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Seasonal movements of black-tailed deer on northern Vancouver Island 1979

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SEASONAL MOVEMENTS OF BLACK—TAILED DEER ON NORTHERN VANCOUVER ISLAND by ALTON SIDNEY 3ARESTAD B . S c , U n i v e r s i t y of B r i t i s h Columbia, 1971 M-Sc, U n i v e r s i t y of B r i t i s h C o l u a b i a , 1973 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n FACULTY OF GRADUATE STUDIES ( F a c u l t y of F o r e s t r y ) He accept t h i s t h e s i s as conforming t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1979 (c) A l t o n Sidney Harestad, 1979 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I ag r ee tha t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r ag ree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head o f my Depar tment o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Faculty of Forestry The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date t T u A C IS1'?'?'? A b s t r a c t Columbian b l a c k - t a i l e d deer (Qdocoileus hemionug cplumbianus Richardson) were radio-tagged i n a deep s n o w f a l l r e g i o n on northern Vancouver I s l a n d , B r i t i s h Columbia. These deer were monitored to determine s e a s o n a l movements and h a b i t a t use. Deer e x h i b i t e d e i t h e r r e s i d e n t or migratory movement pa t t e r n s . Resident deer made seasonal s h i f t s i n t h e i r home range c e n t r e s but t h e i r seasonal home ranges overlapped. In migratory deer, summer home ranges were separated from both s p r i n g and winter home ranges, although t h e i r s p r i n g and winter home ranges overlapped. A l t i t u d i n a l m i g r a t i o n s occurred by deer moving between high and low e l e v a t i o n h a b i t a t s . H o r i z o n t a l m i g r a t i o n s o c c u r r e d by deer moving between a s m a l l t r i b u t a r y v a l l e y and the main v a l l e y . Seasonal movements of b l a c k - t a i l e d deer r e s u l t from h a b i t a t s e l e c t i o n by deer s e a s o n a l l y moving t o more f a v o u r a b l e h a b i t a t s as determined by more a v a i l a b l e energy and n u t r i e n t s , and lower r i s k of p r e d a t i o n . The c a u s a l d i f f e r e n c e s between v e r t i c a l and h o r i z o n t a l m i g r a t i o n s as w e l l as seasonal s h i f t s i n home range c e n t r e s can be r e s o l v e d by a model of h a b i t a t s e l e c t i o n based on these f a c t o r s . The. d e n s i t i e s of a v a i l a b l e d i g e s t i b l e dry matter i n Amabilis F i r - Twisted S t a l k , and Mountain Hemlock - Copperbush a s s o c i a t i o n s are comparable with those i n the shrub and c o n i f e r s e r a i stages. T h i s abundance o f deer food i n high e l e v a t i o n h a b i t a t s suggests t h a t f o r e s t h a r v e s t i n g i n high e l e v a t i o n s w i l l not a f f e c t deer p o p u l a t i o n s , i f t h e i r other h a b i t a t requirements are met. In areas where f o r e s t e d summer ranges already e x i s t , low e l e v a t i o n l o g g i n g of Sword Fern - Western Red Cedar, Deer Fern - Western Hemlock, and Western Hemlock - Plagiothecium a s s o c i a t i o n s w i l l p r o v i d e deer with sources of abundant food c l o s e r t o t h e i r winter ranges than the high e l e v a t i o n summer ranges. Use of these food sources may r e s u l t i n only a r e d i s t r i b u t i o n and not an i n c r e a s e i n the deer p o p u l a t i o n . Logging o f Amabilis F i r - Western Hemlock, S a l a l - D o u g l a s - f i r , and S a l a l - Western Hemlock a s s o c i a t i o n s may be d e t r i m e n t a l to deer p o p u l a t i o n s because of t h e i r need f o r these h a b i t a t s d u r i n g winter. Management p o l i c i e s emphasizing p r e s e r v a t i o n of severe winter range could be d e t r i m e n t a l to deer p o p u l a t i o n s . H a b i t a t management f o r b l a c k - t a i l e d deer must i n c l u d e p r o v i s i o n of mild winter range as w e l l as severe winter range. Because mild winter range p r o v i d e s deer with g r e a t e r amounts of a v a i l a b l e energy and n u t r i e n t s , i t may be as important t o the over-winter s u r v i v a l of deer as i s severe winter range. The m o b i l i t y of b l a c k - t a i l e d deer and t h e i r s e n s i t i v i t y to snow suggest t h a t few deer would be trapped i n high e l e v a t i o n s by e a r l y s n o w f a l l s . C o r r i d o r s j o i n i n g high and low e l e v a t i o n s appear unnecessary to f a c i l i t a t e deer m i g r a t i o n s . i v Table of Contents A b s t r a c t i i L i s t Of Ta b l e s . ... v i L i s t Of F i g u r e s • ... v i i Acknowledgement • l x 1. I n t r o d u c t i o n 1 1.1. Scope And O b j e c t i v e s 2 2. M a t e r i a l s And Methods 8 2.1. Study Area 8 2.2. Study P e r i o d 11 2.3. C l i m a t i c Data 12 2.4. H a b i t a t Assessments 12 2.5. E f f e c t Of Snow On The Posture Of Shrubs 15 2.6. Tagging 16 2.7. L o c a t i n g Tagged Deer 16 2.8. S p a t i a l A n a l y s i s 18 2.9. Track Counts , 19 2.10. Night Counts 20 2.11. Sample S i z e 20 3. R e s u l t s 22 3.1. Snowpack In The Study Area 22 3.2. Abundance Of Deer Food 25 3.2.1. Abundance Of Food During Summer ............... 40 3.2.2. Abundance Of Food During Winter 44 3.3. Dens i t y Of A v a i l a b l e D i g e s t i b l e Dry Matter 57 3.4. Seasonal Movements Of Kadio-tagged Deer 60 3.4.1. S t a t i s t i c a l Parameters Of Home Ranges 63 3.4.2. Home Range S i z e 66 3.4.3. P o s i t i o n Of Home Ranges , 89 3.4.4. Occupancy Of Seasonal Home Ranges 93 3.4.5. Topographical Features Of Seasonal Home Ranges 101 3.5. I n d i r e c t Measures Of Seasonal Movements ., 108 3.6. Seasonal Use Of H a b i t a t s . .120 4. D i s c u s s i o n ...136 4.1. S i z e Of Home Ranges ..136 4.2. Seasonal Movements And N u t r i t i o n ...,138 4.3. Seasonal Movements And S o c i a l O r g a n i z a t i o n 154 4.4. Model Of Seasonal Movements 156 4.5. Seasonal H a b i t a t s And F o r e s t H a r v e s t i n g ., ^..163 4.6. M i g r a t i o n C o r r i d o r s 168 5. L i t e r a t u r e C i t e d 171 Appendix I 181 v i L i s t of Tables I. Food A v a i l a b l e In H a b i t a t s During Summer .. 27 I I . Radio-tagged Deer And Seasons Monitored 61 I I I . S t a t i s t i c a l C h a r a c t e r i s t i c s Of Seasonal Home Ranges 64 IV. S i z e Of Seasonal Home Ranges 67 V. D i f f e r e n c e s In S i z e Of Home Ranges 86 VI. D i s t a n c e s Between Seasonal Home Ranges ............. 91 VII . E l e v a t i o n s Of Home Ranges 102 V I I I . Slope And Aspect Of Home Ranges . .. 106 IX. Use Of Fo r e s t e d And Cutover H a b i t a t s 123 X. Daytime Use Of C o n i f e r S e r a i Stage By Resident OFL62 In S p r i n g And Summer 132 XI. Density Of D i g e s t i b l e Dry Matter A v a i l a b l e During Summer On Seasonal Home Ranges 148 v i i L i s t o f F i g u r e s 1. Study Area . , 9 2. Snowdepths On Mount Cain 23 3. Percent Cover And Biomass Of Lichen 32 4. Annual Growth And Stem Height Of Shrubs 35 5. Abundance Of Food A v a i l a b l e In Summer 41 6. Crown Depth And Stem Height Of Shrubs 45 7. V e r t i c a l D i s t r i b u t i o n Of Shrub Annual Growth 47 8. Food A v a i l a b l e In H a b i t a t s During Winter 53 9. Dens i t y Of D i g e s t i b l e Dry Matter 58 10. Seasonal Home Ranges Of A l t i t u d i n a l M igrator OFL61 .. 70 11. Seasonal Home Ranges Of A l t i t u d i n a l M igrator OFL68 . 72 12. Seasonal Home Ranges Of A l t i t u d i n a l Migrator OFL67 . 74 13. Seasonal Home Ranges Of A l t i t u d i n a l Migrator OFL60 . 76 14. Seasonal Home Ranges Of H o r i z o n t a l Migrator OFL71 .. 78 15. Seasonal Home Ranges Of Resident OFL58 ............. 80 16. Seasonal Home Ranges Of Resident OFL62 ., 82 17. Standard Distance D e v i a t i o n And S i z e Of Home Range . 84 18. P e r i o d s Of Occupancy Of Seasonal Home Ranges 94 19. Winter M i g r a t i o n s Of OFL68 And 0FL61 In Response To Snow f a l l s ... 98 20. Seasonal Movement P a t t e r n s In Study Area 109 21. E l e v a t i o n Of Highest Deer Track On Mount Cain Road . 1 1 1 22. Night Counts In The Mount Cain S e c t o r .............. 114 23. Night Counts In The Croman S e c t o r 118 24. Use Of Fo r e s t e d And Cutover H a b i t a t s 121 25. H a b i t a t Use During Each Season 126 v i i i 26. H a b i t a t Use During Summer By Migratory And Resident Deer o .......... 129 27. Model Of Seasonal Movements 157 i x acknowledgement Dr. F.L. Bunnell provoked many o f the concepts developed i n t h i s t h e s i s and I am indebted to him f o r h i s guidance and m o t i v a t i o n . Thanks a l s o go to Drs. H.D..Fisher, K. Graham, J.P. Kimmins, J.H. Myers, and D.M. Shackleton f o r t h e i r a d v i c e and d i r e c t i o n . S i n c e re g r a t i t u d e i s extended to the Englewood Logging D i v i s i o n of Canadian F o r e s t Products Co. L t d . , p a r t i c u l a r l y Stan Chester, Gordon Flowerdew, Greg Jones, and J u l i u s Kapitany. The i n s p i r a t i o n given by Danny Johnson i s a p p r e c i a t e d and I thank the r e s i d e n t s of Woss f o r t h e i r h o s p i t a l i t y and encouragement. From the i n c e p t i o n of t h i s p r o j e c t Ian Smith through h i s o b j e c t i v i t y and i n s i g h t made s u b s t a n t i a l c o n t r i b u t i o n s to my approach and a t t i t u d e i n w i l d l i f e r e s e a r c h . Anthea F a r r by her enthusiasm and ide a s c o n t r i b u t e d to the design of the p r o j e c t and c o l l e c t i o n of data. I thank Dr. Don Eastman, A l l a n E d i e , Richard E l l i s , Dr. D a r y l l Hebert, Byron Mason, Bud P r a t t , Bud Smith, George T a y l o r , and Hans Weber f o r t h e i r e n l i g h t e n i n g d i s c u s s i o n s . Jim R o c h e l l e and Susan Stevenson permitted use of t h e i r data. Canadian F o r e s t Products Co. L t d . , H.R. MacMillan Family F e l l o w s h i p s , the W i l d l i f e Research D i v i s i o n and Region 1 of the B.C. F i s h and W i l d l i f e Branch, and the U n i v e r s i t y of B.C. provided f i n a n c i a l and l o g i s t i c support. 1 1. I n t r o d u c t i o n The Columbian b l a c k - t a i l e d deer, Odocoileus hemionus columbianus (Richardson), i s a s m a l l subspecies of mule deer and hen c e f o r t h w i l l be r e f e r r e d to as b l a c k - t a i l e d deer. I t i n h a b i t s the c o a s t a l r e g i o n of North America from northern C a l i f o r n i a to about 54°N i n B r i t i s h Columbia where i t merges with the S i t k a deer ( 0_. h^ s i t k e n s i s Merriam ) (Cowan 1956).. The abundance and a c c e s s i b i l i t y of b l a c k - t a i l e d deer makes i t one of the most popular b i g game s p e c i e s i n B r i t i s h Columbia. E a r l y s t u d i e s r e p o r t e d t h a t few b l a c k - t a i l e d deer i n h a b i t e d the c o a s t a l old-growth f o r e s t s (Cowan 1945, E i n a r s e n 1946, Brown 1961). These observations were made i n the C o a s t a l D o u g l a s - f i r f o r e s t s which have minor amounts of herb and shrub understory and hence, provided l i t t l e food f o r deer. Since removal o f the f o r e s t canopy allowed l u x u r i a n t growth o f grasses, herbs, and shrubs, f o r e s t h a r v e s t i n g was concluded t o be h i g h l y b e n e f i c i a l to t h i s deer s p e c i e s (Cowan 1945, E i n a r s e n 1946, Leopold 1950, Brown 1961, Gates 1968, Smith 1968). These s t u d i e s were conducted i n areas where snow depths were r e l a t i v e l y shallow and snow cover was ephemeral. The authors recognized t h a t deer needed t a l l v e g e t a t i o n f o r s e c u r i t y cover, and t h a t e x t e n s i v e lo g g i n g could be d e t r i m e n t a l t o b l a c k - t a i l e d deer p o p u l a t i o n s . However, working i n milder c l i m a t e s , they had no reason to expect t h a t mature f o r e s t s would be r e q u i r e d as winter h a b i t a t f o r deer i n areas of deep s n o w f a l l . In the C o a s t a l Western Hemlock and the s u b a l p i n e Mountain Hemlock b i o g e o c l i m a t i c zones ( sensu K r a j i n a 1965) on Vancouver I s l a n d , Edie and Harestad (1971) and Smith and Davies (1973) 2 observed t h a t b l a c k - t a i l e d deer were abundant i n some p r i s t i n e f o r e s t s f a r from logged areas. In these r e g i o n s of deeper s n o w f a l l , f o r e s t e d h a b i t a t s used as winter range by b l a c k - t a i l e d deer were thought to be c r i t i c a l to the deer's s u r v i v a l l o c a l l y (Robinson 1956, Edwards 1956, Cowan and Guiguet 1965, Smith 1972, Alaska Dept. F i s h and Game 1973, Jones 1974 and 1975, Bloom 1978). These winter ranges are f r e q u e n t l y old-growth f o r e s t s of high wood volume and easy a c c e s s i b i l i t y , and thus sought a f t e r by the f o r e s t i n d u s t r y . Jones (1974, 1975) and Bloom (1978) c o n s i d e r e d e f f e c t s of f o r e s t h a r v e s t i n g on b l a c k - t a i l e d deer p o p u l a t i o n s i n areas with deep winter snow cover. T h e i r r e s u l t s i n d i c a t e t h a t h a r v e s t i n g of f o r e s t e d winter ranges could have a d e t r i m e n t a l e f f e c t on deer abundance. The d i s p a r i t i e s among these s t u d i e s i n d i c a t e t h a t e f f e c t s of f o r e s t h a r v e s t i n g on b l a c k - t a i l e d deer are not c l e a r l y understood. Controversy over e f f e c t s of f o r e s t h a r v e s t i n g on deer abundance and competition f o r use of old-growth f o r e s t s has c r e a t e d c o n f l i c t s between users of timber and deer r e s o u r c e s . These c o n f l i c t s can be p a r t i a l l y a t t r i b u t e d t o a l a c k of b a s i c knowledge concerning movements, food requirements, h a b i t a t use, and p o p u l a t i o n dynamics of b l a c k - t a i l e d deer . 1.1. Scope And O b j e c t i v e s In response to the need f o r more i n f o r m a t i o n about b l a c k - t a i l e d deer, a s e r i e s of p r o j e c t s was i n i t i a t e d by Dr. F. L. B u n n e l l . Movements of b l a c k - t a i l e d deer are d e s c r i b e d i n t h i s t h e s i s while complementary s t u d i e s are concerned with food h a b i t s , n u t r i t i v e q u a l i t y of the f o r a g e , and the abundance and 3 d i s t r i b u t i o n o f l i c h e n s and shrubs. No p u b l i s h e d s t u d i e s have been made on the s p a t i o - t e m p o r a l d i s t r i b u t i o n s of f r e e r a n g i n g b l a c k - t a i l e d deer i n c o a s t a l f o r e s t ecosystems. S t u d i e s of home range and sea s o n a l movements have been conducted on Eocky Mountain mule deer, 0̂ . h.. hemionus (E a f i n e s g u e ) , but these s t u d i e s were of deer l i v i n g i n open h a b i t a t s i n c o n s t r a s t to the b l a c k - t a i l e d deer which i n B r i t i s h Columbia occupies f o r e s t e d h a b i t a t s . V a r i a t i o n i n s p a t i o - temporal d i s t r i b u t i o n , p a r t i c u l a r l y s o c i a l o r g a n i z a t i o n , of ungulates has been demonstrated to be h i g h l y dependent upon h a b i t a t s t r u c t u r e (Estes 1974, Jarman 1974). Understanding of sp a t i o - t e m p o r a l d i s t r i b u t i o n s are important t o the understanding of mammalian s o c i a l o r g a n i z a t i o n a l systems which have become i n c r e a s i n g l y focused upon i n t h e o r e t i c a l c o n s i d e r a t i o n s of mammalian behaviour (Eisenberg 1966, Crook 1970, Alexander 1974, Ge i s t 1974, Crook e t a l . 1976). H a b i t a t use by b l a c k - t a i l e d deer i s of p a r t i c u l a r i n t e r e s t i n B r i t i s h Columbia because of the m o d i f i c a t i o n s t o the deer's environment made by f o r e s t r y p r a c t i s e s , and because i n f o r m a t i o n on the h a b i t a t requirements of b l a c k - t a i l e d deer i s necessary f o r f o r e s t management plans. Although c e r t a i n a s p e c t s o f h a b i t a t requirements have been s t u d i e d , some have been assumed by e x t r a p o l a t i o n from deer p o p u l a t i o n s i n southern and snow-free r e g i o n s . Because of d i f f e r e n c e s i n cl i m a t e and v e g e t a t i o n between B r i t i s h Columbia and these r e g i o n s , i t i s necessary to examine the d i s p e r s i o n p a t t e r n s of b l a c k - t a i l e d deer and co n s i d e r t h e i r s e a s o n a l movments over the whole year. 4 Seton (1909) wrote t h a t "no wi l d animal roams a t random over the country; each has a home r e g i o n , even i f i t has not an a c t u a l home". This phenomenon of l o c a l i z a t i o n of an animal"s a c t i v i t i e s i s proposed to have adaptive value by p r o v i d i n g the animal with f a m i l i a r i t y of an area. T h i s f a m i l i a r i t y would give the animal knowledge of food s o u r c e s , p r o t e c t i v e cover, and r e f u g i a , thus i n c r e a s i n g i t s e f f i c i e n c y of f i n d i n g food and i t s c a p a b i l i t y of evading predators and u l t i m a t e l y i n c r e a s i n g i t s f i t n e s s (Davis e t a l ^ 1948, B l a i r 1953, Metzgar 1967, Covich 1976, Crook et al.. 1976). F o l l o w i n g Burt (1943), I c o n s i d e r home range to be the area t r a v e r s e d by an animal during i t s normal a c t i v i t i e s a s s o c i a t e d with f e e d i n g , r e s t i n g , r e p r o d u c t i o n , and avoidance of p r e d a t o r s . Seasonal movements i n c l u d e both m i g r a t i o n and sea s o n a l s h i f t s i n the c e n t r e s of home ranges. M i g r a t i o n i s the p e r i o d i c departure from, and r e t u r n t o , an area. T y p i c a l l y , the migrating animal moves from one seasonal home range to another. The' s e a s o n a l home ranges of a migratory animal aire separated, and zones between them are used mainly f o r t r a v e l . The animal spends l i t t l e time i n the zone between seasonal home ranges r e l a t i v e t o the amount of time t h a t i t spends i n the home ranges a t each end. Seasonal s h i f t s i n home range d i f f e r from m i g r a t i o n s i n t h a t much of the same home range i s used throughout the yea r . However, the i n t e n s i t y of use of p o r t i o n s of the home range i s a l t e r e d s e a s o n a l l y . Although l o c a l i z a t i o n o f a c t i v i t i e s i s b e n e f i c i a l because of the f a m i l i a r i t y gained of the home range, not a l l the animal's requirements can be obtained at the same p l a c e . T h i s 5 w i l l be e s p e c i a l l y t r u e i f there are temporal changes i n the a v a i l a b i l i t y of r e s o u r c e s . Animals are t h e r e f o r e o b l i g e d t o move over an area to s a t i s f y t h e i r requirements. The extent of these movements, and hence the s i z e of home range i n v e r t e b r a t e s , i s r e l a t e d to t h e i r energy requirements with m o d i f i c a t i o n s to the r e l a t i o n s h i p o c c u r r i n g because o f t r o p h i c s t a t u s and h a b i t a t p r o d u c t i v i t y (McNab 1963, Schoener 1968, Turner et al.. 1969, Harest'ad and B u n n e l l , i n press) . For mammals, home range s i z e expands with i n c r e a s e s i n energy requirements, and c o n t r a c t s with i n c r e a s e s i n h a b i t a t p r o d u c t i v i t y (Harestad and B u n n e l l , i n p r e s s ) . S i n c e the s i z e of home' range depends on the animal's requirements and the a v a i l a b i l i t y df energy, i t f o l l o w s t h a t l o c a t i o n of the home range may a l s o be i n f l u e n c e d by these f a c t o r s . The l i n k between food a v a i l a b i l i t y and seasonal movements has been proposed f o r over 80 years (Morgan 1896, Adams 1919). More r e c e n t s t u d i e s (Mackie 1970, Bergerud 1974, LeResche 1974, Bertram and Rempel 1977) have not progressed beyond the statement of t h i s c a u s a l r e l a t i o n s h i p . Other s t u d i e s have d e s c r i b e d movements of ungulates with changes i n l o c a l food sources (Byford 1969, Strandgaard 1972), but no q u a n t i f i c a t i o n o f the food supply was made. Some s t u d i e s have demonstrated p o t e n t i a l n u t r i t i o n a l d i f f e r e n c e s between the forages on the s e a s o n a l ranges (Dealy 1959, K l e i n 1965 and 1970, Hebert 1973). Two main processes concerning the food supply are used to e x p l a i n seasonal movements. In areas where forage i s a v a i l a b l e throughout the year or d u r i n g s p r i n g and summer when the snowpack has melted, q u a l i t y of the forage i s suggested as the 6 most important f a c t o r i n d u c i n g migratory behaviour (Dalke e t a l . 