i n p a r t i c u l a r . 2) To determine the n u t r i t i o n a l v a l u e of a l e c t o r i o i d l i c h e n s . 3) To es t imate by h a b i t a t s , the temporal p a t t e r n i n the a v a i l a b i l i t y of n o n -a r b o r e a l l i c h e n fo rages (the a v a i l a b i l i t y of shrubs above snowpack s u r f a c e s , and the c o n d i t i o n of snowpacks f o r c r a t e r i n g by ca r ibou ) based on genera l i n d i c e s developed from h a b i t a t - s p e c i f i c snowpack measurements. 4) To i n v e n t o r y a r b o r e a l a l e c t o r i o i d l i c h e n abundance on s tand ing t r e e s , and on the ground as l i t t e r f a l l , i n f o r e s t e d h a b i t a t s , and to examine these r e s u l t s f o r p a t t e r n s i n r e l a t i o n to h a b i t a t c l a s s i f i c a t i o n f a c t o r s . 5) From h a b i t a t - s p e c i f i c snowpack measurements, t o es t imate by h a b i t a t s , the temporal p a t t e r n i n the r e l a t i v e a v a i l a b i l i t y of a l e c t o r i o i d l i c h e n s on s tand ing t r e e s . These est imates a re used l a t e r (Chapter VI ) to eva luate t h e i r i n f l u e n c e on the w in te r movements and h a b i t a t use p a t t e r n s of c a r i b o u . METHODS Food Hab i ts M i c r o h i s t o l o g i c a l a n a l y s i s of f e c a l samples ( D a v i t t and Nelson 1980, Stewart 1967) was used to es t imate b o t a n i c a l compos i t ion and q u a n t i f i c a t i o n of c a r i b o u d i e t s i n the w in te r of 1979-80. F resh f e c a l samples were compounded i n t o two d i e t groups, each represented by a t l e a s t 15 f e c a l p e l l e t c o l l e c t i o n s : the e a r l y w in te r d i e t , composed of c o l l e c t i o n s made between November and e a r l y January from ICH and ESSF- low h a b i t a t t y p e s ; and the l a t e 41 w i n t e r d i e t , composed of c o l l e c t i o n s made between l a t e January and March from ESSF- low to Park land h a b i t a t t y p e s . The b o t a n i c a l compos i t ion of the d i e t s was i d e n t i f i e d to the l e v e l of major p l a n t t y p e s : l i c h e n s , c o n i f e r s , shrubs, f o r b s , and graminoids (sedges and g r a s s e s ) . L ichens were f u r t h e r subd iv ided i n t o the a l e c t o r i o i d genera of A l e c t o r i a and B r y o r i a , and the n o n - a l e c t o r i o i d l i c h e n s . Q u a n t i t a t i v e est imates of d i e t compos i t ion were expressed as the percentage each fo rage component comprised of the t o t a l su r face a rea f o r a l l d i s c e r n i b l e p l a n t fragments (Stewart 1967) i n 200 random f i e l d s of v iew f o r each d i e t (B .B . D a v i t t , p e r s . comm. 1982). F e c a l ana lyses were conducted a t the W i l d l i f e H a b i t a t Laboratory , Department of F o r e s t r y and Range Management, Washington S t a t e U n i v e r s i t y , Pu l lman, Washington. Because t h i s technique may be i n a c c u r a t e ( reviews by G i l l et a l . 1983, Holechek et a l . 1982a, P u l l i a m and Nelson 1979), w i t h r e s u l t s b i a s e d to l e s s d i g e s t i b l e and /o r more m i c r o s c o p i c a l l y d i s c e r n i b l e p l a n t s , the d a t a were used o n l y as i n d i c a t i o n s of c a r i b o u w i n t e r d i e t s , p a r t i c u l a r l y the t rend i n use of p l a n t types between e a r l y and l a t e w i n t e r . A d d i t i o n a l i n f o r m a t i o n on e a r l y w in te r c a r i b o u d i e t s was ob ta ined from examinat ion of rumen contents c o l l e c t e d from f i v e c a r i b o u found i l l e g a l l y shot i n e a r l y November 1978, i n ESSF - low. An attempt was made to ana lyze rumen contents (at the W i l d l i f e Research Laboratory , F i s h and W i l d l i f e Branch, B r i t i s h Columbia M i n i s t r y of Environment, V i c t o r i a ) by washing samples through s i e v e s w i t h openings of 5.66 and 4.00 mm. U n f o r t u n a t e l y these r e t a i n e d o n l y the l a r g e r p l a n t f ragments, and so t h i s rumen a n a l y s i s i s p robab ly b o t a n i c a l l y incomplete and s e r i o u s l y b i a s e d q u a n t i t a t i v e l y . There fo re , o n l y p l a n t types and /o r t a x a i d e n t i f i e d i n the rumen sample r e s i d u e s a re noted i n Appendix B. Forage u t i l i z a t i o n was a l s o determined by i n s p e c t i o n of f eed ing s i t e s a long f r e s h c a r i b o u t r a i l s i n both w i n t e r s , where u t i l i z a t i o n of each forage 42 type was recorded as a s i n g l e f eed ing o b s e r v a t i o n , r e g a r d l e s s of how much of the fo rage may have been ea ten . The forages were c a t e g o r i z e d i n t o p l a n t t y p e s : a r b o r e a l l i c h e n s , t e r r e s t r i a l l i c h e n s , shrubs, herbs ( f o r b s , f e r n s and h e r b - l a y e r woody spec ies ) and graminoids (sedges, grasses and h o r s e t a i l s ) . U t i l i z a t i o n of a r b o r e a l l i c h e n s was f u r t h e r c a t e g o r i z e d by the source of these l i c h e n s : s tand ing t r e e s , w i n d f a l i e n t r e e s ( i n c l u d i n g broken t r e e tops > 3 m i n l e n g t h ) , and l i t t e r f a l l ( i n c l u d i n g f a l l e n b ranches ) . Chemical Composi t ion and D i g e s t i b i l i t y of A l e c t o r i o i d L ichens Samples of a l e c t o r i o i d l i c h e n s growing i n mature f o r e s t canopy l e v e l s a c c e s s i b l e t o c a r i b o u were c o l l e c t e d a t mid-monthly i n t e r v a l s from November 1979 t o March 1980. Samples were c o l l e c t e d i n the v i c i n i t y of the ICH-low (900 t o 1000 m) and the ESSF- low (1500 t o 1600 m) snow course s i t e s on both no r th and south a s p e c t s . C o l l e c t i o n s made on d i f f e r e n t aspec ts were combined. Samples were c leaned of f o r e i g n m a t e r i a l , o v e n - d r i e d a t 50°C, and ground i n a W i ley m i l l . N i t rogen and ether e x t r a c t were determined by the standard A . O . A . C . (1975) methods. Crude p r o t e i n was es t imated by m u l t i p l y i n g n i t r o g e n by 6 .25 . Gross energy was determined by bomb c a l o r i m e t r y , ash by the method of H a r r i s (1970), and n e u t r a l detergent f i b e r (NDF), a c i d detergent f i b e r (ADF) and permanganate l i g n i n were a l l determined by the methods of Goer ing and Van Soest (1970) as mod i f i ed by Waldren (1971). H e m i c e l l u l o s e was est imated by s u b t r a c t i n g ADF from NDF, and c e l l u l o s e was est imated as the d i f f e r e n c e between ADF and l i g n i n . In v i t r o d ry matter d i g e s t i b i l i t y (IVDMD) ( T i l l e y and Te r ry 1963) was obta ined u s i n g rumen inoculum from a f i s t u l a t e d cow mainta ined on hay. A l l a n a l y s e s were conducted at the Range Research S t a t i o n , A g r i c u l t u r e Canada, Kamloops, B .C. A v a i l a b i l i t y of Winter Forages  T e r r e s t r i a l fo rages The a v a i l a b i l i t y of shrub f o r a g e s , and the snow c o n d i t i o n s f o r c r a t e r i n g 43 f o r f o r a g e s , were es t imated d u r i n g the w i n t e r of 1979-80. Shrubs cons idered t o be p o t e n t i a l w in te r forages were the common spec ies or genera repo r ted t o be eaten by mountain c a r i b o u (Bierman 1967, B l o o m f i e l d 1979, Edwards and R i t c e y 1960, Freddy 1974). Those s e l e c t e d were Vaccin ium membranacium, V. o v a l i f o l i u m , Ribes s p p . , Rhododendren a l b i f l o r u m , M e n z i e s i a f e r r u g i n e a , Sorbus s i t c h e n s i s , S a l i x spp. Rosa s p p . , and Pach i s t ima m y r s i n i t i e s , which were a l l e s s e n t i a l l y i n the low shrub st ratum (< 2 m). Shrub h e i g h t s and percent cover were measured a t a r b o r e a l l i c h e n i n v e n t o r y p l o t s and a t snow courses i n snow f r e e p e r i o d s f o r a l l of the 19 h a b i t a t - c e l l s except A l p i n e . Data from n o r t h and south aspects were combined, r e s u l t i n g i n a t o t a l of 9 s i t e s , r e p r e s e n t i n g immature and mature s e r a i types from ICH-low t o P a r k l a n d . For each s i t e , average h e i g h t s and percentage cover were computed f o r each shrub taxon , and a combined average shrub h e i g h t , weighted a c c o r d i n g to the average percent cover of shrub t a x a , was c a l c u l a t e d . F i n a l l y , the index of Net Shrub A v a i l a b i l i t y above snowpack su r face was obta ined by : Net Shrub A v a i l a b i l i t y = Weighted Average Shrub Height (cm) - Average Snow Depth (cm). With snowcover, the a v a i l a b i l i t y of fo rages i n the herb and low shrub l a y e r s depended on the c o n d i t i o n s f o r d i g g i n g f eed ing c r a t e r s , i n c l u d i n g dep th , d e n s i t y , and hardness of e i t h e r the whole or p o r t i o n s of the snowpack ( P r u i t t 1979, R u s s e l l and M a r t e l l 1984). Snowpacks cons ide red favourab le f o r c r a t e r i n g by c a r i b o u and re indee r a re g e n e r a l l y sha l lower than 50 to 60 cm, but t h r e s h o l d depths can range from 65 t o 90 cm and deeper ( R u s s e l l and M a r t e l l 1984). There fo re , I a r b i t r a r i l y des ignated mean snowpack depths < 55 cm as f a v o u r a b l e , those from 55 t o 100 cm as unfavourable but p o s s i b l y w i t h i n t h r e s h o l d s , arid those > 100 cm as beyond the upper t h r e s h o l d t o c r a t e r i n g . Snow c r u s t s repor ted to i n h i b i t c r a t e r i n g by c a r i b o u i n c l u d e those > 4 to 5 cm t h i c k (Pegau 1964), or those > 5 cm t h i c k and very hard ( i . e . , 6500 44 2 g/cm ) (Henshaw 1968). A d d i t i o n a l l y , c r u s t s i n the upper 10 to 15 cm of snowpacks can a l s o d e t e r c a r i b o u c r a t e r i n g a c t i v i t y ( P r u i t t 1979), r e g a r d l e s s of t h i c k n e s s . In the present study , s u b s i d i a r y i n d i c e s t o c r a t e r i n g c o n d i t i o n s i n snowpacks l e s s than 101 cm deep i n c l u d e d : w i t h i n the upper 70 cm of snowpacks, 1) the sum of i c e l a y e r or c r u s t t h i c k n e s s ( a f t e r M i l l e r et 2 a l . 1982), and 2) the occur rence of c r u s t s > 5 cm t h i c k and > 1000 g/cm h a r d ; and the occur rence of c r u s t s , r e g a r d l e s s of t h i c k n e s s and hardness, w i t h i n the upper 15 cm of snowpacks. A r b o r e a l a l e c t o r i o i d l i c h e n s 1. L i chen i nven to ry The abundance of a r b o r e a l a l e c t o r i o i d l i c h e n s on s tand ing t r e e s and on the ground as l i t t e r f a l l were est imated w i t h i n p l o t s e s t a b l i s h e d i n the c e n t r a l p o r t i o n of the study a rea (F igu re 1 ) . Fo res t stands (a f o r e s t cover map t y p e ; B .C . M i n i s t r y of Fo res ts 1967) were s u b j e c t i v e l y s e l e c t e d as r e p r e s e n t a t i v e of the areas occup ied by w i n t e r i n g c a r i b o u w i t h i n each of the f i v e h a b i t a t types o c c u r r i n g below the A l p i n e (Table 1 ) . Most of the i n v e n t o r y e f f o r t was devoted to mature f o r e s t s tands , and to the ESSF Zone h a b i t a t types (ESSF- low, ESSF-h igh and P a r k l a n d ) , because these were the areas predominant ly used by c a r i b o u i n l a t e w in te r w i t h i n the study area (Edwards and R i t c e y 1959, R i t c e y 1974, 1976). a) P l o t es tab l i shment and d e s c r i p t i v e measurements: The number of p l o t s i n v e n t o r i e d w i t h i n a stand ranged from two to seven. P l o t s were l o c a t e d s y s t e m a t i c a l l y and p o s i t i o n e d a t 50 m i n t e r v a l s a long a f i x e d - b e a r i n g t r a n s e c t o r i e n t a t e d e i t h e r p e r p e n d i c u l a r or d i a g o n a l t o e l e v a t i o n con tou rs . T ransects were s t a r t e d 75 to 100 m w i t h i n the boundaries of a s tand , and from logg ing roads or c u t o v e r s . A two-s tage sampling procedure (Cochran 1977) was used w i t h i n p l o t s . The f i r s t stage i n v o l v e d measurements and d e s c r i p t i o n s of s i t e and v e g e t a t i o n 45 c h a r a c t e r i s t i c s (Walmsley et a l . 1980) w i t h i n a c i r c u l a r p l o t (0.04 h a ) . For each t r e e > 10.0 cm DBH (diameter a t b reas t h e i g h t ) , s p e c i e s , c o n d i t i o n ( l i v e , d e c l i n i n g or dead) , DBH (5 .0 cm d i v i s i o n s ) , and he ight (3 .0 m d i v i s i o n s ) were reco rded . In each p l o t , a r e p r e s e n t a t i v e t r e e from the dominant (A l ) and main (A2) t r e e canopies was aged by c o r i n g . The second stage sample was a randomly s e l e c t e d h a l f - p l o t ( ha l f c i r c l e , 0.02 h a ) , i n which a r b o r e a l l i c h e n abundance was v i s u a l l y es t imated f o r each t r e e > 10.0 cm DBH. The ground area was a l s o searched to es t imate l i c h e n l i t t e r f a l l . b) L i chen e s t i m a t i o n procedure : The e x t e n s i v e a r b o r e a l l i c h e n i n v e n t o r y p rec luded i n t e n s i v e and t i m e -consuming l i c h e n biomass sampling procedures a v a i l a b l e (Edwards et a l . 1960, P i k e et a l . 1972, 1977, S c o t t e r 1962, Stevenson 1978, 1979). I ns tead , l i c h e n abundance was v i s u a l l y est imated w i t h a technique adapted from Stevenson (1979). An a l e c t o r i o i d l i c h e n clump, w i t h an o v e n - d r i e d weight of 5.0 g , was des ignated as a Standard L ichen U n i t (SLU) . I t was used i n sample p l o t s as a re fe rence t o es t imate l i c h e n q u a n t i t y i n S L U ' s , recorded t o the nearest 0.25 SLU, on t r e e t runks and on branches w i t h i n the t r e e crown volume of 0 t o 6 m. A l s o est imated was the percentage c l a s s (0, 25, 50, 75, and 100%) of the t o t a l l i c h e n es t imate c o n s i s t i n g of A l e c t o r i a sarmentosa. A l e c t o r i o i d l i c h e n l i t t e r f a l l w i t h i n each p l o t was es t imated i n a s i m i l a r manner. To d e f i n e the v e r t i c a l p r o f i l e of l i c h e n abundance i n the 0 t o 6 m stratum of the f o r e s t canopy, I subsampled a minimum of 20 randomly s e l e c t e d t r e e s per h a b i t a t type , f o r l i c h e n abundance w i t h i n c o n s e c u t i v e 0.5 m he ight i n t e r v a l s . For each h a b i t a t type , the l i c h e n es t imates f o r these t r e e s were pooled to represent the 0 to 6 m f o r e s t canopy, and then the percentage of the t o t a l 0 t o 6 m l i c h e n est imate con ta ined w i t h i n each 0.5 m he ight i n t e r v a l of the f o r e s t canopy was computed. 46 c) R e l i a b i l i t y of l i c h e n abundance e s t i m a t e s : To assess the c o n s i s t e n c y of my v i s u a l es t imates of l i c h e n abundance, I p e r i o d i c a l l y c o l l e c t e d l i c h e n s from branches a f t e r e s t i m a t i n g t h e i r q u a n t i t y . These samples were c leaned of f o r e i g n m a t e r i a l , o v e n - d r i e d a t 60°C f o r 24 hours , and weighed to the nearest 0.01 g , and then I c a l c u l a t e d a r a t i o e s t i m a t o r (Cochran 1977:150-164) between the a c t u a l and est imated w e i g h t s . Accord ing to Stevenson (1979 :9 ) , many of these samples would be r a t e d as " h i g h - r e l i a b i l i t y " v i s u a l e s t i m a t e s , and thus the r a t i o es t imator would be b i a s e d . But the i n t e n s i v e methods necessary t o overcome t h i s l i m i t a t i o n (Stevenson 1979) were beyond the scope of the p resent s tudy . The re fo re , my v i s u a l est imates cannot be conver ted to biomass e s t i m a t e s . However, i f t h i s b i a s e d , b r a n c h - l e v e l r a t i o i s p o s i t i v e and r e l a t i v e l y p r e c i s e , the v i s u a l es t imates f o r the 0 t o 6 m i n t e r v a l of t r e e s can be used as i n d i c e s of r e l a t i v e l i c h e n abundance. Other s t u d i e s have demonstrated s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s between a r b o r e a l l i c h e n biomass and v i s u a l abundance es t imates (Harestad 1979, P i k e 1981, P i k e et a l . 1972, Rhoades 1981, Stevenson 1978). d) S t a t i s t i c a l p rocedures : In ana lyses of the l i c h e n i n v e n t o r y d a t a , a l i c h e n p l o t , r a t h e r than an i n d i v i d u a l t r e e , was the sample u n i t . L i chen p l o t t o t a l s were the summation of l i c h e n es t imates f o r a l l t r e e s sampled i n the p l o t , and were expressed as SLU per 0.02 ha f o r the 0 to 6 m stratum of the f o r e s t canopy. A l though the pr imary sample u n i t s ( s i t e and v e g e t a t i o n p l o t s ) were s y s t e m a t i c a l l y s e l e c t e d , the subun i ts ( l i c h e n i n v e n t o r y p l o t s ) were randomly s e l e c t e d h a l f -p l o t s , and thus the p l o t t o t a l s of l i c h e n abundance were assumed to have been c o l l e c t e d f o l l o w i n g a s imple random sampling p rocedure . Sample s t a t i s t i c s were medians (0 .5 q u a n t i l e s ) , i n t e r q u a r t i l e ranges ( d i f f e r e n c e s between the 0.75 and 0.25 q u a n t i l e s ) , and ranges of l i c h e n p l o t 47 t o t a l s ( a f t e r Tukey 1977). Means and c o e f f i c i e n t s of v a r i a t i o n of l i c h e n es t imates were a l s o computed, but o n l y as genera l i n d i c e s t o l i c h e n abundance parameters r a t h e r than as unbiased sample s t a t i s t i c s . L i chen abundance i n r e l a t i o n t o h a b i t a t c l a s s i f i c a t i o n f a c t o r s were eva luated by Spearman's rank c o r r e l a t i o n , and the Mann-Whitney and K r u s k a l l - W a l l i s t e s t s (Conover 1980). 2 . A v a i l a b i l i t y of a r b o r e a l l i c h e n Amounts of a r b o r e a l a l e c t o r i o i d l i c h e n s a v a i l a b l e to c a r i b o u over the w i n t e r of 1979-80 were determined f o r each h a b i t a t - c e l l , f o r each w i n t e r i n t e r v a l . They were instantaneous es t imates because no a l lowances were made f o r l i c h e n q u a n t i t i e s tha t may have been cropped i n e a r l i e r w i n t e r i n t e r v a l s . Car ibou g r a z i n g - r e a c h e s were observed to range from 1.6 to 2 .2 m, t h e r e f o r e 2 .0 m was a r b i t r a r i l y s e l e c t e d as the average g r a z i n g - r e a c h . The lower l e v e l f o r the s tand ing c a r i b o u , or g r a z i n g base , of each 2.0 m v e r t i c a l s t ratum was e i t h e r the ground, or the mean snowpack depth minus the mean c a r i b o u t r a c k depth . There fo re , the p o s i t i o n of each 2 .0 m stratum a long the v e r t i c a l a x i s of the f o r e s t canopy s h i f t e d up or down between w i n t e r i n t e r v a l s , depending on snowpack depth and c o n d i t i o n . I used the v e r t i c a l p r o f i l e of l i c h e n abundance i n the f o r e s t canopy ( the percentage of the t o t a l 0 t o 6 m l i c h e n es t imate con ta ined w i t h i n each 0.5 m he ight i n t e r v a l ) and the median l i c h e n p l o t t o t a l f o r the 0 to 6 m canopy st ratum, t o generate curves of l i c h e n a v a i l a b l e from success i ve 0.5 m he ight increments i n each h a b i t a t . Regress ion techniques (Sokal and Rohl f 1981) were used to determine the h a b i t a t - s p e c i f i c equat ions of a v a i l a b l e l i c h e n a g a i n s t g r a z i n g base l e v e l . 48 RESULTS Food Hab i ts A r b o r e a l a l e c t o r i o i d l i c h e n s were a major component of the c a r i b o u ' s w i n t e r d i e t , e s p e c i a l l y i n the second h a l f of t h i s season (Table 4 ) . Other l i c h e n s were a l s o p r e v a l e n t i n the d i e t , but t h e i r l e v e l s d i d not change over the w in te r (Table 4 ) . Examinat ion of rumen contents and f eed ing s i t e s (Appendix B) showed t h i s u n i d e n t i f i e d l i c h e n category was composed of a r b o r e a l f o l i o s e s p e c i e s and c r u s t o s e s p e c i e s on c o n i f e r ba rk , as w e l l as t e r r e s t r i a l s p e c i e s . There fo re , a c t u a l use of a r b o r e a l l i c h e n was even h igher i f these n o n - a l e c t o r i o i d a r b o r e a l taxa a re i n c l u d e d . Intake of c o n i f e r m a t e r i a l was h igher i n l a t e w i n t e r , whereas use of o t h e r , t e r r e s t r i a l v a s c u l a r p l a n t s ( f o r b s , graminoids and shrubs) decreased t o very low l e v e l s by l a t e w in te r (Table 4 ) . Feeding s i t e examinat ion (Table 5) r e f l e c t e d the same genera l t r e n d i n d i e t compos i t ion between e a r l y and l a t e w i n t e r as was shown by the f e c a l a n a l y s i s (Table 4 ) . Over w i n t e r , use of t e r r e s t r i a l fo rages ( t e r r e s t r i a l l i c h e n s , shrubs, herbs and graminoids) d e c l i n e d d r a m a t i c a l l y , w h i l e use of a r b o r e a l a l e c t o r i o i d l i c h e n s i n c r e a s e d t o dominate the d i e t . Obvious c o n i f e r browsing was not d e t e c t e d , but as almost a l l a r b o r e a l l i c h e n f e e d i n g s i t e s were a s s o c i a t e d w i t h c o n i f e r s u b s t r a t e s , i t was assumed tha t they were i nges ted t o g e t h e r . Standing t r e e s were the main source of a r b o r e a l l i c h e n s i n l a t e w i n t e r , and depending on h a b i t a t type , i n e a r l y w i n t e r as w e l l (Table 5 ) . Dur ing e a r l y w i n t e r , c a r i b o u i n ESSF h a b i t a t s , p a r t i c u l a r l y i n ESSF- low, foraged on s tand ing t r e e l i c h e n s u b s t a n t i a l l y more o f t e n than those i n ICH h a b i t a t s (Table 5) . Important, a d d i t i o n a l sources of a r b o r e a l l i c h e n s used throughout w in te r were f a l l e n t r e e s and l i c h e n l i t t e r f a l l (Table 5) , and i n f a c t were p o s s i b l y 49 Tab le 4. Composit ion (% cover) of p l a n t types i n e a r l y and l a t e w i n t e r , 1979-80, f e c a l samples of North Thompson c a r i b o u determined by m i c r o h i s t o l o g i c a l a n a l y s i s . DIET COMPOSITION (% cover) PLANT TYPE TAXON OR PLANT PART EARLY WINTER (NOV - 15 JAN) LATE WINTER (16 JAN - MAR) ARBOREAL ALECTORIOID LICHENS A l e c t o r i a sp. B r y o r i a spp. T o t a l A l e c t o r i o i d 13.4 15.0 28.4 17.2 27.1 44.3 OTHER LICHENS 13.0 14.4 CONIFER Stems Needles 6.0 5.3 17.9 18.7 T o t a l Con i fe r 11.3 36.5 SHRUB3 Stems L e a ? 5.6 29.6 2.1 1.5 T o t a l Shrub 35.2 3.6 FORBS 11.7 1.2 GRAMINOIDSC 0.4 0.0 Inc ludes low-growing woody s p e c i e s . P a x i s t i m a m y r s i n i t e s leaves prominent . Grasses and sedges. 50 Tab le 5 . Percentage use of both forage types and v a r i o u s sources of a r b o r e a l l i c h e n s , observed a t c a r i b o u feed ing s i t e s ( exc lud ing those a t a c t i v e l o g g i n g o p e r a t i o n s ) i n f a l l and e a r l y w in te r of 1978-79 and 1979-80 combined. For l a t e w i n t e r , o n l y q u a l i t a t i v e r a t i n g s of use can be r e p o r t e d . N = number of o b s e r v a t i o n s ; ICH = ICH-low + ICH-h igh ; ESSF = ESSF- low + ESSF-h igh . FALL (OCT) EARLY WINTER (NOV - 15 JAN) LATE WINTER (16 JAN - MAR) PARKLAND ICH ESSF ICH + ESSF ESSF + PARKLAND FORAGE TYPE 3 % USE (N=50) % USE (N=71) % USE (N=93) % USE (N=164) R e l a t i v e Rat ing Use ARBOREAL LICHENS Source : L i t t e r f a l l b W i n d f a l l e n t r e e s Stand ing t r e e s 4 0 _0 8 11 11 12 13 48 10 12 32 very low very low dominant T o t a l 4 30 73 54 TERRESTRIAL LICHENS 30 0 0 0 0 SHRUBS 8 41 13 25 very low HERBS C 14 23 8 14 0 GRAMINOIDS 44 6 6 6 0 a Use of more than one fo rage type was sometimes noted a t a feed ing s i t e . G e n e r a l l y e n t i r e t r e e s , but a l s o broken t r e e tops >3 m i n l e n g t h . Low-growing woody s p e c i e s , such as Cornus canadensis and Rubus pedatus, a s s i g n e d to herb s t ra tum. 51 more important f o r c a r i b o u than the d a t a i n Tab le 5 i n d i c a t e . Bes ides wind, ava lanches and l ogg ing a l s o f e l l e d t r e e s which were used by c a r i b o u . Logging o c c u r r e d i n ICH-low to ESSF- low, throughout much of the w i n t e r , but l i c h e n on these f e l l e d t r e e s and s l a s h were used more i n e a r l y w i n t e r than l a t e w i n t e r . In a l l c a s e s , however, c a r i b o u a l s o used a v a i l a b l e a r b o r e a l l i c h e n and t e r r e s t r i a l forages i n ad jacent unlogged f o r e s t s . Use of forages i n the herb and low shrub s t r a t a was g e n e r a l l y l i m i t e d t o e a r l y w i n t e r (Table 4 and 5 ) , when they were not yet comple te ly b u r i e d , or were a c c e s s i b l e by pawing through r e l a t i v e l y sha l low snow (< 30 cm). In a d d i t i o n t o a wide v a r i e t y of herb l a y e r p l a n t s , c a r i b o u i n e a r l y w in te r used the low (mean he ight < 40 cm) evergreen shrub P a x i s t i m a m y r s i n i t e s , whose leaves were prominent i n the e a r l y w i n t e r f e c a l samples (B. D a v i t t , p e r s . comm. 1982) . Stems of t a l l e r deciduous shrub spec ies were a l s o used (Appendix B ) , but o n l y very l i g h t l y . Observat ions of f eed ing i n snow depths between 30 and 50 cm were l i m i t e d because of the r a p i d accumulat ion of snow, which may e x p l a i n why no c r a t e r i n g was observed w i t h i n t h i s range of snow depths . C r a t e r i n g was not observed i n snowpacks deeper than 50 cm, except f o r sha l low scrapes around f a l l e n t r e e s w i t h a r b o r e a l l i c h e n s , and f o r one repo r t of s i m i l a r sc rap ings to browse Jun ipe rus sp . (K. Blom, p e r s . comm. 1980). A d d i t i o n a l l y , d u r i n g a e r i a l surveys i n l a t e March and A p r i l , c a r i b o u t r a c k s were found o c c a s i o n a l l y congregat ing around l i m i t e d snow- f ree s i t e s i n the A l p i n e , suggest ing c a r i b o u o b t a i n e d herb stratum forages a t t h i s t ime . Otherwise , most obse rva t ions of c a r i b o u f o r a g i n g when snowpacks exceeded 50 cm were on a r b o r e a l l i c h e n s . N u t r i t i v e Q u a l i t y of A l e c t o r i o i d L ichens A l though there was a suggest ion of i n c r e a s i n g mean IVDMD's i n the order of A l e c t o r i a - l o w , A l e c t o r i a - h i g h , to B r y o r i a - h i g h , the d i f f e r e n c e s were not s i g n i f i c a n t (Table 6). Gross energy a l s o d i d not d i f f e r among the th ree Table 6. N u t r i e n t composi t ion and i n v i t r o dry matter d i g e s t i b i l i t y o f a r b o r e a l a l e c t o r i o i d l i c h e n genera from low and h igh e l e v a t i o n , mature f o r e s t s i t e s , North Thompson c a r i b o u w i n t e r range, w in te r 1979-80. CONSTITUENT3 . GROSS (X % dry matter, + ISD) ENERGY LICHEN ELEV HEM I ETHER (X kcal/g SAMPLE (m) PERIOD N d IVDMD CP NDF CELL CELL LIGNIN EXTRACT ASH + ISD) Bryoria spp. 1500- NOV- 5 37.4 a 4.44 a 37.8 a 28.4 a 4.3 a 5.1 a 1.98 a 1.65 a 4.11 a - High 1600 MAR (4.0) (0.77) (5.1) (5.9) (0.7) (0.6) (0.47) (0.15) (0.06) Alectoria sp. 1500- NOV- 5 32.4 a 2.12 b 22.4 b 19.9 b 1.4 b 1.1 b 4.98 b 1.10 b 4.19 a - High 1600 MAR (3.9) (0.16) (2.4) (2.2) (0.4) (0.4) (0.29) (0.26) (0.06) Alectoria sp. 900- DEC- 4 29.7 a 2.90 c 25.1 b 21.7 b 1.6 b 1.8 b 7.10 c 1.14 b 4.20 a - Low 1000 MAR (5.6) (0.37) (4.7) (4.5) (0.4) (0.5) (0.84) (0.22) (0.12) IVDMD, In vi t r o dry matter d i g e s t i b i l i t y (using cow rumen inoculum); CP, crude protein; NDF, neutral detergent fiber; ADF, acid detergent fiber; HEMI CELL, hemicellulose; CELL, cellulose. Values in a column with a common letter are not different at p < 0.05 as determined by ANOVA and Scheffe"'s multiple comparison test. Bryoria spp. was a random mixture of species of this genus; Alectoria sp. was exclusively Alectoria sarmentosa; only Alectoria was collected at 1000 ro because Bryoria was uncommon in the lower canopy. Number of monthly samples. 53 samples (Table 6 ) . In a l l o ther measures of n u t r i e n t compos i t i on , B r y o r i a -h igh had the h ighes t v a l u e s , except i t s ether e x t r a c t which was the l o w e s t . A l e c t o r i a - l o w was h igher than A l e c t o r i a - h i g h i n crude p r o t e i n , ADF and ether e x t r a c t (Table 6 ) . T e r r e s t r i a l Forage A v a i l a b i l i t y The shrub a v a i l a b i l i t y index shows tha t f o r a l l h a b i t a t s , shrub forages (< 2 m) were l a r g e l y b u r i e d by l a t e December ( i n t e r v a l 4) and remained so u n t i l the beg inn ing of snowmelt i n A p r i l ( a f t e r i n t e r v a l 11) (F igu re 9 ) . Because snow accumulat ion i n 1979-80 was s i m i l a r t o the l ong - te rm average (F igu re 3 ) , c a r i b o u face a s u b s t a n t i a l r e d u c t i o n i n the a v a i l a b i l i t y of shrub and other t e r r e s t r i a l forages most w i n t e r s . Deciduous shrubs or t r e e s i n the t a l l shrub st ratum (2 to 10 m) and c o n i f e r r e g e n e r a t i o n , a v a i l a b l e above the snowpacks of many h a b i t a t s throughout w i n t e r , were not eaten by c a r i b o u . P r i o r t o w i n t e r i n t e r v a l 4, snowpacks from ESSF- low up to A l p i n e were sha l lower than 101 cm (F igure 2 ) , and thus were r a t e d e i t h e r favourab le (< 55 cm) or un favourab le (56 t o 100 cm) f o r c r a t e r i n g . A l though c r u s t s were 2 common, they were < 5 cm t h i c k and u s u a l l y < 1000 g/cm h a r d . These c o n s t r a i n t s suggested that c r a t e r i n g c o n d i t i o n s i n suba lp ine and a l p i n e reg ions p r i o r t o i n t e r v a l 4 may have been w i t h i n a c c e p t a b l e l i m i t s f o r c a r i b o u , but not always f a v o u r a b l e . La te r i n December and i n t o A p r i l or May, however, these h igher e l e v a t i o n snowpacks exceeded the c r a t e r i n g t h r e s h o l d of 100 cm (F igu re 2 ) . A l though snowpack depths i n the lower e l e v a t i o n , ICH h a b i t a t s were l e s s than i n the h igher e l e v a t i o n s , they s t i l l were r a t e d e i t h e r as unfavourab le or as exceeding the t h r e s h o l d (> 100 cm) f o r c r a t e r i n g by i n t e r v a l 4 or 5, and remained so u n t i l i n t e r v a l 11 (F igu re 10) . A d d i t i o n a l l y over t h i s p e r i o d , snowpacks i n a l l ICH h a b i t a t - c e l l s , r e g a r d l e s s of depth , o f t e n were m u l t i c r u s t e d , and u s u a l l y conta ined e i t h e r c r u s t s i n the top 15 cm, or c r u s t s 54 WINTER INTERVAL I I I I I I I I I OCT NOV DEC JAN FEB MAR APR MAY JUN 1979 1980 F i g u r e 9. Net Shrub A v a i l a b i l i t y index i n mature and immature s e r a i types of h a b i t a t t y p e s , w in te r 1979-80, North Thompson. Index i s the weighted average shrub h e i g h t , minus the average snowpack depth (see t e x t ) . • , P a r k l a n d ; ESSF -h igh ; 0/ ESSF- low; 4, ICH -h igh ; A , ICH- low. 55 F i g u r e 10. I nd ices of c o n d i t i o n s f o r c a r i b o u f o r a g i n g i n the shrub and herb v e g e t a t i v e s t r a t a i n ICH Zone h a b i t a t t ypes , by s e r a i t ypes , w inter 1979-80, North Thompson: 1) . C r a t e r i n g c o n d i t i o n s based on snowpack depths (SD), where "+" a re c o n s i d e r e d favourab le (<55 cm), "-" a re unfavourable (>55 cm, <100 cm), and "—" a re beyond upper t h r e s h o l d (>100 cm); 2) . C r u s t c o n d i t i o n s ( C O , showing the number of s i t e s (a) w i t h c r u s t s i n the top 70 cm of snowpacks that were both > 5 cm t h i c k and > 1000 g/cm hard ( f i r s t v a l u e ) ; and (b) w i t h c r u s t s , r e g a r d l e s s of t h i c k n e s s or hardness, i n the top 15 cm of snowpacks (second v a l u e ) . In both c a s e s , the t o t a l number of s i t e s i s 4 (except i n i n t e r v a l 3 , when i t was 2 ) , because the 2 snow-p r o f i l e i n v e s t i g a t i o n s i t e s (see t e x t ) f o r each of the p a i r e d nor th and south aspect h a b i t a t - c e l l s a re combined; 3) . C r u s t i n g index (open c i r c l e s and broken l i n e ) , which i s the average, between p a i r e d nor th and south a s p e c t s , o f the sum of a l l i c e l a y e r or c r u s t t h i c k n e s s e s w i t h i n the top 70 cm of snowpacks (not shown i f snowpack depths > t h r e s h o l d of 100 cm); 4) . Net Shrub A v a i l a b i l i t y index (from F i g u r e 9) ( s o l i d c i r c l e s and l i n e ) . C •1 (D o o 3 rt H-3 C & UJ 5 CD < § 6 x o in *\ t - vi x o I—< Ui X MATURE ICH-HIGH so cc 0.0 120 80-40-0.0 0.0 0.0 0.0 0.4 M 0.4 0.2 4.4 2.4 2,4 o / o--1—I I I ICH-LOW • + • • - - - -' - -0,0 0,0 0.0 0,0 2,4 0,4 4.4 2,4 4,4 4.4 SD CC 0,0 4.4 £ 120 o m < m E 80-tr — X UJ X p--o o I \ /°-°-o / \ / / \ / / v / / M V I ? I 2 I 3 I 4 I 5 I 6 I 7 I 8 I 9 110 111 J . J . OCT NOV DEC JAN FEB MAR WINTER INTERVALS, 1979-80 IMMATURE ICH-HIGH so • + -CC 0.0 0,0 0,0 0,0 0,2 0.0 0.0 0.0 0.0 2.4 0,0 0.0 V " i i * i—i—i—i—r-T—r 15 -10 - 5 ICH-LOW SD • • • - - - - — — CC 0.0 0,0 0,0 0,0 0,4 2.0 2.0 0.0 0.0 4,4 0,0 0,0 r-15 -x 10 y I 1 I 2 1 3 1 4 I 5 I 6 I 7 • 8 I 9 "10'11 — I 1 I I I 1 5 g OCT NOV DEC JAN FEB MAR WINTER INTERVALS, 1979-80 > 5 cm t h i c k and > 1000 g/cm hard , or both (F igu re 10) , a l l of which f u r t h e r reduced t h e i r f a v o u r a b i l i t y f o r c r a t e r i n g . A r b o r e a l A l e c t o r i o i d L ichen Abundance And A v a i l a b i l i t y R e l i a b i l i t y of l i c h e n abundance est imates Us ing 109 double samples of a r b o r e a l l i c h e n to assess the r e l i a b i l i t y of my v i s u a l es t imates of l i c h e n abundance, a r e g r e s s i o n of a c t u a l l i c h e n weight a g a i n s t es t imated weight (number of SLU's) showed that the r e l a t i o n s h i p was l i n e a r and passed through the o r i g i n (Pearson 's r=0.88, p<0.001, n=109). A r a t i o es t imato r (r=Y/X) was computed, because the r e s i d u a l v a r i a n c e of Y ( a c t u a l weight) was approx imate ly p r o p o r t i o n a l to X (es t imated weight) (Cochran 1977:158) . The r a t i o between one SLU and the a c t u a l l i c h e n weight was 1 .0 :11 .4 (SE r a t i o = 0 . 3 9 , n=109). The i n d i v i d u a l sample r a t i o s v a r i e d from 4.4 t o 2 1 . 6 . Because the o v e n - d r i e d weight of one SLU was 5.0 g , the o v e r a l l r a t i o ( 1 .0 :11 .4 ) conver ts to 1.0 g est imated weight t o 2 .3 g a c t u a l we ight . In summary, these l i c h e n abundance est imates were r e l a t i v e l y p r e c i s e ( i . e . , c o n s i s t e n t ) but i n a c c u r a t e , and i t was assumed t h a t t h i s was s i m i l a r f o r a l l my e s t i m a t e s . Furthermore, i t was assumed tha t t h e r e was an o v e r a l l p o s i t i v e c o r r e l a t i o n , but u n s p e c i f i e d p r e d i c t i v e r e l a t i o n s h i p , between v i s u a l l y es t imated abundance and a c t u a l biomass of l i c h e n a t the p l o t l e v e l . The re fo re , p l o t t o t a l s of v i s u a l l i c h e n est imates were taken as acceptab le i n d i c e s of r e l a t i v e l i c h e n abundance. Abundance of a r b o r e a l l i c h e n 1. W i t h i n and between h a b i t a t types A l l mature f o r e s t h a b i t a t - c e l l s were sampled f o r l i c h e n (Table 7 ) . L o g i s t i c a l c o n s t r a i n t s p rec luded an i n v e n t o r y i n a l l immature h a b i t a t - c e l l s except i n ESSF- low (Table 7 ) , however they a l l a t l e a s t r e c e i v e d a " w a l k -through" reconna issance f o r l i c h e n abundance. Only aspect c o u l d be compared w i t h i n a l l h a b i t a t t y p e s . But f i r s t , i t 58 Tab le 7 . L o c a t i o n s , s i t e and stand c h a r a c t e r i s t i c s , and a r b o r e a l a l e c t o r i o i d l i c h e n abundance est imates f o r the 0 t o 6 m f o r e s t canopy stratum of f o r e s t stands i n the North Thompson. LICHEN PLOT TOTALS (SLU/0.02 ha) HABITAT HABITAT TYPE LOCATION3 STAND No. N* X ELEV (m) ASP= STAND AGE (yr) CV (%) RANGE MEDIAN (+95% CI) IMEAN] MATURE STANDS: ICH- BLUE R. 1 5 875 S 251-300 4.6 92.3 0.5-9.75 0.75 low BLUE R. 2 5 887 N 201-250 0.7 52.8 0.25-1.25 (0.5-8.25) [2.6] ICH- MILEDGE 3 5 1231 S 251-300 9.4 67.0 1.75-19.0 7.75 high BLUE R. 4 5 1212 N 251-300 8.4 32.0 5.50-11.5 (5.5-11.5) [8.9] ESSF- AVOLA 5 4 1506 S 141-200 23.3 28.8 15.0-31.75 low AVOLA 6 3 1568 S 251-300 33.7 44.8 23.25-51.0 AVOLA 7 3 1583 s 251-300 44.0 64.3 25.0-76.5 AVOLA 8 S 1611 s 201-250 56.5 50.8 27.25-99.0 35.0 AVOLA 9 3 1657 s 201-250 31.1 37.1 19.0-42.0 (27.5-44.5) AVOLA 10 5 1512 N 141-200 42.4 22.3 33.25-56.5 [39.0] AVOLA 11 3 1610 N 251-300 28.4 66.6 7.5-44.5 AVOLA 12 4 1623 N 201-250 33.4 32.2 22.25-46.5 AVOLA 13 3 1650 N 201-250 51.2 17.8 41.0-58.5 ESSF- AVOLA 14 4 1718 K 141-200 53.1 35.8 30.25-69.5 38.5 high AVOLA 15 2 1740 S 201-250 52.9 46.5 35.5-70.25 (30.5-68.0) AVOLA 16 3 1760 S 141-200 33.0 39.4 21.25-47.0 [43.4] MILEDGE 17 5 1800 s 141-200 38.1 12.4 30.25-42.0 PARK- MILEDGE 18 3 1845 s 201-250 SO.3 17.4 42.0-59.5 70.4 LAND MILEDGE 19 3 1827 N 201-250 73.2 49.6 38.5-110.75 (42.0-145.5) GRD HOG 20 3 1800 H 201-250 143.2 24.8 106.5-177.5 [88.9] IMMATURE STANDS: ESSF- AVOLA 21 4 1672 N 41-60 3.7 37.4 2.5-5.5 low AVOLA 22 2 1615 S 81-100 9.3 7.7 8.75-9.75 AVOLA 23 7 1637 N 100-150 66.6 40.0 18.0-100.0 See Figure 1. Number of plots. C Aspect class: N = 315°-0° and 0°-135°; S = 135°-315° d Total number of Standard Lichen Units in the 0 to 6 mforest canopy stratum per 0.02 ha. 59 i s important to note tha t the no r th aspect of the Park land l o c a t e d on Ground Hog Mountain conta ined two to th ree t imes more l i c h e n than the other two Pa rk land stands (Table 7 ) . Th is d i f f e r e n c e was due t o f a c t o r s independent of aspect ( reconnaissance of nearby south aspect stands on Ground Hog found s i m i l a r l i c h e n abundances), so I d i d not i n c l u d e i t i n the a n a l y s i s of aspect f o r the P a r k l a n d . No s i g n i f i c a n t d i f f e r e n c e ( a l l p - v a l u e s >0.2) were found between mature f o r e s t s on nor th and south aspects w i t h i n any of the h a b i t a t t y p e s , except i n ICH-low where the d i f f e r e n c e was marg ina l (Mann-Whitney T=19.0, 0.05<p<0.1). In ESSF- low, the most f u l l y i n v e n t o r i e d h a b i t a t t y p e , there were no s i g n i f i c a n t d i f f e r e n c e s i n l i c h e n abundance i n mature stands between: the 1500 t o 1600 m and 1601 to 1680 m e l e v a t i o n subc lasses (M-W T=294, p=0.16); the four t reatment combinat ions of the aspect and e l e v a t i o n f a c t o r i a l ( K r u s k a l l - W a l l i s T=3.92, p=0.27); or the th ree stand age subc lasses of 141 t o 200 y e a r s , 201 t o 250 y e a r s , and 251 to 300+ years (K-W T=2.09, p=0.35). Nor was the re a d i f f e r e n c e i n l i c h e n abundances between these n i n e mature s tands , when cons ide red as independent t reatments (K-W T=12.36, p=0.14). In comparing the two s e r a i types (immature and mature) w i t h i n ESSF- low, stand number 23 (Table 7) was c l a s s e d as immature, but of the 70 t r e e s sampled, 26% were veterans (mature) w i t h s i g n i f i c a n t l y g r e a t e r l i c h e n loads than the immature t r e e s (M-W T=1041.5, p<0.0001). Th is l a r g e component of v e t e r a n t r e e s i n f l a t e d the l i c h e n abundance est imates f o r t h i s s tand , and so the es t imates were cons idered u n r e p r e s e n t a t i v e of the 100 t o 141 year o l d f o r e s t age c l a s s . When stand 23 i s i n c l u d e d i n the immature s e r a i t ype , the re i s no d i f f e r e n c e between l i c h e n loads of immature and mature ESSF- low f o r e s t s (M-W T=278.0, p=0.5) , but i f i t i s exc luded , immature had s i g n i f i c a n t l y lower l i c h e n abundance than mature stands (M-W T=23.0, p<0.0002). Reconnaissances of immature stands i n other h a b i t a t types a l s o 60 suggested tha t they con ta ined much l e s s l i c h e n than p a i r e d mature s tands . L ichen abundance i n mature h a b i t a t - c e l l s (Table 7) d i f f e r e d between the f i v e h a b i t a t types ( K r u s k a l l W a l l i s T=49.9, p<0.001), and i n c r e a s e d w i t h e l e v a t i o n from ICH-low up to P a r k l a n d . (Spearman's rank c o r r e l a t i o n between e l e v a t i o n and l i c h e n abundance of i n d i v i d u a l p l o t s = 0 . 7 5 ; p<0.01, n=76). In summary, a l though i n each h a b i t a t type v a r i a b i l i t y i n l i c h e n abundance w i t h i n and between stands was r e l a t i v e l y h igh (CV's i n Tab le 7 ) , the f o l l o w i n g c o n d i t i o n s were accepted f o r c a l c u l a t i n g l i c h e n a v a i l a b i l i t y : 1) The o r i g i n a l d i v i s i o n of stands i n t o immature (<140 years ) and mature (>140 years ) s e r a i types can be ma in ta ined , assuming that mature h a b i t a t - c e l l s g e n e r a l l y conta ined much g rea te r l i c h e n q u a n t i t i e s than p a i r e d immature h a b i t a t - c e l l s . 2) L i chen p l o t t o t a l s of a l l mature stands w i t h i n h a b i t a t types can be p o o l e d , because the i n i t i a l s e p a r a t i o n by aspect was found not to be impor tan t . 3) The f i v e f o r e s t e d h a b i t a t types a re v a l i d d i v i s i o n s f o r l i c h e n abundance e s t i m a t e s , and an o v e r a l l es t imate of l i c h e n abundance f o r mature h a b i t a t - c e l l s i s the median of l i c h e n p l o t t o t a l s f o r the h a b i t a t type (Table 7 ) . 2 . Abundance of a l e c t o r i o i d l i c h e n by genera The r e l a t i v e abundance of a l e c t o r i o i d l i c h e n genera ( A l e c t o r i a sp . and B r y o r i a spp. ) i n the 0 t o 6 m f o r e s t canopy stratum d i f f e r e d between h a b i t a t types ( F i g u r e 11) . In mature s tands , A. sarmentosa comprised v i r t u a l l y a l l of the l i c h e n load i n the ICH h a b i t a t s , but d e c l i n e d s t e a d i l y w i t h i n c r e a s i n g e l e v a t i o n u n t i l i t represented l e s s than 7% i n the P a r k l a n d . In immature ESSF- low s tands , the r e l a t i v e p r o p o r t i o n s of the two genera resembled those i n the P a r k l a n d , r a t h e r than those i n mature ESSF- low stands (F igu re 11) . 61 MATURE IMMATURE STANDS STANDS (ESSF-LOW) 50 100 0 50 100 PERCENT OF TOTAL LICHEN ESTIMATE F i g u r e 11 . R e l a t i v e abundance (%) of A l e c t o r i a sp . ( c l e a r ) i n the 0 to 6 m mature f o r e s t stands by h a b i t a t type , low, Nor th Thompson. B r y o r i a spp. (c ross -hatched) and stratum of the f o r e s t canopy, f o r and f o r immature stands i n j u s t ESSF-62 3 . A r b o r e a l l i c h e n l i t t e r The abundance of a l e c t o r i o i d l i c h e n l i t t e r i n mature stands (F igu re 12) was s i g n i f i c a n t l y d i f f e r e n t among the f i v e h a b i t a t types ( K r u s k a l l - W a l l i s T=11.97, p<0.02), decreas ing w i t h i n c r e a s i n g e l e v a t i o n (Spearman's r= -0 .40 , p<0.01, n=65), i n c o n t r a s t to l i c h e n abundance i n the 0 to 6 m canopy stratum which i n c r e a s e d w i t h e l e v a t i o n (Table 7 ) . However, the r e l a t i v e abundance of A. sarmentosa l i t t e r d e c l i n e d w i t h i n c r e a s i n g e l e v a t i o n (F igu re 12) , p a r a l l e l i n g i t s t rend i n r e l a t i v e abundance on t r e e s ( F i g u r e 11 ) . A v a i l a b i l i t y of a r b o r e a l l i c h e n over w in te r L ichen abundance w i t h i n the 0 to 6 m f o r e s t canopy (F igu re 13) i n c r e a s e d w i t h i n c r e a s i n g canopy h e i g h t , whereas the lower l i m i t of l i c h e n i n the canopy i n c r e a s e d w i t h i n c r e a s i n g e l e v a t i o n of the h a b i t a t t y p e . These v e r t i c a l l i c h e n p r o f i l e s , together w i t h the median l i c h e n p l o t t o t a l s (Table 7 ) , and the 2 m g r a z i n g - r e a c h of c a r i b o u , were used t o generate curves of l i c h e n a v a i l a b l e from d i f f e r e n t g r a z i n g bases (mean snow depth minus mean c a r i b o u t r a c k depth) f o r each h a b i t a t t ype , and a r e g r e s s i o n was f i t t e d to each curve (F igu re 14) . In each h a b i t a t , l i c h e n a v a i l a b l e to c a r i b o u i n c r e a s e d i n a c u r v i l i n e a r manner as the g r a z i n g base rose (F igu re 14) . The form of the l i c h e n a v a i l a b i l i t y curves d i f f e r e d because the v e r t i c a l d i s t r i b u t i o n p r o f i l e s of l i c h e n d i f f e r e d between h a b i t a t s (F igu re 13) . For each h a b i t a t type , es t imates of l i c h e n a v a i l a b i l i t y were c a l c u l a t e d f o r n o r t h and south a s p e c t s , because g r a z i n g base d i f f e r e d between them. Es t imates were not made f o r immature h a b i t a t - c e l l s due t o l a c k of da ta (Table 7 ) . Snow courses were not sampled a f t e r l a t e March, so g r a z i n g bases a f t e r t h i s t ime were approximated by t o t a l snow depths (F igu re 2 ) . Instantaneous est imates of a v a i l a b l e a r b o r e a l l i c h e n (F igu re 15) were v e r y low i n a l l h a b i t a t s p r i o r t o the heavy s n o w f a l l s of i n t e r v a l 4, w i t h ESSF- low p r o v i d i n g the most l i c h e n . Over the deep snowpack p e r i o d of 63 % ALECTORIA 5 HI 86 80 12 LU <_> z < a z CD < < 2 Li_ -C LU O a •—I o « c r o i — u LU 4H 3 H 2 J T I l I J. I T I I I I JL ICH LOW (9) ICH HIGH (10) ESSF LOW (25) ESSF HIGH (12) PARK LAND (9) HABITAT TYPE Figure 12. Abundance of arboreal alectorioid lichen on the ground, as an index of lichen l i t t e r f a l l abundance, for mature serai types of habitat types. Median, 95% confidence limits of the median, interquartile range, and range i n plot totals of l i t t e r f a l l abundance, the number of plots sampled (values in parentheses), and the percentage of the total lichen l i t t e r f a l l estimate consisting of Alectoria sp. are presented by habitat type. F i g u r e 13. D i s t r i b u t i o n of a r b o r e a l a l e c t o r i o i d l i c h e n abundance by 0 .5 m he ight i n t e r v a l s i n the 0 t o 6 ID f o r e s t canopy stratum of mature s e r a i types by h a b i t a t t y p e s , North Thompson. Values i n parentheses denote sample s i z e of t r e e s randomly s e l e c t e d from l i c h e n p l o t s . 