1965, K l e i n 1965 and 1970, Hebert 1973). These n u t r i t i v e d i f f e r e n c e s i n the f o r a g e a v a i l a b l e on seasonal ranges are due l a r g e l y t o d i f f e r e n c e s i n the p h e n o l o g i c a l c o n d i t i o n of the forage (Cook 1972, K l e i n 1965), and can r e s u l t from d i f f e r e n c e s i n topography, temperature, or p r e c i p i t a t i o n . In mountainous r e g i o n s , p h e n o l o g i c a l d i f f e r e n c e s are r e l a t e d t o e l e v a t i o n and are thought t o induce a l t i t u d i n a l m i g r a t i o n by the animal f o l l o w i n g the most n u t r i t i o u s s t a t e of the forage ( R u s s e l l 1932, Dixon 1934, Longhurst et a l . 1952, Knowlton 1960, Dalke et a l . 1965, K l e i n 1965, Hebert 1973, S t e l f o x 1976). The second main process used t o e x p l a i n m i g r a t i o n i n North American ungulates i s the e f f e c t of snow on food a v a i l a b i l i t y . Snow covers food s o u r c e s , r e s t r i c t s the f o r a g i n g animal's m o b i l i t y , and i n c r e a s e s c o s t s of locomotion. Through m i g r a t i o n , animals seek out areas of a p p r o p r i a t e snow depth and d e n s i t y , where food i s a v a i l a b l e (Leege and Hickey 1977 , T e l f e r 1978). The c u r r e n t l y accepted p a t t e r n of seasonal movements by b l a c k - t a i l e d deer i s t h a t of r e s i d e n t p o p u l a t i o n s i n low s n o w f a l l r e g i o n s and migratory p o p u l a t i o n s i n deep s n o w f a l l r e g i o n s . The m i g r a t i o n s are proposed as p r o g r e s s i v e movements by the p o p u l a t i o n moving i n phase with high q u a l i t y p h e n o l o g i c a l stages of the forage (Dealy 1959, K l e i n 1965) . This proposed p a t t e r n i m p l i e s a t r a n s i t i o n a l s e r i e s of short term home ranges duri n g the migratory p e r i o d and would i n v o l v e the whole p o p u l a t i o n . Winter and summer home ranges have been observed f o r a non-migratory p o p u l a t i o n of b l a c k - t a i l e d deer (Dasmann and Taber 1956) but no s t u d i e s have been made of the complete annual 7 behaviour of a migratory p o p u l a t i o n . Furthermore the a c t u a l m i g r a t i o n s have not been d e s c r i b e d f o r i n d i v i d u a l deer but i n f e r r e d from changes i n populat i o n d i s p e r s i o n . In t h i s study, my o b j e c t i v e s were to determine i f b l a c k - t a i l e d deer occupying c o a s t a l f o r e s t ecosystems, modified by l o g g i n g p r a c t i s e s , do have seasonal home ranges, what p a t t e r n o f seas o n a l home range use e x i s t s , and to e x p l o r e some f a c t o r s which promote movements by deer between seasonal home ranges. F i n a l l y these movements are considered with regard to changes th a t c o u l d be implemented i n f o r e s t r y p r a c t i s e s and deer management p o l i c i e s t o enhance deer p o p u l a t i o n s . 8 2. M a t e r i a l s And Methods 2. 1. Study Area The study area i s l o c a t e d on northern Vancouver I s l a n d , 20 km east of Woss, B r i t i s h Columbia and i s c e n t r e d at 50°12'N 126°25'W. The a r e a , 187 km2 i n exten t , i n c l u d e s the upper Davie B i v e r V a l l e y and the Croman Creek V a l l e y ( F i g . 1). The T s i t i k a R i v e r o r i g i n a t e s i n and d r a i n s the northern s i d e of the area. Although the Davie R i v e r V a l l e y i s wider than the Croman Creek V a l l e y , the topography on both s i d e s of the Davie R i v e r i s s i m i l a r t o t h a t found on the east s i d e of Croman Creek. There i s a steep s i d e h i l l a d jacent to the v a l l e y f l o o r t h a t r i s e s to between 600 and 700 m. Above t h i s e l e v a t i o n , the s l o p e i s g e n t l e as the land r i s e s to 1000 m before steepening near the peaks of Mount Cain and M a q u i l l a Peak. Access to the study area i s from the Nimpkish V a l l e y through a system of log g i n g roads running the l e n g t h of Croman Creek and Davie R i v e r . T r i b u t a r y roads l e a d up the slop e s of the mountains to e l e v a t i o n s of about 600 m i n Croman Creek V a l l e y and as high as 1150 m on Mount Cain. Four t o p o g r a p h i c a l s e c t o r s are d e l i n e a t e d i n F i g u r e 1. Most of the t a g g i n g , l o c a t i o n of tagged deer, and h a b i t a t assessments were conducted i n the Croman (1) and Mount Cain (2) s e c t o r s . The b i o g e o c l i m a t i c zones rep r e s e n t e d i n the study area are the C o a s t a l Western Hemlock Zone i n the lower e l e v a t i o n s (200 to 900 m) , the s u b a l p i n e Mountain Hemlock Zone i n the upper e l e v a t i o n s (800 to 1600 m), and the A l p i n e Zone near the mountain tops (above 1500 m) (sensu K r a j i n a 1965). In Croman V a l l e y where the c l i m a t e i s c o o l e r and 9 F i g u r e 1. Study a r e a . Shaded areas are logged, unshaded areas are unlogged. S e c t o r s are numbered and t h e i r boundaries shown by dashed l i n e s cr waterways : 1. Croman, 2. Mount C a i n , 3. M a g u i l l a , 4 . Hoomak. 10 11 s n o w f a l l g r e a t e r , the s u b a l p i n e Mountain Hemlock Zone extends c l o s e r to the v a l l e y .bottom than i t does i n the Mount Cain (2) s e c t o r . F o r e s t h a r v e s t i n g began i n the study area i n 1948 along the f l a t v a l l e y bottom near Davie R i v e r . Much of the lower e l e v a t i o n f o r e s t s were logged f i r s t and then e x t r a c t i o n of the s i d e h i l l and higher e l e v a t i o n f o r e s t s began. By 1975, 39% of f o r e s t s below 800 m i n e l e v a t i o n were logged, while only 7% of f o r e s t s above 800 m were logged. The f o u r s e c t o r s of F i g u r e 1 d i f f e r i n the p r o p o r t i o n s o f the f o r e s t s t h a t have been c u t . Mount Cain (2) i s the most e x t e n s i v e l y logged s e c t o r . Here, 64% of the f o r e s t below 800 m i n e l e v a t i o n i s logged. In comparison, the Croman (1) s e c t o r has only 27% of the lower e l e v a t i o n f o r e s t s logged. The p a t t e r n of f o r e s t h a r v e s t i n g was predominantly c l e a r - c u t t i n g , while i n more r e c e n t years, patch c u t t i n g of b l o c k s l e s s than 81 ha has been conducted. Logged areas were u s u a l l y slashburned. During the study immature s e r a i stages i n the study area ranged up to 27 years o l d . 2.2. Study P e r i o d Field-work began i n June 1974 and continued through to May 1977. T e c h n i c a l d i f f i c u l t i e s with the r a d i o - t r a n s m i t t e r s subverted attempts a t tagging and l o c a t i n g deer i n 1974. R e l i a b l e r a d i o - t r a n s m i t t e r s were obtained and a t t a c h e d to deer by the s p r i n g and e a r l y summer of 1975. The deer were l o c a t e d i n t e n s i v e l y u n t i l the s p r i n g of 1976. The i n t e n s i t y of l o c a t i o n of the deer was reduced i n the summer of 1976 while e v a l u a t i o n s of s e a s o n a l h a b i t a t s were made. The deer were l o c a t e d u n t i l 12 December 1976 and the p r o j e c t terminated i n May 1977. 2.3. C l i m a t i c Data F i v e weather s t a t i o n s sponsored by the Resource A n a l y s i s Branch (B.C. M i n i s t r y of Environment) were maintained i n the study area. Monthly minimum and maximum temperatures were taken and a continuous r e c o r d o f temperature was obtained using r e c o r d i n g thermographs. During p e r i o d s with no snow, monthly p r e c i p i t a t i o n was recorded, while d u r i n g p e r i o d s with snow monthly snowpack depths were measured. In a d d i t i o n to the snow depths measured at the weather s t a t i o n s , snow depth and percent of ground covered by snow were estimated every two weeks a t s t a t i o n s l o c a t e d every 100 m of e l e v a t i o n from 300 to 1200 m a l o n g the Mount Cain road. Snow depths were sometimes measured more o f t e n , e s p e c i a l l y d u r i n g p e r i o d s o f i n t e n s e r a d i o monitoring or frequent s n o w f a l l . 2.4. H a b i t a t Assessments The l o c a t i o n s f o r each r a d i o - t a g g e d deer were t r a n s f e r r e d t o a e r i a l photographs. Seasonal home ranges were o u t l i n e d on the photographs and then s t r a t i f i e d a c c o r d i n g t o major mature p l a n t a s s o c i a t i o n s and immature s e r a i s t a g e s . The mature s e r a i stages w i l l be r e f e r r e d t o as f o r e s t e d p l a n t a s s o c i a t i o n s or, simply, a s s o c i a t i o n s and the immature s e r a i stages r e f e r r e d to as s e r a i stages . Seasonal home ranges were i n s p e c t e d on the ground and, i f necessary, the s t r a t i f i c a t i o n was a l t e r e d . T y p i c a l examples of a s s o c i a t i o n s and s e r a i stages were s e l e c t e d w i t h i n the seas o n a l home ranges. At these s i t e s , H a b i t a t Assessments were 13 conducted which i n c l u d e d a p h y s i o g r a p h i c d e s c r i p t i o n , l i s t of p l a n t s p e c i e s and t h e i r percent cover and d i s t r i b u t i o n , and estimates of shrub abundance. L i s t s of p l a n t s p e c i e s and estimates of percent cover were ob t a i n e d by the r e l e v e methods used by O r l o c i (1964) and Brooke e t a l . (1970) . P l a n t a s s o c i a t i o n s i n f o r e s t s used by radio-tagged deer were determined through comparison of l i s t s of p l a n t s p e c i e s and t h e i r percent cover at H a b i t a t Assessment s i t e s t o those o f the a s s o c i a t i o n s d e f i n e d by O r l o c i (1964), Brooke e t a l . (1970), and B e l l (1971). Common names of these a s s o c i a t i o n s are used and correspond to those of B e l l (1971). Cutovers used by deer were c l a s s i f i e d i n t o f i v e s e r a i stages t h a t are c h a r a c t e r i z e d by t h e i r percent cover and height of c o n i f e r s , shrubs, bracken f e r n ( P t e r i d i u m aquilinum (L.) Kuhn), and herbs. The c r i t e r i a used i n c l a s s i f i c a t i o n of s e r a i stages were ( i n ascending h i e r a r c h y ) : newly logged - r e c e n t l y logged and l e s s than one year o l d c u t o v e r ; herb - percent cover of herbs i s g r e a t e r than the percent cover of P_. aquilinum ; f e r n - percent cover of P. aquilinum i s g r e a t e r than the percent cover of herbs ; shrub - percent cover of shrubs i s g r e a t e r than 20% ; c o n i f e r - t o t a l percent cover of c o n i f e r s l e s s than 10 m high i s g r e a t e r than 20% . F o r e s t e d plan t a s s o c i a t i o n s used by deer were d i v i d e d i n t o two groups: those i n the C o a s t a l Western Hemlock Zone and those i n the s u b a l p i n e Mountain Hemlock Zone. Within each b i o g e o c l i m a t i c zone, the a s s o c i a t i o n s were arranged a c c o r d i n g to t h e i r t y p i c a l p o s i t i o n on the slope and t h e i r moisture regime ( a f t e r B e l l 1971). S e r a i stages were arranged i n order of 14 i n c r e a s i n g s u c c e s s i o n a l age. The abundance of l i c h e n , c o n s i s t i n g mainly of A l e c t o r i a sarmentosa (Ach.) Ach. , was estimated at each H a b i t a t Assessment s i t e by low l e v e l , o b l i q u e a e r i a l photographs. Colour p o s i t i v e s of the f o r e s t canopy were p r o j e c t e d onto a screen so t h a t the c e n t r a l p o r t i o n of the image covered an area gridded i n t o 450 one cm squares. The percentage of l i c h e n cover i n each square was c l a s s e d from 0 to 3. The c l a s s e s corresponded t o the f o l l o w i n g percent cover ranges; 0 = 0-5%, 1 = 6-25%, 2 = 26-75% 3 = 76-100%. The c l a s s e s were assig n e d percentage values as the mid-point i n the range of the c l a s s and an estimate of t o t a l percent cover of l i c h e n was o b t a i n e d f o r each s i t e . For some s i t e s , a r e l a t i o n s h i p was determined between t h i s percent cover and an independent estimate of l i c h e n biomass obtained by Stevenson (1978). Using t h i s r e l a t i o n s h i p , the percent cover estimate f o r a r b o r e a l l i c h e n s at each Ha b i t a t Assessment s i t e was converted to biomass (kg h a - 1 ) . Shrub abundance was estimated f o r Vaceinium p a r y i f o l i u m Smith, Xs. alaskaense Howell ( i n c l u d i n g other Vaceinium species) , and G a u l t h e r i a s h a l l o n Pursh. by i d e n t i f y i n g between one and f o u r c l a s s e s of r e l a t i v e shrub d e n s i t y at the H a b i t a t Assessment s i t e . The p r o p o r t i o n of area a t the s i t e e x h i b i t i n g each of these c l a s s e s of shrub d e n s i t y was then estimated. In a r e p r e s e n t a t i v e area of each c l a s s of shrub d e n s i t y , a p l o t was s e l e c t e d and the height o f each stem rooted i n the p l o t was measured. Stems l e s s than 30 cm i n height were counted but t h e i r h e i g h t s were not measured. Estimates of the amount of food c o n t r i b u t e d by these shrubs were made by c l i p p i n g , d r y i n g , and 15 weighing the annual growth of shoots from stems of v a r i o u s h e i g h t s . S p e c i e s - s p e c i f i c r e g r e s s i o n s o f the height:annual growth r e l a t i o n s h i p s were then used to es t i m a t e the food c o n t r i b u t e d by a l l stems measured i n the H a b i t a t Assessments. 2.5. E f f e c t Of Snow On The Posture Of Shrubs The a v a i l a b i l i t y of shrubs to deer during p e r i o d s of snow cover depends on s t r u c t u r a l r e a c t i o n s of shrub stems t o snow accumulation and melt. I was not a b l e to measure the e f f e c t of newly f a l l e n snow on the depression of shrub stems. The winter when these e f f e c t s were t o be i n v e s t i g a t e d , 1976-1977, was very mild and l i t t l e snow f e l l except during l a t e winter i n the higher e l e v a t i o n s . Some i n s i g h t i n t o the de p r e s s i o n and subsequent ascent of shrubs was ob t a i n e d i n the s p r i n g of 1976 by marking stems b u r i e d beneath the snow and then measuring the change i n height of the marker a f t e r the snow had melted. On June 6, 1976, an area was chosen t h a t had an abundance of shrubs and a shallow snowpack (30 cm) remaining from winter. The area was i n an Am a b i l i s F i r - Twisted S t a l k a s s o c i a t i o n i n the f o r e s t 250 m southeast of the 900 m Mount Cain weather s t a t i o n . A s m a l l hole was dug i n the snow u n t i l a shrub stem was encountered. A numbered p i e c e of f l a g g i n g tape was attached to the stem and a second marker was s e c u r e l y placed on the ground d i r e c t l y below the marked stem. The v e r t i c a l d i s t a n c e between the two markers was measured. Some stems were marked above the f i r s t major b i f u r c a t i o n , while other stems were marked i n the crown of the shrub. On J u l y 2, 1976, a f t e r the snow had completely melted and the stems regained t h e i r snow-free po s t u r e s , h e i g h t s between the 16 markers were remeasured. Most Vaceinium alaskaense , although Smith were a l s o marked. of the shrubs marked were s e v e r a l Menziesia. f e r r u g i n e a 2.6. Tagging Deer were tagged from d i f f e r e n t p a r t s of the study area to ensure t h a t movements under d i f f e r e n t environmental c o n d i t i o n s were r e p r e s e n t e d . Most of these deer were f r e e - r a n g i n g when tagged and were immobilized using a muscle r e l a x a n t , s u c c i n y l c h o l i n e c h l o r i d e , a d m i n i s t e r e d i n l i q u i d form by Capture Darts (Palmer Chemical Co.) or i n powdered form by Pneu Darts (Pneu Dart I n c ) . The remaining deer t h a t were: tagged,, were captured i n s i n g l e gate C l o v e r t r a p s (Clover 1956) . 