65 GRAZING BASE (m) Figure 14. Relationship between instantaneous estimates of arboreal alectorioid lichen available to caribou (assuming a grazing-reach of 2.0 m) and grazing base level above ground level in mature serai types of habitat types, North Thompson. The following regression equations are empirically fjtted to be used only for predictive purposes (all p-values <0.05, and a l l r -values >0.98); L = arboreal lichen available in a 2.0 m forest canopy stratum (SLU per 0.02 ha; see text); GB = Grazing Base (m) = (Mean Snow Depth) - (Mean Caribou Track Depth); note that equation for Parkland is not used for GB > 3 m; curve for ICH-low is not shown:. . Parkland (•), ln(L+l) = .3325 GB + 1.7936 GB - .7503 GB + .0856 GB ; ESSF-high (#), ln(L+l) = .1484 + 1.9432 GB - .4026 GB^  + .0278 GB^ ; ESSF-low (O), ln(L) = .2162 + 2.2918 GB - .7019 GB^  + .0764 GB^ ; ICH-high (A)» ln(L+l) = .3282 + 1.0336 GB - .2906 GB^  + .0278 GB ; ICH-lOW ln((L+l)*10) =2.3364 + 0.1697 GB - .0243 GB . 66 A5n F i g u r e 15. Instantaneous est imates of a r b o r e a l a l e c t o r i o i d l i c h e n a v a i l a b l e to c a r i b o u (assuming a g r a z i n g - r e a c h of 2 .0 m) i n mature s e r a i types of h a b i t a t t y p e s , averaged between n o r t h and south a s p e c t s , over snow-free p e r i o d s and w i n t e r 1979-80, North Thompson. Symbols as i n F igures 9 and 14; P a r k l a n d - B (broken l i n e ) and ICH- low-B (broken l i n e ) assume that the a b s o l u t e abundance of l i c h e n i n the 0 to 6 m f o r e s t canopy stratum equals that of ESSF- low and ICH-h igh , r e s p e c t i v e l y (see t e x t ) . 67 i n t e r v a l s 4 t o 11, the r e l a t i v e amount of a v a i l a b l e l i c h e n was o rdered , from low t o h i g h , a long the ascending e l e v a t i o n a l g rad ient of ICH- low t o Park land (F igu re 15) . Maximum l i c h e n a v a i l a b i l i t i e s occur red i n i n t e r v a l s 10 or 11, when snow depths were maximum (F igu re 2) and hence when g r a z i n g bases were h i g h e s t . A f t e r i n t e r v a l 11 ( e a r l y A p r i l ) , s p r i n g snowmelt caused g r a z i n g bases t o lower , and thus l i c h e n a v a i l a b i l i t i e s to d e c l i n e ( F i g u r e 15) . Es t imates of abso lu te abundance of l i c h e n i n Park land were so much g reate r than a l l other h a b i t a t s (Table 7 ) , t ha t the q u e s t i o n of o v e r e s t i m a t i o n a r o s e , and s i m i l a r l y , the ve ry low est imates i n ICH-low (Table 7) may be underest imates . Taking a v e r y c o n s e r v a t i v e approach, however , i f the median l i c h e n p l o t t o t a l of Pa rk land i s reduced by 50% to equal tha t of ESSF- low, and i f the median l i c h e n p l o t t o t a l of ICH-low i s r a i s e d t o equal tha t of ICH-h igh (Table 7 ) , the r e l a t i v e r a n k i n g of l i c h e n a v a i l a b i l i t i e s e s s e n t i a l l y remains unchanged among h a b i t a t t y p e s , p a r t i c u l a r l y over the deep snowpack i n t e r v a l s of 4 to 11 (see ICH- low-B and P a r k l a n d - B , F i g u r e 15) . In both c a s e s , t h i s p r i m a r i l y r e f l e c t s the impact of d i f f e r i n g snow c o n d i t i o n s ( i . e . , g r a z i n g base l e v e l s ) among h a b i t a t types on r e l a t i v e l i c h e n a v a i l a b i l i t i e s . In other words, even i f i t i s assumed tha t the a b s o l u t e abundance of l i c h e n (median l i c h e n p l o t t o t a l s ) among h a b i t a t types w i t h i n each of the B i o g e o c l i m a t i c Zones of ICH and ESSF are e q u a l , these est imates con f i rm tha t l i c h e n a v a i l a b i l i t i e s w i l l i n c r e a s e w i th e l e v a t i o n , from ICH-low up to P a r k l a n d , over most of the w i n t e r . Instantaneous est imates of a v a i l a b l e l i c h e n (F igure 15) assume no c ropp ing of l i c h e n s i n preceeding i n t e r v a l s . There fo re , another method of i n d e x i n g the v a l u e of a h a b i t a t f o r c a r i b o u g r a z i n g a r b o r e a l l i c h e n s i s by the d i r e c t i o n and r a t e o f 'change i n i t s instantaneous l i c h e n a v a i l a b i l i t y e s t i m a t e s . H a b i t a t s w i t h h i g h e r , p o s i t i v e r a t e s of change i n a v a i l a b l e l i c h e n , would presumably p r o v i d e g r e a t e r q u a n t i t i e s of "new", u n e x p l o i t e d 68 l i c h e n throughout the w i n t e r as g r a z i n g bases e l e v a t e d . Over the deep snowpack w in te r i n t e r v a l s of 4 t o 11 ( F i g u r e 15) , l i n e a r r e g r e s s i o n s of a v a i l a b l e l i c h e n a g a i n s t t ime i n t e r v a l were p o s i t i v e and s i g n i f i c a n t i n a l l f i v e h a b i t a t types ( a l l p - v a l u e s <0.006). The s lopes of these r e g r e s s i o n s a re i n d i c e s of the r a t e s of i n c r e a s e i n a v a i l a b l e l i c h e n . Covar iance a n a l y s i s showed tha t the s lopes were s i g n i f i c a n t l y d i f f e r e n t among h a b i t a t s (p<0.0001), and the v a l u e s p r o g r e s s i v e l y i n c r e a s e d w i t h e l e v a t i o n from ICH-low t o P a r k l a n d . The above r e l a t i o n s h i p s h e l d when the lower est imates of l i c h e n a v a i l a b i l i t i e s f o r Park land ( P a r k l a n d - B , F i g u r e 15) were used. DISCUSSION Winter D ie t A r b o r e a l l i c h e n s , p a r t i c u l a r l y a l e c t o r i o i d s p e c i e s , were a major component of the c a r i b o u ' s w in te r d i e t , which became i n c r e a s i n g l y important as snowpacks deepened. Car ibou r e a d i l y and o p p o r t u n i s t i c a l l y obta ined a r b o r e a l l i c h e n s from s t a n d i n g , w i n d f a l i e n or l o g g e r - f e l l e d t r e e s , and from l i t t e r f a l l , but s tand ing t r e e s were the pr imary source , e s p e c i a l l y i n l a t e w i n t e r . The a v a i l a b i l i t y of t e r r e s t r i a l fo rages favoured by c a r i b o u ( p l a n t s i n the herb stratum and low (< 40 to 50 cm) evergreen shrubs) d e c l i n e d s u b s t a n t i a l l y everywhere by e a r l y w i n t e r , and remained e s s e n t i a l l y n e g l i g i b l e through the remainder of w i n t e r . Th is was due to b u r i a l by snow and to p r o g r e s s i v e d e t e r i o r a t i o n of c r a t e r i n g c o n d i t i o n s , which rendered b u r i e d fo rage more d i f f i c u l t t o d e t e c t and o b t a i n (Bergerud 1974a, Fancy and White 1985, R u s s e l l and M a r t e l l 1984). Over most of the w i n t e r , t h e r e f o r e , a r b o r e a l a l e c t o r i o i d l i c h e n s e v i d e n t l y were a more economic a l t e r n a t i v e t o c a r i b o u than e i t h e r c r a t e r i n g f o r b u r i e d f o rages , or browsing c o n i f e r r egene ra t i on and the l i m i t e d amounts of t a l l e r deciduous shrubs a v a i l a b l e above snowpack s u r f a c e s . Both the temporal t rend i n the w in te r d i e t 69 compos i t ion and the genera l l a c k of c r a t e r i n g a c t i v i t y of c a r i b o u i n the p resent study agree w i t h the r e s u l t s of p rev ious s t u d i e s of mountain ca r ibou ( B l o o m f i e l d 1979, Edwards and R i t c e y 1959, 1960, Freddy 1974, Layser 1974, S c o t t and Servheen 1984, 1985, Simpson et a l . 1985). The amount of a r b o r e a l l i c h e n i n the e a r l y w in te r d i e t of c a r i b o u depended on the h a b i t a t s used. For example, i n November and December, a l e c t o r i o i d l i c h e n s were used more i n ESSF than i n ICH h a b i t a t s (Table 5 ) , l a r g e l y because of the fo rmer ' s deeper snowpacks. Another f a c t o r tha t c o n t r i b u t e d t o t h i s , however, was the g r e a t e r a v a i l a b i l i t y o f l i c h e n s i n ESSF h a b i t a t s , e s p e c i a l l y i n ESSF- low, than i n ICH h a b i t a t s d u r i n g e a r l y w in te r ( F igu re 15) . In t h i s study , as i n many other mountain c a r i b o u s t u d i e s (Edwards and R i t c e y 1959, 1960, Evans 1964, Freddy 1974, Layser 1974, S c o t t and Servheen 1984, Simpson et a l . 1985), f eed ing s i t e examinat ions suggested that a l e c t o r i o i d l i c h e n was the major , i f not almost s o l e , fo rage of ca r ibou i n l a t e w i n t e r . Whi le demonstrat ing that a l e c t o r i o i d l i c h e n s d i d i n c r e a s e i n prominence compared to e a r l y w i n t e r , a n a l y s i s of l a t e w i n t e r f e c a l m a t e r i a l r e v e a l e d h i g h p r o p o r t i o n s of both c o n i f e r and n o n - a l e c t o r i o i d l i c h e n components (Table 4 ) . The o c c a s i o n a l u t i l i z a t i o n by c a r i b o u of c o n i f e r m a t e r i a l without a r b o r e a l l i c h e n has been noted i n some s t u d i e s (Bergerud 1972, F l i n n 1959). But I found that a l l f eed ing s i t e s a t c o n i f e r subs t ra tes possessed a r b o r e a l l i c h e n s , and that a l e c t o r i o i d l i c h e n samples o f t e n conta ined c o n i f e r l i t t e r . Both obse rva t i ons suggest tha t c o n i f e r m a t e r i a l was u n i n t e n t i o n a l l y i nges ted (see a l s o A h t i and Hepburn 1967, Bergerud 1972, Bergerud and R u s s e l l 1964, B l o o m f i e l d 1979, Edwards and R i t c e y 1960). In e a r l y w i n t e r , both a r b o r e a l and t e r r e s t r i a l , n o n - a l e c t o r i o i d l i c h e n s were ea ten . The f i n d i n g of c r u s t o s e l i c h e n on c o n i f e r bark i n the rumen 70 contents suggested that some of these l i c h e n s were u n i n t e n t i o n a l l y i n g e s t e d . In l a t e w i n t e r , c r a t e r i n g was r a r e l y observed , and the n o n - a l e c t o r i o i d l i c h e n s used were probab ly main ly a r b o r e a l f o l i o s e s p e c i e s , as was found by B l o o m f i e l d (1979) . R o c h e l l e (1980) and Thomas et a l . (1984), working w i t h b l a c k - t a i l e d deer (0 . h . columbianus) and barren -ground c a r i b o u (R. t . g roen land icus ) r e s p e c t i v e l y , found that IVDMD's of a r b o r e a l a l e c t o r i o i d l i c h e n s were c o n s i d e r a b l y h igher than that of c o n i f e r m a t e r i a l . T h i s suggests tha t i n the present study c o n i f e r m a t e r i a l was p o s s i b l y overest imated r e l a t i v e to a l e c t o r i o i d l i c h e n s by f e c a l a n a l y s i s because of d i f f e r e n t i a l d i g e s t i b i l i t y . I t i s not c l e a r i f and i n what d i r e c t i o n o ther forages were mis represented by the same a n a l y s i s , however. N e v e r t h e l e s s , r e g a r d l e s s of the q u a n t i t a t i v e accuracy of the f e c a l a n a l y s i s , i t was assumed that a summation of the a l e c t o r i o i d l i c h e n and c o n i f e r f r a c t i o n s would index the importance of the former fo rage to c a r i b o u . Co r respond ing ly , these l i c h e n s were an important e a r l y w in te r fo rage ( index of 40%), and the p r i n c i p a l l a t e w i n t e r fo rage ( index of 81%) (Table 4 ) . N u t r i t i o n a l Va lue of A l e c t o r i o i d L ichens A l though d e f i c i e n t i n m i n e r a l s and n i t r o g e n , forage l i c h e n s c o n t a i n a h igh p r o p o r t i o n of s o l u b l e ca rbohydra tes , and t h e r e f o r e a re h i g h l y d i g e s t i b l e ( i n v i v o d i g e s t i b i l i t i e s rang ing from 56 t o 75% (White et a l . 1981)) by c a r i b o u and r e i n d e e r , thereby p r o v i d i n g an important source of energy d u r i n g the e n e r g e t i c s t r e s s of w in te r ( K l e i n 1982, R u s s e l l and M a r t e l l 1984, Skogland 1984, White et a l . 1981). Consequent ly , the mean IVDMD's I ob ta ined f o r B r y o r i a spp. (37.4%) and A l e c t o r i a s p . (29.7 to 32.4%) p robab ly s u b s t a n t i a l l y underest imated t h e i r t r u e i n v i v o DMD's by c a r i b o u . One reason f o r t h i s may have been the use of cow rumina l inoculum, which was not adapted to d i g e s t i n g l i c h e n s (see Holechek et a l . 1982b, Thomas and Kroeger 1980, 71 T r u d e l l et a l . 1980). For example, the IVDMD l e v e l s f o r a l e c t o r i o i d l i c h e n s determined i n s t u d i e s u s i n g rumen inoculum of bar ren -ground c a r i b o u (Thomas et a l . 1984) and b l a c k - t a i l e d deer ( R o c h e l l e 1980) adapted to these l i c h e n s were c o n s i d e r a b l y h igher (> 59%). That A l e c t o r i a sp . r e l i n q u i s h e d prominence i n the lower f o r e s t canopy to B r y o r i a spp. w i t h i n c r e a s i n g e l e v a t i o n ( F i g u r e 11) was observed by o thers ( A h t i 1962, B l o o m f i e l d 1979, Edwards et a l . 1960, Freddy 1974). I t i s not c l e a r , however, i f these two genera d i f f e r a p p r e c i a b l y i n n u t r i t i o n a l v a l u e to c a r i b o u . F i r s t , B r y o r i a was h ighest i n a l l i n d i c e s t o c e l l w a l l components (NDF, ADF, h e m i c e l l u l o s e , c e l l u l o s e and l i g n i n ) , but i t s mean IVDMD tended t o be h i g h e s t , though not s i g n i f i c a n t l y . However, con f idence i n t h i s l a t t e r s t a t i s t i c a l e v a l u a t i o n i s l i m i t e d , because Person et a l . (1980) demonstrated tha t the r e l a t i v e d i g e s t i b i l i t i e s of l i c h e n s by c a r i b o u measured by i n v i t r o and i n v i v o (ny lon -bag) techniques can d i s a g r e e . Second, the crude p r o t e i n content of both genera was below the 5.5 t o 9.0% d i e t a r y range est imated necessary f o r n i t r o g e n maintenance by w i l d ruminants (Robbins 1983). N e v e r t h e l e s s , a l though Rang i fe r possess p h y s i o l o g i c a l adapta t ions t o n i t r o g e n d e f i c i e n t w i n t e r d i e t s ( review of R u s s e l l and M a r t e l l 1984), the h igher crude p r o t e i n of B r y o r i a may confer some advantage by r e t a r d i n g the d e p l e t i o n of l a b i l e p r o t e i n reserves d u r i n g nega t i ve n i t r o g e n balance (Gasaway and Coady 1974). F i n a l l y , because l i c h e n d i e t s a re a l s o u s u a l l y poor i n m i n e r a l s (Hyvar inen et a l . 1977), the h igher ash content of B r y o r i a may be of some b e n e f i t t o c a r i b o u . Abundance and A v a i l a b i l i t y of A r b o r e a l A l e c t o r i o i d L ichen The p o s i t i v e a s s o c i a t i o n between a r b o r e a l a l e c t o r i o i d l i c h e n abundance w i t h i n the lower f o r e s t canopy stratum (0 t o 6 m) and e l e v a t i o n support the p r e l i m i n a r y assessments of Edwards et a l . (1960) and the v i s u a l a p p r a i s a l s of A h t i (1962) and M i l l e r (1977) w i t h i n the study a r e a . S i m i l a r l y , wide s p a t i a l 72 v a r i a b i l i l t y i n a r b o r e a l l i c h e n abundance w i t h i n h a b i t a t s ( e l e v a t i o n zones) was noted a l s o by A n t i (1962) and by M i l l e r (1977). T h i s v a r i a t i o n may be p a r t i a l l y e x p l a i n e d by macrotopographic f e a t u r e s o ther than a s p e c t , such as landtype ( D e t r i c k 1984). However, w h i l e D e t r i c k ' s (1984) r e s u l t s suggest tha t e l e v a t i o n a lone may not be the best p r e d i c t o r of a r b o r e a l l i c h e n i n the lower 6 m of mature f o r e s t s , i t was adequate f o r d e s c r i b i n g the broad t rend i n l i c h e n abundance observed i n the present s tudy . The tendency f o r l i c h e n abundance i n the lower 6 m of the f o r e s t canopy stratum to i n c r e a s e w i t h he ight up the canopy has a l s o been noted by o thers (Edwards et a l . 1960, D e t r i c k 1984, Van Daele and Johnson 1983). F a c t o r s a f f e c t i n g v e r t i c a l l i c h e n p r o f i l e s i n c l u d e snowpack depths , a v a i l a b i l i t y of branch s u b s t r a t e or shape of t r e e s , and p rev ious g r a z i n g of l i c h e n ( A h t i 1962, Edwards et a l . 1960, Schroeder 1974, Tay lo r 1922). A d d i t i o n a l l y , the f i n d i n g t h a t the lower-most occur rence of l i c h e n i n the f o r e s t canopy p r o g r e s s i v e l y s h i f t e d upwards w i t h i n c r e a s i n g e l e v a t i o n , was a l s o noted by M i l l e r (1977) . Th is t rend was p o s i t i v e l y c o r r e l a t e d w i t h snowpack depths w i t h i n the p resen t study ; and o the r s t u d i e s have suggested tha t these lower p o s i t i o n s of l i c h e n a re s n o w - l i n e s (Gough 1975, Lang et a l . 1980, M i l l e r 1977, Schroeder 1974). In summary, a l e c t o r i o i d l i c h e n abundance w i t h i n the lower f o r e s t canopy stratum i n c r e a s e d w i t h i n c r e a s i n g he ight up the canopy w i t h i n h a b i t a t s , and w i t h i n c r e a s i n g e l e v a t i o n among h a b i t a t s . Consequent ly , f o r much of the w i n t e r , l i c h e n a v a i l a b l e to c a r i b o u a l s o i n c r e a s e d b r o a d l y w i t h e l e v a t i o n (from ICH-low up t o P a r k l a n d ) , because of a p o s i t i v e a s s o c i a t i o n between e l e v a t i o n and snowpack depth , and thus , very g e n e r a l l y , w i t h g r a z i n g base h e i g h t . An important except ion o c c u r r e d i n the e a r l y p o r t i o n of e a r l y w i n t e r , i n snow- f ree or sha l low snow c o n d i t i o n s , when ESSF- low i n s t e a d of h igher e l e v a t i o n h a b i t a t s o f f e r e d the most a v a i l a b l e l i c h e n (F igure 15) . And 73 importantly, the p o s i t i v e r e l a t i o n s h i p between r e l a t i v e l i c h e n a v a i l a b i l i t y and elevation holds, even i f i t i s conservatively assumed that the absolute abundance of l i c h e n ( i n the lower 6 m f o r e s t canopy stratum) among habitat types within each of the Biogeoclimatic Zones of ICH and ESSF are equal, rather than increasing with elevation. 74 V. SEASONAL DISTRIBUTION OF CARIBOU INTRODUCTION The major purpose of t h i s s e c t i o n i s to eva lua te i f the sample of r a d i o c o l l a r e d c a r i b o u was r e p r e s e n t a t i v e of the w i n t e r i n g c a r i b o u p o p u l a t i o n i n the study a r e a . Th is assessment i s c r i t i c a l , because observa t ions of n o n -r a d i o c o l l a r e d c a r i b o u were o f t e n f o r t u i t o u s l y o b t a i n e d , e s p e c i a l l y d u r i n g ground surveys , and cou ld be b i a s e d to more open h a b i t a t s , due to d i f f e r e n t i a l v i s i b i l i t y among h a b i t a t s . Thus, they cou ld be of lower u t i l i t y than a r e p r e s e n t a t i v e sample of r a d i o c o l l a r e d (marked) c a r i b o u l o c a t i o n s i n a s s e s s i n g the r e l a t i v e i n f l u e n c e of locomot ion c o n d i t i o n s i n snow and a r b o r e a l a l e c t o r i o i d l i c h e n a v a i l a b i l i t y to c a r i b o u w in te r d i s t r i b u t i o n s (Chapter V I ) . Other purposes of t h i s s e c t i o n a re to present home range l o c a t i o n s and s i z e s , and to d e s c r i b e the seasona l movement and h a b i t a t use p a t t e r n s of c a r i b o u . METHODS Capture and R a d i o t r a c k i n g Between December 1978 through A p r i l 1979, four f r e e - r a n g i n g c a r i b o u were captured by d a r t i n g w i t h i m m o b i l i z i n g drugs and instrumented w i t h r a d i o t r a n s m i t t e r s ( W i l d l i f e M a t e r i a l s , I n c . ) . A th ree -e lement y a g i antenna was used f o r r e l o c a t i n g c a r i b o u from the ground and from a h e l i c o p t e r . A p a i r of four -e lement y a g i antennae were used f o r t r a c k i n g from f i x e d - w i n g a i r c r a f t , one on each s i d e of the a i r c r a f t . In ground t r a c k i n g , l o c a t i o n s were determined by t r i a n g u l a t i o n u s i n g a t l e a s t th ree b e a r i n g s . When f e a s i b l e , the es t imated l o c a t i o n was v e r i f i e d . L a t e r , the t r i a n g u l a t e d a r e a , or e r r o r po lygon , was p l o t t e d on 1:20 c h a i n f o r e s t cover maps, and the c e n t r e of t h i s a r e a was taken as the l o c a t i o n of the r a d i o c o l l a r e d c a r i b o u . 75 Most a e r i a l t r a c k i n g was conducted from s i n g l e eng ine , f i x e d - w i n g a i r c r a f t (DeHav i l l and Beaver, and Cessnas 172 and 182), a l though h e l i c o p t e r s were o c c a s i o n a l l y used. Loca t ions of r a d i o c o l l a r e d an imals and, i n w i n t e r , the d i s t r i b u t i o n of t r a c k s i n the v i c i n i t y of l o c a t i o n s were p l o t t e d d i r e c t l y on 1:50,000 topograph ic and f o r e s t cover maps, and l a t e r t r a n s f e r r e d to 1:20 c h a i n f o r e s t cover maps. Home ranges were d e l i n e a t e d u s i n g the minimum home range polygon method (Dalke and Sime 1938), and t h e i r s i z e s c a l c u l a t e d u s i n g the program HOME (Harestad 1981). A maximum of one r a d i o l o c a t i o n per day per i n d i v i d u a l inst rumented an imal was used i n dete rmin ing range s i z e s . A e r i a l Surveys Dur ing f l i g h t s to r e l o c a t e r a d i o c o l l a r e d c a r i b o u , d i r e c t obse rva t ions and t r a c k s i n snow of n o n - r a d i o c o l l a r e d c a r i b o u were a l s o recorded t o compare w i t h the movements and h a b i t a t d i s t r i b u t i o n of r a d i o c o l l a r e d c a r i b o u . The a e r i a l survey technique recogn i zed r e l a t i v e o b s e r v a b i l i t y b i a s e s due t o d i f f e r e n t i a l f o r e s t cover and v a r i a b l e t e r r a i n e f f e c t s . I found, as d i d Freddy (1974), tha t the moderate t o good c a r i b o u o b s e r v a b i l i t y zone was above 1400 to 1500 m e l e v a t i o n , where the f o r e s t began to open up, and where s teep , lower s i d e s lopes u s u a l l y graded i n t o moderate t o m i l d l y s loped topography. A i r c r a f t were f lown a t speeds of 130 t o 160 km/h, and a t above-ground a l t i t u d e s of 150 to 300 m. F i g u r e 16 shows the standard f l i g h t rou te I t r i e d t o complete each f l i g h t . A l l c a r i b o u or c a r i b o u t r a c k s were c i r c l e d and t r a c k s were b a c k - t r a i l e d when f e a s i b l e . For each group of c a r i b o u (a group was one or more i n d i v i d u a l s ) , whether s i g h t e d or no t , the d i s t r i b u t i o n of t r a i l systems i n the snow were o u t l i n e d on 1:50,000 topographic and /o r f o r e s t cover f l i g h t maps. Car ibou s i g h t e d were c l a s s i f i e d where p o s s i b l e t o sex and to age c l a s s of a d u l t , y e a r l i n g or c a l f . I a l s o r a t e d the age of t r a c k s as e i t h e r f r e s h 76 F igu re 16. The standard w in te r a e r i a l survey rou te ( s o l i d l i n e ) , and most secondary f l i g h t routes (broken l i n e s ) , i n the North Thompson study a r e a . 77 ( s i n c e the l a s t s n o w f a l l ) or o l d (before the l a s t s n o w f a l l but made a f t e r the p rev ious f l i g h t ) . Very o l d t r a c k s (observed d u r i n g a p rev ious f l i g h t ) were exc luded . Coding of h a b i t a t - u s e : Car ibou or t h e i r t r a c k s i n a h a b i t a t - c e l l were recorded as one h a b i t a t -use o b s e r v a t i o n . A p a r t i c u l a r h a b i t a t - c e l l c o u l d o c c a s i o n a l l y be represented more than once a long a t r a i l system, i n which case i t was dec ided to r e c o r d a h a b i t a t - c e l l o n l y once per group per f l i g h t . A l though h a b i t a t types were h i g h l y c o r r e l a t e d w i t h e l e v a t i o n , they spanned unequal e l e v a t i o n a l w i d t h s , and some over lapped i n e l e v a t i o n a l d i s t r i b u t i o n (Table 1 ) . There fo re , the d i s t r i b u t i o n of a c a r i b o u g roup 's t r a i l system was a l s o recorded by presence i n the f o l l o w i n g seven e l e v a t i o n c l a s s e s (based on 30.5 m (100 f t ) i n t e r v a l topograph ic maps): <1006.5 m (< 3300 f t ) ; 1006.5 to 1311.5 m (3300 t o 4300 f t ) ; 1311.5 to 1494.5 m (4300 to 4900 f t ) ; 1494.5 to 1677.5 m (4900 t o 5500 f t ) ; 1677.5 to 1860.5 m (5500 to 6100 f t ) ; 1860.5 to 2043.5 m (6100 t o 6700 f t ) ; and > 2043.5 m (>6700 f t ) . RESULTS Group Dynamics of R a d i o c o l l a r e d Car ibou Over the 1979-80 w in te r study, and e v i d e n t l y over much of the o ther p e r i o d s of i n v e s t i g a t i o n , a s t a b l e , core group of animals was a s s o c i a t e d w i t h each of the t h r e e c o l l a r e d cows (Table 8 ) , and sometimes these groups were a f f i l i a t e d w i t h other ones. The c o l l a r e d male, on the o ther hand, was e i t h e r s o l i t a r y or p a r t of a sma l l group of p robab ly other males, d u r i n g much of the non -winter p e r i o d s . However, d u r i n g w i n t e r the ma le ' s group was a f f i l i a t e d w i t h o ther groups over s u b s t a n t i a l p e r i o d s of t ime (Table 8 ) . The re fo re , the l o c a t i o n s of the four r a d i o c o l l a r e d i n d i v i d u a l s a p p l i e d to a much l a r g e r number of c a r i b o u . Table 8. R a d i o c o l l a r e d ca r ibou c h a r a c t e r i s t i c s , o b s e r v a t i o n p e r i o d s , number of l o c a t i o n s (N) , home range s i z e s , and comments on t h e i r a s s o c i a t i o n s w i t h o ther c a r i b o u , Nor th Thompson. C = c a l f . HOME RANGE SIZE (km2) ANIMAL NUMBER BEX AGE CAPTURE LOCATION OBSERVATION PERIOD TOTAL STUDY8 (N) ANNUAL'5 (N> WINTER PERI0DC (N) COMMENTS 1 F sub adult Spahats Creek 14 1 DEC 1978 to AUG 1980 575 (45) 554 (26) 413 (17) - captured from a group of 8(2C); primary group = 4(1C) - JAN - APR 1979: largest group «= 12(3C); 7<2C) + 5(1C) - JUN - AUG 1979 and 1980: no complete count (> 3) - SEP - DEC 1979: > 5, largest group (rut) » 9?2C) - JAN - APR 1980: largest group = 12(2C); 5(1C) + 7(1C) 2 F adult Chappell Creek 28 26 MAR 1979 to AUG 1980 314 (87) 310 (78) 153 (63) - captured from a group of 8(1C); primary group = 4(1C) - JUN - OCT 1979: no complete count (suspect 5) - NOV - FEB 1979-80: 5(1C), and sometimes 5(0C) more - MAR - APR 1980: largest group • 12(1C); 5(1C) + 7 - JUN - AUG 1980: no complete count (> 6-7) 3 F adult Ground Hog Mountain 12 25 APR 1979 to APR 1980 613 (42) 613 (40) 276 (29) - captured from a group of 7(3C) - JUN - OCT 1979: no complete count (< 6) - NOV - APR 1979-80: largest group •= 9(2C) - Radiocollar battery failure after APR 1980 4 M adult Chappell Creek 12 1 APR 1979 to AUG 1980 491 (69) 491 (64) 362 (52) - captured from the same group of 8(1C) as No. 2 - JUN-NOV 1979 & JUN-AUG 1980: no complete count (< 3) - DEC - FEB 1979-80: 8(2C); 3(0C) + 5(2C) - MAR - APR 1980: largest group = 12(1C); 7 + 5(1C) (the group of 5 included Animal No. 2) a: All locations, 1978-80. b: 19 June 1979 to 13 June 1980, except for No. 3 which was 30 April 1979 to 25 April 1980. c: Intensive study period, winter 1979-80 (winter intervals 1 to 11). 79 Home Ranges Most r a d i o l o c a t i o n s were ob ta ined du r i ng w in te r 1979-80 (Table 8 ) , and sample s i z e s were g e n e r a l l y low, t h e r e f o r e annual range s i z e s (F igure 17, Tab le 8) may be underest imated . However, when a l l l o c a t i o n s obta ined over the l eng th of the study are i n c l u d e d , most a re enc losed w i t h i n the ranges shown i n F i g u r e 17 and make l i t t l e d i f f e r e n c e to est imates of home range s i z e s (Table 8 ) . Th is suggests tha t these y e a r - l o n g ranges were p robab ly reasonab le approx imat ions , and r e f l e c t s some degree of f i d e l i t y or t r a d i t i o n t o the areas used by i n d i v i d u a l c a r i b o u . The annual ranges, and the areas used over the 23 October 1979 t o 2 A p r i l 1980 (winter i n t e r v a l s 1 to 11) i n t e n s i v e study p e r i o d , were w e l l d i s t r i b u t e d over the study a rea (F igu re 17) . Furthermore, over w i n t e r , o ther c a r i b o u groups were d i s t r i b u t e d throughout much of the same a r e a , o v e r l a p p i n g w i t h the r a d i o c o l l a r e d c a r i b o u and t h e i r groups. These p o i n t s demonstrate tha t the r a d i o c o l l a r e d c a r i b o u were not i s o l a t e d , and were l i k e l y r e p r e s e n t a t i v e of the c a r i b o u p o p u l a t i o n . Comparison of R a d i o c o l l a r e d and N o n - r a d i o c o l l a r e d Car ibou D i s t r i b u t i o n s The w in te r a e r i a l survey observa t ions of c a r i b o u and t h e i r t r a c k s ( F igu re 18) i n d i c a t e d tha t the c a r i b o u p o p u l a t i o n was o f t e n w ide l y d i s t r i b u t e d by e l e v a t i o n and h a b i t a t type a t any p a r t i c u l a r p e r i o d . Although sample s i z e s of d i s t r i b u t i o n s of c a r i b o u and t h e i r t r a c k s by e l e v a t i o n c l a s s ( F igu re 18) and by h a b i t a t type were o f t e n low f o r , and /o r d i s p a r a t e between r a d i o c o l l a r e d and n o n - r a d i o c o l l a r e d c a r i b o u groups f o r i n d i v i d u a l f l i g h t s , i t was thought tha t c h i - s q u a r e t e s t s of independence (Conover 1980:158) would s t i l l be u s e f u l e x p l o r a t o r y ana lyses to compare t h e i r d i s t r i b u t i o n s . To reduce the e f f e c t of d i f f e r e n t i a l o b s e r v a b i l i t y between r a d i o c o l l a r e d and n o n - r a d i o c o l l a r e d groups, these ana lyses were c o n s t r a i n e d t o the mid to h igh e l e v a t i o n c l a s s e s (> e l e v a t i o n c l a s s 3 ; F i g u r e 80 F igu re 17. Y e a r - l o n g home ranges of r a d i o c o l l a r e d c a r i b o u i n the Nor th Thompson, f o r the p e r i o d June 1979 t o June 1980 f o r r a d i o N o . ' s 1, 2 , and 4, and A p r i l 1979 t o A p r i l 1980 f o r r a d i o No. 3 (see a l s o Tab le 8 ) . Broken l i n e = boundary between moist and wet c l i m a t i c r e g i o n s . 81 F igure 18. Average (+ range; numbers i n d i c a t e sample s i z e ) e l e v a t i o n - c l a s s of a e r i a l survey observa t ions of (A) r a d i o c o l l a r e d and (B) n o n - r a d i o c o l l a r e d car ibou groups, September 1979 t o August 1980, North Thompson. November 1979 t o A p r i l 1980 d a t a on l y a re f o r i n d i v i d u a l f l i g h t s . Only e l e v a t i o n c l a s s e s > 3 (1310 to 1495 m) were cons idered because of r e l a t i v e l y poorer o b s e r v a b i l i t y c o n d i t i o n s a t lower e l e v a t i o n s . 82 18) , and t o the h a b i t a t types from ESSF- low t o A l p i n e , because of the r e l a t i v e l y poorer o b s e r v a b i l i t y c o n d i t i o n s i n lower e l e v a t i o n s . By i n d i v i d u a l f l i g h t s from November 1979 t o A p r i l 1980, no s i g n i f i c a n t d i f f e r e n c e s were found ( a l l p > 0.11) between the d i s t r i b u t i o n s of these two c a r i b o u p o p u l a t i o n samples, e i t h e r by e l e v a t i o n c l a s s or by h a b i t a t t y p e . T h i s supports the o v e r a l l impress ion tha t t rends i n the means and ranges of e l e v a t i o n c l a s s e s of r a d i o c o l l a r e d and n o n - r a d i o c o l l a r e d c a r i b o u groups (F igu re 18) f o l l o w e d a very s i m i l a r p a t t e r n over the 1979-80 w i n t e r . (Spearman's rank c o r r e l a t i o n between average e l e v a t i o n c l a s s e s of these two groups f o r the 16 f l i g h t s from November t o A p r i l of the 1979-80 w in te r ( F igu re 18) was 0 .83 , p < 0 .002 . ) Both ana lyses show that f o r w i n t e r a e r i a l surveys the poo led d i s t r i b u t i o n of the four r a d i o c o l l a r e d c a r i b o u and t h e i r r e s p e c t i v e groups was s i m i l a r to tha t of the n o n - r a d i o c o l l a r e d c a r i b o u groups . And thus , i t was i n f e r r e d t h a t the t o t a l w i n t e r d i s t r i b u t i o n a l da ta set f o r the r a d i o c o l l a r e d c a r i b o u ( i . e . , ground and a e r i a l l o c a t i o n s ) was r e p r e s e n t a t i v e of the study a r e a p o p u l a t i o n . In f a c t , because r a d i o c o l l a r e d c a r i b o u c o u l d be l o c a t e d whatever the v i s i b i l i t y , they represent a r e l a t i v e l y unbiased sample of the c a r i b o u p o p u l a t i o n ' s w i n t e r d i s t r i b u t i o n s . A l t i t u d i n a l M i g r a t i o n A l t i t u d i n a l m i g r a t i o n s , from h i g h to low and reascent t o h i g h e l e v a t i o n s , occur red t w i c e d u r i n g the annual c y c l e ( F igu re 19 ) . Over l a t e s p r i n g to e a r l y f a l i (June t o O c t o b e r ) , c a r i b o u occup ied ESSF- low to A l p i n e h a b i t a t s . From l a t e f a l l to e a r l y w i n t e r (November t o J a n u a r y ) , as snowpacks a t h i g h e l e v a t i o n summer ranges deepened and were p o o r l y s u p p o r t i v e , c a r i b o u descended t o e a r l y winter range d i s t r i b u t e d from ESSF- low down t o ICH h a b i t a t s ( i . e . , to mid and low e l e v a t i o n s ) . Dur ing t h i s p e r i o d , c a r i b o u u s i n g the lowest e l e v a t i o n , ICH-low h a b i t a t type (F igure 19) were those 2200-. 115) 1800-O ~ uoo-LU _J LU 1000-600-1 SEP 220CT (17) (23) 115) (8) (2) (8) 17) (16) - (4) <191 (20) T (16) (6) T (12) :{} f <} (91 (10) (*> T no) (16) I f 2 I 3 I 4 I 5 • 6 I 7 I » I a I WINTER INTERVAL 8 ' 9 ' 10 3 -30 APR MAY JUN JUL AUG J . J . OCT NOV DEC JAN FEB MAR ALPINE PARK LAND ESSF HIGH LICHEN RESERVE ESSF LOW ICH HIGH ICH LOW LU CL >-CD < F i g u r e 19. Mean (+ 2SE and range; sample s i z e i n parentheses) e l e v a t i o n s of r a d i o c o l l a r e d c a r i b o u i n the North Thompson. Open symbols are f o r September 1979 t o August 1980, w i t h means over the 1979-80 winter i n t e n s i v e - s t u d y (23 October t o 2 A p r i l ) c a l c u l a t e d f o r w in te r i n t e r v a l s of 1 to 11 (see Appendix A ) . S o l i d symbols are f o r December 1978 to August 1979, and means f o r December 1978 to March 1979 a re f o r monthly i n t e r v a l s . » 84 p r i m a r i l y i n the h i g h s n o w f a l l r e g i o n ( F i g u r e 17 ) . F i rmer , m id -w in te r (January or February) snowpack c o n d i t i o n s a l l owed c a r i b o u t o reascend to h igher e l e v a t i o n h a b i t a t s ( i . e . , t o mid and h igh e l e v a t i o n s ) . Then i n e a r l y s p r i n g ( l a t e A p r i l and May) c a r i b o u descended to snow- f ree , low e l e v a t i o n ICH h a b i t a t s , be fo re reascend ing once aga in by l a t e s p r i n g (June ) . A l t i t u d i n a l m i g r a t i o n i s the movement up or down major t o p o g r a p h i c a l f e a t u r e s , and has both v e r t i c a l and h o r i z o n t a l components (Baker 1978) . F igu re 19 p r e s e n t s o n l y the v e r t i c a l movements of the r a d i o c o l l a r e d c a r i b o u , but an ext remely v a r i a b l e p a t t e r n of h o r i z o n t a l movements and s p a t i a l r e l a t i o n s h i p s between h igh use a r e a s , or p a r t i a l ranges, was superimposed upon these g e n e r a l i z e d e l e v a t i o n a l p a t t e r n s . In l a t e f a l l and e a r l y w i n t e r , c a r i b o u tended t o s h i f t t o lower e l e v a t i o n s (< 1500 m), a l though they a l s o made excurs ions t o h igher e l e v a t i o n s . Movements appeared to be f requent and o f t e n c i r c u i t o u s and l o c a l i z e d w i t h i n one d ra inage , but o c c a s i o n a l l y movements were e x t e n s i v e , such as between d r a i n a g e s . L a t e r i n w i n t e r , when c a r i b o u ascended t o the suba lp ine and a l p i n e , t h e i r h i g h use areas were r e l a t i v e l y w e l l - d e f i n e d cont iguous topograph ic u n i t s connected by c o r r i d o r s i n which movements appeared to be d i r e c t and r e l a t i v e l y r a p i d . These l a t e w in te r p a r t i a l ranges were u s u a l l y on suba lp ine p l a t e a u s , subdued r i d g e s , or the r e l a t i v e l y moderate t e r r a i n of benches, b a s i n s and shoulders of more rugged mountain b l o c k s . Over both w i n t e r s , there appeared t o be a g rad ien t i n the t i m i n g and extent of c a r i b o u a l t i t u d i n a l m i g r a t i o n s between the mo is t , o r lower s n o w f a l l , and the wet, or h igher s n o w f a l l , c l i m a t i c reg ions (F igu re 17 ) . Car ibou i n the low s n o w f a l l compared t o the h igh s n o w f a l l r e g i o n : a) i n e a r l y w i n t e r , d i d not descend as low ( i . e . , most l y j u s t down t o ESSF- low, r a t h e r than to ICH h a b i t a t s ) , or i f they d i d , o n l y f o r sho r te r d u r a t i o n s ; b) i n mid 85 w i n t e r , ascended t o , or expanded l a t e r a l l y on , h igher e l e v a t i o n ranges e a r l i e r ; c) i n l a t e w i n t e r , d i s p e r s e d down from h igh e l e v a t i o n ranges e a r l i e r , e v i d e n t l y because of comparat i ve ly e a r l i e r s p r i n g c o n d i t i o n s at those low e l e v a t i o n s . DISCUSSION A e r i a l survey da ta on e l e v a t i o n and i n t e r r e l a t e d h a b i t a t d i s t r i b u t i o n c l e a r l y demonstrated tha t the pooled d i s t r i b u t i o n of the four r a d i o c o l l a r e d c a r i b o u and t h e i r r e s p e c t i v e groups over the w in te r of 1979-80 was r e p r e s e n t a t i v e of the c a r i b o u p o p u l a t i o n w i n t e r i n g i n the North Thompson study a r e a . A l s o , the a l t i t u d i n a l m i g r a t i o n and h a b i t a t d i s t r i b u t i o n p a t t e r n of c a r i b o u du r i ng t h i s study p a r a l l e l e d the genera l d e s c r i p t i o n repor ted e a r l i e r f o r t h i s a rea (Edwards and R i t c e y 1959), and f o r mountain c a r i b o u elsewhere ( B l o o m f i e l d 1979, Sco t t and Servheen 1984, 1985, Simpson et a l . 1985). E l e v a t i o n a l (and h a b i t a t type) d i s t r i b u t i o n s were wide w i t h i n , and over lapped between, seasona l p e r i o d s , but c a r i b o u were predominant ly c l u s t e r e d from mid to low e l e v a t i o n s i n e a r l y w in te r (and i n s p r i n g ) , and from mid to h i g h e l e v a t i o n s i n l a t e w in te r (and i n summer). The h igh m o b i l i t y of c a r i b o u , p a r t i c u l a r l y s h o r t - t e r m e l e v a t i o n a l o s c i l l a t i o n s , and r e g i o n a l c l i m a t i c d i f f e r e n c e s , p a r t i c u l a r l y i n snow, c o n t r i b u t e d t o t h i s d i s t r i b u t i o n a l v a r i a b i l i t y . N e v e r t h e l e s s , i n a r e l a t i v e , i f not a b s o l u t e , sense, the temporal p a t t e r n i n c a r i b o u e l e v a t i o n a l d i s t r i b u t i o n was g e n e r a l l y ve ry synchronous throughout the study a r e a , suggest ing t h a t a s i m i l a r p r o c e s s , d r i v e n by common envi ronmental f a c t o r s , was i n o p e r a t i o n throughout the study a r e a . 86 V I . CARIBOU WINTER DISTRIBUTION IN RELATION TO MOBILITY CONDITIONS IN SNOW AND ARBOREAL LICHEN AVAILABILITY INTRODUCTION The purpose of t h i s s e c t i o n i s t o eva lua te the r e l a t i v e i n f l u e n c e of both the a v a i l a b i l i t y of a r b o r e a l a l e c t o r i o i d l i c h e n on s tand ing t r e e s and the energy c o s t of locomot ion i n snow on c a r i b o u h a b i t a t use over the w in te r of 1979-80. These two f a c t o r s a re t r e a t e d as i n d i c e s of energy parameters : the energy a v a i l a b l e i n fo rage (energy i n t a k e ) , and the energy c o s t of o b t a i n i n g t h i s forage (energy e x p e n d i t u r e ) . C o n v e n t i o n a l l y , r e g r e s s i o n methods should be used t o es t imate the dependence of c a r i b o u h a b i t a t use upon these two envi ronmental f a c t o r s , i n which they would e i t h e r be i n t e g r a t e d t o y i e l d a net energy a v a i l a b i l i t y va lue f o r each h a b i t a t ( to then be used as the independent v a r i a b l e ) , or serve as two independent v a r i a b l e s i n a m u l t i p l e r e g r e s s i o n model . However, n e i t h e r of these a n a l y t i c a l approaches a re a p p r o p r i a t e , because the two envi ronmental f a c t o r s are rep resented by r e l a t i v e i n d i c e s . A d d i t i o n a l l y , i t i s important t o note that most of the r a d i o l o c a t i o n d a t a (89%, from N o . ' s 2, 3 and 4) over the i n t e n s i v e 1979-80 w i n t e r study p e r i o d , and a l l of the snow and a r b o r e a l l i c h e n i nven to ry d a t a were c o l l e c t e d i n areas that were w i t h i n e i t h e r the boundary (or t r a n s i t i o n ) a rea between c l i m a t i c reg ions or the wet c l i m a t i c r e g i o n (see F igu res 1 and 17) , which c o l l e c t i v e l y were assumed to be a h igher s n o w f a l l r e g i o n . N e v e r t h e l e s s , because i t appeared t h a t a s i m i l a r p rocess d i r e c t e d ca r ibou d i s t r i b u t i o n s throughout the study a r e a , a l l th ree v a r i a b l e s ( c a r i b o u h a b i t a t and /o r e l e v a t i o n d i s t r i b u t i o n , locomot ion c o s t s i n snow, and l i c h e n a v a i l a b i l i l t y ) a re t r e a t e d as i n d i c e s , w i t h the e x p e c t a t i o n t h a t , f o r each v a r i a b l e , d i r e c t i o n s r a t h e r than magnitudes of temporal p a t t e r n s w i l l be s i m i l a r throughout the study a r e a . There fo re , the ana lyses r e l y on nonparametr ic s t a t i s t i c a l procedures t o d i s c e r n temporal t rends i n 87 c a r i b o u responses t o the two envi ronmental f a c t o r s . In t h i s s e c t i o n , c a r i b o u h a b i t a t d i s t r i b u t i o n s over w in te r a re assessed r e l a t i v e to energy c o s t of locomot ion i n snow and t o a r b o r e a l l i c h e n a v a i l a b i l i t y s e p a r a t e l y (A) ( b i v a r i a t e c o r r e l a t i o n a l a n a l y s e s ) , be fo re c o n s i d e r i n g t h e i r combined e f f e c t (B) ( d e s c r i p t i v e m u l t i v a r i a t e a n a l y s e s ) . And f i n a l l y , the e f f e c t of locomot ion i n snow i s exp lored f u r t h e r by a s s e s s i n g c a r i b o u responses to changes, r a t h e r than s t a t e s , i n t h i s f a c t o r on a s e q u e n t i a l b a s i s (C ) . A . I n d i v i d u a l E f f e c t s of Energy Cost of Locomotion and A r b o r e a l L ichen  A v a i l a b i l i t y on Car ibou Hab i ta t Use Data C o n s i d e r a t i o n s and B i v a r i a t e C o r r e l a t i o n a l Ana lyses The r e l a t i v e importance of energy c o s t of locomot ion i n snow and a r b o r e a l l i c h e n a v a i l a b i l i t y to c a r i b o u was eva lua ted by c o r r e l a t i n g (Spearman's rank c o r r e l a t i o n ) the observed f requency of r a d i o l o c a t i o n s f i r s t w i t h energy c o s t , and then w i t h l i c h e n a v a i l a b i l i t y , i n each of the 19 h a b i t a t - c e l l s f o r each w in te r i n t e r v a l . I t i s not the a c t u a l r - v a l u e s t h a t a re of most i n t e r e s t , but the p a t t e r n s of s i g n i f i c a n t c o r r e l a t i o n s w i t h these two env i ronmenta l v a r i a b l e s over w i n t e r . L o c a t i o n s of recent r a d i o c o l l a r e d c a r i b o u t r a c k s i n snow observed d u r i n g a e r i a l r a d i o t r a c k i n g were combined w i t h the cor respond ing r a d i o l o c a t i o n i n order to i n c r e a s e sample s i z e s of c a r i b o u o b s e r v a t i o n s ; a l though s t r i c t l y , t h i s i s s t a t i s t i c a l l y q u e s t i o n a b l e because they were not independent obse rva t i ons and because of d i f f e r e n t i a l v i s i b i l i t y between h a b i t a t s . These a e r i a l t r a c k l o c a t i o n s were assumed to be s u b s i d i a r y w in te r r a d i o l o c a t i o n s , and ana lyses were conducted w i t h a c t u a l r a d i o l o c a t i o n s a lone , and then w i t h r a d i o l o c a t i o n s combined w i t h t r a c k l o c a t i o n s . Ana lyses r e s u l t s were s i m i l a r between the two d a t a - s e t s (see l a t e r ) , i n d i c a t i n g that c a r i b o u h a b i t a t 88 d i s t r i b u t i o n was not a p p r e c i a b l y a l t e r e d . The A l p i n e , which possessed no a r b o r e a l l i c h e n , and the immature h a b i t a t - c e l l s f o r each of ICH- low, ICH-h igh , ESSF-low and ESSF -h igh , i n which a r b o r e a l l i c h e n a v a i l a b i l i t y v a r i e d from zero (non fo res ts ) t o most ly n e g l i g i b l e (immature f o r e s t s ) amounts, were a l l ass igned ze ro l i c h e n a v a i l a b i l i t y . Consequent ly , a v a i l a b l e l i c h e n was c o n s i s t e n t l y c h a r a c t e r i z e d by 9 h a b i t a t - c e l l s t i e d a t z e r o v a l u e i n the c o r r e l a t i o n a l a n a l y s e s . Car ibou h a b i t a t use by w in te r i n t e r v a l s was a l s o c h a r a c t e r i z e d by v a r i a b l e numbers of t i e s . Because of e x t e n s i v e t i e s , Spearman's rank c o r r e l a t i o n s were computed as Pearson 's r on the ranks and average ranks (Conover 1980: 214; 252) . To p r o v i d e more g e n e r a l l y a p p l i c a b l e s t a t i s t i c a l summary statements , these c o r r e l a t i o n s were a l s o made f o r longer w in te r p e r i o d s , by p o o l i n g data from c o n s e c u t i v e w in te r i n t e r v a l s showing s i m i l a r i t i e s i n a s s o c i a t i o n s between c a r i b o u use and the two envi ronmental f a c t o r s . S i n c e the est imated va lues of a l l th ree f a c t o r s sometimes v a r i e d c o n s i d e r a b l y between w in te r i n t e r v a l s , they were t ransformed to a common s c a l e ( o r d i n a l s c a l e of 1 to 19 h a b i t a t - c e l l s ) by rank ing them w i t h i n w in te r i n t e r v a l s , be fo re p o o l i n g i n t o w in te r p e r i o d s . The c o r r e l a t i o n s were then conducted us ing these poo led ranks r a t h e r than the i n i t i a l v a r i a b l e v a l u e s . R e s u l t s 1. Car ibou Hab i ta t Use and Energy Cost of Locomotion Car ibou d i s t r i b u t i o n s were s i g n i f i c a n t l y , i n v e r s e l y c o r r e l a t e d w i t h energy c o s t s of locomotion o n l y i n the e a r l y w in te r i n t e r v a l s of 3,4 and 5 (Table 9 ) . These i n v e r s e a s s o c i a t i o n s r e f l e c t e d the c a r i b o u ' s e a r l y w in te r descent to the mature s e r a i t ypes of ESSF- low, ICH-h igh and ICH- low, where locomot ion c o n d i t i o n s i n snow were l e a s t r e s t r i c t i v e (F igu re 20 ) ; or synonymously, avoidance of a l l immature h a b i t a t - c e l l s i n g e n e r a l , and of the 89 Table 9 . Spearman's rank c o r r e l a t i o n c o e f f i c i e n t s between the number of car ibou r a d i o l o c a t i o n s i n h a b i t a t - c e l l s (HAB USE) and 1) the r e l a t i v e energy cost of locomot ion i n snow (ENERGY COST, as i n F igu re 20) , and 2) the a r b o r e a l a l e c t o r i o i d l i c h e n a v a i l a b i l i t y (AVAIL LICHEN, as i n F i g u r e 20) , of h a b i t a t - c e l l s , over w in te r 1979-80, North Thompson. Spearman's rank correlation coefficients between caribou HAB USE and: WINTER INTERVALa ENERGY COST AVAIL LICHEN ENERGY COST AVAIL LICHEN WINTER PERIOD3 1. 