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 Inc.) were attached to s e l e c t e d a d u l t s and y e a r l i n g s . The radio-tagged deer were eartagged with a p l a s t i c f l a p on which a r e f l e c t i v e number was attached, and with numbered Rototags (Nasco Co.) or metal c l i p t a g s . 2.7. L o c a t i n g Tagged Deer Radio-tagged deer were l o c a t e d on v a r i o u s schedules depending upon a c c e s s i b i l i t y of the deer and type and value of the i n f o r m a t i o n obtained from the l o c a t i o n s . Radio-tagged deer were l o c a t e d at l e a s t weekly when I was i n the study area. During c e r t a i n p e r i o d s , l o c a t i o n s were made more f r e q u e n t l y with s e l e c t e d deer being l o c a t e d every 12 hours. During a ten day s e s s i o n i n August 1975, a radio-tagged deer was r e l o c a t e d every two hours i n order to determine the optimum schedule f o r 17 monitoring movements. Radio-tagged deer were l o c a t e d using a whip antenna and a hand h e l d , t h r e e element Yagi antenna. The whip antenna was used f o r p r e l i m i n a r y search and l o c a t i o n of radio-tagged deer from a moving v e h i c l e . The Yagi antenna was used t o determine the d i r e c t i o n of the radio-tagged deer from known l o c a t i o n s . When rad i o - t a g g e d deer were l o c a t e d , I recorded the tag number, date, time, my l o c a t i o n , b e a r i n g of the r a d i o s i g n a l , and comments. When tagged deer were s i g h t e d , I recorded the tag number, date, time, l o c a t i o n , and comments. Bearings of the r a d i o s i g n a l d i r e c t i o n were q u i c k l y obtained a t three t o f i v e d i f f e r e n t l o c a t i o n s . The rad i o - t a g g e d deers' l o c a t i o n s were estimated by t r i a n g u l a t i o n . Bearings d i s t i n c t l y d i f f e r e n t from the other bearings were not i n c l u d e d i n the f i n a l estimate of a l o c a t i o n . Aberrant b e a r i n g s f r e q u e n t l y r e s u l t e d from s i g n a l bounces and were e a s i l y d e t e c t e d a f t e r I became f a m i l i a r with the study a r e a . The l o c a t i o n e s t i mate was judged as being " a c c u r a t e " , "rough", or "very rough" depending upon the degree of i n t e r s e c t i o n of the bear i n g s . This accuracy index was based on whether at l e a s t two of the v e r t i c e s of the i n t e r s e c t i o n t r i a n g l e were w i t h i n a c i r c l e of a r a d i u s of l e s s than 100 m ( a c c u r a t e ) , 100 to 250 m (rough), and g r e a t e r than 250 m (very rough). Most of the estimates f e l l w i t h i n the accurate c l a s s . During the s p r i n g and summer o f 1975, r e l i a b i l i t y o f the telemetry system was t e s t e d by t a k i n g s i g n a l s from deer i n the f i e l d and immediately t r i a n g u l a t i n g t h e i r l o c a t i o n s . The estimated l o c a t i o n s were v i s i t e d and confirmed by o b s e r v a t i o n of the t a r g e t deer. A f t e r 18 many l o c a t i o n s were confirmed, I was s a t i s f i e d t h a t the t r i a n g u l a t i o n methods were g i v i n g good estimates of a deer's l o c a t i o n s . In the f i e l d , a map (3.16 cm to 1.0 km) with r e c t a n g u l a r c o o r d i n a t e s was used t o l o c a t e tagged deer and l o c a t i o n s from which bearings were taken. B e a r i n g p o s i t i o n s were then l o c a t e d on a 2.08 cm to 100 m f o r e s t cover map and t r i a n g u l a t i o n s performed. Estimated l o c a t i o n s of rad i o - t a g g e d deer and l o c a t i o n s of tagged deer were recorded as p o l a r c o o r d i n a t e s using a s e r i e s of o r i g i n s . O r i g i n s were placed so that each was near a c o n c e n t r a t i o n of l o c a t i o n s , thus minimizing e r r o r . These " l o c a l " o r i g i n s were s t a n d a r d i z e d to a s i n g l e common o r i g i n and the p o l a r c o o r d i n a t e s converted to r e c t a n g u l a r c o o r d i n a t e s f o r use i n p l o t t i n g and a n a l y s i s o f l o c a t i o n data. 2.8. S p a t i a l A n a l y s i s Home ranges are an i n t e g r a t e d expression of an animal's l o c a t i o n s and movements over a s p e c i f i c time i n t e r v a l . Thus, there can be d a i l y , s e a s o n a l , and l i f e t i m e home ranges. Home ranges can be considered as a p r o p o r t i o n of the known l o c a t i o n s f o r an animal w i t h i n a p a r t i c u l a r time p e r i o d . The a b s o l u t e or 100% home range i n c l u d e s a l l the known l o c a t i o n s of an i n d i v i d u a l . Other e x p r e s s i o n s of home ranges i n c l u d e only the c l o s e s t 90% or 50% of the i n d i v i d u a l ' s known l o c a t i o n s . C o n s i d e r a t i o n of onl y a p o r t i o n o f the observed l o c a t i o n s i s u s e f u l i n i d e n t i f y i n g cores of i n t e n s e use, and f o r e l i m i n a t i n g unusual movements whose i n c l u s i o n would c r e a t e erroneous estimates of home range parameters. 19 L o c a t i o n s and movements o f animals are u s u a l l y c o n s i d e r e d as home ranges and can be presented i n a number of ways. The s t a t i s t i c a l methods (see Van Winkle (1975) f o r review), although e l e g a n t , do not always provide e a s i l y i n t e r p r e t e d s p a t i a l i n f o r m a t i o n . On the other hand, the t r a d i t i o n a l minimum home range method (Dalke and Sime 1938) does provide a simple s p a t i a l d e s c r i p t i o n . I have used both the s t a t i s t i c a l and the minimum home range methods t o d e s c r i b e deer movements. The minimum home range method was modified t o i d e n t i f y c e n t r a l c o r e s of home range where deer were most o f t e n l o c a t e d . Geographical techniques developed by Neft (1966) were adapted f o r a n a l y s i s of deer l o c a t i o n s . Using these t e c h n i q u e s , the l o c a t i o n s of a deer can be t r e a t e d l i k e any other v a r i a b l e , and a mean l o c a t i o n and the v a r i a b i l i t y about t h a t mean l o c a t i o n can be c a l c u l a t e d . Thus, i n the a n a l y s i s of my home range data, I provide a l e v e l of d e s c r i p t i v e s t a t i s t i c s comparable t o t h a t commonly a v a i l a b l e f o r u n i v a r i a t e data. 2.9. Track Counts During winter and e a r l y s p r i n g , n i g h t counts were not always p o s s i b l e i n high e l e v a t i o n s . In order t o d e t e c t when deer were i n these areas, t r a c k counts were made. Mount Cain Road was t r a v e l l e d and the h i g h e s t e l e v a t i o n at which a deer t r a c k e i t h e r c r o s s e d or f o l l o w e d along the road was recorded. These data can be used to determine when deer f i r s t v i s i t high e l e v a t i o n s i n s p r i n g and when deer l a s t leave these e l e v a t i o n s i n winter. 20 2. 10. Night Counts P o r t i o n s of the study area were searched a t n i g h t using a s p o t l i g h t shone from a v e h i c l e t r a v e l l i n g along predetermined road t r a n s e c t s . Three night counts were attempted every two weeks. Because of weather and other commitments, counts were sometimes made l e s s f r e q u e n t l y . During c e r t a i n p e r i o d s of i n t e n s e r e l o c a t i o n of radio-tagged deer, n i g h t counts were conducted each n i g h t . The numbers of deer s i g h t e d along these f i x e d road t r a n s e c t s provide e s t i m a t e s of r e l a t i v e deer abundance.in the cutover areas throughout the year. These n i g h t counts are an i n d i r e c t measure of se a s o n a l movements of the deer p o p u l a t i o n . B a d i o - t r a n s m i t t e r s and f l a p tags were covered with r e f l e c t i v e tape and so were r e a d i l y v i s i b l e when i l l u m i n a t e d at n i g h t . Numbers on the tags could u s u a l l y be read through a window-mounted 20 t o 45 power s p o t t i n g t e l e s c o p e . 2.11. Sample Si z e Funding, l o g i s t i c s of c a p t u r i n g and monitoring, and l o s s e s of study animals to hunters l i m i t e d the number of radio-tagged deer. One of the 10 r a d i o - t r a n s m i t t e r s attached t o deer i n 1975 f a i l e d e a r l y i n the study. Another t r a n s m i t t e r was l o s t when a y e a r l i n g male emigrated. This l e f t e i g h t deer with f u n c t i o n i n g r a d i o s i n the study area a t the opening of hunting season. Deer hunting was not r e s t r i c t e d i n the study area d u r i n g 1975 and three of the remaining e i g h t r a d i o - t a g g e d deer were shot. One of the tagged deer was k i l l e d e a r l y i n September and s i n c e I had only a few l o c a t i o n s f o r him I d i d not i n c l u d e them i n the seasonal movements a n a l y s i s . The two other deer were 21 k i l l e d i n e a r l y winter and some movements were observed. These deer were i n c l u d e d i n the a n a l y s i s even though they were not monitored f o r a complete s e a s o n a l c y c l e . T h i s study thus c o n s i s t s of the complete s e a s o n a l movement p a t t e r n s of f i v e deer and the p a r t i a l p a t t e r n s of two deer. The movements of the r a d i o - t a g g e d deer are r e p r e s e n t a t i v e of movements t h a t can occur and i n d i c a t e p o t e n t i a l movement p a t t e r n s of the p o p u l a t i o n . Track counts and n i g h t counts give broad t r e n d s i n the seasonal d i s p e r s i o n of the deer p o p u l a t i o n . Combined, the radio-tagged deer, t r a c k counts, and night counts should provide an a c c u r a t e d e s c r i p t i o n of the seasonal movements of b l a c k - t a i l e d deer i n the study a r e a . 22 3. R e s u l t s 3.1. Snowpack In The Study Area E l e v a t i o n s below 1200 m were snow-free from J u l y u n t i l l a t e October 1975 ( F i g . 2). The f i r s t s n o w f a l l s below 1200 m o c c u r r e d l a t e i n October and were r e s t r i c t e d to high e l e v a t i o n s (above 900 m). Subsequent s n o w f a l l s p r o g r e s s i v e l y extended to lower e l e v a t i o n s (below 700 m) and reached the v a l l e y bottoms at e l e v a t i o n s of 300 m by mid-November. The snow de p o s i t e d on the ground dur i n g the f i r s t few s n o w f a l l s l a s t e d f o r only a few days before m e l t i n g . A f t e r the f i r s t few s n o w f a l l s and snow melts, snow d e p o s i t e d at e l e v a t i o n s above 900 m began to accumulate. T h i s accumulation o f snow continued u n t i l l a t e March when a maximum snow depth of 289 cm occurred at 1200 m. In A p r i l , the snowpack began to decrease and was completely melted by e a r l y J u l y i n most areas below 1200 m. F i g u r e 2 shows a s u b s t a n t i a l i n c r e a s e i n the snowpack above 1000 m. T h i s d i f f e r e n c e i n depth i s p a r t l y a r e s u l t of a change i n aspect of the Mount Cain Road and the snow depth s t a t i o n s . The s t a t i o n s were on a s p e c t s between south and southwest below 1000 m and between southwest and west above 1000 m. M i d - e l e v a t i o n s (700 to 900 m) r e c e i v e d t h e i r f i r s t snow s l i g h t l y l a t e r than d i d high e l e v a t i o n s . They have a p a t t e r n of snow accumulation s i m i l a r t o high e l e v a t i o n s , except t h a t d u r i n g mild weather, the r a t e of snowmelt i s g r e a t e r than the r a t e of s n o w f a l l and the depth of the snowpack decreases f o r b r i e f p e r i o d s . The snowpack i n m i d - e l e v a t i o n s d i d not completely melt at any time between e a r l y December and e a r l y May. Snow d i d not 23 F i g u r e 2. P e r s p e c t i v e p l o t of date, e l e v a t i o n and snowpack depth along Mount Cain road. Most winter ranges were below 700 m where snow depths were shallow and snow cover was i n t e r m i t t e n t . Summer ranges above 700 m had deep accumulating snowpacks and continuous snow cover over winter.  25 accumulate i n low e l e v a t i o n s (300 m to 700 m) f o r as l o n g a p e r i o d o r to as gr e a t a depth, as i t d i d i n high and mid- e l e v a t i o n s . S e v e r a l times i n winter, low e l e v a t i o n s were snow- f r e e . They were snow-free a f t e r l a t e A p r i l 1976, much sooner than were high e l e v a t i o n s ( F i g . 2). On Mount C a i n , depth o f the snowpack i n c r e a s e d with i n c r e a s i n g e l e v a t i o n except f o r on the v a l l e y f l o o r along the Davie R i v e r . The v a l l e y f l o o r f r e q u e n t l y had deeper and more p e r s i s t e n t snow cover than the adjacent s o u t h - f a c i n g s i d e h i l l . P art of the d i f f e r e n c e i n snowpack between the v a l l e y f l o o r and the s i d e h i l l i s a r e s u l t of t h e i r d i f f e r e n c e s i n s l o p e and aspect. Snow depths i n Croman V a l l e y were not monitored as i n t e n s i v e l y as they were on Mount Cain. However, snow was deeper, more f r e g u e n t , and p e r s i s t e d l o n g e r i n upstream p a r t s of the v a l l e y than near the mouth. 3.2- Abundance Of Deer Food Important food p l a n t s of b l a c k - t a i l e d deer i n the study area are A l e c t o r i a sarmentosa , G a u l t h e r i a s h a l l o n , Vaceinium s p e c i e s , Rubus s p e c i e s , Cornus canadensis L., Linnaea b o r e a l i s !•# Epilobium a n g u s t i f o l i u m L., Blechnum s p i c a n t (L.) Roth., Pseudotsuga m e n z i e s i i (Mirb.) Franco, Thuja p l i c a t a Donn, and Tsuqa h e t e r o p h y l l a (Raf.) Sarg. (Jones 1975, R o c h e l l e i n ££§_£._). Besides these s p e c i e s many other p l a n t s are eaten by b l a c k - t a i l e d deer (Cowan 1945, Brown'1961, Gates 1968). The d i v e r s i t y i n the d i e t of b l a c k - t a i l e d deer and the predominance of p a l a t a b l e s p e c i e s allowed estimates to be made of the amount of food a v a i l a b l e at each h a b i t a t assessment s i t e and a composite 26 summary of food r e s o u r c e s a v a i l a b l e i n each p l a n t a s s o c i a t i o n and s e r a i stage was t h e r e f o r e c a l c u l a t e d . Food resources of these h a b i t a t s c o n s i s t e d of f o u r major components; l i c h e n s , shrubs, herbs, and c o n i f e r s . The r e l a t i v e c o n t r i b u t i o n of each component was estimated using d i f f e r i n g techniques as e x p l a i n e d below. L i c h e n The percent cover of l i c h e n , mainly M e e t o r i a sarmentosa , i n the f o r e s t canopy of seasonal h a b i t a t s used by radio-tagged deer i s shown i n Table I. On some s i t e s where percent cover of l i c h e n was measured, biomass estimates were independently obtained by Stevenson (1978). Both the percent cover and biomass estimates were transformed to l o g , 0 and a l i n e a r r e g r e s s i o n performed t o o b t a i n an e m p i r i c a l r e l a t i o n s h i p between the two v a r i a b l e s ( F i g . 3). although the c o e f f i c i e n t of d e t e r m i n a t i o n i s low ( r 2 = 0.41), the s l o p e of the r e g r e s s i o n l i n e i s s t a t i s t i c a l l y d i f f e r e n t from z e r o (p < .06). The p r o p o r t i o n of the standing crop of l i c h e n t h a t f a l l s t o the ground over the winter and thus i s a v a i l a b l e as deer food, i s about 12% (Stevenson 1978). For the purpose of t h i s a n a l y s i s , i t was assumed t h a t s i m i l a r l i t t e r - f a l l occurs over the summer. Th i s assumption l i k e l y overestimates the c o n t r i b u t i o n of l i c h e n to the t o t a l amount of food a v a i l a b l e during summer. However, s i n c e the c o n t r i b u t i o n of l i c h e n to the a v a i l a b l e food i n summer i s s m a l l , t h i s overestimate has o n l y a s l i g h t e f f e c t on the t o t a l amount of a v a i l a b l e food. Krumlik's (1979) measures of annual l i c h e n l i t t e r - f a l l i n high e l e v a t i o n f o r e s t - t y p e s on 27 Table I. Percent cover and estimated food a v a i l a b l e i n summer on f o r e s t e d p l a n t a s s o c i a t i o n s and immature s e r a i s t a g e s used by radio-tagged deer d u r i n g the year. Mean and standard e r r o r of t o t a l weight of food a v a i l a b l e i n each h a b i t a t type are i n d i c a t e d . F o r e s t e d p l a n t a s s o c i a t i o n s : VS = Vaccinium - Skunk Cabbage, SC = Sword Fern - Western Red Cedar, DW = Deer Fern - Western Hemlock, WP = Western Hemlock - Plagiothecium, AW = Am a b i l i s F i r - Western Hemlock, SD = S a l a l - D o u g l a s - f i r , SW = S a l a l - Western Hemlock, AT = Amabilis F i r - Twisted S t a l k , MC = Mountain Hemlock - Copperbush. Immature S e r a i Stages : N = Newly Logged, H = Herb, F = Fern, S = Shrub, C = C o n i f e r . Association or Serai Stage Plot No. % cover Herb kg ha~^ Shrub kg ha"" VS 7 9 . 2 40 . 9 1 0 0 5 . 7 v s 2 0 2 0 . 9 9 3 . 0 7 0 0 . 7 VS 41 5 8 . 4 2 5 9 . 9 1 5 6 . 8 s c 1 3 2 . 1 9 . 3 1 0 . 5 DW 1 9 2 . 6 1 1 . 6 1 8 . 0 WP 3 . 4 1 . 8 . 1 WP 3 9 1 . 3 5 . 8 1 . 4 AW 1 0 1 . 5 6 . 7 6 . 4 AW 1 8 1 . 0 4 . 4 5 . 3 AW 4 4 . 9 4 . 0 2 6 9 . 7 AW 4 5 1 . 6 7 . 1 1 5 9 . 8 Conifer Lichen Total cover kg ha cover kg ha kg ha 2 6 . 0 7 9 . 6 1 7 . 8 2 6 . 0 7 9 . 6 2 8 . 4 9 . 5 2 9 . 1 1 5 . 1 8 . 0 24 . 5 2 5 . 6 2 2 . 0 6 7 . 3 1 7 . 6 5 . 0 1 5 . 3 2 1 . 4 5 . 0 1 5 . 3 2 1 . 3 2 8 . 0 8 5 . 7 2 1 . 3 3 0 . 0 9 1 . 8 1 7 . 1 7 . 0 2 1 . 4 3 2 . 6 1 2 . 5 3 8 . 2 2 2 . 0 1 1 . 0 1 1 3 7 . 2 7 6 . 4 9 4 9 . 7 5 . 6 4 5 1 . 4 n= 3 846 .1 t 3 5 4 . 4 4 9 . 7 9 4 . 0 n=1 9 4 . 0 1 0 . 5 1 0 7 . 4 n=1 1 0 7 . 4 2 3.6 4 0 . 8 2 3 . 2 4 5 . 7 n=2 4 3 . 2 i 3 . 5 2 3 . 2 1 2 2 . 0 9 . 3 1 1 0 . 8 1 3 5 . 6 4 3 0 . 7 2 6 . 5 2 3 1 . 6 n=4 2 2 3 . 8 1 1 4 8 . 3 Table I (cont.) Association Herb Shrub or Plot % _ 1 - 1 Serai Stage No. cover kg ha kg ha SD 2 . 6 2 . 7 3 5 9 . <f SD 5 .9 4 . 0 643.9 SW 4 . 7 3 . 1 2 1 8 . 0 sw 6 1 . 1 ^ . 9 2 1 8 . 1 sw. 8 1 . 4 6 . 2 2 5 3 . 6 sw 1 7 . 7 3 . 1 2 1 . 4 sw 46 1 . 0 1 6 4 . 4 AT 1 2 . 4 1 0 . 7 3 2 3 . 5 AT 2 8 1 . 4 6 . 2 1 0 1 8 . 0 AT 2 9 1.*f 6 . 2 2 7 9 . ^ MC 3 2 . 7 3 . 1 4 0 6 . 5 MC 3 3 1 2 . 5 5 5 . 6 5 3 1 . 0 Conifer L: cover kg ha cover 5.0 1 5 . 3 22.6 . 0 .0 2 3 . 2 23.0 7 0 . 4 35.9 10.0 3 0 . 6 2 3 . 9 8 . 0 24.5 20.9 2 8 . 5 8 7 . 2 17.7 5.0 1 5 . 3 2 8 . 5 1 2 . 0 36.7 3 1 . 8 2 6 . 0 79.6 3 2 . 0 1 6 . 0 49.0 24.9 6.0 1 8 . 4 1 3 . 1 1 . 0 3 . 1 1 8 . 