23 OCT-14 NOV (.24)b .77 **C (.76)** -.02 (.11) .62 ** (.67)** 23 OCT-27 NOV 2. 15 - 27 NOV -.36 (-.08) .53 ** (.64)** [n-38] 3. 28 NOV-12 DEC -.52 ** (-.52)" .45 * (.45)* 4. 13 - 27 DEC -.44 * (-.44)" .14 (.14) -.43 ** (-.44)** .33 ** (.30)** 28 NOV-12 JAN 5. 28 DEC-12 JAN -.48 ** (-.46)"* .45 * (.37) [n-57] 6. 13 - 28 JAN -.08 (.01) .77 ** (.66)** 7. 29 JAN-13 FEB -.17 (-.15) .75 ** (.68)** -.06 (-.01) .64 ** (.57)** 13 JAN-27 FEB 8. 14 - 27 FEB .10 (.09) .49 ** (.47)** [n-57] 9. 28 FEB-9 MAR .51 ** (.45)" .61 ** (.61)** 10. 10 - 21 MAR .50 ** (.48)" .58 ** (.54)** .48 ** (.48)** .54 ** (.55)** 28 FEB-2 APR 11. 22 MAR-2 APR .64 ** (.65)** .60 ** (.61)** [n=57] Sample sizes for correlations for winter intervals are a l l 19, because of 19 habitat-cells. Sample sizes for winter periods, however, are variable, and are shown in brackets. Correlations using radiolocations combined with locations of radio-collared caribou tracks in snow observed during aerial tracking (see text). c 2-tailed p-values: *, p < 0.1; **, p < 0.05. 90 F igure 20. R a d i o c o l l a r e d c a r i b o u o b s e r v a t i o n s , and averages between p a i r e d nor th and south aspect h a b i t a t - c e l l s f o r est imates of r e l a t i v e energy c o s t of locomotion i n snow (ranges shown on l y i f > + 10%) and a r b o r e a l a l e c t o r i o i d l i c h e n a v a i l a b i l i t y (on ly f o r mature h a b i t a t - c e l l s ; and ranges too s m a l l t o show) by h a b i t a t t y p e s , over w in te r 1979-80, North Thompson. N = sample s i z e : non -pa ren thes i zed v a l u e s denote r a d i o l o c a t i o n s ; w h i l e v a l u e s i n parentheses denote r a d i o l o c a t i o n s combined w i th l o c a t i o n s of r a d i o c o l l a r e d car ibou t r a c k s i n snow observed d u r i n g a e r i a l r a d i o t r a c k i n g (see t e x t ) . T, denotes the p o s s i b l e upper s i n k i n g depth t h r e s h o l d of 2 / 3 chest h e i g h t f o r ungulates ( K e l s a l l 1969) ( i . e . , 169% r e l a t i v e i n c r e a s e i n the net energy cos t of l ocomot ion ) . HABITAT TYPE A ALPINE P PARKLAND E - H ESSF - HIGH E - L ESSF - LOW I - H ICH - HIGH I - L ICH - LOW CARIBOU HABITAT USE (% RADIOLOCATIONS) IMMATURE MATURE + -MATURE IMMATURE RADIOLOCATIONS RADIOLOCATIONS PLUS AERIAL TRACK LOCATIONS 91 1. 23 OCT- K NOV. N=17125I A P E-H E - L I -H I - L i n 1—i MATURE IMMATURE T - i 1 ' 1 P T — 1 — r 1 I 2. 15-27 NOV. N = 8(12l A p" E-H E - L I - H I - L ~~hTT~ T— • —r J -i—r L T — i — r ~\ 1 1 UJ CL >-3. 28N0V-12 DEC. N=8I8) A P^  E - L ' I - H " I - L - r 20 I ' I 40 60 I —i— 100 "I— 200 — i 1 1 1 0 2 4 m < x 4. 13 - 27 DEC. N=7(7) A P E - H ' E - L I - H I - L 3d 3r T— I 1 5. 28 DEC-12 JAN. N=15I21) A P E - H I - H' I - L \3-• • i E - i — i — i 6. 13 - 28 JAN. N=23(37) E - L I - H' I - L' If-20 - l 1 — I — i AO 60 1 100 -i 1 200 T 100 200 CARIBOU HABITAT USE (V. RAOIOLOCATIONSI RELATIVE INCREASE IN THE NET COST OF LOCOMOTION (•/.] E AVAILABLE ARBOREAL LICHEN (ln(SLU/.02ha.1l) Figure 20. Continued. 92 MATURE 7. 29 JAN -13 FEB. N=16|19) A " p + l E - H E - L I - H a* r I - L~ • 1 I i r A p' I - H I - L 8. 1A- 27FEB. N=19(23l + z n + -i 1 r-3^ 1 — i — i — i IMMATURE 3r 3 l * — i — i — i T 1 I E -i r LU CL >-9. 26 F E B - 9 MAR. N=20I33) A P E - H' I - H' I T l t . a 20 1.0 —r-60 100 —I 200 •> 1 0 100 200 —' 1 ' 1 0 2 A CD < X 10. 10 - 21 MAR, A p' E - L_ I - H' I - L' N=16I19) -i 1 ' l ii. 22 M A R - 7 APR, N=12(22l A p' E - H' E - L ' I - H' I - L ' 20 J L AO -r— 60 CARIBOU HABITAT USE IV. RADIOLOCATIONS) 100 — i — 200 RELATIVE INCREASE IN THE NET COST OF LOCOMOTION (%) E - i — i — i 0 2 A AVAILABLE ARBOREAL LICHEN lln|SLU/.02ho.U) Figure 20. Continued. 93 L ichen Reserve (ESSF-h igh and Park land) i n p a r t i c u l a r , where locomot ion c o n d i t i o n s were g e n e r a l l y r e l a t i v e l y poor . Although the c o r r e l a t i o n was not s i g n i f i c a n t f o r the preceeding w i n t e r i n t e r v a l 2 (Table 9 ) , c a r i b o u appeared to a v o i d h igher locomot ion c o s t s a t t h i s t ime as w e l l by descending below ESSF-h igh ( F i g u r e 20 ) . The on l y o c c a s i o n s when t r a c k depths i n the mature f o r e s t h a b i t a t - c e l l s exceeded or even approached the 2 /3 chest he igh t upper s i n k i n g depth t h r e s h o l d ( K e l s a l l 1969) occur red i n e a r l y w i n t e r , main ly i n i n t e r v a l 4 (F igu re 20 ) . Such poor m o b i l i t y c o n d i t i o n s were c l e a r l y avo ided by c a r i b o u (F igu re 20) . However, throughout w i n t e r , h a b i t a t - c e l l s where t r a c k depths would be l e s s than 2 /3 chest he igh t were a l s o avoided (F igu re 20 ) , suggest ing that c a r i b o u were a c t u a l l y s e n s i t i v e to a lower t h r e s h o l d . A f t e r the o v e r a l l ve ry poor locomot ion c o n d i t i o n s of i n t e r v a l 4, snowpack s u p p o r t a b i l i t i e s improved through i n t e r v a l s 5 and 6 (F igu res 6 and 20 ) . C o i n c i d e n t w i t h t h i s , c a r i b o u p r o g r e s s i v e l y s h i f t e d from t h e i r apparent confinement i n mature, low e l e v a t i o n f o r e s t s i n i n t e r v a l 4, upward t o h igher e l e v a t i o n s through i n t e r v a l s 5 and 6 ( F i g u r e 20) . Dur ing the l a t e f a l l i n t e r v a l 1, and aga in du r ing the s i x l a t e w in te r i n t e r v a l s of 6 to 11, ca r ibou d i d not f requent h a b i t a t s of r e l a t i v e l y lower energy c o s t s ; the c o r r e l a t i o n s were e i t h e r n o n s i g n i f i c a n t or s i g n i f i c a n t l y p o s i t i v e (Table 9 ) . In i n t e r v a l 1, c a r i b o u m o b i l i t y was p robab ly r e s t r i c t e d ve ry l i t t l e because snowpacks were sha l l ow and con f ined t o the L ichen Reserve and A l p i n e (F igu res 2 and 20 ) . And then through i n t e r v a l s 6 t o 11, when c a r i b o u ma in ly used the mature f o r e s t s of ESSF-low and ESSF -h igh , and Park land ( suba lp ine a r b o r e a l l i c h e n range ) , c a r i b o u g e n e r a l l y showed no c l e a r i n v e r s e a s s o c i a t i o n to energy cos t of l ocomot ion , a l though t h i s f a c t o r sometimes v a r i e d c o n s i d e r a b l y among these h igher e l e v a t i o n h a b i t a t s (F igure 20) . In f a c t , i n i n t e r v a l s 9, 10 and 11, the c o r r e l a t i o n s were s i g n i f i c a n t l y 94 p o s i t i v e (Table 9), r e f l e c t i n g c a r i b o u occupat ion of suba lp ine a r b o r e a l l i c h e n ranges even though energy c o s t s of locomot ion a t lower e l e v a t i o n s (ICH h a b i t a t s ) were r e l a t i v e l y much lower (F igure 20 ) . N e v e r t h e l e s s , on a broader s c a l e than the i n d i v i d u a l h a b i t a t - c e l l , there were some genera l a s s o c i a t i o n s between temporal f l u c t u a t i o n s i n m o b i l i t y c o n d i t i o n s and c a r i b o u d i s t r i b u t i o n s over the l a t e w in te r i n t e r v a l s . These r e l a t i o n s h i p s w i l l be addressed l a t e r . 2 . Car ibou H a b i t a t Use and A r b o r e a l L ichen A v a i l a b i l i l t y Car ibou d i s t r i b u t i o n s over much of the w i n t e r were g e n e r a l l y p o s i t i v e l y c o r r e l a t e d w i t h a v a i l a b l e l i c h e n (Table 9), p r i m a r i l y r e f l e c t i n g t h e i r ve ry low u t i l i z a t i o n of A l p i n e and immature h a b i t a t - c e l l s of the o ther h a b i t a t s ( F igu re 20) which o f f e r e d n e g l i g i b l e a r b o r e a l l i c h e n . There fo re , the c a r i b o u ' s predominant use of mature f o r e s t s i n a l l w in te r i n t e r v a l s , r e g a r d l e s s of h a b i t a t t ype , c o u l d l a r g e l y account f o r these p o s i t i v e and u s u a l l y s i g n i f i c a n t c o r r e l a t i o n s , d e s p i t e the o f t e n wide v a r i a t i o n between h a b i t a t types i n est imated a v a i l a b l e l i c h e n i n mature f o r e s t s ( F igu re 20 ) . D i s r e g a r d i n g the a b s o l u t e v a l u e of the c o r r e l a t i o n c o e f f i c i e n t s , a comparison of the temporal t rend i n these l i c h e n c o r r e l a t i o n s t o the temporal t r end i n the energy cos t of locomot ion c o r r e l a t i o n s i s the most important aspect of these a n a l y s e s . The p o i n t to note i s tha t the weaker p o s i t i v e a s s o c i a t i o n s between c a r i b o u use and a v a i l a b l e l i c h e n of h a b i t a t s were du r i ng e a r l y w in te r ( i n t e r v a l s 3, 4 and 5 ) , the very p e r i o d when the i n v e r s e c o r r e l a t i o n s between c a r i b o u use and energy c o s t of locomot ion of h a b i t a t s were s t rongest (Table 9). In i n t e r v a l s 1, 2 and 3, a l though a r b o r e a l l i c h e n a v a i l a b i l i t y was q u i t e low i n a l l h a b i t a t s (F igu re 15 and 20) , the c o r r e l a t i o n s between c a r i b o u h a b i t a t use and a v a i l a b l e l i c h e n were p o s i t i v e and r e l a t i v e l y h igh (Table 9). These r e s u l t s r e f l e c t e d the c a r i b o u ' s r e l a t i v e l y h igh use of the mature 95 f o r e s t s of ESSF- low and ICH -h igh , which o f f e r e d h i g h and moderate l i c h e n a v a i l a b i l i l t i e s , r e s p e c t i v e l y , over t h i s p e r i o d (F igu re 20 ) . Car ibou d i s t r i b u t i o n s and l i c h e n a v a i l a b i l i t y were not c o r r e l a t e d i n i n t e r v a l 4, and o n l y ve ry weakly c o r r e l a t e d i n i n t e r v a l 5 (Table 9 and F i g u r e 20 ) . Over these two i n t e r v a l s , much g r e a t e r q u a n t i t i e s of a r b o r e a l l i c h e n became a v a i l a b l e i n a l l mature h a b i t a t - c e l l s , e s p e c i a l l y i n the a r b o r e a l l i c h e n range of ESSF-low to Pa rk land (F igu re 20 ) . The c a r i b o u d i d not make a s i g n i f i c a n t ascent to suba lp ine h a b i t a t s , however, u n t i l i n t e r v a l 6. Presumably, these h a b i t a t s were e a r l i e r i n a c c e s s i b l e to c a r i b o u because of p r o h i b i t i v e l y h igh energy expend i tu re . But once access to the suba lp ine ranges improved i n i n t e r v a l 6, through t o i n t e r v a l 11 , the c a r i b o u ' s predominant occupancy of the mature f o r e s t s of ESSF- low and ESSF-h igh and the Pa rk land (F igu re 20) was r e f l e c t e d by h i g h l y p o s i t i v e a s s o c i a t i o n s between c a r i b o u h a b i t a t use and l i c h e n a v a i l a b i l i t y (Table 9 ) . Synonomously, these c o r r e l a t i o n s r e f l e c t e d c a r i b o u avoidance of A l p i n e and immature s e r a i types of a l l o ther h a b i t a t s i n g e n e r a l , and of ICH h a b i t a t s i n p a r t i c u l a r . By j u s t c o n s i d e r i n g the mature s e r a i types of ESSF- low and ESSF-h igh and the P a r k l a n d , however, l a t e w i n t e r c a r i b o u d i s t r i b u t i o n s were not ranked p o s i t i v e l y i n r e l a t i o n to a v a i l a b l e l i c h e n e s t i m a t e s . S p e c i f i c a l l y , r e l a t i v e l i c h e n a v a i l a b i l i t i e s i n c r e a s e d a long the i n c r e a s i n g e l e v a t i o n a l g rad ien t from ESSF- low t o Park land (F igu re 20 ) . Y e t , c a r i b o u u s u a l l y occupied the Pa rk land l e s s than they d i d e i t h e r ESSF- low or ESSF-h igh (F igu re 20 ) . In f a c t , c a r i b o u n o t i c e a b l y occup ied ESSF- low to some extent i n most l a t e w in te r i n t e r v a l s , and sometimes concent ra ted t h e i r occupat ion t h e r e . 96 B. Combined E f f e c t s of Energy Cost of Locomotion and A r b o r e a l L i chen A v a i l a b i l i t y on Car ibou Hab i ta t Use Data C o n s i d e r a t i o n s and D e s c r i p t i v e M u l t i v a r i a t e Ana lyses The f requency d i s t r i b u t i o n s of r a d i o obse rva t ions ( i . e . , r a d i o l o c a t i o n s p l u s a s s o c i a t e d a e r i a l t r a c k l o c a t i o n s ) c l a s s i f i e d a c c o r d i n g t o o rdered c l a s s e s of energy c o s t of locomot ion and a v a i l a b l e l i c h e n were summarized by w i n t e r p e r i o d s (see Tab le 9) i n 5x5 mat r i ces (Table 10 ) . These mat r i ces served as approx imat ions to t h r e e - d i m e n s i o n a l scat te rgrams, i l l u s t r a t i n g s imu l taneous ly the d i s t r i b u t i o n of c a r i b o u obse rva t i ons i n r e l a t i o n to the two envi ronmental f a c t o r s . Th is procedure a l l owed me to i n c l u d e the est imated r e l a t i v e f requency of occur rence of each s p e c i f i c combinat ion of locomot ion cos t and l i c h e n a v a i l a b i l i t y c l a s s e s ( i . e . , m a t r i x - c e l l s ) , f o r comparison w i t h r e l a t i v e c a r i b o u use . The r e l a t i v e f r equenc ies of occur rence , o r a v a i l a b i l i t i e s , of the m a t r i x - c e l l s were est imated w i t h i n the annual home ranges of the r a d i o c o l l a r e d c a r i b o u . F i r s t , a non-mapping technique (Marcum and Lo f tsgaarden 1980) of randomly l o c a t e d p o i n t s was used to es t imate the p r o p o r t i o n s of each of the 19 h a b i t a t - c e l l s i n the annual home ranges . A t o t a l sample s i z e of 200 p o i n t s was a r b i t r a r i l y s e l e c t e d , w i t h 50 p o i n t s a l l o c a t e d to each of the four home ranges . With t h i s i n f o r m a t i o n , together w i t h the es t imates of energy cos t of locomot ion and l i c h e n a v a i l a b i l i t y i n each h a b i t a t - c e l l , I then computed f o r each w in te r i n t e r v a l the p r o p o r t i o n of the composite home ranges c h a r a c t e r i z e d by the c o n d i t i o n s of each m a t r i x - c e l l ( i . e . , the a v a i l a b i l i t y of each m a t r i x - c e l l ) . For each win te r p e r i o d , i n t u r n , the a v a i l a b i l i t y of a m a t r i x - c e l l was taken as the average a v a i l a b i l i t y between the w i n t e r i n t e r v a l s pooled f o r that p e r i o d . To compensate f o r unequal sample s i z e s of c a r i b o u observa t ions between the w i n t e r i n t e r v a l s combined, these o v e r a l l average a v a i l a b i l i t i e s were weighted a c c o r d i n g to the 97 Tab le 10. Two-way mat r ices showing percentage of r a d i o c o l l a r e d c a r i b o u obse rva t i ons by ordered combinat ions ( m a t r i x - c e l l s ) of r e l a t i v e energy cos t of locomot ion i n snow (as i n F i g u r e 20) , and a v a i l a b l e a r b o r e a l a l e c t o r i o i d l i c h e n (as i n F i g u r e 20) , f o r w i n t e r p e r i o d s , w in te r 1979-80, North Thompson. Footnotes : a Sample s i z e of r a d i o l o c a t i o n s combined w i t h l o c a t i o n s of r a d i o c o l l a r e d c a r i b o u t r a c k s i n snow observed d u r i n g a e r i a l t r a c k i n g (see t e x t ) . N i l = no a r b o r e a l l i c h e n , r e f e r r i n g t o A l p i n e , and immature h a b i t a t - c e l l s f o r ICH- low, ICH-h igh , ESSF- low and ESSF-h igh (see t e x t ) . Percentage r a d i o c o l l a r e d c a r i b o u o b s e r v a t i o n s . d Est imated percentage a v a i l a b i l i t y of the m a t r i x - c e l l i n the combined annual home ranges of r a d i o c o l l a r e d c a r i b o u (see t e x t ) . e C h i - s q u a r e g o o d n e s s - o f - f i t t e s t r e s u l t s to two expected d i s t r i b u t i o n s of c a r i b o u by m a t r i x - c e l l s (see t e x t ) : X a , expected tha t c a r i b o u used a v a i l a b l e m a t r i x - c e l l s w i t h equal f requency ; X b, expected that c a r i b o u used a v a i l a b l e m a t r i x - c e l l s i n p r o p o r t i o n to t h e i r r e l a t i v e a v a i l a b i l i t i e s . Blank c e l l s = m a t r i x - c e l l s t ha t d i d not occur i n the w i n t e r p e r i o d . Table 10. Continued. A- 23 OCT - 27 NOV (K = 37)a 98 ENERGY COST LOCOMOTION 0 -25.50 25.51-50.50 50.51-75.50 75.51-100.50 > 100.50 TOTALS NILb 10.8C (30.3)° 2.7 (3.0) 0 (3.9) 0 (0.3) 13.5 (37.5) IRACX -2.0 81.1 (57.8) 5.4 (3.7) 0 (1.0) 86.5 (62.5) 4.0 -8.0 8.1 -16.0 20.0 -40.0 TOTALS 91.9 (88.1) 2.7 (3.0) 0 (3.9) 5.4 (4.0) 0 (1.0) (X2a = 137.5; X2!. - 10.3; X20.001, 6d.f. » 22.5) B. 28 NOV - 12 JAN (N = 36) ENERGY COST LOCOMOTION 0 -25.50 25.51-50.50 50.51-75.50 75.51-100.50 > 100.50 TOTALS , NIL 5.6 (16.3) 0 (9.8) 0 (3.4) 2.8 (8.0) 8.4 (37.5) TRACE -2.0 22.2 (17.0) 22.2 (7.7) 8.3 (8.7) 8.3 (2.9) 0 (1.5) 61.0 (37.8) 4.0 -8.0 27.8 (9.8) 2.8 (4.8) 0 (S.S) 30.6 (20.1) 8.1 -16.0 0 (0.S) 0 (0.7) 0 (1.2) 20.0 -40.0 0 (3.4) 0 (3.4) TOTALS 22.2 (17.0) 55.6 (37.2) 8.3 (18.5) 11.1 (11.6) 0 (IS.7) (X2a » 69.0; X^ = 39.1; X20.001, 14d.f. - 36.1) 99 Table 10. Continued. C. 13 JAN - 27 FEB (N = 79) ENERGY COST LOCOMOTION 0 -25.50 25.51-50.50 50.51-75.50 75.51-100.50 > 100.50 TOTALS NIL 0 (5.2) 5.0 (12.0) 5.0 (6.4) 5.0 (6.5) 0 (7.4) 15.0 (37.5) TRACE -2.0 0 (10.6) 0 (8.2) 2.5 (7.2) 0 (4.5) 2.5 (30.5) 4.0 -8.0 26.6 (14.0) 14.0 (7.5) 40.6 (21.5) 8.1 -16.0 12.7 (2.0) 7.6 (2.5) 20.3 (4.5) 20.0 -40.0 12.7 (2.8) 5.0 (1.4) 3.8 (1.8) 21.5 (6.0) TOTALS 12.7 (18.6) 36.6 (35.6) 38.0 (24.9) 12.6 (13.6) 0 (7.4) (X2a = 98.2; X*b • 137.5; X20.001, 15d.f. «> 37.7) D. 28 FEB - 2 APR (N = 74) ENERGY COST LOCOMOTION 0 -25.50 25.51-50.50 50.51-75.50 75.51-100.50 > 100.50 TOTALS NIL 9.5 (24.4) 5.4 (9.3) 6.7 (3.1) 0 (0.7) 21.6 (37.5) TRACE -2.0 0 (25.9) 0 (4.6) 0 (30.5) 4.0 -8.0 2.7 (4.5) 2.7 (4.5) 8.1 -16.0 1.4 (3.3) 17.6 (10.8) 18.9 (6.0) 6.7 (1.4) 44.6 (21.5) 20.0 -40.0 9.5 (1.1) 8.1 (1.6) 13.5 (3.3) 31.1 (6.0) TOTALS 23.1 (59.2) 31.1 (26.3) 32.4 (9.3) 13.4 (4.5) 0 (0.7) (X a •= 52.7; X b •= 164.7; X 0.001, 13d-f. «= 34.5) 100 sample s i z e of c a r i b o u observa t ions per w in te r i n t e r v a l . S i n g l e c l a s s i f i c a t i o n c h i - s q u a r e g o o d n e s s - o f - f i t t e s t s (Conover 1980:189) were used t o compare observed c a r i b o u d i s t r i b u t i o n s by m a t r i x - c e l l s 2 2 to each of two expected d i s t r i b u t i o n s (X a & X b, Tab le 10) . The n u l l hypothes is i n both cases was that c a r i b o u were randomly d i s t r i b u t e d r e l a t i v e to the combinat ions of locomot ion c o s t and a v a i l a b l e l i c h e n o c c u r r i n g i n each win te r p e r i o d . The f i r s t expected d i s t r i b u t i o n was t h a t c a r i b o u would use a v a i l a b l e m a t r i x - c e l l s w i t h equal f requency . The second expected d i s t r i b u t i o n was based on use p r o p o r t i o n a l to the r e l a t i v e a v a i l a b i l i t i e s of the m a t r i x - c e l l s . Th is expected d i s t r i b u t i o n n e c e s s i t a t e d some m a t r i x - c e l l s to have very low expected v a l u e s (< 1 . 0 ) . A l though i t i s not c l e a r how smal l expected v a l u e s may be (Conover 1980), recent l i t e r a t u r e concern ing the adequacy of the c h i - s q u a r e g o o d n e s s - o f - f i t t e s t i n d i c a t e s that the minimum expected c e l l v a l u e s can be as low as one (F ienberg 1980), or more g e n e r a l l y , tha t the average expected v a l u e can be l e s s than one (Conover 1980). R e s u l t s Both n u l l hypotheses were r e j e c t e d ( a l l p - v a l u e s but one <0.001, Tab le 10) , i n d i c a t i n g that i n each w in te r p e r i o d c a r i b o u g e n e r a l l y were not randomly d i s t r i b u t e d over the a v a i l a b l e a r r a y of locomot ion cos t and a v a i l a b l e l i c h e n combinat ions i n r e l a t i o n t o e i t h e r t h e i r uni form or p r o p o r t i o n a l expected d i s t r i b u t i o n s . 1. Late f a l l - e a r l y w in te r (23 October to 27 November) In the l a t e f a l l - e a r l y w in te r t r a n s i t i o n , c a r i b o u were m i g r a t i n g downslope, and ma in ly used mature f o r e s t s (F igu re 20) , c h a r a c t e r i z e d by low energy c o s t s of locomot ion and low a r b o r e a l l i c h e n a v a i l a b i l i t y (Table 10a) . However, over t h i s p e r i o d , l i c h e n a v a i l a b i l i t y was a t i t s l owest , w h i l e locomot ion c o s t s were s t i l l r e l a t i v e l y low, a l though showing an i n c r e a s i n g 101 t r e n d (F igu re 20 ) . 