2 hen Total - 1 kg ha kg ha 2 9 . 6 4 0 7 . 0 3 3 . 0 6 8 0 . 9 n=2 5 0 4 . 4 t 1 3 7 . 7 2 0 1 . 9 ^ 9 3 . ^ 3 7 . ^ 2 9 1 . 0 2 1 . 4 3 0 5 . 7 1 0 . 7 1 2 2 . 4 7 7 . 5 2 6 1 . 6 n=5 2 9 4 . 8 i 1 3 2 . 7 1 2 2 . 1 4 9 3 . 0 1 2 5 . 3 1 2 2 9 . 1 4 4 . 3 3 7 8 . 9 n=3 7 0 0 . 3 - ^ 6 1 .5 3 . 1 4 3 1 . 1 1 2 . 1 6 0 1 . 8 n=2 5 1 6 . 4 t 1 2 0 . 7 Table I (cont.) Association or Plot Serai Stage No. Herb of /O cover kg ha - 1 Shrub kg ha""1 N 3 8 1 . 2 5 . 3 5 . 4 H 9 41 . 0 1 8 2 . 9 5 . 7 H 1 1 3 6 . 8 1 6 3 . 8 . 3 H 14 6 1 . 3 2 7 2 . 8 . 3 H 1 5 42 . 1 1 8 7 . 3 . 5 H 1 6 1 3 . 1 5 8 . 3 . 0 H 2 1 5 6 . 5 2 5 1 . 4 20 . 1 H 2 3 3 6 . 2 1 6 1 . 1 8 3 . 8 II 24 9 1 . 2 4 0 5 . 8 1 2 . 1 H 3 0 1 1 . 5 5 1 . 2 5 5 . 5 H 3 1 3 2 . 2 1 4 3 . 3 3 . 4 F 1 2 4 3 . 9 1 9 4 . 5 . 0 Conifer Lichen Total cover kg ha cover kg ha kg ha 3 3 . 5 1 0 2 . 5 . 0 . 0 1 1 3 . 2 n=1 1 1 3 . 2 . 5 1 . 5 . 0 . 0 1 9 0 . 1 . 0 . 0 . 0 . 0 1 6 4 . 1 2 . 5 7 . 6 . 0 . 0 2 8 0 . 7 1 . 0 3 . 1 . 0 . 0 1 9 0 . 9 3 . 0 9 . 2 . 0 . 0 6 7 . 5 1 0 . 0 3 0 . 6 . 0 . 0 3 0 2 . 1 6 . 5 1 9 . 9 . 0 . 0 2 6 4 . 8 4 . 0 1 2 . 2 . 0 . 0 4 3 0 . 1 1 . 0 3 . 1 . 0 . 0 1 0 9 . 8 1 . 5 4 . 6 . 0 . 0 1 5 1 . 3 n= 1 0 2 1 5 . 1 - 1 0 6 . 1 8 . 5 2 6 . 0 . 0 . 0 2 2 0 . 5 n=1 2 2 0 . 5 Table I (cont.) Association Herb Shrub or Plot of _1 -1 Serai Stage No. cover kg ha kg ha S 2 7 1 . 9 8 . 4 2 3 4 . 0 S 3 4 1 2 . 3 5 4 . 7 3 9 . 6 S 3 6 3 1 . 6 1 4 0 . 6 . 2 S 3 7 3 8 . 9 1 7 3 . 1 7 . 5 S 40 8 4 . 6 3 7 6 . 5 3 . 0 S 4 3 4 2 . 5 1 8 9 . 1 2 9 0 . 0 C 2 2 2 6 . 7 1 1 8 . 8 1 2 . 7 C 2 5 6 . 7 2 9 . 8 4 6 9 . 4 C 2 6 1 . 9 8 . 4 4 6 1 . 2 C 3 5 1 - 3 5 . 8 5 1 5 . 8 c 42 6 . 0 2 6 . 7 1 4 1 . 3 Conifer cover kg ha - 1 Lichen of /o cover kg ha - 1 Total kg ha" 1 2 1 . 0 6 4 . 3 . 0 . 0 3 0 6 . 7 4 . 0 1 2 . 2 . 0 . 0 1 0 6 . 5 2 . 5 7 . 6 . 0 . 0 1 4 8 . 4 8 . 5 2 6 . 0 . 0 . 0 2 0 6 . 6 2 3 . 0 7 0 . 4 . 0 . 0 4 4 9 . 9 6 . 5 1 9 . 9 . 0 . 0 4 9 9 . 0 n=6 2 8 6 . 2 t 1 6 1 . 3 6 o . o 1 8 3 . 6 . 0 . 0 3 1 5 . 1 2 8 . 0 8 5 . 7 . 0 . 0 5 8 4 . 9 8 0 . 0 2 4 4 . 8 . 0 . 0 7 1 4 . 4 5 9 . 5 1 8 2 . 1 . 0 . 0 7 0 3 . 7 1 1 5 . 5 3 5 3 . 4 . 0 . 0 5 2 1 . 4 n=5 5 6 7 . 9 - 1 6 3 . 0 32 F i g u r e 3. L i n e a r r e g r e s s i o n of percent cover of l i c h e n on l i c h e n biomass transformed by l o g l o . r 2 = .11 , p< .06. L = .0006 P * - i s t where L i s l i c h e n biomass and P i s percent l i c h e n cover. L i c h e n biomass i n c r e a s e s e x p o n e n t i a l l y with i n c r e a s e s i n percent cover of l i c h e n . 2 0 3 0 P E R C E N T C O V E R O F L I C H E N 34 c o a s t a l B r i t i s h Columbia ranged between 71 and 426 kg h a - 1 . In t h i s study high e l e v a t i o n f o r e s t p l a n t a s s o c i a t i o n s (Amabilis F i r - Twisted S t a l k and Mountain Hemlock - Copperbush a s s o c i a t i o n s ) were estimated to have between 9 and 376 kg h a - 1 of annual l i c h e n l i t t e r - f a l l . The s i m i l a r i t y between Krumlik's (1979) measures and my e s t i m a t e s l e d me to accept the values f o r my study area. Shrubs Almost a l l shrubs at the H a b i t a t Assessment s i t e s were Vaceinium p a r v i f o l i u m , Xs. alaskaense , or G a u l t h e r i a s h a l l o n . The c o n t r i b u t i o n by shrubs to the food a v a i l a b l e to deer was estimated as the annual shoot growth of these s p e c i e s . In a l l three s p e c i e s , the c u r r e n t year's annual growth i n c r e a s e d with i n c r e a s i n g stem h e i g h t ( F i g . 4) . In both Vaceinium s p e c i e s , v a r i a t i o n i n the stem h e i g h t accounts f o r 72% or more of the v a r i a t i o n i n annual growth. In G a u l t h e r i a s h a l l o n , the c o e f f i c i e n t of determination i s lower with only 49% of the v a r i a t i o n i n annual growth being e x p l a i n e d by v a r i a t i o n i n stem h e i g h t s . T h i s low c o e f f i c i e n t of d e t e r m i n a t i o n i s l i k e l y the r e s u l t o f the more p r o s t r a t e growth form of G. s h a l l o n compared to the v e r t i c a l growth forms o f the Vaceinium s p e c i e s . Hence, hei g h t from ground t o crown top may not be the best p r e d i c t o r of annual growth i n G a u l t h e r i a s h a l l o n . In both Vaceinium s p e c i e s , the r a t e of i n c r e a s e i n annual growth i n c r e a s e s with i n c r e a s i n g stem h e i g h t . In G a u l t h e r i a s h a l l o n , the r a t e of i n c r e a s e i n annual growth i s not s i g n i f i c a n t l y d i f f e r e n t from one (p>.05). 35 Fi g u r e . 4 . Height of shoot annual growth per stem and stem h e i g h t i n shrubs important as deer f o r a g e . ft = annual growth ( g ) , H = height from the ground t o the top of the shrub crown (cm) . Vaccinium p a r v i f olium : A = .00056 H*-8 *••<>, p<.00, r 2 = . 85 Vaccinium alaskaense : A = .0093 H L - 3 2 1 . 3 0 , p<.00, r 2=.72 G a u l t h e r i a s h a l l o n : A = .019 H»-p<-00, r2=.49  37 The number and heights of stems were determined f o r the three shrub s p e c i e s on p l o t s w i t h i n the H a b i t a t assessment s i t e s . Using the height-annual growth r e l a t i o n s h i p s ( F i g . 4) and assuming they were the same f o r a l l h a b i t a t types, annual growth produced by shrubs at each s i t e was estimated. In these c a l c u l a t i o n s , Vaceinium s p e c i e s other than V. p a r v i f o l i u m were co n s i d e r e d to have the same height-annual growth r e l a t i o n s h i p as V. alaskaense . Shrub stems l e s s than 30 cm high were very numerous but a t most s i t e s c o n t r i b u t e d l i t t l e to the t o t a l amount of food a v a i l a b l e from shrubs. To i n c r e a s e e f f i c i e n c y of the H a b i t a t Assessment these stems were counted but not measured. Stems l e s s than 30 cm high were assigned a h e i g h t of 10 cm i n c a l c u l a t i o n of the annual growth of shrubs produced at the H a b i t a t Assessment s i t e s . T h i s assigned height was chosen because I f e l t i t best represented the average.annual growth of stems l e s s than 30 cm high. For comparison, the t o t a l annual growth of shrubs was a l s o c a l c u l a t e d with stems l e s s than 30 cm being assigned heights of 0 cm and 30 cm (Appendix 1). At most s i t e s , c o n t r i b u t i o n to t o t a l annual growth by stems l e s s than 30 cm was s m a l l and use o f e i t h e r a s s i g n e d height makes l i t t l e d i f f e r e n c e to the estimate of annual growth..In some s i t e s , there were s u b s t a n t i a l d i f f e r e n c e s i n the t o t a l annual growth estimate depending upon the assigned height chosen f o r stems l e s s than 30 cm. These s i t e s were mainly i n h a b i t a t s where th e r e are high d e n s i t i e s of s h o r t stems of G a u l t h e r i a s h a l l o n O v e r a l l the assigned height of 10 cm f o r stems l e s s than 30 cm was thought t o be most r e p r e s e n t a t i v e and so was used i n a l l c a l c u l a t i o n s of food c o n t r i b u t e d by shrubs (Table I ) . 38 Herbs The c o n t r i b u t i o n of herbs and f e r n s to the deer food a v a i l a b l e at the H a b i t a t Assessment s i t e s was estimated by c o n v e r t i n g percent cover of herbs and f e r n s to biomass (kg ha-*). The t o t a l percent cover o f herbs and f e r n s , except P t e r i d i u m aquilinum , i s given i n Table I . The t o t a l percent cover i s the sum of percent covers of a l l herb and f e r n s p e c i e s (excluding P*. aquilinum ) and was obtained from the f l o r i s t i c l i s t at each H a b i t a t Assessment s i t e . Species with l e s s than 5% cover were assigned a percent cover of 0.1. The t o t a l percent cover was converted to biomass by a f a c t o r c a l c u l a t e d from Gates (1968). In Gates (1968 : 49), f o u r s i t e s were g i v e n at which percent cover and wet weight of annual herb p r o d u c t i o n biomass were measured. Dry weight of t h i s biomass was estimated as 35% of i t s wet weight. The dry weights of herbs were then d i v i d e d by t h e i r r e s p e c t i v e percent covers and a mean dry weight of for a g e per percent cover was obtained. T h i s c a l c u l a t i o n gave 4.45 kg h a - 1 of forage f o r 1% ground cover of the herb l a y e r . The conv e r s i o n f a c t o r depends upon the hei g h t s of the herbs comprising the percent cover estimate (Traczyk and Traczyk 1977). However, i n most of the h a b i t a t assessments where herbs made a s u b s t a n t i a l c o n t r i b u t i o n to the t o t a l food source, Epilobium a n q u s t i f o l i u m was the s p e c i e s with the g r e a t e s t percent cover. T h i s predominance of E. a n q u s t i f o l i u m would m i t i g a t e the problem of d i f f e r i n g biomass : cover r e l a t i o n s h i p s between s p e c i e s . The c o n t r i b u t i o n of herbs t o the t o t a l amount of food i s given i n Table I, acknowledging p o t e n t i a l e r r o r s i n v o l v e d i n e s t i m a t i o n of herbaceous forage using the above 39 method. C o n i f e r s The c o n t r i b u t i o n by c o n i f e r s t o the a v a i l a b l e deer food at the H a b i t a t Assessment s i t e s was estimated i n a manner s i m i l a r to t h a t used f o r herbs. Percent cover of c o n i f e r s was estimated d i f f e r e n t l y i n logged and unlogged s i t e s due to d i f f e r e n c e s i n the a v a i l a b i l i t y of c o n i f e r s as food f o r deer. In the logged areas, the t o t a l percent cover of c o n i f e r s below 10 m high was used i n Table I. In f o r e s t e d areas, the percent cover of c o n i f e r s l e s s than 2 m high was used. The two approaches were employed because, i n logged areas, c o n i f e r s below 10 m high had branches r e a c h i n g t o . t h e ground. In unlogged areas, c o n i f e r s 2 t o 10 m high d i d not have low r e a c h i n g branches. A f a c t o r used to convert percent cover of c o n i f e r s t o biomass of deer food was c a l c u l a t e d from Gates (1968). The dry weights were expressed as 42% of the wet weights using data f o r Pseudotsuqa m e n z i e s i i given by Gates (1968). Four s i t e s were given i n Gates (1968 : 49) at which he measured both the percent cover of c o n i f e r s and t h e i r biomass a v a i l a b l e as deer f o r a g e . At one of these s i t e s , c o n i f e r biomass was much higher than the trend from the other t h r e e s i t e s . This value appeared to be a r e s u l t of a misplaced decimal p o i n t and so was not used i n c a l c u l a t i o n of the c o n v e r s i o n f a c t o r . Using the remaining t h r e e s i t e s , the c o n v e r s i o n f a c t o r used i n Table I was, 1% of c o n i f e r cover e q u a l l e d 3.06 kg h a - 1 of c o n i f e r forage. 40 3.2.1. Abundance Of Food During Summer T o t a l amounts of food a v a i l a b l e t o deer d u r i n g summer are given i n Table I. Estimates made by Gates (1968) of food biomass a v a i l a b l e to deer i n summer are with i n the 95% co n f i d e n c e i n t e r v a l s of my e s t i m a t e s . Although Gates (1968) worked i n the C o a s t a l D o u g l a s - F i r B i o g e o c l i m a t i c Zone, agreement of our data supports assumptions t h a t I made to estimate shrub p r o d u c t i v i t y . Average food abundance f o r each a s s o c i a t i o n and s e r a i stage i s presented i n F i g u r e 5. Four of the nine a s s o c i a t i o n s (Vaccinium- Skunk Cabbage, S a l a l - D o u g l a s - f i r , Amabilis F i r - T w i s t e d S t a l k , and Mountain Hemlock-Ccpperbush) had much grea t e r food abundance than the other f i v e a s s o c i a t i o n s . In these f o u r a s s o c i a t i o n s most of the a v a i l a b l e food was c o n t r i b u t e d by shrubs. Two a s s o c i a t i o n s , Amabilis F i r - W e s t e r n Hemlock and S a l a l - Western Hemlock, had moderate amounts of forage; shrubs were again the main component. The remaining three a s s o c i a t i o n s , Sword Fern-Western Red Cedar, Deer Fern-Western Hemlock, and Western Hemlock-Plagiothecium, had s m a l l amounts of food. Food i n these a s s o c i a t i o n s was comprised mainly of c o n i f e r s . In a l l p l a n t a s s o c i a t i o n s , except the Vaccinium-Skunk Cabbage a s s o c i a t i o n , herbs were a s m a l l p o r t i o n of t o t a l a v a i l a b l e food. In the Vaccinium-Skunk Cabbage a s s o c i a t i o n , herbs were a minor component compared to t o t a l food abundance (15%), but were gr e a t e r i n abundance than i n any of the other a s s o c i a t i o n s and about t w o - t h i r d s as abundant as herbs i n young s e r a i stages. C o n i f e r s provided most of the a v a i l a b l e food i n the newly logged s e r a i s t a g e . Data f o r t h i s s e r a i stage were based on only one s i t e (a Salal-Western Hemlock a s s o c i a t i o n before i t was 41 F i g u r e 5. Abundance of food a v a i l a b l e to deer during summer i n h a b i t a t s used by radio-tagged deer over the year. Number of assessment s i t e s are i n d i c a t e d above the histograms. F o r e s t e d p l a n t a s s o c i a t i o n s : VS = Vaceinium - Skunk Cabbage, SC = Sword Fern - Western Red Cedar, DW = Deer Fern - Western Hemlock, WP = Western Hemlock - Plagiothecium, AW = Amabilis F i r - Western Hemlock, SD = S a l a l - D o u g l a s - f i r , SW = S a l a l - Western Hemlock, AT = Amabilis F i r - Twisted S t a l k , MC = Mountain Hemlock - Copperbush .. Immature S e r a i Stages : N = Newly Logged, H = Herb, F = Fern, S = Shrub, C = C o n i f e r . 80CH 60CH Q O 400-j o LL_ 200H VS SC DW WP AW SD Coasta l Western Hemlock Zone herb | | shrub l l l l l l l conifer i H H lichen - r S Immature Serai Stages SW AT MC Mountain Hemlock Zone - T " N Forested Plant Associat ions 43 l o g g e d ) . At other s i t e s with d i f f e r e n t climax p l a n t a s s o c i a t i o n s , herbs or shrubs may form the g r e a t e s t component o f a v a i l a b l e f o o d . In herb, f e r n , and shrub s e r a i stages, herbs formed the gr e a t e s t component of a v a i l a b l e food. The shrub s e r a i stage had l e s s herb food than did the herb and f e r n s e r a i stages; however, i t had a g r e a t e r t o t a l food abundance due to i n c r e a s e d amounts o f shrubs ( F i g . 5). In the o l d e s t s e r a i stage c o n s i d e r e d , herbs were r e p l a c e d by shrubs and c o n i f e r s as the major components of the a v a i l a b l e food. In t h i s s e r a i stage shrub food was more abundant than c o n i f e r f o od. T o t a l food abundance i n the c o n i f e r s e r a i stage was grea t e r than i n other s e r a i s t a ges. In c o n t r a s t to f o r e s t e d p l a n t a s s o c i a t i o n s where the main component of the a v a i l a b l e food was shrubs, food i n young s e r a i stages c o n s i s t e d mainly of herbs. Old s e r a i s t a g e s were s i m i l a r to f o r e s t e d p l a n t a s s o c i a t i o n s i n t h a t shrubs comprised most of the a v a i l a b l e food. However, o l d e r s e r a i stages had much g r e a t e r amounts of c o n i f e r forage than d i d f o r e s t e d p l a n t a s s o c i a t i o n s . In t o t a l food abundance, young s e r a i stages had more food a v a i l a b l e i n summer than some f o r e s t e d p l a n t a s s o c i a t i o n s ,but much l e s s than the most p r o d u c t i v e f o r e s t e d p l a n t a s s o c i a t i o n s ( F i g . 5) . The c o n i f e r s e r a i stage was comparable i n food abundance t o some f o r e s t e d p l a n t a s s o c i a t i o n s , but food was l e s s abundant i n t h i s s e r a i stage than i n the Vaccinium-Skunk Cabbage and Amabilis F i r - T w i s t e d S t a l k a s s o c i a t i o n s . 44 3.2.2. abundance Of Food During Winter During w i n t e r , snow accumulation and melt ( F i g . 2) a f f e c t the amount of food a v a i l a b l e to deer. Snow can a f f e c t food a v a i l a b i l i t y i n two ways: i t can bury food sources or i t can r e s t r i c t deer m o b i l i t y and thus prevent deer from o b t a i n i n g exposed food. The degree to which snow covers and b u r i e s food p l a n t s can be evaluated by c o n s i d e r i n g the v e r t i c a l d i s t r i b u t i o n of the shrub component of the food r e s o u r c e s . The c u r r e n t year's shoot annual growth of shrubs i s contained w i t h i n the crown and i s a major winter food source f o r deer (Jones 1975, R o c h e l l e i n prep.). Crown depths of the three shrub s p e c i e s c o n s i d e r e d important i n the study area were a n e a r l y constant p r o p o r t i o n of t o t a l stem height (37 to 49%) ( F i g . 6). Regression eguations ( F i g . 6) were used t o p r e d i c t crown depths of shrub stems measured on p l o t s a t the H a b i t a t Assessment s i t e s . Noting t h a t the amount of food produced by each stem can be determined from the height-annual growth r e l a t i o n s h i p s ( F i g . 4 ) , and assuming t h a t the annual growth of each stem i s apportioned evenly over crown depth, then the v e r t i c a l d i s t r i b u t i o n of shrub annual growth w i t h i n each f o r e s t e d p l a n t a s s o c i a t i o n o r s e r a i stage can be simulated ( F i g . 7). The amount of annual growth o c c u r r i n g above a given height was c a l c u l a t e d so t h a t the e f f e c t of snow could be e v a l u a t e d . The e f f e c t of snow through depression of shrubs and thus t h e i r b u r i a l by shallower snow depths, i s not accommodated i n F i g u r e 7. Such displacement would cause the amounts of food exposed above the snow to be l e s s than those i n d i c a t e d . Under c e r t a i n snow c o n d i t i o n s , downward displacement 45 F i g u r e 6. Crown depth and stem height i n shrubs important as deer forage. The r e l a t i o n s h i p between crown depth and stem height i n shrubs a l l o w s p r e d i c t i o n s of the v e r t i c a l d i s t r i b u t i o n of shoot annual growth. C = crown depth (cm), H = h e i g h t from ground t o top cf crown (cm) . Vaccinium p a r v i f o l i u m : C = - . 7 0 + .49±.09 H , p< - 0 0 , r 2 = . 7 9 Vaccinium alaskaense : C = 1.51 • . 3 7 ± . 0 4 H , p< . 0 0 , r 2 = .69 G a u l t h e r i a s h a l l o n : C = . 9 7 + .49±.06 H , p< . 