2 . E a r l y w i n t e r (28 November t o 12 January) In e a r l y w i n t e r , ca r ibou descended t o ma in ly ICH- low, ICH-h igh and ESSF-low (F igu re 20 ) , demonstrat ing c l o s e a s s o c i a t i o n s t o r e l a t i v e l y lower energy c o s t s of locomot ion p l u s lower l i c h e n a v a i l a b i l i t i e s a t t h i s t ime (Table 10b) . Th is was when h igh energy c o s t s ( i . e . , >100%) were more p reva len t than i n any other p e r i o d , and l i c h e n a v a i l a b i l i t y was i n t r a n s i t i o n between very low t o more abundant q u a n t i t i e s , f o l l o w i n g the p a t t e r n of i n c r e a s e i n g r a z i n g base l e v e l s . The areas of low energy cos t used by c a r i b o u were mature f o r e s t s ( t h e r e f o r e o f f e r i n g c a r i b o u a t l e a s t some a r b o r e a l l i c h e n ) , which g e n e r a l l y were used i n p r o p o r t i o n s exceeding t h e i r a v a i l a b i l i t y (Table 10b) . Car ibou d i s t r i b u t i o n s were p robab ly not more s t r o n g l y a s s o c i a t e d w i t h areas of g r e a t e r a v a i l a b l e l i c h e n , because they were uncommon, and were a l s o most ly a s s o c i a t e d w i t h , or i s o l a t e d by areas o f , h i g h energy c o s t s (Table 10b). In e a r l y w i n t e r , c a r i b o u t o l e r a t e d energy c o s t s up t o 100%, but o n l y i n mature f o r e s t s , c o n c e n t r a t i n g t h e i r a c t i v i t i e s i n areas where energy c o s t s of locomot ion were < 50% (Table 10b) . Energy c o s t s of locomot ion > 100% probab ly exceeded an upper t h r e s h o l d of t o l e r a n c e f o r most c a r i b o u movements. However, i t i s d i f f i c u l t t o propose a more exact v a l u e f o r t h i s t h r e s h o l d , because v a l u e s from i n d i v i d u a l h a b i t a t - c e l l s i n t h i s upper c l a s s ranged from 101% t o 250% (F igu re 20) . 3 . Late w in te r (13 January to 2 A p r i l ) In l a t e w i n t e r , ca r ibou demonstrated st ronger a f f i n i t i e s t o h igher a r b o r e a l l i c h e n a v a i l a b i l i t y than to lower energy c o s t (Table 10 c , d ) , by ascend ing to and remaining on a r b o r e a l l i c h e n ranges i n mature f o r e s t s from ESSF- low to P a r k l a n d (F igure 20 ) . T h i s c o i n c i d e d w i t h both a steady i n c r e a s e i n a r b o r e a l l i c h e n a v a i l a b i l i t y and a moderating of energy c o s t s , compared t o the e a r l y w in te r p e r i o d . A l s o i n l a t e w i n t e r , almost a l l combinat ions of 102 energy c o s t and a v a i l a b l e l i c h e n among mature suba lp ine f o r e s t h a b i t a t - c e l l s ( a v a i l a b l e l i c h e n > 4.0 to 8.0 c l a s s ) were used by c a r i b o u i n p r o p o r t i o n s exceeding t h e i r a v a i l a b i l i t y (Table 10 c , d ) . Th is s imply was because c a r i b o u avo ided the A l p i n e and the immature h a b i t a t - c e l l s of a l l o ther h a b i t a t types (zero l i c h e n c l a s s ) , a long w i t h the mature f o r e s t s of ICH h a b i t a t s ( t r a c e t o 2 .0 l i c h e n c l a s s ) . Once on the a r b o r e a l l i c h e n ranges , c a r i b o u appeared somewhat more t o l e r a n t of h igher energy c o s t s ( i . e . , 50 t o 100%), p robab ly because of g r e a t e r a r b o r e a l l i c h e n a v a i l a b i l i t y (Table 10 c , d ) . However, i n the f i r s t h a l f of l a t e w i n t e r (13 January to 27 February ) , the c o n s i s t e n t d e c l i n e i n c a r i b o u use a long the i n c r e a s i n g energy c o s t g rad ien t w i t h i n each of the moderate, abundant and very abundant l i c h e n c l a s s e s (Table 10c) , suggests they were s t i l l s e n s i t i v e to r e l a t i v e energy c o s t s , and tha t a v a i l a b l e l i c h e n c l a s s e s were not a l l e q u a l l y a c c e s s i b l e . In the next h a l f of l a t e w i n t e r , l i c h e n a v a i l a b i l i t i e s were even h igher (Table lOd ) , and may e x p l a i n why c a r i b o u appeared t o be even l e s s r e s p o n s i v e to energy c o s t s . S i m i l a r to e a r l y w i n t e r , c a r i b o u i n l a t e w in te r u s u a l l y were not observed i n a reas where energy c o s t s exceeded 100%. However, such energy c o s t s were uncommon, and fu r thermore , c o i n c i d e d w i t h areas of assumed zero a r b o r e a l l i c h e n (Table 10 c , d ) . T h e r e f o r e , c a r i b o u may have avoided these areas e i t h e r by chance or because of t h e i r l a c k of l i c h e n fo rage , r a t h e r than because they were p r o h i b i t i v e l y c o s t l y t o t r a v e l i n . C. Genera l Car ibou Responses t o Locomotion C o n d i t i o n s i n Snow Moen (1976:197) , i n a study of energy c o n s e r v a t i o n adapta t ions of w i n t e r i n g deer , found that " . . . d e e r responses t o changes (my emphasis) i n weather and snow c o n d i t i o n s a re r e l a t i v e to p r e v i o u s l y e x i s t i n g c o n d i t i o n s r a t h e r than averages f o r the e n t i r e w i n t e r . " . A c c o r d i n g l y , i n t h i s 103 s u b s e c t i o n the d i r e c t i o n a l t r e n d , r a t h e r than a b s o l u t e magnitude, i n temporal f l u c t u a t i o n s of both c a r i b o u e l e v a t i o n a l (or h a b i t a t ) d i s t r i b u t i o n s and locomot ion c o n d i t i o n s i n snow are compared on a s e q u e n t i a l b a s i s . The preceed ing c o r r e l a t i o n a l ana lyses (Table 9) and da ta p r e s e n t a t i o n s ( F i g u r e 20) i l l u s t r a t e d that the major w i n t e r a l t i t u d i n a l m i g r a t i o n p a t t e r n s of c a r i b o u were r e l a t e d to genera l t rends i n suba lp ine locomot ion c o n d i t i o n s , and tha t t h e i r m i d - w i n t e r ascending m i g r a t i o n was a genera l move to g rea te r a r b o r e a l l i c h e n a v a i l a b i l i t y . However, a t f i n e r l e v e l s of r e s o l u t i o n , c a r i b o u use among the mature f o r e s t s of ESSF- low, ESSF-h igh and Park land i n l a t e w in te r ( i n t e r v a l s 6 to 11) , was not c l e a r l y a s s o c i a t e d w i t h e i t h e r es t imated a r b o r e a l l i c h e n a v a i l a b i l i t i e s or locomot ion c o n d i t i o n s i n snow among these h a b i t a t s (see F i g u r e 20 ) . On a broader l e v e l than i n d i v i d u a l h a b i t a t - c e l l s , n e v e r t h e l e s s , there was an a s s o c i a t i o n between t rends i n c a r i b o u d i s t r i b u t i o n and genera l locomot ion c o n d i t i o n s over l a t e w i n t e r . These a s s o c i a t i o n s , masked by the c o r r e l a t i o n a l ana lyses based on the more d e t a i l e d , 19 h a b i t a t - c e l l a n a l y t i c a l d e s i g n , a re addressed i n t h i s s u b s e c t i o n . 1. E l e v a t i o n a l D i s t r i b u t i o n Data C o n s i d e r a t i o n s and Ana lyses S t a t i s t i c a l t e s t s of hypotheses were not conducted here , because the f o l l o w i n g ana lyses were cons idered e x p l o r a t o r y and d e s c r i p t i v e , hav ing been conce ived a p o s t e r i o r i t o the o r i g i n a l 19 h a b i t a t - c e l l a n a l y t i c a l d e s i g n . However, t h i s treatment remains c o n s i s t e n t w i t h the o r i g i n a l o b j e c t i v e of a s s e s s i n g the i n f l u e n c e of locomot ion c o n d i t i o n s i n snow on c a r i b o u h a b i t a t d i s t r i b u t i o n . A d d i t i o n a l l y , i n determin ing the d i r e c t i o n a l t rend of a v a r i a b l e ( i . e . , i n c r e a s i n g or d e c l i n i n g ) between consecut i ve i n t e r v a l s , i t s c o n s e c u t i v e va lues were t r e a t e d as o r d i n a l i n s c a l e , and un less t i e d , were 104 assumed t o be d i f f e r e n t . The average energy c o s t s of locomot ion f o r the e leven h a b i t a t - c e l l s from ESSF- low t o A l p i n e served as an index of c a r i b o u locomot ion c o n d i t i o n s i n snow on the suba lp ine a r b o r e a l l i c h e n ranges (F igu re 21 ) ; i t s temporal t rend p a r a l l e l s those computed e a r l i e r f o r sma l le r combinat ions of h a b i t a t - c e l l s ( F igu re 6 ) . R e s u l t s The t rend i n average e l e v a t i o n s of r a d i o l o c a t i o n s tended t o t r a c e an i n v e r s e d i r e c t i o n a l p a t t e r n t o the t rend i n the locomot ion index (F igu re 21) . In other words, s e q u e n t i a l l y between s u c c e s s i v e l y p a i r e d w in te r i n t e r v a l s , as locomot ion c o n d i t i o n s d e t e r i o r a t e d c a r i b o u tended to move downward, and as locomot ion c o n d i t i o n s subsequent ly improved c a r i b o u s h i f t e d upward. Th is r e l a t i o n s h i p a p p l i e d both to the e a r l y - t o - m i d w in te r a l t i t u d i n a l m i g r a t i o n p a t t e r n , and most i m p o r t a n t l y , t o s h i f t s i n the c a r i b o u ' s . l a t e w i n t e r d i s t r i b u t i o n s among suba lp ine a r b o r e a l l i c h e n range h a b i t a t s . 2 . H a b i t a t D i s t r i b u t i o n Data C o n s i d e r a t i o n s and Analyses Because h a b i t a t type and e l e v a t i o n were i n t e r r e l a t e d , i t was expected that the i n v e r s e d i r e c t i o n a l r e l a t i o n s h i p between locomot ion c o n d i t i o n s and c a r i b o u e l e v a t i o n a l d i s t r i b u t i o n s would be p a r a l l e l e d by s i m i l a r r e l a t i o n s h i p s when h a b i t a t use was c o n s i d e r e d . In accordance w i t h c a r i b o u w i n t e r range and f o r e s t r y management concerns , s e q u e n t i a l comparisons were l i m i t e d t o the two l a t e w i n t e r , a r b o r e a l l i c h e n range components of the L ichen Reserve and ESSF-low ( lower s u b a l p i n e ) , below the r e s e r v e . E a r l i e r i t was shown that the mature f o r e s t s of the L ichen Reserve o f f e r e d r e l a t i v e l y g r e a t e r a v a i l a b l e l i c h e n than those of the lower suba lp ine (F igures 15 and 20) , p a r t i c u l a r l y over l a t e w i n t e r . The re fo re , the pr imary o b j e c t i v e of t h i s 105 2 2 0 0 n 1 8 0 0 - .... H 0 0 -1 0 0 0 -600' / \ / v ' \ / \ / \ / \ / \ / \ / 1 SEP 220CT f • /V / \ / \ / \ ' \ / \ \ I \ \r \' V ' \l " I 2 I 3 1 T~T 5^  I T"! 7 I 8 I 9 I 10 I 11 1 I I I I I OCT NOV DEC JAN F E B WINTER INTERVALS. 1979-80 MAR F igu re 21. Comparison of t rend between mean (+ 2SE and range) e l e v a t i o n s of r a d i o c o l l a r e d c a r i b o u (from F i g u r e 19) and an index of c a r i b o u locomot ion c o n d i t i o n s i n snow i n suba lp ine and a l p i n e h a b i t a t s ( s o l i d c i r c l e s and broken l i n e ) , w in te r 1979-80, North Thompson. The locomot ion index i s the average of r e l a t i v e i n c r e a s e i n the net c o s t of locomotion i n snow among the 11 h a b i t a t - c e l l s from ESSF- low t o A l p i n e . 106 a n a l y s i s was t o e v a l u a t e i f the temporal f l u c t u a t i o n s i n the use of e i t h e r the lower suba lp ine or the L ichen Reserve corresponded t o changes i n locomot ion c o n d i t i o n s , e s p e c i a l l y over l a t e w i n t e r . R e s u l t s A l though the lower suba lp ine and L ichen Reserve were both used by c a r i b o u i n most w i n t e r i n t e r v a l s , r e l a t i v e use was g r e a t e r f o r the lower suba lp ine i n e a r l y w i n t e r , and u s u a l l y g rea te r f o r the L i c h e n Reserve i n l a t e w in te r (Table 11) . On a broad s p a t i a l s c a l e , t h e r e f o r e , c a r i b o u d i s t r i b u t i o n s i n l a t e w in te r were g e n e r a l l y p o s i t i v e l y a s s o c i a t e d w i t h a r b o r e a l l i c h e n a v a i l a b i l i t i e s on the suba lp ine ranges . But most i m p o r t a n t l y i n l a t e w i n t e r , when the locomot ion index changed between i n t e r v a l s , the i n t e n s i t y i n c a r i b o u use of the L ichen Reserve u s u a l l y changed i n the o p p o s i t e d i r e c t i o n (Table 11) . In c o n t r a s t , between many s u c c e s s i v e w i n t e r i n t e r v a l s , i n t e n s i t y of ca r ibou use of the lower suba lp ine was d i r e c t l y or p o s i t i v e l y a s s o c i a t e d w i t h the d i r e c t i o n a l t r end i n locomot ion c o n d i t i o n s , e s p e c i a l l y i n l a t e winter (Table 11 ) . Th is p a t t e r n suggested t h a t , among other purposes , the lower suba lp ine served c a r i b o u as a re fuge from poor locomot ion c o n d i t i o n s a t h igher e l e v a t i o n s , i n both the e a r l y and l a t e w i n t e r p e r i o d s . The lower suba lp ine u s u a l l y o f f e r e d lower energy c o s t s of locomot ion than the L ichen Reserve (F igure 22 ) . In l a t e w i n t e r , t h i s d i f f e r e n t i a l appeared to c o n t r i b u t e markedly to the c a r i b o u 1 s p a t t e r n of e l e v a t i o n a l (F igu re 21) and h a b i t a t (Table 11, F i g u r e 22) use w i t h i n the suba lp ine a r b o r e a l l i c h e n ranges . For example, between i n t e r v a l s 7 and 8, as locomot ion c o n d i t i o n s d e t e r i o r a t e d , c a r i b o u moved downward toward the lower s u b a l p i n e , where locomot ion c o n d i t i o n s were more favourab le (F igu re 22 ) . Then, between i n t e r v a l s 8 and 9, the d ramat ic improvement i n locomot ion 107 Table 11. S e q u e n t i a l comparisons between d i r e c t i o n s of change i n c a r i b o u use of d i f f e r e n t suba lp ine h a b i t a t s and i n ca r ibou locomot ion c o n d i t i o n s i n snow i n the s u b a l p i n e , w in te r 1979-80, North Thompson. CARIBOU HABITAT USE (%) LOCOMOTION LICHEN WINTER INTERVAL COST INDEX 3 ESSF- low RESERVE 0 SNOW 1 SEP-22 OCT o d 21.4 78.6 FREE u A A ,_, e V <+) 1. 23 0CT-14 NOV 12.7 A 40.0 A (-) 44.0 V ( + ) 2 . 15 - 27 NOV 60.4 41.7 16.6 EARLY A V (+) V ( + ) WINTER 3 . 28 NOV-12 DEC 83.4 A 37.5 V (+) 0 4. 13 - 27 DEC 141.0 0 0 V A (+) A (+) 5 . 28 DEC-12 JAN 65.9 V 47.6 V (-> 4.8 A (+> 6. 13 - 28 JAN 36.6 35.0 59.5 A V (+) A (-) 7. 29 JAN-13 FEB 57.6 A 26.3 A (-) 73.7 V <+> LATE 8. 14 - 27 FEB 84.2 61.0 39.0 WINTER V V (-) A (+) 9. 28 FEB-9 MAR 18.8 A 12.0 A (-) 85.0 V ( + ) 10. 10 - 21 MAR 78.4 V 42.0 V (-) 38.0 A (+) 11 . 22 MAR-2 APR 55.8 4.5 95.5 Average of r e l a t i v e i n c r e a s e i n the net energy cost of locomot ion i n snow (% over no snow; Parker et a l . 1984) among the 11 h a b i t a t - c e l l s from ESSF-low to A l p i n e (from F i g u r e 20 ) . Percentage c a r i b o u r a d i o l o c a t i o n s , combined w i t h l o c a t i o n s of r a d i o -c o l l a r e d c a r i b o u t r a c k s i n snow observed du r ing a e r i a l r a d i o t r a c k i n g . Includes A l p i n e ; ca r ibou use of A l p i n e was low (F igure 20 ) , and i n c l u s i o n does not a l t e r r e s u l t s of s e q u e n t i a l compar isons. D i r e c t i o n of change between s u c c e s s i v e t ime i n t e r v a l s . Agreement or disagreement w i t h proposed d i r e c t i o n a l t r e n d ; i . e . , as the energy c o s t of locomotion i n c r e a s e s , the percentage c a r i b o u use of h a b i t a t decreases ( the p lus s i g n i n d i c a t e s agreement w i t h t h i s p r o p o s a l ) . 108 MATURE 180n • LICHEN RESERVE (N = U) o E S S F - LOW (N=2) ICH (N = U) o o o o Lu o I/) o o H LU Z UJ X LU < UJ or o z UJ > UJ or 120-OCT NOV DEC JAN FEB WINTER INTERVALS, 1979-80 MAR F i g u r e 22. D i s t r i b u t i o n (%) of c a r i b o u observat ions (numbers on F i g u r e ) by groupings of h a b i t a t types (mature and immature s e r a i types combined) compared t o averages of r e l a t i v e i n c r e a s e s i n the net cost of locomot ion i n snow f o r mature s e r a i types of these h a b i t a t type groupings (from F i g u r e 7 ) , w in te r 1979-80, North Thompson. Car ibou observat ions r e f e r t o r a d i o l o c a t i o n s combined w i t h a e r i a l t r a c k - l o c a t i o n s of r a d i o c o l l a r e d c a r i b o u (see t e x t ) (from F igu re 20 and Table 11) . 109 c o n d i t i o n s i n a l l h a b i t a t s c o i n c i d e d w i t h a reascent by c a r i b o u to the L ichen Reserve and A l p i n e . A s i m i l a r p a t t e r n was repeated between i n t e r v a l s 9, 10 and 11 (F igu re 22 ) . Other obse rva t ions a l s o co r robora ted tha t c a r i b o u movements were r e s t r i c t e d d u r i n g p e r i o d s of poor locomot ion c o n d i t i o n s i n l a t e w i n t e r . For example, each of the four r a d i o c o l l a r e d c a r i b o u groups moved to a new p a r t i a l range o n l y between l a t e February and mid March i n w i n t e r 1979-80, c o i n c i d i n g w i t h the dramat ic and wide spread improvement i n locomot ion c o n d i t i o n s d u r i n g i n t e r v a l 9 ( F igu re 22 ) . These movements ranged from 5 to 35 km, and i n v o l v e d t r a v e r s i n g one to two i n t e r v e n i n g d r a i n a g e s . 3 . A e r i a l Survey Observat ions The o v e r a l l p a t t e r n i n c a r i b o u d i s t r i b u t i o n a l s h i f t s d e s c r i b e d above i s co r robora ted by a e r i a l survey obse rva t i ons of n o n - r a d i o c o l l a r e d c a r i b o u (F igu re 18b) . Dur ing p e r i o d s of heavy and f requent s n o w f a l l s i n the l a t e w in te r of both w i n t e r s of s tudy , c a r i b o u were more o f t e n found i n denser and /o r lower e l e v a t i o n suba lp ine f o r e s t s , and they appeared to be r e l a t i v e l y sedentary . In comparison, when s n o w f a l l s were i n f r e q u e n t or l e s s severe , c a r i b o u were u s u a l l y found i n more open f o r e s t s and a t h igher e l e v a t i o n s , and e x t e n s i v e movements were more common. 110 V I I . SUMMARY DISCUSSION Net Energy Model T r a d e - o f f s between c o s t s and b e n e f i t s i n an a n i m a l ' s environment were proposed by Moen (1976, 1978) and by Peek e t a l . (1982) to account f o r gene ra l h a b i t a t use p a t t e r n s i n u n g u l a t e s . However, Harestad and B u n n e l l (1979) and Harestad et a l . (1982)' proposed s imple e n e r g e t i c models of seasona l movements and h a b i t a t use by e l k (C. e. r o o s e v e l t i ) and b l a c k - t a i l e d deer , which appear more d i r e c t l y a p p l i c a b l e to c a r i b o u i n the p resent s tudy . T h i s i s because t h e i r models were developed f o r ungulates l i v i n g i n a mountainous r e g i o n of deep s n o w f a l l and dense c o n i f e r o u s f o r e s t . In t h e i r models, seasonal movements or s h i f t s i n the degree of use among h a b i t a t s by ungulates are responses to changes i n the r e l a t i v e f a v o u r a b i l i t y or b e n e f i t of h a b i t a t s . They proposed that the an imals a re a b l e t o e v a l u a t e the r e l a t i v e f a v o u r a b i l i t y of d i f f e r e n t h a b i t a t s i n terms of b e n e f i t s and c o s t s t o t h e i r f i t n e s s , and so use those h a b i t a t s o f f e r i n g the g r e a t e r net b e n e f i t . In the net b e n e f i t model 's b a s i c form, the f a v o u r a b i l i t y of a h a b i t a t i s based upon the r e l a t i v e net energy a v a i l a b l e to the an imal (Harestad et a l . 1982), which i s an i n t e g r a t i o n of the b e n e f i t s of a v a i l a b l e f o r a g e , or energy, and the energy expend i ture of locomot ion i n snow to a c q u i r e f o r a g e . To t h i s r e l a t i v e net energy parameter , Harestad (1979) added another : the c o s t to f i t n e s s , represented by the r i s k of p r e d a t i o n . Moen (1976, 1978) a l s o suggested that h a b i t a t use by w h i t e - t a i l e d deer i n w in te r was based upon net b e n e f i t s , i n v o l v i n g i n t e g r a t i o n of a v a i l a b l e forage and e n e r g e t i c c o s t s of movement i n snow, and p o s s i b l y w i t h thermal environment c o n s i d e r a t i o n s . Peek et a l . (1982) added s e c u r i t y c o n s i d e r a t i o n s to these f a c t o r s . The r e l a t i v e net energy parameter s u b s t a n t i a l l y e x p l a i n s much of the w i n t e r movements and h a b i t a t use p a t t e r n s of c a r i b o u observed i n t h i s s tudy . Both locomot ion c o n d i t i o n s i n snow and a r b o r e a l a l e c t o r i o i d l i c h e n I l l a v a i l a b i l i t y were major , a l though not the o n l y , c o n t r i b u t i n g f a c t o r s toward the net energy v a l u e of h a b i t a t s i n w i n t e r . E a r l y Winter Net energy framework Car ibou w i n t e r d i e t and f o r a g i n g behaviour were d i v e r s e , and determined p r i m a r i l y by the e f f e c t s of snowpack c o n d i t i o n s on forage a v a i l a b i l i t y , e s p e c i a l l y of t e r r e s t r i a l p l a n t s . In e a r l y w i n t e r , t e r r e s t r i a l fo rages and a r b o r e a l l i c h e n sources bes ides s tand ing t r e e s , were t h e r e f o r e important f a c t o r s i n c a r i b o u w i n t e r ecology and d i s t r i b u t i o n . The accumulat ion p a t t e r n of the t y p i c a l l y s o f t , e a r l y w i n t e r snowpacks r e s u l t e d i n an ascending e l e v a t i o n a l g r a d i e n t of both worsening locomot ion c o n d i t i o n s and reduced a v a i l a b i l i t y of f avoured , low t e r r e s t r i a l fo rages due t o b u r i a l . Dur ing much of t h i s p e r i o d t h e r e f o r e , energy c o s t of locomot ion i n snow was e s s e n t i a l l y i n v e r s e l y c o r r e l a t e d w i t h t e r r e s t r i a l fo rage a v a i l a b i l i t y . S i m i l a r l y , both of these f a c t o r s were compara t i ve l y more favou rab le f o r c a r i b o u i n mature f o r e s t s than i n adjacent immature s e r a i t y p e s , due to s n o w f a l l i n t e r c e p t i o n by the mature f o r e s t canopy. Moreover, an a d d i t i o n a l advantage of mature f o r e s t s , r e g a r d l e s s of h a b i t a t t ype , was t h a t they o f f e r e d more a v a i l a b l e a r b o r e a l l i c h e n than d i d immature s e r a i t y p e s . Car ibou descent to the e a r l y w in te r range of mature f o r e s t s between ESSF- low and ICH-low was a move t o b e t t e r locomot ion c o n d i t i o n s and t o g r e a t e r t e r r e s t r i a l fo rage a v a i l a b i l i t y , i n a d d i t i o n to a t l e a s t some a v a i l a b l e a r b o r e a l l i c h e n . In summary, these lower e l e v a t i o n f o r e s t s , compared both to ad jacent immature s e r a i types and to a l l h igher e l e v a t i o n h a b i t a t s ( i . e . , ESSF -h igh t o A l p i n e ) , appeared t o be the most e n e r g e t i c a l l y economical h a b i t a t s f o r ca r ibou over t h i s p e r i o d of accumulat ing s o f t snow. 112 Among these e a r l y w in te r range h a b i t a t s , the net energy t o c a r i b o u was p robab ly s i m i l a r . At the upper range, i n ESSF- low, the g r e a t e r a r b o r e a l l i c h e n a v a i l a b i l i t y would compensate f o r a r e l a t i v e l y lower a v a i l a b i l i t y of t e r r e s t r i a l fo rages due to e a r l i e r b u r i a l by snow; w h i l e lower down, i n ICH-low, a r b o r e a l l i c h e n a v a i l a b i l i t y was lower , but t e r r e s t r i a l fo rage a v a i l a b i l i t y was g rea te r because of sha l lower snowpacks. E a r l y w i n t e r f e e d i n g s i t e i n s p e c t i o n s a l s o showed that a r b o r e a l l i c h e n s on s tand ing t r e e s were used much more h e a v i l y i n ESSF f o r e s t s than i n ICH f o r e s t s a t t h i s t ime . In e a r l y w i n t e r , t h e r e f o r e , the s i g n i f i c a n t b i v a r i a t e c o r r e l a t i o n s between c a r i b o u h a b i t a t use and e i t h e r locomot ion c o s t s i n snow or a v a i l a b l e a r b o r e a l l i c h e n (Table 9) were confounded by m u l t i c o l l i n e a r i t i e s between these two and o ther f a c t o r s . F i r s t , the c a r i b o u ' s predominant use of mature f o r e s t s below the L ichen Reserve was p o s s i b l y more s t r o n g l y a s s o c i a t e d w i t h o v e r a l l g rea te r forage a v a i l a b i l i t i e s ( t e r r e s t r i a l and a r b o r e a l fo rages combined), than to avoidance of poor locomot ion c o n d i t i o n s a t the h igher e l e v a t i o n s per se . (However, the i n t e r s e c t i o n "of both b e t t e r m o b i l i t y and f o rage a v a i l a b i l i t y c o n d i t i o n s s u b s t a n t i a l l y c o n t r i b u t e s t o a more f a v o u r a b l e net b e n e f i t f o r c a r i b o u . ) Second, a l e c t o r i o i d l i c h e n s on s tand ing t r e e s were o n l y one i tem on one source i n a d i v e r s e e a r l y w i n t e r d i e t and f o r a g i n g s t r a t e g y . T h e r e f o r e , the s i g n i f i c a n t p o s i t i v e a s s o c i a t i o n s between c a r i b o u h a b i t a t use and a v a i l a b l e a r b o r e a l l i c h e n i n e a r l y w in te r e i t h e r were somewhat spur ious or o n l y r e f l e c t e d r e a l p a r t i a l a s s o c i a t i o n s . T h i s was e s p e c i a l l y t r u e f o r the r e l a t i v e l y h i g h p o s i t i v e a s s o c i a t i o n s i n i n t e r v a l s 1 t o 3 , p r i o r to the heavy s n o w f a l l s of December, when a v a i l a b l e l i c h e n i n the f o r e s t canopy was u n i v e r s a l l y low, and when c a r i b o u h e a v i l y u t i l i z e d other fo rages and other sources of a r b o r e a l l i c h e n . The heavy s n o w f a l l s and r a p i d snow accumulat ions of December 1979, however, r e s u l t e d i n the most adverse f o r a g i n g and locomot ion c o n d i t i o n s of 113 the w i n t e r . In a l l h a b i t a t s , even mature ICH f o r e s t s , t e r r e s t r i a l forage a v a i l a b i l i t y now d e c l i n e d s u b s t a n t i a l l y due to b u r i a l by snow and to un favourab le c r a t e r i n g c o n d i t i o n s . A l s o , c a r i b o u locomot ion i n snow markedly d e t e r i o r a t e d . In p rev ious e a r l y w i n t e r p e r i o d s w i t h i n low e l e v a t i o n s of the study a r e a , c a r i b o u were observed e x p e r i e n c i n g great d i f f i c u l t y t r a v e l l i n g i n such snow c o n d i t i o n s , when t r a c k depths approached or e q u a l l e d chest he ight (Edwards and R i t c e y 1959; F. R i c h t e r , p e r s . comm. 1978). I t was not ev ident i n the p resent study , however, t ha t c a r i b o u were a c t u a l l y immobi l i zed w i t h i n ICH f o r e s t s by the deep snow accumulat ions of December 1979, except perhaps t e m p o r a r i l y d u r i n g or j u s t a f t e r s n o w f a l l s . In summary, d u r i n g these adverse f o r a g i n g and locomot ion c o n d i t i o n s c a r i b o u were c o n f i n e d p r i m a r i l y t o mature f o r e s t s of the low e l e v a t i o n , ICH-low and ICH-h igh h a b i t a t s . Other workers have a l s o i n d i c a t e d that the t y p i c a l a r r i v a l of deep, s o f t snow to low e l e v a t i o n s c o u l d impose s i m i l a r d i f f i c u l t c o n d i t i o n s on c a r i b o u i n e a r l y w i n t e r (Edwards and R i t c e y 1959, 1960, S c o t t and Servheen 1984, Simpson et a l . 1985). C o n c u r r e n t l y , the r a p i d l y accumulat ing snowpacks r e s u l t e d i n a marked i n c r e a s e i n a l e c t o r i o i d l i c h e n a v a i l a b i l i t y on s tand ing t r e e s . Th is i n c r e a s e was e s p e c i a l l y conspicuous i n ESSF compared to ICH f o r e s t s . Consequent ly , the net e n e r g e t i c d i f f e r e n t i a l between low and h igh e l e v a t i o n ranges was l e s s c l e a r l y d e f i n e d than e a r l i e r i n w i n t e r when snowpacks were s h a l l o w e r . Now the f o r e s t e d areas of h igher locomot ion c o s t s were combined w i t h the h igher a r b o r e a l l i c h e n a v a i l a b i l i t i e s ( i . e . , ESSF- low to P a r k l a n d ) ; w h i l e the f o r e s t e d areas of r e l a t i v e l y lower locomot ion c o s t s were combined w i t h the lower a r b o r e a l l i c h e n a v a i l a b i l i t i e s ( i . e . , ICH h a b i t a t s ) . The re fo re , once the heavy, e a r l y w i n t e r s n o w f a l l s a r r i v e d , i t appeared tha t the h igher e l e v a t i o n f o r e s t s were beg inn ing t o o f f e r c a r i b o u g reater food a v a i l a b i l i t y , main ly a r b o r e a l a l e c t o r i o i d l i c h e n s . The c a r i b o u ' s access 114 to these h a b i t a t s was r e s t r i c t e d , however, by poor locomot ion c o n d i t i o n s i n snow (see a l s o Edwards and R i t c e y 1959). T h i s was i l l u s t r a t e d by the c a r i b o u ' s upward m i g r a t i o n c o i n c i d e n t w i t h the eventua l improvement o v e r a l l i n locomot ion c o n d i t i o n s , r a t h e r than c o i n c i d e n t w i t h the e a r l i e r i n c r e a s e i n a r b o r e a l l i c h e n a v a i l a b i l i t y . Grad ient i n a l t i t u d i n a l m i g r a t i o n i n e a r l y w i n t e r In both w i n t e r s of study, some c a r i b o u groups d i d not descend as low i n e l e v a t i o n as o the rs d i d i n e a r l y w i n t e r , occupying most ly ESSF- low, even d u r i n g the heavy s n o w f a l l s . As snow r a p i d l y accumulated i n t h i s p e r i o d , the cor respond ing i n c r e a s e i n a r b o r e a l l i c h e n a v a i l a b i l i t y c o u l d have p o t e n t i a l l y b e n e f i t e d these c a r i b o u s u b s t a n t i a l l y ; tha t i s , i f they were a b l e t o t o l e r a t e the ve ry c o s t l y f o r a g i n g movements u n t i l snowpacks e v e n t u a l l y s e t t l e d . Each w i n t e r , an i n c r e a s e i n a r b o r e a l l i c h e n a v a i l a b i l i t y , and a decrease i n t e r r e s t r i a l p l a n t a v a i l a b i l i t y , was p r e d i c t a b l e , but the t i m i n g i n the sett lement of the e a r l y w in te r snow accumulat ions was n o t . Thus, c a r i b o u that remain a t h igher e l e v a t i o n s i n e a r l y w in te r f a c e the p o s s i b i l i t y of severe i m m o b i l i z a t i o n , moreso and /o r f o r longer d u r a t i o n s than those a t lower e l e v a t i o n s . I t may be important tha t many of these c a r i b o u a t h igher e l e v a t i o n s were c u r s o r i l y a s s o c i a t e d w i t h the f o l l o w i n g : the lower s n o w f a l l r e g i o n , where locomot ion i n snow and t e r r e s t r i a l fo rage a v a i l a b i l i t y may both have been more favou rab le than a t comparable e l e v a t i o n s e lsewhere ; or a c t i v e l o g g i n g , r e g a r d l e s s of c l i m a t i c r e g i o n , where a r b o r e a l l i c h e n was e x t r a o r d i n a r i l y abundant, and m o b i l i t y was e a s i e r because of s k i d - t r a i l s and plowed roads . A d d i t i o n a l l y , these c a r i b o u were o f t e n observed i n upper v a l l e y s , or near suba lp ine bogs and l a k e s . Such landtypes i n suba lp ine (ESSF) f o r e s t s were 115 found by D e t r i c k (1984) t o have r e l a t i v e l y abundant a r b o r e a l l i c h e n , suggest ing that c a r i b o u congregat ing i n such s i t e s were compensated f o r g r e a t e r locomot ion c o s t s . And f i n a l l y , Cowan (1974) noted tha t many n o r t h e r n , mountainous ungulates demonstrate a c r o p h i l i a , whereby they remain a t the h ighes t p o s s i b l e e l e v a t i o n on t h e i r w i n t e r range. Car ibou tha t remained i n ESSF h a b i t a t s may have e x h i b i t e d a c r o p h i l i a , perhaps as a p reda to r avoidance s t r a t e g y , independent of net e n e r g e t i c c o n s i d e r a t i o n s . Bergerud (1978a) opined tha t the lowland Columbia f o r e s t ( i . e . , ICH Zone) was not e s s e n t i a l t o e a r l y w i n t e r i n g c a r i b o u i n southeastern B r i t i s h Columbia . N e v e r t h e l e s s , most North Thompson c a r i b o u d i d use mature ICH f o r e s t s s u b s t a n t i a l l y , which seemed to be the most e n e r g e t i c a l l y economical a reas d u r i n g e a r l y w i n t e r over much of the study a r e a . I n f l u e n c e of a r b o r e a l l i c h e n at l o g g i n g o p e r a t i o n s i n e a r l y w in te r A c t i v e l o g g i n g i n both w i n t e r s of study occur red throughout the study a r e a o u t s i d e of We l l s Gray Park . At l e a s t some use of l o g g i n g s i t e s f o r a r b o r e a l l i c h e n fo rage by both r a d i o c o l l a r e d and n o n - r a d i o c o l l a r e d c a r i b o u groups was noted i n e a r l y w i n t e r ; however, these s i t e s were abandoned i n l a t e w i n t e r , once access t o s tand ing t r e e sources improved. In t h i s study , as w e l l as i n tha t of Simpson et a l . (1985), a c t i v e l o g g i n g o p e r a t i o n s were most a t t r a c t i v e to c a r i b o u i n e a r l y w i n t e r , because of r e d u c t i o n s i n a v a i l a b i l i t y and /o r a c c e s s i b i l i t y of c o n v e n t i o n a l fo rages at t h i s t i m e . L o c a t i o n of w i n t e r l o g g i n g c o i n c i d e d w i t h the h a b i t a t s used most h e a v i l y i n e a r l y w i n t e r : ICH- low, ICH-h igh and ESSF- low. A l though l ogg ing opera t ions d i d somewhat i n f l u e n c e l o c a l movements and d i s t r i b u t i o n s of c a r i b o u i n e a r l y w i n t e r , my genera l impress ion was that l o g g e r - f e l l e d t r e e s were a supplemental r a t h e r than pr imary source of e a r l y w in te r fo rage f o r most c a r i b o u , and thus were a secondary f a c t o r i n f l u e n c i n g the major p a t t e r n of 116 c a r i b o u w in te r d i s t r i b u t i o n s . T h i s l a t t e r p o i n t was shown by c a r i b o u i n We l l s Gray Park and i n unlogged s e c t i o n s of the study a rea o u t s i d e of the park , where they appeared to migrate a l t i t u d i n a l l y and occup ied h a b i t a t s i n s i m i l a r p a t t e r n s t o c a r i b o u i n areas where w in te r l ogg ing d i d o c c u r . Late Winter Car ibou movements between low and h i g h e l e v a t i o n ranges The m i d - w i n t e r c a r i b o u ascent to the l a t e w in te r range of ESSF- low t o Park land most c l e a r l y was a movement toward r e l a t i v e l y g r e a t e r a r b o r e a l a l e c t o r i o i d l i c h e n a v a i l a b i l i t y . More g e n e r a l l y , t h i s movement appeared t o be toward r e l a t i v e l y g rea te r t o t a l a v a i l a b l e fo rage , as p r e v i o u s l y contended by Edwards and R i t c e y (1959, 1960) and Edwards et a l . (1960), and as r e c e n t l y i n d i r e c t l y demonstrated by Simpson et a l . (1985). Bergerud (1972, 1974a, 1974b), M i l l e r (1974, 1976) and Skogland (1978) a l s o recogn i zed fo rage a v a i l a b i l i t y , as mediated by changing snowpack c o n d i t i o n s , t o be a major s t imu lus f o r movements and s h i f t s i n h a b i t a t occupancy by c a r i b o u or r e i n d e e r throughout w i n t e r . Compared t o ESSF h a b i t a t s , ICH h a b i t a t s would be subopt imal t o c a r i b o u i n l a t e w i n t e r , d e s p i t e lower locomot ion c o s t s . Th is was because t e r r e s t r i a l fo rage a v a i l a b i l i t y , d r a m a t i c a l l y reduced over e a r l y w i n t e r , cont inued to d e c l i n e due t o b u r i a l by snow and t o p r o g r e s s i v e d e t e r i o r a t i o n of c r a t e r i n g c o n d i t i o n s , and a r b o r e a l l i c h e n a v a i l a b i l i t y , a l though s l i g h t l y i n c r e a s e d , was s t i l l ve ry low. In c o n t r a s t , the suba lp ine (ESSF Zone) f o r e s t s i n l a t e w in te r not o n l y p rov ided g r e a t e r r e l a t i v e abundances but a l s o g r e a t e r p o s i t i v e i n c r e a s e s over t ime i n a r b o r e a l l i c h e n . Bes ides g r e a t e r a v a i l a b l e f o r a g e , c a r i b o u use of suba lp ine f o r e s t s , once locomot ion c o n d i t i o n s i n snow improved, was c o n s i s t e n t w i t h the net energy model of h a b i t a t u t i l i z a t i o n . Now, energy expendi tures f o r locomot ion i n 117 suba lp ine f o r e s t s were presumably s u f f i c i e n t l y below c a r i b o u t h r e s h o l d s , or e l s e low enough i n r e l a t i o n t o the a v a i l a b i l i t y of energy here that they were more t o l e r a b l e t o c a r i b o u . In genera l then , g rea te r forage a v a i l a b i l i t y combined w i t h somewhat h igher locomot ion c o s t s i n ESSF f o r e s t e d h a b i t a t s o f f e r e d c a r i b o u g r e a t e r net energy than lower forage a v a i l a b i l i t y combined w i t h lower locomot ion c o s t s i n ICH f o r e s t e d h a b i t a t s . Whi le a p p a r e n t l y not the most e n e r g e t i c a l l y economical s t r a t e g y , to remain i n lower e l e v a t i o n s over l a t e w i n t e r c a r i b o u presumably would be compel led to browse t a l l deciduous shrubs and c o n i f e r s , supplemented by a r b o r e a l l i c h e n s , a l l of which were of low a v a i l a b i l i t y . C r a t e r i n g may a l s o p r o v i d e a d d i t i o n a l f o r a g e , p r i m a r i l y v a s c u l a r p l a n t s because t e r r e s t r i a l l i c h e n abundance i s low ( A h t i 1962, p resent s t u d y ) . But c r a t e r i n g would be q u i t e c o s t l y and not o p t i m a l f o r c a r i b o u because of deep, moderately dense and m u l t i c r u s t e d snowpacks ( P r u i t t 1979, R u s s e l l and M a r t e l 1984), c h a r a c t e r i s t i c o f the i n l a n d - c o a s t a l c l i m a t e (see Prowse and Owens 1984) o f the North Thompson. Browse t w i g s , c o n i f e r m a t e r i a l , and dead leaves of graminoids and shrubs a re p o o r l y d i g e s t e d , w h i l e l i c h e n s , both a r b o r e a l and t e r r e s t r i a l , a re h i g h l y d i g e s t e d by bar ren -ground ca r ibou i n w in te r (Thomas et a l . 1984, White and T r u d e l l 1980, White et a l . 1981). Forage l i c h e n s , i n c l u d i n g a l e c t o r i o i d s p e c i e s , a re repo r ted to have a s y n e r g i s t i c e f f e c t i n enhancing the no rma l l y poor d i g e s t i b i l i t y of of v a s c u l a r p l a n t s i n w in te r ( K l e i n 1982, 1983, R o c h e l l e 1980). The re fo re , a l a t e w in te r d i e t i n the suba lp ine h a b i t a t s predominated by a r b o r e a l l i c h e n but w i t h some c o n i f e r m a t e r i a l would be more n u t r i t i o n a l l y and e n e r g e t i c a l l y b e n e f i c i a l t o c a r i b o u than a d i e t i n the lower e l e v a t i o n s predominated by browse but w i t h o n l y a sma l l amount of a r b o r e a l l i c h e n . 118 Car ibou h a b i t a t use w i t h i n h i g h e l e v a t i o n ranges The widespread occupat ion of the ESSF Zone f o r e s t e d h a b i t a t s i n l a t e w i n t e r c o u l d be l a r g e l y e x p l a i n e d by the net energy model as w e l l . The g r e a t e r l i c h e n a v a i l a b i l i t i e s combined w i t h the u s u a l l y g rea te r locomot ion c o s t s of the L ichen Reserve c o u l d more or l e s s ba lance the r e l a t i v e lower l i c h e n a v a i l a b i l i t i e s but g e n e r a l l y lower locomot ion c o s t s of ESSF- low. Thereby, the net energy to c a r i b o u c o n c e i v a b l y was approx imate ly equal between ESSF- low and the L ichen Reserve . N e v e r t h e l e s s , o v e r a l l i n l a t e w i n t e r , c a r i b o u u t i l i z e d the L ichen Reserve s l i g h t l y more than ESSF- low, r e f l e c t i n g e a r l i e r obse rva t ions w i t h i n the study a rea that found " t i m b e r l i n e f o r e s t s " ( i . e . , e s s e n t i a l l y the L ichen Reserve) (Edwards and R i t c e y 1959) or f o r e s t s above 5500 f t (1680 m) e l e v a t i o n ( R i t c e y 1974, 1976) were used most h e a v i l y by c a r i b o u . Perhaps t h i s tendancy i n d i c a t e s that the net b e n e f i t t o c a r i b o u was u s u a l l y g rea te r i n the L i c h e n Reserve. Observat ions of o thers ( R i t c e y 1974, 1976) a l s o showed that ESSF- low was used to some extent i n l a t e w i n t e r . The present study , though, found tha t c a r i b o u use of ESSF-low on o c c a s i o n equaled or even exceeded tha t of the L ichen Reserve . I t appeared tha t d u r i n g p e r i o d i c d e t e r i o r a t i o n of locomot ion c o n d i t i o n s ( i . e . , d u r i n g major s n o w f a l l phases ) , c a r i b o u moved t o the lower suba lp ine t o a v o i d the g rea te r locomot ion impediments i n the L ichen Reserve . T h e r e f o r e , the net energy of ESSF- low apparent l y sometimes exceeded tha t of the L i c h e n Reserve over l a t e w i n t e r . Other s t u d i e s i m p l i c a t e d changing locomot ion c o n d i t i o n s i n snow w i t h some w i n t e r movements and s h i f t s i n h a b i t a t use by c a r i b o u . Such changes c o u l d be p r e c i p i t a t e d by f a c t o r s such as c r u s t s ( S c o t t e r 1964, Stardom 1975, P r u i t t 1959), deepened snowpacks (Darby and P r u i t t 1984, P r u i t t 1959, Skogland 1978), or snowpacks so f tened by s o l a r r a d i a t i o n (Skogland 1978). 119 In f l uence of o the r f a c t o r s i n l a t e w i n t e r : A l though b r o a d l y c o i n c i d e n t w i t h changes i n locomot ion c o n d i t i o n s , o ther weather f a c t o r s , s i n g l y or combined, may have i n f l u e n c e d shor t term l a t e w i n t e r h a b i t a t use p a t t e r n s and net energy r e l a t i o n s h i p s . These i n c l u d e s t rong winds , low temperatures, and f r e e z i n g r a i n , a l l common at h i g h mountainous e l e v a t i o n s (Barry 1981, Yoshino 1975), and which may depress an a n i m a l ' s thermal environment (Moen 1973:274) toward c r i t i c a l l e v e l s . The A l p i n e and the t y p i c a l l y more open f o r e s t s of the L ichen Reserve would p r o v i d e low s h e l t e r from inclement weather . There fo re , c a r i b o u moves t o denser s u b a l p i n e f o r e s t s and /o r t o below topographic c r e s t s sometimes may have been shor t term thermoregulatory responses . In o ther s t u d i e s , c a r i b o u and r e i n d e e r moved to the s h e l t e r of f o r e s t cover or i r r e g u l a r topography i n response to s t rong winds or o ther inc lement weather (Henshaw 1968, K e l s a l l 1968, P r u i t t 1959, White et a l . 1981), suggest ing the c o n s e r v a t i o n of hea t . B l o o m f i e l d (1979) a l s o noted that mountain c a r i b o u w i n t e r i n g i n suba lp ine reg ions s h i f t e d t o denser f o r e s t s i n response t o inc lement weather, a t the expense of g rea te r a r b o r e a l l i c h e n a v a i l a b i l i t i e s i n nearby, more open f o r e s t s . T h i s i s d e s p i t e other f i n d i n g s that c r i t i c a l temperatures f o r Rang i fe r i n s t i l l a i r were i n the ve ry low range of -30° t o -55° C ( N i l s s e n et a l . 1984, rev iew of R u s s e l l and M a r t e l l 1984). Mountain sheep and mountain goats w i n t e r i n g at h i g h e l e v a t i o n s have a l s o been r e p o r t e d to seek s h e l t e r , i n c l u d i n g denser f o r e s t c o v e r , i n response t o low temperature, wind and p r e c i p i t a t i o n , as w e l l as t o barometr ic p ressu re changes i n a n t i c i p a t i o n to storms (Foster 1982, Hoefs and Cowan 1979, S inger and Doherty 1985, Smith 1977, T i l t o n and W i l l a r d 1982). In c o n t r a s t , Bergerud (1974a) repo r ted that f o r e s t s appeared unimportant as thermal s h e l t e r to w i n t e r i n g c a r i b o u i n Newfoundland. S i m i l a r l y , a l though p o s s i b l y p r e f e r r e d , thermal cover of f o r e s t o v e r s t o r y , or even s u b s t i t u t e s 120 such as i r r e g u l a r topography or shrub l a y e r v e g e t a t i o n , may not be a h a b i t a t requirement f o r deer , e l k and moose (A lces a l c e s ) (Peek et a l . 1982). The a l t i t u d i n a l s h i f t s observed over l a t e w i n t e r were not r e l a t e d i n any obv ious way to f l u c t u a t i o n s i n a r b o r e a l l i c h e n a v a i l a b i l i t y . For example, major snow accumulat ions would g e n e r a l l y e l e v a t e c a r i b o u i n t o reach of new a r b o r e a l l i c h e n sources , which presumably would counteract any o ther i n f l u e n c e s ( i . e . , d e t e r i o r a t i n g locomot ion or thermal c o n d i t i o n s ) to move e lsewhere . Car ibou avoidance of human d i s t u r b a n c e s , such as snowmobiles or h e l i c o p t e r s k i i n g a c t i v i t i e s , may have a l s o prompted some l a t e w i n t e r movements. I t i s important t o no te , however, tha t c a r i b o u i n e a r l y w i n t e r were t o l e r a n t of a c t i v e l ogg ing a c t i v i t i e s , w h i l e throughout the w in te r a t l e a s t some c a r i b o u were not averse t o c r o s s i n g t r a n s p o r t a t i o n c o r r i d o r s . A l though sometimes avo ided , Bergerud et a l . (1984) concluded that p e r i o d i c human-re lated d i s t u r b a n c e s through harassment can be t o l e r a t e d by c a r i b o u and other deer spec ies wi thout negat i ve e f f e c t s on p r o d u c t i v i t y and s u r v i v a l . Whi le i t was suspected tha t some types of human a c t i v i t i e s e l i c i t e d c a r i b o u avoidance responses i n the present study , more s p e c i f i c research i s needed. Adequacy of A r b o r e a l L i c h e n Range The adequacy of the c u r r e n t s tand ing crop of a r b o r e a l a l e c t o r i o i d l i c h e n i n suba lp ine f o r e s t s t o meet the o v e r - w i n t e r i n g maintenance requirements of the North Thompson c a r i b o u p o p u l a t i o n i s important and r e q u i r e s a d d r e s s i n g . In the S e l k i r k Mountains, S c o t t and Servheen (1984) found that c a r i b o u use among suba lp ine f o r e s t s i n l a t e w in te r was not s t r o n g l y a s s o c i a t e d w i t h a r b o r e a l l i c h e n abundance r a t i n g s ; and thus , s i n c e i t d i d not appear to i n f l u e n c e h a b i t a t use , l i c h e n biomass was p o s s i b l y adequate f o r c a r i b o u w i n t e r requ i rements . Approx imate ly 20 years p r i o r to the present study , A h t i 121 (1962) b e l i e v e d that the a r b o r e a l l i c h e n resource i n s u b a l p i n e f o r e s t s of the W e l l s Gray Pa rk -Nor th Thompson range was u n d e r - u t i l i z e d , and cou ld s u s t a i n a g r e a t e r d e n s i t y of w i n t e r i n g c a r i b o u . In the present study, as i n Freddy (1974), c a r i b o u g r a z i n g i n t e n s i t y on a r b o r e a l a l e c t o r i o i d l i c h e n u s u a l l y appeared to be l i g h t . Heavy l i c h e n g r a z i n g p ressu re was on l y observed l o c a l l y i n the suba lp ine d u r i n g o c c a s i o n a l i n t e r v a l s of ve ry poor locomot ion i n snow, when c a r i b o u t e m p o r a r i l y were ya rded . S i m i l a r l y , the da ta of Simpson et a l . (1985) i m p l i e d an o v e r a l l l i g h t g r a z i n g p ressu re on the a r b o r e a l l i c h e n resource i n l a t e w i n t e r , because a l a r g e p r o p o r t i o n (approx imate ly 40%) of a r b o r e a l l i c h e n s i t e s cons ide red a v a i l a b l e to c a r i b o u were unused. A l though i t appeared t o be l i g h t , the a c t u a l g r a z i n g i n t e n s i t y on the a r b o r e a l l i c h e n s tand ing crop i s unknown. S i m i l a r l y , the annual p r o d u c t i o n of these l i c h e n s i s unknown, but i t i s assumed to be low because of t h e i r slow growth; Frey (1952) repo r ted that A l e c t o r i a jubata (assumed to be of the genus B r y o r i a , a f t e r Brodo and Hawksworth 1977) growth was 14 mm per y e a r . In range management, the concept of g r a z i n g c a p a c i t y of a range i n v o l v e s l i m i t i n g h e r b i v o r e g r a z i n g i n t e n s i t y to some a l l o w a b l e p r o p o r t i o n of the annual fo rage p r o d u c t i o n i n order t o prevent ove rg raz ing and a d e c l i n i n g t r e n d i n fo rage p roduct ion (Stoddart et a l . 