0 0 , r 2 = .88  47 F i g u r e 7 . V e r t i c a l d i s t r i b u t i o n of shrub annual growth i n f o r e s t e d p l a n t a s s o c i a t i o n s and s e r a i stages. Ordinate i s the biomass a v a i l a b l e above the height from the ground on the a b s c i s s a . T h i s biomass i s the amount of food t h a t would be a v a i l a b l e above the snowpack assuming no displacement of shrubs. Estimates of t o t a l a v a i l a b l e annual shoot growth of three main shrub s p e c i e s decrease with i n c r e a s i n g height above the ground. When snowdepths are 50 cm, approximately 50% of the shrub food i n f o r e s t e d h a b i t a t s i s b u r i e d , whereas 80% of the shrub food i n immature s e r a i stages i s b u r i e d . These estimates do not i n c l u d e the e f f e c t s of shrub displacement by the snowpack. F o r e s t e d p l a n t a s s o c i a t i o n s : VS = Vaceinium - Skunk Cabbage, SC = Sword Fern - Western Red Cedar, DW = Deer Fern - Western Hemlock, WP = Western Hemlock - Plagiothecium, AW = A m a b i l i s F i r - Western Hemlock, SD = S a l a l - D o u g l a s - f i r , SW = S a l a l - Western Hemlock, AT = Amabilis F i r - Twisted S t a l k , MC = Mountain Hemlock - Copperbush . Immature S e r a i Stages : N = Newly Logged, H = Herb, F = Fern, S = Shrub, C = C o n i f e r . k8 49 of shrub crowns c o u l d permit the complete b u r i a l of shrubs by shallow snowpacks. The magnitude of d i f f e r e n c e s i n shrub abundance between p l a n t a s s o c i a t i o n s and s e r a i stages does not permit a d i r e c t comparison of the s e n s i t i v i t y of shrub abundance t o snow depth i n these h a b i t a t s ( F i g . 7 ) . D i f f e r e n c e s i n s e n s i t i v i t y of shrub a v a i l a b i l i t y t o snow depth i s more e v i d e n t when the v e r t i c a l d i s t r i b u t i o n of shrub annual growth i s c o n s i d e r e d r e l a t i v e to the t o t a l amount of shrubs a v a i l a b l e d u r i n g snow-free p e r i o d s . G e n e r a l l y , food abundance was l e s s a f f e c t e d by snow i n f o r e s t e d than i n c u t o v e r areas. T h i s d i f f e r e n c e r e s u l t s because shrubs were t a l l e r i n f o r e s t s than i n cutovers. I f only b u r i a l by snow i s considered and no displacement o f stems i s accounted f o r , then, i n f o r e s t e d h a b i t a t s , snow depths of between 50 and 110 cm are needed t o cover 75% of the food provided by shrubs; i n logged areas snow depths of between 20 and 50 cm achieve the same e f f e c t . E f f e c t Of Snow On Posture Of Shrubs In the Am a b i l i s F i r - Twisted S t a l k a s s o c i a t i o n at 900 m, n e a r l y a l l the shrub stems were p r o s t r a t e on the ground on June 6, 1976 and covered by up to 30 cm of snow. At t h i s time the mean d i s t a n c e and 95% confidence l i m i t from the ground to the markers on Vaccinium alaskaense stems b u r i e d beneath the snow was 8.8 ± 4.2 cm (n = 17); f o r Menziesia f e r r u q i n e a stems t h i s d i s t a n c e was 6.2 ± 3.1 cm (n = 3). On J u l y 2 a f t e r the snow had melted and the shrubs had returned to t h e i r snow-free p o s t u r e s , the mean d i s t a n c e from the ground t o the markers was 64.1 ± 14.5 50 cm f o r Vaceinium alaskaense and 102.0 ± 36.2 cm f o r Menzie s i a f e r r u q i n e a . Before the snow had completely melted, the shrubs were depressed to l e s s than 14% of t h e i r snow-free h e i g h t . The markers were l o c a t e d near the crowns of the stems suggesting t h a t deer food provided by shrub crowns was a l s o v e r t i c a l l y r e d i s t r i b u t e d by snow. On June 6, most of the Vaceinium alaskaense crowns were w i t h i n 10 cm of the ground and covered with snow even though the snow was g e n e r a l l y l e s s than 30 cm deep. I t appears t h a t V. alaskaense stems are b u r i e d by the deepening snowpack and become entrapped w i t h i n i t . Because of snow metamorphosis the snow compacts and decreases i n depth. The entrapped stems are p u l l e d down with the c o l l a p s i n g snowpack. The shrub stems are e v e n t u a l l y r e l e a s e d a t the bottom of the snowpack when t h e i r encasing snow melts. On s l o p i n g t e r r a i n snowcreep would a l s o c o n t r i b u t e to the b u r i a l process. Where shrubs are covered by snow i n winter and entrapped i n the snowpack, the displacement of crowns would make the shrubs u n a v a i l a b l e as deer food u n t i l v i r t u a l l y a l l the snow had melted. When the snowpack melts, the amount of a v a i l a b l e food c o n t r i b u t e d by shrubs i s i n c r e a s e d . The b u r i a l of shrubs by snow i s dependent not only on snow depth, but a l s o on d u r a t i o n of snow cov e r , r e l a t i v e r a t e s of snowpack accumulation and melt, and the shrub's s t r u c t u r e . Although not q u a n t i f i e d , i n t e r c e p t i o n of f a l l i n g snow by crowns of Vaceinium s p e c i e s was u s u a l l y i n s u f f i c i e n t t o cause l a r g e v e r t i c a l displacements of the stems. However, G a u l t h e r i a s h a l l o n i n t e r c e p t s snow r e a d i l y and consequently i s n o t i c e a b l y d i s p l a c e d a f t e r a s n o w f a l l . 51 Amount Of Food A v a i l a b l e During Winter The amount of food exposed above the snowpack changed with each s n o w f a l l and period o f snow melt. To i l l u s t r a t e the e f f e c t o f snow depth on food abundance, snow depths recorded on March 31, 1976 were a p p l i e d to the v e r t i c a l d i s t r i b u t i o n of shrub food f o r each H a b i t a t Assessment s i t e . Snow depths i n Figure 2 were used f o r logged a r e a s . Snow depths i n f o r e s t e d h a b i t a t s were estimated using the r e l a t i o n s h i p modified from F i t z h a r r i s (1975) : C = -26.0 + 0.65 L C = the amount of snow beneath a canopy, L = snow depth i n logged areas. F i t z h a r r i s (1975) expressed snow depths i n cm of water e g u i v a l e n t but found no c o n s i s t e n t t r e n d s i n snow d e n s i t i e s i n s i d e and o u t s i d e of f o r e s t e d areas. T h e r e f o r e I m u l t i p l i e d the y i n t e r c e p t by 10 to estimate snow depth. The amount o f food c o n t r i b u t e d by shrubs and exposed above the snowpack was c a l c u l a t e d on the b a s i s of d i r e c t b u r i a l by snow and d i d not i n c l u d e downward displacement of the stems. Herbs were c o n s i d e r e d u n a v a i l a b l e to deer during these snow c o n d i t i o n s . C o n i f e r s were thought to have the same a v a i l a b i l i t y i n winter as they had i n summer. T h i s assumption would overestimate the abundance of the c o n i f e r component i n young s e r a i stages where the young t r e e s are s h o r t and would be covered with snow. Since t h e r e was only a s m a l l amount of c o n i f e r food a v a i l a b l e i n these areas d u r i n g snow-free p e r i o d s ( F i g . 5), t h i s assumption would not make s u b s t a n t i a l d i f f e r e n c e s to annual trends i n food abundance. In o l d e r s e r a i stages and i n f o r e s t e d h a b i t a t s , the c o n i f e r understory was much t a l l e r . Snow 52 would cover some of the lower c o n i f e r food s o u r c e s , and at the same time r a i s e the s u b s t r a t e so t h a t p r e v i o u s l y u n a v a i l a b l e c o n i f e r food sources would be w i t h i n reach of deer. Consequently, the assumption would not i n t r o d u c e major e r r o r s i n e s t i m a t i o n of the c o n i f e r component over the range of snow depths encountered. The c o n t r i b u t i o n by l i c h e n s was based on the t o t a l f i v e month l i t t e r - f a l l and was estimated as 12% of the t o t a l l i c h e n biomass present (Stevenson 1978). These es t i m a t e s of food exposed above the snow depths recorded on March 31 are i l l u s t r a t e d i n Figure 8. They c o n s i d e r only b u r i a l of shrubs; e f f e c t s of shrub displacement on these estimates would be s u b s t a n t i a l f o r some h a b i t a t s and minor i n o t h e r s . The v e r t i c a l d i s t r i b u t i o n of shrubs would be most a f f e c t e d i n areas where th e r e were p a r t i a l r e d u c t i o n s i n the snowpack while s t i l l having a continuous snow cover throughout winter. In these areas, shrubs would be p r o g r e s s i v e l y d i s p l a c e d downward with each s n o w f a l l and subsequent metamorphosis of the snowpack. On the s o u t h - f a c i n g s l o p e of Mount Cain where snow depths i n F i g u r e 2 were obta i n e d , e l e v a t i o n s above 700-800 m had continuous snow cover throughout winter. These e l e v a t i o n s would be subjected to the displacement of shrubs by the s e t t l i n g snowpack. On the more n o r t h e r l y f a c i n g and l e s s steep s l o p e s , the e l e v a t i o n above which shrub entrapment and displacement o c c u r r e d would extend lower than 700-800 m. With one e x c e p t i o n a l l the s i t e s c l a s s e d as e i t h e r a m a b i l i s F i r - T w i s t e d S t a l k or Mountain Hemlock-Copperbush a s s o c i a t i o n s were above 700 m. The e x c e p t i o n a l s i t e was at an e l e v a t i o n of 678 m and on a n o r t h - n o r t h e a s t - f a c i n g slope. A l l of the s i t e s 5 3 F i g u r e 8. Abundance of food a v a i l a b l e to deer d u r i n g winter on seasonal home ranges. Number of assessment s i t e s are i n d i c a t e d above the histograms. Arrows i n d i c a t e t h a t the shrub component would be reduced because of displacement of t h e i r crowns by snow. For e s t e d p l a n t a s s o c i a t i o n s : VS = Vaccinium - Skunk Cabbage, SC = Sword Fern - Western Bed Cedar, DW = Deer Fern - Western Hemlock, WP = Western Hemlock - Plagiothecium, AW = A m a b i l i s F i r . - Western Hemlock, SD = S a l a l - D o u g l a s - f i r , SW = S a l a l - Western Hemlock, AT = A m a M l i s F i r - Twisted S t a l k , MC = Mountain Hemlock - Copperbush . Immature S e r a i Stages : N = Newly Logged, H = Herb, F = Fern, S = Shrub, C = C o n i f e r . I I shrub | 1 conifer llHU lichen H r°h T 1 SC DW WP AW SD Coastal Western Hemlock Zone SW AT MC Mountain Hemlock Zone T N H F S Immature Serai Stages Forested Plant Associat ions 5 5 are w i t h i n the a l t i t u d i n a l zone i n which shrub entrapment and displacement would occur. Thus, food abundance i n winter i s l i k e l y overestimated f o r A m a b i l i s F i r - T w i s t e d S t a l k and Mountain Hemlock-Copperbush a s s o c i a t i o n s . Another f o r e s t e d p l a n t a s s o c i a t i o n f o r which food abundance i s probably overestimated was the Vaccinium-Skunk Cabbage a s s o c i a t i o n . Estimates of food abundance i n t h i s a s s o c i a t i o n were based on three areas i n the Croman V a l l e y bottom. Two of these H a b i t a t Assessment s i t e s were l o c a t e d i n the middle and upper p o r t i o n s of the v a l l e y . These s i t e s had deeper snow and l o n g e r l a s t i n g snow cover than d i d s i m i l a r e l e v a t i o n s i n the Davie B i v e r V a l l e y . Although few snow depths were taken i n Croman V a l l e y , the snow regime was s i m i l a r to t h a t of mid- e l e v a t i o n s on the s o u t h - f a c i n g slope of Mount C a i n . C o n s i d e r i n g the deeper snowpack and shrub displacement, the amount of food exposed i n the Vaccinium-Skunk Cabbage a s s o c i a t i o n would be l e s s than estimated i n F i g u r e 8. Because of p o t e n t i a l o ver-estimates of food abundance i n winter on Amabilis F i r - Twisted S t a l k , Mountain Hemlock - Copperbush, and Vaccinium - Skunk Cabbage a s s o c i a t i o n s , d i r e c t comparison of these a s s o c i a t i o n s with others i n F i g u r e 8 may be m i s l e a d i n g . Estimates f o r the other p l a n t a s s o c i a t i o n s were based on s i t e s l o c a t e d below 700 m and t h e r e f o r e should be comparable and r e p r e s e n t a t i v e of a c t u a l amounts of food exposed above the snowpack. Since snow cover i n these lower e l e v a t i o n s was i n t e r m i t t e n t over winter, 1 displacement of shrubs through entrapment i n the snowpack would be much l e s s than t h a t a t the higher e l e v a t i o n s . 56 During winter, low e l e v a t i o n f o r e s t e d p l a n t a s s o c i a t i o n s g e n e r a l l y had more food exposed above the snowpack than d i d logged areas. Herb, f e r n , and shrub s e r a i stages had more food than A m a b i l i s f i r - Western Hemlock and S a l a l - Western Hemlock a s s o c i a t i o n s i n summer but had much l e s s i n winter ( F i g . 5 and 8 ) . Newly logged, herb, f e r n , and shrub s e r a i stages p r o v i d e d even l e s s food than Sword Fern-Western Red Cedar, and Deer Fern- Western Hemlock a s s o c i a t i o n s and were s i m i l a r i n food abundance to the Western Hemlock-Plagiothecium a s s o c i a t i o n . Of the s i x f o r e s t e d p l a n t a s s o c i a t i o n s t h a t can be compared, Am a b i l i s Fir-Western Hemlock, S a l a l - D o u g l a s - f i r , and Salal-Western Hemlock a s s o c i a t i o n s had g r e a t e r amounts of food than d i d other f o r e s t e d a s s o c i a t i o n s . These d i f f e r e n c e s were mainly due to d i f f e r e n c e s i n shrub abundance. Rochelle ( i n prep. ) measured 96 and 392 kg h a - 1 of a v a i l a b l e deer forage i n low and m i d - e l e v a t i o n f o r e s t e d h a b i t a t s r e s p e c t i v e l y . These values are s i m i l a r to my estimates of a v a i l a b l e deer forage (43 to 504 kg h a - 1 ) a t these e l e v a t i o n s . The c o n i f e r s e r a i stage was the only logged h a b i t a t t h a t had s u b s t a n t i a l amounts of food d u r i n g winter. This s e r a i stage had more food a v a i l a b l e than d i d Amabilis F i r - Western Hemlock and S a l a l - Western Hemlock a s s o c i a t i o n s , but l e s s than t h a t i n the S a l a l - D o u g l a s - f i r a s s o c i a t i o n . In the c o n i f e r s e r a i stage and the three f o r e s t a s s o c i a t i o n s i n which food was most abundant, the shrub component of the t o t a l a v a i l a b l e food was g r e a t e r than the c o n i f e r and l i c h e n components. 57 The amounts of food a v a i l a b l e t o deer i n the d i f f e r e n t f o r e s t e d p l a n t a s s o c i a t i o n s and s e r a i stages were not determined f o r s p r i n g but evaluated q u a l i t a t i v e l y and presented l a t e r . 3 . 3 . D e n s i t y Of A v a i l a b l e D i g e s t i b l e Dry Matter The d e n s i t i e s of food a v a i l a b l e to deer i n the h a b i t a t s d u r i n g summer and winter ( F i g . 5 and 6) were converted to d e n s i t i e s of d i g e s t i b l e dry matter ( F i g . 9) using f a c t o r s p r ovided by Roc h e l l e ( i n prep.) f o r the major fo r a g e components. During summer the Vaccinium - Skunk Cabbage, Amabilis F i r - Twisted S t a l k , and Mountain Hemlock - Copperbush a s s o c i a t i o n s had the h i g h e s t d e n s i t i e s of a v a i l a b l e d i g e s t i b l e dry matter of a l l the f o r e s t e d p l a n t a s s o c i a t i o n s ( F i g . 9). During winter the d e n s i t y of d i g e s t i b l e dry matter a v a i l a b l e i n these a s s o c i a t i o n s d e c l i n e d and may be below the d e n s i t i e s of d i g e s t i b l e dry matter a v a i l a b l e i n the Amabilis F i r - Western Hemlock, S a l a l - D o u g l a s - f i r , and S a l a l - Western Hemlock a s s o c i a t i o n s . The Sword Fern - Western Red Cedar, Deer Fern - Western Hemlock, and Western Hemlock - Plagiothecium a s s o c i a t i o n s have low d e n s i t i e s of a v a i l a b l e d i g e s t i b l e dry matter i n both summer and winter. In c u t o v e r areas d u r i n g summer the d e n s i t i e s of a v a i l a b l e d i g e s t i b l e dry matter i n a l l s e r a i stages except the newly logged s e r a i stage were s i m i l a r to those a v a i l a b l e i n the Vaccinium -Skunk Cabbage, Amabilis F i r - Western Hemlock, S a l a l - D o u g l a s - f i r , S a l a l - Western Hemlock, A m a b i l i s F i r - Twisted S t a l k , and Mountain Hemlock - Copperbush a s s o c i a t i o n s ( F i g . 9 ) . During winter a l l s e r a i stages, except the c o n i f e r s e r a i stage 5 8 F i g u r e 9. Density of d i g e s t i b l e dry matter during winter and summer i n h a b i t a t s used by radio-tagged deer.. Number of assessment s i t e s are i n d i c a t e d above the histograms. F o r e s t e d p l a n t a s s o c i a t i o n s : VS = Vacciaium - S k u n k Cabbage, SC = Sword Fern - Western Red Cedar, DW = Deer Fern - Western Hemlock, WP = Western Hemlock - Plagiothecium, AW = Am a b i l i s F i r - Western Hemlock, SD = S a l a l - D o u g l a s - f i r , SW = S a l a l - Western Hemlock, AT = Amabilis F i r - Twisted S t a l k , MC = Mountain Hemlock - Copperbush . Immature S e r a i Stages : N = Newly Logged, H = Herb, F = Fern, S = Shrub, C = C o n i f e r .  60 had low d e n s i t i e s of a v a i l a b l e d i g e s t i b l e dry matter. These d i f f e r e n c e s i n the d e n s i t y of a v a i l a b l e d i g e s t i b l e dry matter between summer and winter were p r i m a r i l y a r e s u l t of the l a c k of herbs and b u r i a l of shrubs by snow duri n g the winter. The d e n s i t y of d i g e s t i b l e dry matter a v a i l a b l e to deer d u r i n g the s p r i n g on the f o r e s t e d p l a n t a s s o c i a t i o n s and s e r a i stages c o u l d not be adequately estimated and so are not i n c l u d e d i n t h i s s e c t i o n . T h i s season w i l l be compared q u a l i t a t i v e l y t o the other seasons when the movements and h a b i t a t use of the deer- have been presented. The i m p l i c a t i o n s of the r e l a t i v e d e n s i t i e s of a v a i l a b l e d i g e s t i b l e dry matter t o the sea s o n a l movements of b l a c k - t a i l e d deer w i l l be d i s c u s s e d l a t e r . F i r s t seasonal movements and h a b i t a t use of b l a c k - t a i l e d deer are d e s c r i b e d . These movements are then evaluated with regard to the d e n s i t i e s of a v a i l a b l e d i g e s t i b l e dry matter and other f a c t o r s . 3 . 