1975). Assuming tha t annual l i t t e r f a l l r a t e s of a r b o r e a l l i c h e n s i n mature f o r e s t s approximate the annual turnover and thus annual p r o d u c t i o n of t h i s f o r a g e , Stevenson (1979) est imated that c a r i b o u can a n n u a l l y consume 13% of the l i c h e n s tand ing crop wi thout d e p l e t i n g t h i s fo rage base . I f t h i s so , then the a p p a r e n t l y low o v e r a l l l i c h e n g r a z i n g i n t e n s i t y of c a r i b o u observed i n t h i s and other s t u d i e s may not n e c e s s a r i l y imply tha t t h e ' c u r r e n t a r b o r e a l l i c h e n resource i s a c t u a l l y adequate f o r long term c a r i b o u p o p u l a t i o n needs. In o ther words, i t i s not known i f the a r b o r e a l l i c h e n range i s overgrazed 122 and i t s p r o d u c t i v i t y i s d e c l i n i n g , or i f the range i s u n d e r u t i l i z e d ; i f o n l y a 13% u t i l i z a t i o n of the s tand ing crop i s s u s t a i n a b l e , over c ropp ing may be o c c u r r i n g but i s unrecogn izab le because the l i c h e n crop c o u l d s t i l l appear adequate f o r the shor t term. Evans (1964) proposed that l i g h t g r a z i n g i n t e n s i t y , l a r g e ranges and nomadic behaviour were adaptat ions of mountain c a r i b o u t o prevent over e x p l o i t a t i o n of slow growing a r b o r e a l l i c h e n s . Bergerud (1978b) thought tha t i n genera l c a r i b o u r e q u i r e vas t space to a v o i d p redators and summer i n s e c t harassment, and t o respond to v a r i a b i l i t y i n w in te r food supp ly ; and a l s o , as an a d a p t a t i o n to the slow growing l i c h e n f l o r a , which presumably c o u l d be s u s c e p t i b l e to o v e r g r a z i n g . For c a r i b o u p o p u l a t i o n s c o e x i s t i n g w i t h p r e d a t o r s , however, Bergerud (1980) contended t h a t the pr imary need f o r l a r g e ranges was to min imize c o n t a c t s w i t h p r e d a t o r s . Furthermore, he concluded that such space r a t h e r than n u t r i t i o n a l f a c t o r s was a dens i ty -dependent p o p u l a t i o n l i m i t i n g resource i n such c a s e s . And i n f a c t , Bergerud (1980) est imated t h a t , a l though w i n t e r n u t r i t i o n may v a r y a n n u a l l y due to weather v a r i a t i o n and may sometimes l ead t o m o r t a l i t y and lowered p r o d u c t i v i t y i n a dens i ty - i ndependent manner, the space r e q u i r e d by c a r i b o u t o o b t a i n adequate forage i s c o n s i d e r a b l y l e s s than that r e q u i r e d to a v o i d p r e d a t o r s . Bergerud (1980) d i d p r e d i c t , though, t ha t f o r c a r i b o u not sub ject to p r e d a t i o n , and who are not f r e e to d i s p e r s e or migrate t o l o c a t e g reate r forage a v a i l a b i l i t y , food l i m i t a t i o n may o c c u r . Skogland (1985) concluded that the p r imary f a c t o r r e g u l a t i n g w i l d r e i n d e e r herds i n Norway, where i n f a c t wolves a r e absent and m i g r a t i o n s can be o b s t r u c t e d , i s dens i ty -dependent l i m i t a t i o n of w i n t e r f ood . In the North Thompson,, c a r i b o u c o e x i s t w i t h wolves as w e l l as cougars ( F e l i s conco lo r ) and coyotes (Canis l a t r a n s ) . I f the v a s t space requirement to a v o i d p redato rs proposed by Bergerud (1980) i s mani fest by c a r i b o u i n 123 w i n t e r , then c a r i b o u w i n t e r i n g i n the North Thompson may u s u a l l y ( i . e . , except p o s s i b l y i n randomly o c c u r r i n g severe w i n t e r s ) have an abundant rese rve of w in te r f o r a g e , i n c l u d i n g a r b o r e a l l i c h e n . In f a c t , Bergerud (1978a) d i d propose that a r b o r e a l l i c h e n s were ve ry abundant, and presumably more than s u f f i c i e n t f o r c a r i b o u requ i rements , i n the p resent study a rea and i n the S e l k i r k Mounta ins . Stevenson (1979) quest ioned t h i s argument, however, based on a c t u a l a r b o r e a l l i c h e n biomass es t imates i n the S e l k i r k Mountains . At any r a t e , Bergerud (1978a) s t i l l favoured an extremely c o n s e r v a t i v e approach to a r b o r e a l l i c h e n range management, whereby f o r e s t s i n e s s e n t i a l l y the ESSF Zone would be p r o t e c t e d from l o g g i n g and f i r e s . Such a c a u t i o u s and c o n s e r v a t i v e treatment of the a r b o r e a l l i c h e n resource has a l s o been advocated s t r o n g l y by Edwards and R i t c e y (1959) and R i t c e y (1974, 1976, 1978, 1979). Car ibou Locomotion Thresho lds From the fo rma l snow course d a t a i t appeared t h a t c a r i b o u g e n e r a l l y avo ided areas where t r a c k depths exceeded 36.5 cm ( i . e . , 100% r e l a t i v e i n c r e a s e i n the net energy expend i tu re f o r locomot ion based upon a snow 3 d e n s i t y of 0.2 g/cm , F i g u r e 20) , o r approx imate ly 52% of chest h e i g h t . T h i s i s sha l lower than the t w o - t h i r d s chest he ight (or f o r e - l e g length) or deeper s i n k i n g depths (> 46.7 cm f o r c a r i b o u i n t h i s study) cons ide red by o the rs t o s e v e r e l y r e s t r i c t ungulate movements (Coady 1974, H e l l e 1981, K e l s a l l 1969, Nieminen and H e l l e 1980, Sweeney and Sweeney 1984). In formal o b s e r v a t i o n s , however, d i d o c c a s i o n a l l y f i n d c a r i b o u t r a c k depths between t w o - t h i r d s t o f u l l chest h e i g h t . Car ibou reduced a c t i v i t y i n such snow c o n d i t i o n s , though, as an energy c o n s e r v a t i o n s t r a t e g y (Moen 1976). In s h o r t , a s i n k i n g depth tha t can serve as a c o n s i s t e n t upper t h r e s h o l d of t o l e r a n c e f o r c a r i b o u c o u l d not be adequate ly determined i n the present s tudy . 124 In f a c t , a maximum t o l e r a b l e s i n k i n g depth may be approximated by the chest he igh t or f o r e l e g l eng th (see H e l l e 1981, Nieminen and H e l l e 1980). Ungulates can s t i l l move i n snow when s i n k i n g depths equal or exceed chest h e i g h t , but u s u a l l y o n l y by the v e r y exhaust i ve process of p lung ing ( K e l s a l l 1969, M a t t f e l d 1974, Parker et a l . 1984). At sha l lower s i n k i n g depths , energy expend i tures t o walk i n c r e a s e e x p o n e n t i a l l y w i t h s i n k i n g depth ( M a t t f e l d 1974, Parker et a l . 1984) . T h e r e f o r e , i n s t e a d of a f i x e d , c r i t i c a l maximum or t h r e s h o l d v a l u e , an animal may have v a r i a b l e t o l e r a n c e s t o s i n k i n g depth i n snow. As p r e v i o u s l y d i s c u s s e d , such t o l e r a n c e s l i k e l y depend l a r g e l y on fo rage a v a i l a b i l i t y , which would compensate f o r the energy expendi ture of locomot ion t o a c q u i r e i t (Harestad and Bunne l l 1979, Harestad et a l . 1982, Moen 1976, 1978, P o t v i n and Huot 1983) . N e v e r t h e l e s s , i t i s noteworthy tha t the ca r ibou s i n k i n g depth of 36.5 cm, or 52% chest h e i g h t , c o i n c i d e s w i t h s i n k i n g depths of 43.1% and 57.4% of chest he igh t tha t prompt deer and e l k , r e s p e c t i v e l y , to move t o sha l lower snow ( rev iew of Parker et a l . 1984) . S i m i l a r l y , Sweeney and Sweeney (1984) found t h a t e l k p r e f e r r e d h a b i t a t s w i t h l e s s than 40 cm of p e n e t r a b l e snow, or approx imate ly 47% of chest h e i g h t , a l though up to 70 cm was t o l e r a b l e . Comparison of Snow and Locomotion C o n d i t i o n s Between Winters The magnitude and temporal p a t t e r n of locomotion c o s t s i n snow c o u l d vary between w i n t e r s , due to d i f f e r e n c e s i n weather c o n d i t i o n s and p a t t e r n s , f o r example i n p r e c i p i t a t i o n type and i n temperature f l u c t u a t i o n s . D i f f e r e n c e s i n snow c o n d i t i o n s were observed between the two w i n t e r s of s tudy , and were thought to have s t r o n g l y c o n t r i b u t e d to some important d i f f e r e n c e s i n c a r i b o u movements and d i s t r i b u t i o n . The wet ter and warmer e a r l y w i n t e r c o n d i t i o n s of 1979-80 r e s u l t e d i n an 125 e a r l i e r and more d ramat ic set t lement of snow accumulat ions than d i d the compara t i ve l y d r i e r and c o l d e r c o n d i t i o n s i n w in te r 1978-79. A c c o r d i n g l y , the m id -w in te r ascending m i g r a t i o n to suba lp ine ranges occur red n o t i c e a b l y e a r l i e r , by about a month, i n the second w i n t e r . K. Simpson (pe rs . comm. 1984), D. K ing ( p e r s . comm. 1983), and R u s s e l l et a l . (1982) a l s o noted that s o f t , e a r l y w i n t e r snow c o n d i t i o n s c o u l d p e r s i s t i n t o February or March and thereby i n h i b i t c a r i b o u ascent t o suba lp ine h a b i t a t s . On the other hand, K. Simpson ( p e r s . comm. 1984) and S c o t t and Seervheen (1985) both observed r e l a t i v e l y e a r l y ascending m i g r a t i o n s of mountain c a r i b o u because of e a r l y snowpack s e t t l e m e n t . There fo re , the d u r a t i o n of use i n lower e l e v a t i o n f o r e s t e d ranges , whether i n the ICH Zone or i n ESSF- low, w i l l va ry between w i n t e r s . The i m p l i c a t i o n to c a r i b o u h a b i t a t and f o r e s t r y management and r e s e a r c h i s t o determine more c l o s e l y the amount of a rea and the d u r a t i o n of use i n low e l e v a t i o n ranges over many w i n t e r s r e p r e s e n t i n g a wide range of weather c o n d i t i o n s . Management and Research I m p l i c a t i o n s Throughout both w in te rs of s tudy , the North Thompson c a r i b o u p o p u l a t i o n used the e n t i r e a r r a y of h a b i t a t types a v a i l a b l e t o them, from v a l l e y s to summits: ICH-low t o A l p i n e . Furthermore, use was s u b s t a n t i a l i n each h a b i t a t type d u r i n g p o r t i o n s of each w i n t e r , i m p l y i n g that none can yet be d i s r e g a r d e d as a w i n t e r range requirement of the p o p u l a t i o n . An e x c e p t i o n may o c c u r , a t l e a s t i n some w i n t e r s , i n the assumed lower s n o w f a l l r e g i o n , where ICH h a b i t a t s e v i d e n t l y were of r e l a t i v e l y lower importance. Th is apparent r e g i o n a l r e l a t i o n s h i p r e q u i r e s more i n t e n s i v e s tudy . Moreover, c a r i b o u used mature f o r e s t s (> 140 years o ld ) much more than younger s e r a i s tages , i n c l u d i n g recent c u t o v e r s , a l though both s e r a i types 126 were commonly a v a i l a b l e . The reason f o r t h i s appeared t o be t h a t , because of s n o w f a l l i n t e r c e p t i o n combined w i t h g r e a t e r a r b o r e a l l i c h e n a v a i l a b i l i t y , mature f o r e s t h a b i t a t s were more e n e r g e t i c a l l y f a v o u r a b l e to c a r i b o u i n t h i s r e g i o n of deep snowpack accumu la t i on . For example, through most of the w i n t e r , r e l a t i v e fo rage a v a i l a b i l i t y ( c o l l e c t i v e l y , t e r r e s t r i a l and a r b o r e a l components) was g r e a t e r and locomot ion r e s t r i c t i o n was lower i n mature f o r e s t s than i n a s s o c i a t e d n o n - f o r e s t s and e a r l y s e r a i f o r e s t s . Mid s e r a i , g e n e r a l l y c l o s e d - c a n o p i e d f o r e s t s were not w e l l a s s e s s e d . But i n these a reas i t s t i l l appeared tha t fo rage a v a i l a b i l i t i e s were lower than i n mature f o r e s t s , a l though snow accumulat ions and thus m o b i l i t y c o n d i t i o n s may be moderated compared t o e a r l i e r s e r a i s t a g e s . Other f a c t o r s tha t may have c o n t r i b u t e d somewhat to the v a l u e of mature f o r e s t s t o c a r i b o u i n c l u d e b e t t e r s e c u r i t y (or h i d i n g ) cover and thermal c o v e r . In summary, mature f o r e s t s o f f e r w i n t e r i n g c a r i b o u g rea te r e n e r g e t i c b e n e f i t s than cutovers and immature f o r e s t s . Co r respond ing ly , ca r ibou i n w i n t e r demonstrated movement and h a b i t a t use p a t t e r n s predominant ly among mature or o l d - g r o w t h f o r e s t s g e n e r a l l y c o n s i s t e n t w i t h a s t r a t e g y of o p t i m i z i n g energy b a l a n c e . Cont inued l o s s of the cover and forage resource advantages of mature f o r e s t s would be a n e g a t i v e p ressu re upon energy ba lances of w i n t e r i n g c a r i b o u , which c o u l d p o t e n t i a l l y l e a d to lower c a r i b o u p o p u l a t i o n p r o d u c t i v i t y and s i z e . The r e s u l t s of the p resent study show that mature f o r e s t s are r e q u i r e d r a t h e r than j u s t p r e f e r r e d h a b i t a t of c a r i b o u throughout w in te r (see a l s o Hanley e t a l . 1984, R i t c e y 1974, 1976). However, the response of a c a r i b o u p o p u l a t i o n t o the l o s s of w in te r range w i l l depend on the p o p u l a t i o n ' s r e l a t i o n s h i p to the n u t r i t i o n a l c a r r y i n g c a p a c i t y of the range ( K l e i n 1982) . There i s u n c e r t a i n t y r e g a r d i n g the r e l a t i v e importance of w in te r food r e s o u r c e s , p a r t i c u l a r l y a r b o r e a l l i c h e n s , and of p r e d a t i o n i n l i m i t i n g the 127 c u r r e n t North Thompson c a r i b o u p o p u l a t i o n (see a l s o rev iew of Stevenson and H a t l e r 1985). At p r e s e n t , the o v e r - w i n t e r e n e r g e t i c s , the q u a n t i t y and q u a l i t y of w i n t e r f o rage , and the s i z e , dynamics and l i m i t i n g f a c t o r s of the Nor th Thompson c a r i b o u p o p u l a t i o n a re not s u f f i c i e n t l y understood t o permit f o r m u l a t i n g a d e f i n i t i v e c a u s a l r e l a t i o n s h i p between c a r i b o u p o p u l a t i o n response and w i n t e r h a b i t a t change. To d e f i n e the amount of mature f o r e s t t ha t must be r e t a i n e d as w in te r h a b i t a t , the c u r r e n t Nor th Thompson c a r i b o u p o p u l a t i o n ' s r e l a t i o n s h i p to the n u t r i t i o n a l c a r r y i n g c a p a c i t y of t h e i r t o t a l ( e a r l y and l a t e ) w in te r range must be determined, and the c a r i b o u p o p u l a t i o n s i z e d e s i r e d must be d e f i n e d . Research i s a l s o necessary to determine i f second-growth f o r e s t s can be manipulated by s i l v i c u l t u r a l t reatments (Nyberg et a l . 1986) t o produce more u s e f u l w in te r h a b i t a t , and i n p a r t i c u l a r t o enhance the p r o d u c t i o n of a r b o r e a l l i c h e n s . Pending f u r t h e r r esea rch add ress ing these concerns , i t i s i m p e r a t i v e t o implement a ve ry c o n s e r v a t i v e f o r e s t h a r v e s t i n g , as w e l l as an a c t i v e f i r e supp ress ion , regimen w i t h i n areas i d e n t i f i e d as c a r i b o u w i n t e r range. Such c a u t i o n was advocated by o thers as w e l l , i n c l u d i n g Bergerud (1978a), R i t c e y (1974, 1976, 1978) and Stevenson and H a t l e r (1985) . E s s e n t i a l l y , t h i s i m p l i e s t h a t i n i t i a l l y e x t e n s i v e areas of mature f o r e s t must be reserved as c a r i b o u w in te r h a b i t a t . Moreover, mature f o r e s t s below 1680 m (5500 f t ) , i n the more merchantable Engelmann s p r u c e - s u b a l p i n e f i r and cedar -hemlock f o r e s t s below the proposed L ichen Reserve, must be among the areas r e s e r v e d . The present study demonstrated that such h a b i t a t s were not on l y c r i t i c a l i n e a r l y w in te r but i n l a t e w in te r ( i . e . , lower p o r t i o n of ESSF) as w e l l . F u r t h e r , use of ESSF f o r e s t s below the proposed L ichen Reserve (ESSF-low) i n l a t e w in te r may not have been a c a s u a l o p t i o n f o r c a r i b o u . I ns tead , i t appeared that the lower ESSF p e r i o d i c a l l y was an important re fuge from l e s s t o l e r a b l e m o b i l i t y or thermal c o n d i t i o n s at h igher 128 e l e v a t i o n s , i n a d d i t i o n to e s s e n t i a l l y be ing a cont inuous component of the c a r i b o u ' s l a t e w i n t e r a r b o r e a l l i c h e n range . I t i s t h e r e f o r e unwise a t p resent t o assume that the proposed L i c h e n Reserve i s even s o l e l y adequate as l a t e w in te r a r b o r e a l l i c h e n range. And f i n a l l y , c o n f l i c t s between c a r i b o u w in te r range requirements and f o r e s t h a r v e s t i n g are exacerbated because some c a r i b o u summering w i t h i n the p r o t e c t i o n of We l l s Gray Park migrate to w i n t e r ranges i n ad jacent Timber Supply Areas , i n c r e a s i n g the l o c a l importance of these w i n t e r i n g areas to the We l l s Gray Park - North Thompson p o p u l a t i o n . 129 V I I I . LITERATURE CITED A h t i , T. 1962. E c o l o g i c a l i n v e s t i g a t i o n s on l i c h e n s i n We l ls Gray P r o v i n c i a l Park w i t h s p e c i a l r e f e r e n c e t o t h e i r importance to mountain c a r i b o u . Unpubl . R e p t . , Parks B r . , B .C . Dept. R e c r e a t i o n and Conserv . , V i c t o r i a , B .C . 69pp. A h t i , T. and R . L . Hepburn. 1967. P r e l i m i n a r y s t u d i e s on woodland c a r i b o u range, e s p e c i a l l y on l i c h e n stands , i n O n t a r i o . Ont. 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P r e s s , Cambridge, U.K. 813pp. Yosh ino , M.M. 1975. C l imate i n a sma l l a r e a . Un iv . of Tokyo P r e s s . 549pp. 11 10 i 122 MAR-1 15 31 15 30 15 31 15 31 15 29 15 31 15 OCT NOV DEC JAN F E B MAR APR 1979 1980 Appendix A. D a i l y snow water equ iva len ts recorded by the Mount S a i n t Anne snowpi l low (1770 m e l e v a t i o n ; Inventory and Eng ineer ing Branch, unpub l i shed ) , w in te r 1979-80, North Thompson. A l s o shown are dates of sampling (S) snow courses i n the p resent study , and the dates of the 11 w in te r i n t e r v a l s cent red about those samples. «* o 141 APPENDIX B Forage p l a n t s used by mountain c a r i b o u i n l a t e f a l l and w i n t e r (October to A p r i l ) , 1978 t o 1980, North Thompson. I. P l a n t Type c o n i f e r stem c o n i f e r needle shrub stem shrub l e a f herbaceous d e c o r t i c a t e d twigs u n i d e n t i f i e d leaves graminoids Equisetum f e r n s moss bark u n i d e n t i f i e d l i c h e n a l e c t o r i o i d l i c h e n ( f r u t i c o s e ) other f r u t i c o s e l i c h e n s f o l i o s e - l i c h e n c r u s t o s e l i c h e n I I . Taxon or Spec ies I n d e n t i f i e d c F e c a l Rumen F e e d i n g - s i t e Samples Samples I n s p e c t i o n X X X X X X X X X X X X X X X X X X X X X X X X X X X 1 ) . N o n - l i c h e n : Ab ies l a s i o c a r p a X X A lnus sp . X A r n i c a l a t i f o l i a X Asteraceae ( u n i d e n t i f i e d ) X Carex spp. X X C o p t i s sp . X Cornus canadensis X X Ep i lob ium spp. X Equisetum spp. X X E r i g e r o n pe reg r inus X Hieracium g r a c i l e X M e n z i e s i a f e r r u g i n e a X P a x i s t i m a m y r s i n i t e s X X P i c e a engelmanni i X X X Poa spp. X P y r o l a spp. X R ibes (genus o n l y ) X R ibes l a c u s t r e X Rosa gymnocarpa X 142 APPENDIX B (cont inued) F e c a l Rumen F e e d i n g - s i t e Samples Samples I n s p e c t i o n Rubus (genus on l y ) X Rubus pedatus X S a l i x spp. X X Sambucus racemosa X Sorbus s i t c h e n s i s X Thuja p l i c a t a X T i a r e l l a u n i f o l i a t a X T r i e n t a l i s l a t i f o l i a X Tsuga h e t e r o p h y l l a X Vaccin ium (genus on ly ) X V. caespi tosum X V. membranaceum X V. o v a l i f o l i u m X Vahlodea a t ropurpurea X V a l e r i a n a s i t c h e n s i s X 2 ) . L i c h e n s ; A l e c t o r i a sarmentosa X X^ X B r y o r i a spp. X X X C e t r a r i a s u b a l p i n a X C ladon ia c a r n e o l a X C ladon ia ecmocyna X D a c t y l i n a s p . f X Leptogium sp . X L o b a r i a pu lmonar ia X P e l t i g e r a spp. X P l a t i s m a t i a g lauca X Notes ; a : C o l l e c t e d 5 November 1978 i n ESSF- low h a b i t a t type (1600 m), a t Spahats Creek. b: Inc ludes u n i d e n t i f i e d t a x a . c : Both f e c a l and rumen samples were ana lyzed t o the l e v e l of p l a n t t y p e s . Any f u r t h e r i n f o r m a t i o n was c a s u a l l y noted , and t h e r e f o r e the i n f o r m a t i o n presented i n t h i s s e c t i o n i s i ncomple te , d : Macroscop ic i n d e n t i f i c a t i o n of a l e c t o r i o i d l i c h e n s d u r i n g c o l l e c t i o n of rumen samples; i t was assumed that both genera of a l e c t o r i o i d l i c h e n s were p r e s e n t , e : T e n t a t i v e i d e n t i f i c a t i o n ( f r u t i c o s e l i c h e n ) , f : T e n t a t i v e i d e n t i f i c a t i o n ( g e l a t i n o u s f o l i o s e l i c h e n ) . 

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