4 , Seasonal Movements Of Radio-tagged Deer S u f f i c i e n t data were c o l l e c t e d from seven radio-tagged deer (Table II) to c o n s i d e r t h e i r p a t t e r n s of seasonal movements. The l o c a t i o n s of these deer over the year suggested t h a t g e n e r a l l y t h r e e s e a s o n a l home ranges were used, c o r r e s p o n d i n g t o s p r i n g , summer, and winter. For f i v e deer, seasonal home ranges of each deer were separated. For two deer the se a s o n a l home ranges of each deer overlapped e x t e n s i v e l y . In both of these l a t t e r deer, seasonal home ranges were d e f i n e d by d i f f e r e n t a r e a l d i s t r i b u t i o n s of l o c a t i o n s o b t a i n e d between c e r t a i n dates. The dates were based on s h i f t s i n l o c a t i o n s of the deer together 61 Table I I . L i s t o f radio-tagged deer and seasons f o r which home range data were ob t a i n e d . A l l radio-tagged deer were a d u l t s . Deer Sex Sector 0FL61 male Croman OFL68 female Mount Cain O F L 6 7 female Maquilla 0 F L 6 0 female Croman 0FL71 * female Croman-Hoomak O F L 5 8 female Mount Cain OFL62 male Croman * horizontal migrator Comments, Observation Period, Spring Summer Winter (Number Of Locations) X X X X X X X X X X X X X X X X X X X X May 1 9 7 5 to September 1 9 7 6 . ( 1 0 6 ) no locations obtained for spring; k i l l e d at beginning of winter, 1 9 7 5 ; accompanied by one fawn. July to November 1 9 7 5 . ( 3 6 ) June 1975 to June 1 9 7 6 . ( 9 8 ) accompanied by one fawn i n 1 9 7 6 . May 1 9 7 5 to A p r i l 1 9 7 6 . (64) accompanied by two fawns i n 1 9 7 6 . J u l y 1 9 7 5 to Sept- ember 1 9 7 6 . ( 2 1 2 ) few locations obtained for spring; k i l l e d at beginning of winter, 1 9 7 5 . A p r i l to November 1 9 7 5 . ( 4 7 ) May 1 9 7 5 to June 1 9 7 6 . ( 1 6 5 ) 63 with the occurrence of seasonal movements by the f i v e migratory deer and n i g h t count o b s e r v a t i o n s . S p r i n g home ranges were occupied between March and June; summer home ranges between June and November; and winter home ranges between November and March. These p e r i o d s of seasonal home range occupancy d i f f e r e d between deer and are d i s c u s s e d more f u l l y i n S e c t i o n 3.4,4. 3.4.1. S t a t i s t i c a l Parameters Of Home Ranges S t a t i s t i c a l e v a l u a t i o n of seasonal changes i n the p o s i t i o n of home range c e n t r e s can be made i f the l o c a t i o n s approximate a b i v a r i a t e normal d i s t r i b u t i o n . The l o c a t i o n s of each deer were grouped by season and the d i s p e r s i o n parameters o f these groups were estimated. A r i t h m e t i c mean c e n t r e s ( a f t e r Neft 1966) were c a l c u l a t e d f o r the seasonal d i s t r i b u t i o n s of radio-tagged deer. The deer's l o c a t i o n s i n each s e a s o n a l home range were hypothesized t o be d i s t r i b u t e d about the a r i t h m e t i c mean c e n t r e a c c o r d i n g t o a b i v a r i a t e normal d i s t r i b u t i o n . Comparisons of sea s o n a l d i s t r i b u t i o n s t o b i v a r i a t e n o r m a l i t y were t e s t e d using the " r i n g " t e s t (Kowalski 1970). The " r i n g " t e s t compares the frequency d i s t r i b u t i o n of d i s t a n c e s between l o c a t i o n s and the a r i t h m e t i c mean c e n t r e , t o the frequency d i s t r i b u t i o n of these d i s t a n c e s i n a b i v a r i a t e normal d i s t r i b u t i o n . The Kolmogorov- Smirnov one-sample t e s t ( S i e g e l 1956 : 47) was then used to t e s t the s i g n i f i c a n c e of d i f f e r e n c e s between the two d i s t r i b u t i o n s . S ixteen of the 21 s e a s o n a l home ranges were not s i g n i f i c a n t l y d i f f e r e n t (p > .05) from a b i v a r i a t e normal d i s t r i b u t i o n (Table I I I ) . F i v e home ranges d i f f e r e d s i g n i f i c a n t l y (p < .05) from a b i v a r i a t e normal d i s t r i b u t i o n i n 6 4 Table I I I . S t a t i s t i c a l c h a r a c t e r i s t i c s of seasonal home ranges. A r e a l d i s t r i b u t i o n s t h a t are s i g n i f i c a n t l y d i f f e r e n t (p<.05) from a b i v a r i a t e normal d i s t r i b u t i o n are u n d e r l i n e d . The " r i n g t e s t " , i n c o r p o r a t i n g the Kolmogorov-Smirnov t e s t , was used to compare the seasonal a r e a l d i s t r i b u t i o n s with the b i v a r i a t e normal d i s t r i b u t i o n . Standard Distance Deviation ( m ) + spring summer winter OFL61 376.6 (34) 1001.6 (39) 534.7 (33) OFL68 - 395.1 (26) 649.9 (10) OFL67 250.3 (50) 495.7 (10) 491.0 (38) OFL60 311.6 (15) 679.2 (20) " • winter range 398.2 (12) " a u x i l i a r y winter range 412.1 (17) 0FL71* 157.4 (19) 490.5 (167) 262.2 (26) 0 F L 5 8 171.6 (3) 924.5 (29) 370.6 (15) 0 F L 6 2 484.2 (50) 508.1 (46) 455.2 (69) + number of locations are enclosed i n brackets * horizontal migrator Skewnees / Kurtosis spring summer winter .18 / .38 .87 / - . 1 0 .28 / .34 .44 / .30 .34 / .71 .12 / .50 .25 / .51 .26 / .42 .44 / .05 1.08 / -.46 .24 / - . 0 7 ; .17 / .29 .73 / - . 19 1.36 / - . 5 0 .19 / .71 . 2 0 / . 8 2 .24 / .81 .31 / .03 .12 / .57 .47 / - . 2 5 .19 / - . 2 6 66 t h a t they were a l l l e p t o k u r t i c (more l o c a t i o n s near the mean cen t r e and at the t a i l s than i n a normal d i s t r i b u t i o n ) and s l i g h t l y skewed ( s l i g h t l y asymmetrical). In one i n s t a n c e , t h a t of the summer home range of OFL67, the d i f f e r e n c e between the observed d i s t r i b u t i o n and the hypothesized b i v a r i a t e normal d i s t r i b u t i o n , was l i k e l y caused by i n a c c u r a c i e s i n l o c a t i o n . The summer home range o f 0FL67 was l o c a t e d i n a remote area and, because of poor radi o r e c e p t i o n , I was abl e t o get a c c u r a t e l o c a t i o n s on only a few oc c a s i o n s . The l o c a t i o n o f OFL67, when p r e c i s e l o c a t i o n was not p o s s i b l e , was estimated on the b a s i s of s e v e r a l days's o b s e r v a t i o n s . T h i s e s t i m a t i o n r e s u l t e d i n s e v e r a l l o c a t i o n s o c c u r r i n g a t the same p o s i t i o n and, when coupled with a s m a l l sample s i z e , gave the appearance of a l e p t o k u r t i c d i s t r i b u t i o n . Of the remaining f o u r home ranges t h a t d i f f e r e d s i g n i f i c a n t l y (p < .05) from b i v a r i a t e n o r m a l i t y two home ranges, OF158 summer and OFL62 s p r i n g , were not d i f f e r e n t at a p r o b a b i l i t y l e v e l of 0.01. In a l l four home ranges, the d i f f e r e n c e s from the b i v a r i a t e normal d i s t r i b u t i o n although s i g n i f i c a n t , were not s u b s t a n t i a l with k u r t o s i s r e a c h i n g a maximum of 0.82 and skewness a maximum of 0.26. 3.4.2. Home Range S i z e Home range s i z e was c a l c u l a t e d u s i n g modified v e r s i o n s of the minimum home range method f i r s t proposed by Dalke and Sime (1938) (Table I V ) . The 10055 home range i s the area enclosed by a convex polygon surrounding the outermost l o c a t i o n s of the deer during a p a r t i c u l a r season. T h i s i s the most commonly used 67 Table IV- Size of seasonal home ranges. The 90% home ranges eliminate i n f l a t e d home range sizes caused by extreme locations. The 50% home range i s the area of intense deer use. Number of locations SP SM WT 1 0 0 % SP SM WT 0FL61 3 4 3 9 3 3 OFL68 - 2 6 1 0 0FL67 5 0 1 0 3 8 0 F L 6 0 1 5 2 0 " winter range 12 " aux. winter range 1 7 8 9 . 3 4 o 6 . 6 1 8 6 . 7 6 6 . 9 4 9 . 7 6 6 . 8 6 3 . 2 7 9 . 3 27.0 1 3 8.I _ 4 9 . 5 5 9 . 5 0FL71* 1 9 1 6 7 2 6 6 . 7 1 8 5 . 6 3 6 . 6 0 F L 5 8 3 2 9 1 5 0FL-62 5 0 46 6 9 . 3 1 5 2 . 0 1 6 . 0 146.1 147.5 104.5 mean * horizontal migrator 5 6 . 0 1 6 5 . 7 7 2 . 7 Size of Home Range (ha) 9 0 % SP SM W T 3 8 . 6 2 7 4 . 1 8 4 . 7 3 4 . 0 1 3 . 3 2 1 . 3 1 6 . 8 6 5 . 3 14 . 9 8 8 . 4 2 0 . 3 3 3 - 9 5 . 5 3 6 . 4 1 2 . 5 20.0 12 . 0 5 2 . 6 8 8 . 9 83.O 2 6 . 6 7 9 . 8 4 0 . 6 5 0 % SP SM WT 4 . 2 3 0 . 7 1 0 . 6 9 . 0 . 6 4 . 4 - 5 . 5 4 . 6 2 8 . 3 2 . 6 8 . 2 . 5 1 3 . 5 2 . 4 4 . 1 2 . 7 6 . 8 2 9 . 1 2 6 . 5 4 . 1 1 9 . 1 7 . 4 6 9 estimate of home range s i z e . The s i z e of the 100% home range i s s e n s i t i v e to extreme or abnormal l o c a t i o n s of the animal. In order to circumvent t h i s s e n s i t i v i t y , I c a l c u l a t e d the 90% home range . T h i s estimate of home range i s the area enclosed by a polygon surrounding the c l o s e s t 90% of the l o c a t i o n s and e l i m i n a t e s the i n f l a t i o n i n area caused by extreme l o c a t i o n s when the 100% method i s used. A t h i r d e x p r e s s i o n of s i z e of home range i s the 50% home range . T h i s estimate i s the area of a polygon e n c l o s i n g the c l o s e s t 50% of the l o c a t i o n s and i s u s e f u l i n i d e n t i f y i n g the core of deer use w i t h i n the 100 or 90% home ranges. The 90% home ranges (Table IV) are shown i n F i g u r e s 10 to 16. The 50 and 100% home ranges are not d e l i n e a t e d , although l o c a t i o n s of the deer are i n d i c a t e d . S i z e of home range i s an a r e a l e x p r e s s i o n of v a r i a b i l i t y i n a deer*s average p o s i t i o n . Since the area of a c i r c l e i s p r o p o r t i o n a l to the square of i t s r a d i u s then home range s i z e should be p r o p o r t i o n a l to the square of the standard d i s t a n c e d e v i a t i o n . Since the standard d i s t a n c e d e v i a t i o n ( a f t e r Neft 1966) i n c l u d e s a l l l o c a t i o n s , the 100% home range area was used as the dependent v a r i a b l e ( F i g . 17). The r z of the r e g r e s s i o n was 0.61 and the slope of the r e g r e s s i o n l i n e was s i g n i f i c a n t l y d i f f e r e n t from z e r o (p < .05). The exponent of the r e g r e s s i o n equation, 2.52 ± 0.97, i n c l u d e d the hypothesized value of 2 i n i t s 95% confidence l i m i t s . Since 100% home range s i z e was a f u n c t i o n of standar d d i s t a n c e d e v i a t i o n , a t e s t f o r homogeneity of v a r i a n c e was used to determine i f there were s e a s o n a l d i f f e r e n c e s i n the s i z e of 100% home ranges (Tables IV and V). Aside from three e x c e p t i o n s , 70 Figure 10. Seasonal 90% hose ranges of a l t i t u d i n a l migrator OFL6 1. Shaded areas are logged, unshaded areas are unlogged. 90% spring home range o spring location 90% summer home range • summer location ^ 90% winter home range • winter location  72 Figure 11- Seasonal 90% hoae ranges of a l t i t u d i n a l migrator OFL68. Shaded areas are logged, unshaded areas are unlogged. ===== 90S summer home range • summer loc a t i o n 11 90% winter home range • winter location  74 F i g u r e 1 2 . Seasonal 9 0 S hoae ranges of a l t i t u d i a a l a i g r a t o r OFL67. shaded areas are logged, unshaded a r e a s are unlogged. {jjU|j}|{ 9 0 * s p r i n g hoae range o s p r i n g l o c a t i o n ^ ^ ^ ^ 9 0 * summer home range • suamer l o c a t i o n ^ 9 0 % winter home range • winter l o c a t i o n 7 5 76 Figure 13. Seasonal 90% hoae ranges of a l t i t u d i a a l migrator OFL60. Shaded areas are logged, unshaded areas are unlogged. j j j j j i j j j j 90% spring hoae range o spring location • 90% suamer hoae range • summer location ^ 9 0 % winter hone range • winter location  78 Figure 14. Seasonal 90% hose ranges of horizontal aigrator 0FL71. Shaded areas are logged, unshaded areas are unlogged. I l l l l l l l l l 9 0 5 4 spring hone range o spring location zEEEEEz 90* suamer home range • summer location H 90% winter hoae range • winter l o c a t i o n 7 9 80 Figure 15. Seasonal 90% home ranges of resident 0FL58. The 90% spring home range i s not shown nut i t overlaps extensively with the 90% summer home range. Two extreme locations i n summer are indicated with • ; other locations are not shown. Arithmetic mean centres of seasonal home ranges are indicated by: ^ spring, summer, ^ winter. Shaded areas are logged, unshaded areas are unlogged. 90% summer home range 90% winter home range  82 Figure 16. Seasonal 90% borne ranges of resident OFL62. Arithmetic mean centres of seasonal hone ranges are indicated by: ^ spring, summer, ^ winter. Shaded areas are logged, unshaded areas are unlogged. I l l l l l l l l l 90% spring home range 90% summer home range i f 90% winter home range  84 Figure 17. Relationship between standard distance deviation a size of 100% home range. H = .000014 s 2 - 5 2 ± . 9 7 , p<.0 r 2=.61, n=21; where H i s home range size and S i s standa distance deviation.  86 Table V. D i f f e r e n c e s i n s i z e of 100% home ranges using an F - t e s t (Sokal and Rohlf 1969 :186) to compare standard d i s t a n c e d e v i a t i o n s . Spring - Summer Summer - Winter Winter - Spring d.f. f + c P d.f. f c f t P d.f. f c f t P 0FL61 3 8 , 3 3 7 . 0 7 1 . 6 9 ^ . 0 5 3 8 , 3 2 3 . 5 1 1 . 7 9 ^ . 0 5 3 2 , 3 3 2 . 0 1 1.84 • s . 0 5 OFL68 - - - - 9 , 2 5 2 . 7 0 2 . 2 8 2 . 0 5 - - - - 0FL6? 9,49 3 . 9 2 2.12 5 . 0 5 9 , 3 7 1 . 0 2 2 . 1 2 > . 0 5 3 7 , 4 9 3.84 1 . 7 4 . 0 5 0FL60 1 9 , 1 4 4 . 7 5 2.46 s . 0 5 1 9 , 1 1 2 . 9 1 2 . 6 5 0 5 1 1 , 1 4 1 . 6 3 2 . 5 7 > . 0 5 — a u x i l i a r y winter range 1 9 , 1 6 2 . 7 1 2 . 3 5 s . 0 5 1 6 , 1 4 1 . 7 5 2.46 ^ . 0 5 — between winter ranges 1 6 , 1 1 1.07 2 . 7 2 >.05 0 F L 7 1 * 1 6 6 , 1 8 9 .71 1 . 6 6 5 . 0 5 1 6 6 , 2 5 3 . 5 0 1 . 6 1 ^ . 0 5 2 5 , 1 8 2 . 7 7 2 . 1 5 •s . 0 5 O F L 5 8 2 8 , 2 2 9 . 0 2 1 9 . 5 0 2 . 0 5 2 8 , 1 4 6 . 2 2 2 . 3 5 s . 0 5 1 4 , 2 4 . 6 6 1 9 . 4 0 >.05 O F L 6 2 4 5 , 4 9 1 . 1 0 1 . 5 6 > . 0 5 4 5 , 6 8 1.24 1 . 5 9 > . 0 5 4 9 , 6 8 1 . 1 3 1 . 5 6 > . 0 5 + f = f calculated , f.= f table c ' t * horizontal migrator 88 summer home ranges were l a r g e r than e i t h e r winter or s p r i n g home ranges. Distance v a r i a n c e s were not s i g n i f i c a n t l y d i f f e r e n t (p > .05) between the s p r i n g and winter home ranges of OFL58. T h i s s i m i l a r i t y i n home range s i z e probably r e s u l t s from the s m a l l sample s i z e (n = 3) used to est i m a t e the standard d i s t a n c e d e v i a t i o n of her s p r i n g home range. The s i m i l a r i t y i n s i z e between summer and winter home ranges o f OFL67 may be a r e s u l t of i n a c c u r a c i e s i n r e l o c a t i o n as d e s c r i b e d i n S e c t i o n 3.1.1. F i n a l e x c e p t i o n s to general t r e n d s i n seasonal home range s i z e were the home ranges of 0FL62 which stayed the same s i z e throughout the year. These s i m i l a r i t i e s i n home range s i z e were l a r g e l y a r e s u l t of the more remote l o c a t i o n s of OFL62. Comparison of h i s 90 or 50% home range s i z e s i n d i c a t e d t h a t h i s s p r i n g home range was the s m a l l e s t of h i s sea s o n a l home ranges, and so was c o n s i s t e n t with the gen e r a l trends p r e v i o u s l y s t a t e d . Although the summer home range o f OFL62 was l a r g e r than the winter home range , the d i f f e r e n c e was not as great as t h a t observed i n other deer. The mean 100% home range s i z e f o r the seven deer was 56.0 ha i n s p r i n g , 165.7 ha i n summer, and 72.7 ha i n winter. Mean 90% home ranges were between 47 and 55% the s i z e of mean 100% home ranges, and i l l u s t r a t e d the c o n c e n t r a t i o n of l o c a t i o n s about the a r i t h m e t i c mean c e n t r e . Mean 50% home ranges were between 7 and 12% the s i z e of mean 100% home ranges. Thus, i n s p r i n g , h a l f o f a radio-tagged d e e ^ s l o c a t i o n s were i n areas averaging 4.1 ha. I n summer, the area i n c r e a s e d to 19.1 ha. During the winte r , the .core.of deer use as d e l i n e a t e d by the 50% 89 home range dropped i n s i z e and, on average, covered 7.4 ha. These comparisons of d i f f e r e n t percentage home range s i z e s were c o n s i s t e n t with the r e s u l t s of' S e c t i o n 3.1.1. where home ranges were s i m i l a r t o b i v a r i a t e normal d i s t r i b u t i o n s . 3.4.3. P o s i t i o n Of Home Ranges as with u n i v a r i a t e data, the l o c a t i o n s , comprising two seasonal home ranges, can be compared i n order to t e s t the hypothesis t h a t they come from p o p u l a t i o n s with d i f f e r e n t a r i t h m e t i c mean c e n t r e s (Neft 1966). The c o n d i t i o n s of the t e s t are t h a t the d i s t r i b u t i o n s are b i v a r i a t e normal and t h a t the v a r i a n c e s are the same. In S e c t i o n 3.1.1., i t was shown t h a t most home ranges were not d i f f e r e n t from a b i v a r i a t e normal d i s t r i b u t i o n and those t h a t were s i g n i f i c a n t l y d i f f e r e n t , d i f f e r e d only i n minor ways. G i l b e r t (1973) noted t h a t the Student's t - t e s t i s f a i r l y robust with regards t o n o r m a l i t y of the sample data. The t r - t e s t proposed by Neft (1966) i s s i m i l a r i n d e r i v a t i o n to the Student's t - t e s t . Thus, I assumed i t should a l s o be robust with regards to b i v a r i a t e n o r m a l i t y . With u n i v a r i a t e d a t a , i f the v a r i a n c e s are d i f f e r e n t , the Student's t - t e s t can s t i l l be used t o t e s t f o r d i f f e r e n c e s i n the means o f samples. However, the c a l c u l a t e d t value must be o u t s i d e of the i n t e r v a l between the c r i t i c a l t values d e r i v e d from a t a b l e using the upper and lower sample s i z e s to o b t a i n the degrees of freedom (Sokal and Rohlf 1969:375). This same c o n s t r a i n t was a p p l i e d to the t v - t e s t of Neft (1966). 90 For each r a d i o - t a g g e d deer, except f o r OFL58, a r i t h m e t i c mean c e n t r e s of the seasonal home ranges were s i g n i f i c a n t l y d i f f e r e n t (p < .01) (Table VI and F i g s . 10 t o 16). For OFL58, no d i f f e r e n c e i n the p o s i t i o n o f s p r i n g and summer home ranges or summer and winter home ranges c o u l d be d e t e c t e d . Lack of d i f f e r e n c e i n p o s i t i o n between her s p r i n g and summer home ranges was l i k e l y due to the sm a l l sample s i z e (n =3) used to c a l c u l a t e her s p r i n g home range . A second f a c t o r was the high standard d i s t a n c e d e v i a t i o n of OFL58's summer l o c a t i o n s (Table I I I ) . T h i s v a r i a b i l i t y may a l s o have c o n t r i b u t e d t o the l a c k of d i f f e r e n c e between the a r i t h m e t i c mean cen t r e s of her summer and winter home ranges. The high standard d i s t a n c e d e v i a t i o n i n OFL58's summer l o c a t i o n s was due to two extreme movements t h a t may have r e s u l t e d from d i s t u r b a n c e by hunters ( F i g . 15). OFL58 was accompanied by two fawns a few days previous t o the extreme movements. A f t e r OFL58 moved to these extreme l o c a t i o n s , I s i g h t e d her standing i n the cu t o v e r , accompanied by only one fawn. Another fawn was found shot dead 400 m from OFL58. Within a few days a f t e r the extreme movements, OFL58 returned to her low e l e v a t i o n summer range and remained there u n t i l her s i g n a l was l o s t on the second day of the a n t l e r l e s s hunting season. D i s t a n c e s between the a r i t h m e t i c mean c e n t r e s of winter and s p r i n g home ranges were much l e s s than d i s t a n c e s between summer home ranges and winter o r s p r i n g home ranges (Table VI). Dista n c e s between seasonal home ranges and the r e l a t i v e p o s i t i o n s of home ranges were used t o c l a s s i f y radio-tagged deer as e i t h e r migratory or r e s i d e n t deer ( F i g s . 10 to 16 and Table V I ) . Migratory deer had separated summer and winter home ranges. 91 Table VI. Distance between a r i t h m e t i c mean c e n t r e s of home ranges and t e s t s of d i f f e r e n c e s i n t h e i r p o s i t i o n s . Spring - Summer Summer - Winter Winter - Spring distance distance distance (km) t r P (km) P (km) P OFL6I 4 . 5 4 24.62 ^ . 0 1 3.64 18.46 • = . 0 1 . 9 1 7 . 9 9 i . 0 1 OFL-68 - - - 4 . 3 0 23.42 s . 0 1 - - - O F L 6 7 2 . 2 3 2 0 . 7 6 S . 0 1 1 . 4 4 8 . 0 7 s . 0 1 . 7 9 9 . 7 4 S . 0 1 O F L 6 0 2 . 4 5 12.62 5 . 0 1 winter range 2 . 0 2 9 . 0 7 S .01 . 4 4 3 . 0 8 2 . 0 1 If a u x i l i a r y winter range 4 . 0 5 2 0 . 8 7 £ . 0 1 2 . 7 9 2 0 . 6 8 - . 0 1 between winter ranges 2 . 9 3 1 8 . 4 5 < . 0 1 0FL71* 6 . 1 6 5 4 . 1 5 ^ . 0 1 5 . 8 9 5 9 . 5 9 ^ . 0 1 . 2 8 4 . 0 6 s . 0 1 0 F L 5 8 .40 .72 > . 0 5 . 0 9 . 3 6 > . 0 5 . 3 1 2 . 6 8 ^ . 0 1 0 F L 6 2 .34 3.33 s . 0 1 . 2 8 3 . 0 7 5 . 0 1 .62 7 . 1 0 s . 0 1 horizontal migrator r o 93 while t h e i r s p r i n g and winter home ranges were e i t h e r separated or overlapped. Resident deer made se a s o n a l s h i f t s i n t h e i r home range c e n t r e s , although t h e i r home range boundaries remained b a s i c a l l y the same throughout the year. 3.4.4. Occupancy Of Seasonal Home Ranges The dates of occupancy i n seasonal home ranges are shown i n F i g u r e 18. In the f i v e migratory deer (Table VI) the dates of occupancy of home ranges were i d e n t i f i e d by d i s t i n c t changes i n the deer's l o c a t i o n s . In the two r e s i d e n t deer (Table VI) dates of home range occupancy were based both on s h i f t s i n the, core of the deer's l o c a t i o n s and on dates of m i g r a t i o n of other r a d i o - tagged deer. The exact dates of occupancy of r e s i d e n t deer's home ranges were t h e r e f o r e a r b i t r a r y . However, duri n g the pe r i o d s chosen, d i f f e r e n t c e n t r e s of a c t i v i t y were i d e n t i f i e d (Section 3.4.3.). I n d i v i d u a l d i f f e r e n c e s o c c u r r e d i n the dates of occupancy of seasonal home ranges, but g e n e r a l l y s p r i n g home ranges were occupied between March and June, summer home ranges between June and November, and winter home ranges between November and March. Thus, i n the study a r e a , b l a c k - t a i l e d deer e x h i b i t e d t h r e e migratory p e r i o d s d u r i n g the year. The d i s t a n c e s of these m i g r a t i o n s were presented i n S e c t i o n 3.4.3. Spring m i g r a t i o n was the movement of deer between winter and s p r i n g home ranges. The d i s t a n c e s moved were s m a l l , being u s u a l l y l e s s than 0.9 km, but were as great as 2.8 km. Summer m i g r a t i o n was the movement from s p r i n g to summer home ranges, and was u s u a l l y g r e a t e r than the s p r i n g m i g r a t i o n , with d i s t a n c e s extending to 6.1 km. Winter 94 F i g u r e 18. P e r i o d s of occupancy of s e a s o n a l home ranges. SP = s p r i n g , SM = summer, WT = winter, AW = a u x i l i a r y winter. Short v e r t i c a l l i n e s are dates when deer were l o c a t e d . Consecutive l o c a t i o n s on a seasonal range are j o i n e d . 95 SP-j SM- WT i in iii mu i i m—H4- f l II I 1 II—hH—III III M U HIH I Hi II IE 1 OFL61 4 1 M 1 —I 1 1 1 1 1 1 1 " ' 1 1 I I 1 1 SP-, SM- WT OFL68 ( I I I I 11 I H - i 1 1 1 1 1 1 r- -i 1 1 1 cr o cr o SP-i SM- WT •H MM* III I 11 I—l-IIHIBll l ( • I IB I II HI 'ai »i OFL67 -I 1 1 r- l i 1 1 1 ' i SP-i SM- WT AW- SP- SM- WT i—6-rt V I I I n—i H—i—«H ( OFL60 III I I I I — r Vi i . ill - i , 1 1 1 1 > r 1 1 1 1 1 ' i i ~ ' 1 m i nam II 11—III lain 111 OFL71 i l a II i — — M T r - i 1 1 1 r -z. Q if) UJ cr SP-j SM- WT- - i — r 1 1 1 1 r — i OFL58 llll I I I I III I 1—HHI -I 1 1 1 r SPi SM- WT Mil I II I I I — H - t — H -I 1 1 1 1 1— 1 ' f 011II W" I OFL62 Mn i II i — i in i wu I I I mm- - i 1 r ~i 1 1 1 1 1 1 — i 1 1 i A M J J A S O N D J F M A M J J A S 1975 1976 96 migration was the movement from summer to winter home ranges. The d i s t a n c e s moved i n the winter migration were u s u a l l y s l i g h t l y s h o r t e r than those moved d u r i n g the summer migr a t i o n . One deer, OFL60, e x h i b i t e d a f o u r t h m i g r a t i o n . T h i s deer had a winter home range along the s i d e h i l l i n the Croman s e c t o r near i t s s p r i n g home range ( F i g . 13). OFL60 occupied t h i s home range f o r the f i r s t p a r t of the winter and then moved i n mid- January t o her a u x i l i a r y winter range on the s i d e h i l l at the mouth of Croman V a l l e y . She remained there approximately two weeks u n t i l a very m i l d s p e l l i n the weather with consequent snowmelt, and then returned to her e a r l y winter home range . When snow began t o accumulate again i n e a r l y February on the e a r l y winter home range , she retu r n e d t o her a u x i l i a r y winter range and remained there u n t i l the s p r i n g m i g r a t i o n . Another deer, 0FL71, may a l s o have a mid-winter m i g r a t i o n s i m i l a r t o OFL60's. The extreme l o c a t i o n s i n c l u d e d i n the summer home range of 0FL71 ( F i g . 14) were mainly observed d u r i n g the f i r s t p a r t of winter before 0FL71 moved t o her winter home range i n the Hoomak s e c t o r . I n s u f f i c i e n t l o c a t i o n s were taken d u r i n g t h i s movement t o i d e n t i f y an a u x i l i a r y winter home range . The movement of a deer between two of i t s s e a s o n a l home ranges may occur more than once d u r i n g a p a r t i c u l a r migratory p e r i o d . In s e v e r a l deer, movement between se a s o n a l home ranges was c h a r a c t e r i z e d by s h o r t d u r a t i o n v i s i t s before permanent occupancy of the new seasonal home range occurred ( F i g . 18). For example, 0FL61 was l o c a t e d on h i s s p r i n g home range on June 21, 1976. On June 23 he was l o c a t e d on h i s summer home range Twelve hours l a t e r , he was back on h i s s p r i n g home range where 97 he remained u n t i l a t l e a s t June 27. L a t e r on June 29 r OFL61 was r e l o c a t e d on h i s summer home range d u r i n g the day , hut by t h a t n i g h t he had moved to h i s s p r i n g home range and was l o c a t e d there d a i l y u n t i l J u l y 4. Then on J u l y 6 he returned to h i s summer range and remained there through t o November. Short d u r a t i o n v i s i t s p r i o r t o permanent s e a s o n a l occupancy were a l s o observed d u r i n g the winter m i g r a t i o n . In 0FL61 and OFL68, these movements corresponded with s n o w f a l l s at the e l e v a t i o n s of t h e i r summer home ranges ( F i g . 19). although the lower l i m i t of snow d e p o s i t i o n d u r i n g i n i t i a l v i s i t s was w e l l above the winter home ranges, deer moved below the snow l i n e to t h e i r winter home ranges. Some movements between summer and winter home ranges occurred i n l e s s than 12 hours. The d i s t a n c e s t r a v e l l e d were about 3.6 km by 0FL61 and 4.3 km by OFL68. Even though these deer were sometimes monitored every 12 hours few l o c a t i o n s were obtained between t h e i r summer and winter home ranges. T h i s l a c k of l o c a t i o n s along the migratory routes suggests t h a t migration was performed i n l e s s than 12 hours and was a d i r e c t movement between se a s o n a l ranges. Comparison of the winter m i g r a t i o n s of 0FL61 and OFL68 mer i t s f u r t h e r c o n s i d e r a t i o n s i n c e s u b s t a n t i a l b l o c k s of f o r e s t are reserved f o r migration c o r r i d o r s . 0FL61 i n h a b i t e d an area t h a t was v i r t u a l l y unlogged, while OFL68 i n h a b i t e d an area t h a t was e x t e n s i v e l y logged and d i d not have a d i r e c t f o r e s t e d connection to low e l e v a t i o n s . Cutover areas along the d i r e c t route between the summer and winter home ranges of OFL68 were between f i v e and s i x years o l d and vegetated mainly by E£ilobium a n q u s t i f o l i u m . OFL68 was l o c a t e d only once o u t s i d e of i t s 98 F i g u r e 19. Movements between summer and winter home ranges, by migratory deer, 0FL68 and 0FL61, showing the correspondence" of t h e i r winter m i g r a t i o n s t o s n o w f a l l s on t h e i r summer home ranges. The summer home range of OFL68 was c l o s e to the 9:15 m snow-depth s t a t i o n , while the summer home range of 0FL61-:was c l o s e to the 1098 m snow-depth s t a t i o n . 9 9 0 i 1 i 1 i 1 i * i * i * i 1 i 1 i 1 i 1 i 1 i 1 i 1 I 1 I 1 I 16 18 20 22 24 26 28 30 1 3 5 7 9 11 13 15 N O V O C T 100 summer o r winter home ranges. Since t h i s l o c a t i o n was i n the cutover about h a l f way along the d i r e c t route between these home ranges, i t appears t h a t she moved through the cu t o v e r i n order to reach her wint e r home range . No snow was on the ground i n the cutover where she was l o c a t e d , although the summer home range was covered by about 15 cm.of snow. Comparison o f the migratory p a t t e r n s of OFL68 and OFL61 ( F i g . 19) suggest t h a t these deer behaved s i m i l a r l y even though one deer i n h a b i t e d an e x t e n s i v e l y logged area while the other deer i n h a b i t e d an almost completely f o r e s t e d area. The date of permanent seasonal occupancy of s p r i n g home ranges by migratory deer r e f l e c t the s e v e r i t y of the l o c a l c l i m a t e s on the s p r i n g home ranges. OFL71 occupied i t s s p r i n g home range a t the beginning of March. There, the l o c a l c l i m a t e i n the v a l l e y bottom of the Hoomak s e c t o r i s mil d e r than other p o r t i o n s o f the study area. Less snow f e l l i n the Hoomak s e c t o r d u r i n g winter, and shrubs budded and f l u s h e d e a r l i e r than they d i d i n other s e c t o r s . OFL67 was the next r a d i o - t a g g e d deer t o occupy i t s s p r i n g home range. T h i s s l i g h t l y l a t e r s p r i n g migration r e f l e c t e d the longer p e r s i s t i n g snowpack s i n c e the c l i m a t e i n the Davie K i v e r v a l l e y bottom i s more severe than i n the Hoomak s e c t o r but milder than i n the Croman s e c t o r . OFL60, whose s p r i n g home range i s about h a l f way up Croman V a l l e y , occupied i t s s p r i n g home range by m i d - A p r i l , l a t e r than d i d OFL67. 0FL61 occupied i t s s p r i n g home range i n mid-May. The c l i m a t e i n Croman V a l l e y was c o l d e r and snow p e r s i s t e d l o n g e r i n the northern p o r t i o n of the v a l l e y than i n the southern p o r t i o n . The l a t e occupancy of the s p r i n g home range by 0FL61 was 101 c o n s i s t e n t with t h i s v a r i a t i o n i n l o c a l c l i m a t e . D i f f e r e n c e s i n the date of summer home range occupancy were s i m i l a r t o although not as great as those observed f o r the occupancy of s p r i n g home ranges. The occupancy of the winter home ranges r e f l e c t e d the occurrence and s e v e r i t y of the f i r s t s n o w f a l l s . In high e l e v a t i o n s where snow occurred e a r l i e r than at low e l e v a t i o n s ( F i g . 2), deer moved t o t h e i r winter home ranges e a r l i e r than deer with summer home ranges at middle and low e l e v a t i o n s ( F i g s . 10 to 13 and 18). The time d i f f e r e n c e s i n v o l v e d were much s h o r t e r than those observed f o r the occupancy of the s p r i n g and summer home ranges. These s h o r t e r d i f f e r e n c e s are l i k e l y due to the abrupt nature of s n o w f a l l s compared to the lo n g e r p e r i o d s i n v o l v e d i n snowmelt and the g r a d u a l uncovering and p h e n o l o g i c a l development of for a g e p l a n t s during s p r i n g and e a r l y summer. 3.4.5. T o p o g r a p h i c a l Features Of Seasonal Home Ranges The two p a t t e r n s of sea s o n a l movements d e s c r i b e d i n S e c t i o n 3.4.3 were those of migrati o n and of minor s e a s o n a l s h i f t s i n c e n t r e s of a c t i v i t y . These p a t t e r n s were d e f i n e d by the degree of d i f f e r e n c e between c e n t r e s of a c t i v i t y (Table VI) and the degree of o v e r l a p of the home range boundaries ( F i g s . 10 to 16). For migratory deer, two types of seasonal movements were evident, a l t i t u d i n a l migrators and h o r i z o n t a l migrators. These types were i d e n t i f i e d by the magnitude of changes i n e l e v a t i o n made durin g m i g r a t i o n (Table V I I ) . For the thr e e a l t i t u d i n a l migrators with s p r i n g l o c a t i o n s , s p r i n g home ranges were lower i n e l e v a t i o n than e i t h e r t h e i r summer or winter home ranges. 1 0 2 Table VII. E l e v a t i o n s at the a r i t h m e t i c mean c e n t r e s of home ranges showing a l t i t u d i n a l (0FL61, OFL68, OFL67, OFL60) and h o r i z o n t a l (OFL71) migratory p a t t e r n s . Although r e s i d e n t deer can make a l t i t u d i n a l changes i n t h e i r home range c e n t r e s t h e i r home ranges o v e r l a p and so are not a l t i t u d i n a l m i grators. E l e v a t i o n ( m ) s p r i n g summer winter 0FL61 30k 1094 4o8 OFL68 - 878 437 OFL67 358 686 488 OFL60 480 725 • II _ winter range 559 11 a u x i l i a r y winter range 670 0 F L 7 1 * 282 286 276 OFL58 570 555 681 OFL62 288 431 628 * horizontal migrator Change In E l e v a t i o n ( m ) s p r i n g to summer to winter to summer winter s p r i n g +790 +328 +245 +4 -15 +143 - 6 8 6 -441 - 1 9 8 -166 -55 - 1 0 +126 +197 - 1 0 4 - 1 3 0 - 7 9 - 1 9 0 +6 -111 - 3 4 0 1 0 4 Summer home ranges of the a l t i t u d i n a l migrators were higher i n e l e v a t i o n than both t h e i r winter and s p r i n g home ranges (Table V I I ) . In OFL60, the l a t e winter home range was only 55 m lower i n e l e v a t i o n than the summer home range. However, the cl i m a t e and v e g e t a t i o n of these home ranges were d i f f e r e n t s i n c e the l a t e winter home range of OFL60 was on a southern aspect while her summer home range was on a northern aspect. The c e n t r e s of winter home ranges o f a l l a l t i t u d i n a l migrators were on v a l l e y s i d e s at low e l e v a t i o n s . The g e n e r a l p a t t e r n of a l t i t u d i n a l migrators i s t h a t they summer at high e l e v a t i o n s and move down to winter on s i d e h i l l s l o p e s adjacent to the v a l l e y f l o o r . Some deer then move down f u r t h e r t o spend s p r i n g on the v a l l e y f l o o r , while other deer stay on the v a l l e y s i d e s f o r s p r i n g . T h i s p a t t e r n corresponded t o the a l t i t u d i n a l p a t t e r n of snow depth and d u r a t i o n of snow cover ( F i g . 2). Summer ranges were at e l e v a t i o n s where there was deep snow and continuous snow cover over winter, while winter ranges were at e l e v a t i o n s where there was shallow snow and i n t e r m i t t e n t snow cover. Spring home ranges were areas where snow was deeper and snow cover l o n g e r l a s t i n g than on winter ranges but of shallower depth and s h o r t e r d u r a t i o n than on summer ranges. E l e v a t i o n s at the c e n t r e s o f the seasonal home ranges of h o r i z o n t a l migrator 0FL71, were a l l w i t h i n 10 m of one another. Although OFL71 d i d not make an e l e v a t i o n a l change d u r i n g m i g r a t i o n , she d i d accomplish a change i n l o c a l c l i m a t e by moving from Croman V a l l e y , where temperatures are c o l d e r and the snow deeper and more p e r s i s t e n t , t o the Hoomak s e c t o r where the cl i m a t e was milder. 105 The r e s i d e n t deer, OFL58 and OFL62, d i d not e x h i b i t the pa t t e r n s of changes i n e l e v a t i o n and home range s e p a r a t i o n c h a r a c t e r i s t i c of a l t i t u d i n a l m i g r a t o r s . Although based on only three l o c a t i o n s the s p r i n g home range of 0FL58 was c l o s e to the e l e v a t i o n of her summer home range . The winter home range of OFL58 was higher i n e l e v a t i o n than her summer home range . OFL62 e x h i b i t e d a d i f f e r e n t p a t t e r n . His s p r i n g home range was l o c a t e d i n the v a l l e y bottom at an e l e v a t i o n o f 288 m. Although some of t h i s v a l l e y bottom area used d u r i n g the s p r i n g , was a l s o i n c l u d e d i n the summer home range , the c e n t r e of the summer home range was on the lower s i d e h i l l , 143 m higher than the s p r i n g home range c e n t r e . The winter home range of OFL62 was centred h i g h e r on the s i d e h i l l than h i s summer home range . The r e s i d e n t deer d i f f e r e d from the a l t i t u d i n a l migratory deer i n t h a t the c e n t r e s of t h e i r winter home ranges were higher i n e l e v a t i o n than the c e n t r e s of t h e i r summer home ranges. T h i s p a t t e r n may occur because c u t o v e r areas i n low e l e v a t i o n s provide f o r a g i n g h a b i t a t f o r deer during summer ( F i g . 5 ) . I f more r e s i d e n t deer were tagged I would expect some of them to s h i f t t h e i r home range c e n t r e s l a t e r a l l y and others downwards between summer and winter. Slopes on the s p r i n g and summer home ranges of most deer were not as steep as those on t h e i r winter home ranges (Table V I I I ) . E x c e p t i o n s were the s p r i n g home ranges of OFL58 and OFL60 and the summer home ranges of OFL58 and OFL62 which were on steep s i d e h i l l s , and the winter home range of 0FL71 which was gently s l o p e d . No c l e a r trends i n the aspects of sea s o n a l home ranges were evident (Table V I I I ) . A l l as p e c t s were represented 106 Table V I I I . Slope and aspect near the a r i t h m e t i c mean c e n t r e s of home ranges. No c o n s i s t e n t trends are ev i d e n t . Slope (degrees) spring summer winter 0FL61 ^ 1 9 24 OFL68 8 2 2 OFL67 3 7 2 9 OFL60 2 3 6 - " winter range 1 5 " auxiliary winter range 24 0 F L 7 1 * 10 £ 1 10 0 F L 5 8 2 3 14 11 0 F L 6 2 4 34 33 * horizontal migrator spring Aspect summer winter N-NW SW-N S-SE S-SE N-NE W-S-E NW-NE NW W-SE W W-S-E W-SE NW-W SW-W SW-SE NW-W mm E S-E NW SW-SE NW-W 108 i n s p r i n g and summer home.ranges. In winter, home ranges were l o c a t e d on asp e c t s v a r y i n g s o u t h e r l y between northwest and southeast. Seasonal movements of radio-tagged deer are summarized i n Fi g u r e 20. In g e n e r a l , a l t i t u d i n a l migrators moved downward at the beginning of winter and occupy winter home ranges below 650 m i n e l e v a t i o n . T h e i r s p r i n g ranges were u s u a l l y i n v a l l e y bottoms ad j a c e n t to t h e i r winter home ranges. In summer, these deer moved t o high e l e v a t i o n s . Resident deer i n h a b i t e d low e l e v a t i o n s throughout the year and made r e l a t i v e l y small s h i f t s i n t h e i r home ranges between seasons. Where l o c a l c l i m a t e changed s u b s t a n t i a l l y over a h o r i z o n t a l d i s t a n c e , such as between the narrow t r i b u t a r y v a l l e y and the wide main v a l l e y , deer made h o r i z o n t a l migrations and a t t a i n e d d i f f e r e n c e s i n l o c a l c l i m a t e s i m i l a r to those experienced by a l t i t u d i n a l m i g r a t o r s . 3.5. I n d i r e c t Measures Of Seasonal Movements The movements made by the radio-tagged deer were co r r o b o r a t e d by i n d i r e c t measures of movements made by the deer p o p u l a t i o n . These measures were employed t o eva l u a t e i f i n d i v i d u a l movements were b r o a d l y based and r e p r e s e n t a t i v e of the deer p o p u l a t i o n . Deer t r a c k s were observed along Mount Cain road from February to J u l y i n 1975 and from October 1975 t o May 1976. The data were combined and the e l e v a t i o n of the h i g h e s t deer t r a c k on Mount Cain road during winter and s p r i n g i s shown i n F i g u r e 21. The e l e v a t i o n o f the h i g h e s t deer t r a c k decreased from 1200 1 0 9 F i g u r e 2 0 . Seasonal Movement p a t t e r n s of deer i n the.study a r e a . A r i t h m e t i c mean centres of s e a s o n a l home ranges are j o i n e d f o r = s p r i n g , ( s ) = summer, (*T) = winter, (A ) = a u x i l i a r y each deer. r i n t e r . Cutover areas a r e s t i p p l e d . 110 111 F i g u r e . 21. E l e v a t i o n of highest deer t r a c k observed along Mount Cain road. U J 1200H p 800 > U J 4 0 0 H 0 winter spring summer O O O 1975 # % 1975-1976 0 N D J F M A M J J T I M E ( M O N T H S ' ) ro 113 m i n e a r l y October to 700 m i n November. T h i s decrease i n e l e v a t i o n of deer t r a c k s c o i n c i d e d with the descending snow l i n e and i n c r e a s i n g snow depths i n high e l e v a t i o n s ( F i g . 2 ). During winter, deer i n h a b i t e d low e l e v a t i o n s i n the study area ( F i g . 20 and Table V I I ) . In s p r i n g , the h i g h e s t occurrences of deer t r a c k s were higher i n e l e v a t i o n than those observed i n wi n t e r . The e l e v a t i o n o f the highest deer t r a c k i n c r e a s e d throughout s p r i n g and on i n t o summer. Night counts conducted i n the Mount Cain s e c t o r showed t h a t the dates of f i r s t s i g h t i n g s o f deer i n c r e a s e d with i n c r e a s i n g e l e v a t i o n as s p r i n g progressed ( F i g . 22) and were c o n s i s t e n t with t r a c k counts ( F i g . 21). The f i r s t appearances of deer i n n i g h t counts at middle and hi g h e l e v a t i o n s o c c u r r e d soon a f t e r snow cover was reduced t o about 50% i n the c u t o v e r areas. The f i r s t o b s e r v a t i o n s of t r a c k s ( F i g . 21) and s i g h t i n g s o f deer (F i g . 22) i n the higher t r a n s e c t s may be caused by deer making temporary v i s i t s to high e l e v a t i o n s s i m i l a r t o the s p r i n g migratory behaviour e x h i b i t e d by 0FL61 (Section 3.4.4). Although t r a c k counts ( F i g . 21) i n d i c a t e when the f i r s t deer moved i n t o high e l e v a t i o n s a f t e r w i n t e r i n g i n low e l e v a t i o n s , they do not i n d i c a t e when the major i t y of deer moved. Night counts showed when the majority of deer make a l t i t u d i n a l movements. Since deep snow prevented v e h i c u l a r t r a v e l , night counts i n d i c a t e r e l a t i v e abundance of deer w i t h i n t r a n s e c t s d u r i n g p e r i o d s with shallow or no snow. The magnitude of the number of deer km - 1 cannot be compared between a l l t r a n s e c t s s i n c e v i s i b i l i t y , and thus the area censused, d i f f e r e d between t r a n s e c t s . However, w i t h i n a t r a n s e c t , the number of 114 Figure 22. Mean number of deer and 95% conf i d e n c e l i m i t s ( v e r t i c a l bars) counted at n i g h t along road t r a n s e c t s i n the Mount Cain s e c t o r . The number of t r a n s e c t s counted are given above the 95% confidence l i m i t s . Transect 22-B was adjacent t o the low e l e v a t i o n s i d e h i l l f o r e s t t h a t was used i n t e n s i v e l y by deer during winter. Transect A was f u r t h e r from the f o r e s t e d winter range than B and s i t u a t e d i n the v a l l e y bottom next to Davie R i v e r . E l e v a t i o n s are i n d i c a t e d and i n c r e a s e from A t o E. T r a n s e c t s A and B were through c o n i f e r s e r a i stages, while C, D, and E were through herb s e r a i stages. Data f o r 1975 and 1976 are combined. winter spring summer winter 116 deer km - 1 g i v e s a r e l a t i v e index of p o p u l a t i o n d e n s i t y . Seasonal trends between t r a n s e c t s show the movement p a t t e r n s of the deer p o p u l a t i o n . The a l t i t u d i n a l p a t t e r n of deer use i n logged areas at n i g h t ( F i g . 22) was c o n s i s t e n t with movements of radio-tagged deer and p a t t e r n of snow accumulation and melt ( F i g . 2). At low e l e v a t i o n s , deer d e n s i t i e s were g r e a t e s t i n s p r i n g but decreased by e a r l y summer. T h i s i n t e n s e use of low e l e v a t i o n logged areas i n s p r i n g was a l s o e v i d e n t from the l o c a t i o n s of r a d i o - t a g g e d deer (see s e c t i o n 3.6). The decrease i n deer use a t lower e l e v a t i o n s by e a r l y summer corresponds t o m i g r a t i o n s of r a d i o - tagged deer ( F i g . 18) and i n c r e a s e d deer use of f o r e s t e d areas (Section 3.6). Some deer i n h a b i t e d low e l e v a t i o n s throughout the year ( F i g . 22) and are represented by the r a d i o - c o l l a r e d r e s i d e n t deer OFL62 and OFL58 ( F i g s . 15 and 16) . The date of f i r s t deer use i n an area was p r o g r e s s i v e l y l a t e r as e l e v a t i o n i n c r e a s e d ( F i g . 21 and 22). F i r s t deer use i n h i g h e l e v a t i o n s was probably not a r e s u l t of deer t h a t had made t h e i r f i n a l s p r i n g migration but, r a t h e r , a r e s u l t of s h o r t d u r a t i o n v i s i t s by deer to t h e i r summer home ranges ( F i g . 20). The peak i n i n t e n s i t y of deer use a l s o was p r o g r e s s i v e l y l a t e r with i n c r e a s i n g e l e v a t i o n ( F i g . 22). T h i s peak r e p r e s e n t s deer moving from t h e i r s p r i n g home ranges d i r e c t l y t o t h e i r summer home ranges. I n d i v i d u a l deer m6ved d i r e c t l y from t h e i r s p r i n g to summer home ranges. Complete, one-step m i g r a t i o n was e x h i b i t e d by 0FL61, 0FL67, OFL60, and OFL71 ( F i g s . 10 and 12 to 14). At the beginning of winter, deer use decreased i n the high e l e v a t i o n t r a n s e c t s 22-D and 22-E ( F i g . 22). T h i s decrease 117 c o i n c i d e d with the f i r s t s n o w f a l l s . As deer use at high e l e v a t i o n s decreased, deer use i n c r e a s e d at low e l e v a t i o n s ( t r a n s e c t s 22-A and 22-C), i n d i c a t i n g a downward movement by some deer. T h i s downward movement was c o n s i s t e n t with the documented movements of 0FL61, OFL68, and OFL67. The i n c r e a s e of deer numbers a t low e l e v a t i o n s was s m a l l . The reason f o r t h i s s m a l l i n c r e a s e i n numbers was t h a t deer use of f o r e s t s was g r e a t e r d u r i n g winter than i n the other seasons (see s e c t i o n 3.6) and d i f f e r e n c e s between t r a n s e c t s i n v i s i b i l i t y (lower cutovers were e l d e r and had t a l l e r and denser v e g e t a t i o n than the h i g h e r c u t o v e r s ) . In the Croman (1) s e c t o r ( F i g . 1), s e a s o n a l changes i n d i s p e r s i o n of the deer p o p u l a t i o n a l s o occurred ( F i g . 23). S h i f t s i n the p o p u l a t i o n o c c u r r e d over a narrower e l e v a t i o n i n t e r v a l than was observed i n the Mount Cain (2) s e c t o r ( F i g . 22). T r a n s e c t s i n F i g u r e 23 were arranged i n order of d i s t a n c e from the mouth of Croman V a l l e y beginning with t r a n s e c t 23-A adjacent to a f o r e s t e d winter range. Deer use i n Croman V a l l e y was g r e a t e s t d u r i n g e a r l y s p r i n g near the v a l l e y mouth. As s p r i n g progressed, deer moved f u r t h e r up the v a l l e y . Near the beginning of winter, deer use decreased i n upper p o r t i o n s of the v a l l e y while i t i n c r e a s e d near the mouth. The movements of OFL60 and 0FL71 were c o n s i s t e n t with movements of deer along Croman V a l l e y observed through the n i g h t counts. 0FL61 d i d not move h o r i z o n t a l l y along Croman V a l l e y but stayed on the s i d e h i l l f o r the winter ( F i g . 10). Most of the deer p o p u l a t i o n migrated h o r i z o n t a l l y i n Croman V a l l e y , south towards Davie R i v e r . These s h i f t s i n the deer p o p u l a t i o n 118 Figure 23. Mean number of deer and 95% confidence l i m i t s ( v e r t i c a l bars) counted at ni g h t along road t r a n s e c t s i n the Croman S e c t o r . The number of t r a n s e c t s counted are: given above the 95% con f i d e n c e l i m i t s . D i s t a n c e from the_ v a l l e y mouth i n c r e a s e s from A to D. E l e v a t i o n s are i n d i c a t e d . A l l t r a n s e c t s were through herb s e r a i stages. Data f o r 1975 and 1976 are combined. winter spring LL) LU Q winter 580 m D 3 290m A J F M A M J J A S O N D T I M E ( M O N T H S ) 120 corresponded t o p a t t e r n s of snow melt i n s p r i n g and s n o w f a l l and snowpack accumulation i n winter. 3.6. Seasonal Use Of H a b i t a t s Use Of Unlogged And Logged H a b i t a t s Day and n i g h t l o c a t i o n s of ra d i o ^ t a g g e d deer were c l a s s i f i e d as being i n e i t h e r f o r e s t e d or c u t o v e r areas (up to 27 years of age) durin g the th r e e seasons and i n d i c a t e d the r e l a t i v e use made o f these h a b i t a t s by deer throughout the year. The percent use of h a b i t a t s was averaged f o r each s e a s o n a l movement p a t t e r n ( F i g . 24). Resident deer i n c r e a s e d t h e i r use of f o r e s t d u r i n g both day and n i g h t between s p r i n g and winter. The op p o s i t e t r e n d o c c u r r e d i n use of c u t o v e r s . Within each season, use of f o r e s t was g r e a t e r d u r i n g day than at n i g h t , while use of cutovers was g r e a t e r a t n i g h t than i t was durin g the day. Comparison o f the two ty p e s of migratory deer to the r e s i d e n t deer show some s i m i l a r i t i e s i n use of f o r e s t e d and cutover h a b i t a t s . F o r e s t s were used more durin g day than a t n i g h t , while c u t o v e r s were used more at n i g h t than dur i n g day ( F i g . 24 and Tab l e I X ) . Daytime and nighttime use of f o r e s t e d h a b i t a t s d u r i n g summer by migratory deer was g r e a t e r than t h a t by r e s i d e n t deer (Table IX) . When a l l radio-tagged deer were considered together, use of f o r e s t s was g r e a t e r d u r i n g the day than at n i g h t , while c u t o v e r s were used more f r e q u e n t l y a t n i g h t . Daytime use of f o r e s t s was lowest i n s p r i n g and almost doubled i n summer. Use of f o r e s t s d u r i n g winter decreased s l i g h t l y from t h a t d u r i n g summer. In 121 F i g u r e 24. Percent use of f o r e s t e d and cut o v e r h a b i t a t s d u r i n g each season (SP = s p r i n g , SM = summer, WT = w i n t e r ) . Unshaded histograms are daytime use, shaded histograms are nighttime use. Number of deer from which the percent use of f o r e s t e d and cutover h a b i t a t s i n each season was c a l c u l a t e d are i n d i c a t e d above the histograms f o r f o r e s t e d h a b i t a t s . P E R C E N T 123 Table IX. Comparison of use of f o r e s t e d and cut o v e r h a b i t a t s by migratory and r e s i d e n t deer during summer. Migratory deer were i n f o r e s t e d h a b i t a t s more f r e q u e n t l y than were r e s i d e n t deer. Daytime n forested cutover % i n forest migratory 1 8 1 1 6 2 1 9 8 9 . 5 resident 5 8 kO 1 8 6 9 . 0 X2= 1 2 . 6 , p £ . 0 5 n Night time % i n forested cutover forest 8 1 2 6 5 5 3 2 . 1 1 7 2 1 5 1 1 . 8 Fisher's Exact Probability Test p= . 0 5 9 125 cuto v e r s , daytime use was g r e a t e s t during s p r i n g , lowest i n summer, and i n c r e a s e d again i n winter, but not to the i n t e n s i t y observed i n s p r i n g . At n i g h t , use of f o r e s t s i n c r e a s e d from s p r i n g through summer to winter, while use of c u t o v e r s showed a comparable decrease. Use Of Fo r e s t e d P l a n t A s s o c i a t i o n s And S e r a i Stages L o c a t i o n s of radio-tagged deer were combined and a frequency of use c a l c u l a t e d f o r each f o r e s t e d p l a n t a s s o c i a t i o n and s e r a i stage ( F i g . 25). I n d i v i d u a l v a r i a t i o n i n the use of these h a b i t a t s i s d i s c u s s e d where a p p r o p r i a t e . Daytime and nighttime l o c a t i o n s were co n s i d e r e d s e p a r a t e l y . Caution must be used i n i n t e r p r e t i n g these frequency d i s t r i b u t i o n s i n terms of h a b i t a t s e l e c t i o n and pr e f e r e n c e . Since the p r o p o r t i o n o f the study area covered by each p l a n t a s s o c i a t i o n or s e r a i stage i s not known, h a b i t a t p r e f e r e n c e s cannot be c a l c u l a t e d . Some i n s i g h t i n t o p r e f e r e n c e can be obtained through comparison of deer use with c u r s o r y estimates of the extent of each h a b i t a t type. Regardless of h a i i t a t p r e f e r e n c e s , the l o c a t i o n s of deer do i n d i c a t e the v a r i o u s h a b i t a t s used during d i f f e r e n t seasons. Spring In s p r i n g , a l l deer use durin g both day and ni g h t was i n f o r e s t e d plant a s s o c i a t i o n s o r s e r a i stages i n the C o a s t a l Western Hemlock Zone. The Vaccinium-Skunk Cabbage a s s o c i a t i o n was the most f r e q u e n t l y used f o r e s t e d h a b i t a t d u r i n g daytime. The A m a b i l i s F i r - W e s t e r n Hemlock and Salal-Western Hemlock a s s o c i a t i o n s were the next most i n t e n s i v e l y used f o r e s t e d 126 F i g u r e 25. Percent use of f o r e s t e d p l a n t a s s o c i a t i o n s and s e r a i stages by r a d i o-tagged deer duri n g each season. Unshaded histograms are daytime use, shaded l o c a t i o n s are nighttime uŝ e-. u i Number of deer from which the percent use of f o r e s t e d and c utover h a b i t a t s i n each season was c a l c u l a t e d are i n d i c a t e d above the histograms f o r f o r e s t e d h a b i t a t s . Forested p l a n t a s s o c i a t i o n s : VS = Vaceinium - Skunk Cabbage, SC = Sword Fern - Western Red Cedar, DW = Deer Fern - Western Hemlock, WP = Western Hemlock - Plagiothecium, AW = A m a b i l i s F i r - Western Hemlock, SD = S a l a l - D o u g l a s - f i r , SW = S a l a l - Western Hemlock, ftT = Amabilis F i r - Twisted S t a l k , MC = Mountain Hemlock - Copperbush . Immature S e r a i Stages : N = Newly Logged, H = Herb, F = Fern, S = Shrub, C = C o n i f e r . 127 LU O t r LU CL 40' summer day n = 7 night n = 6 • L L i J n — 40H 20 winter day n >= 7 night n = 7 Q L .1 , rjll VS SC DWWP AW SD SW AT MC N H Coastal Western Hemlock Zone Mountain Hemlock Zone Sera! Stages 128 h a b i t a t s . Deer Fern-Western Hemlock and Western Hemlock- Plagiothecium a s s o c i a t i o n s had only minor use, each a c c o u n t i n g f o r l e s s than 6% of the daytime use. There was no daytime use of S a l a l - D o u g l a s - f i r or Sword Fern-Western Red Cedar a s s o c i a t i o n s nor of any a s s o c i a t i o n s i n the su b a l p i n e Mountain Hemlock Zone. Use of f o r e s t e d p l a n t a s s o c i a t i o n s was g e n e r a l l y l e s s at nig h t than during the day. However, the p a t t e r n of use was s i m i l a r i n t h a t the Vaccinium-Skunk Cabbage a s s o c i a t i o n was used the most i n t e n s i v e l y while secondary use was made of the Amabilis F i r - W e s t e r n Hemlock and Salal-Western Hemlock a s s o c i a t i o n s . In c u t o v e r s , the g r e a t e s t daytime use was i n herb and c o n i f e r s e r a i s t a g e s , while l e s s than 5% of the deer use was i n the shrub s e r a i stage. Use of s e r a i stages was g r e a t e r at n i g h t than dur i n g the day. The herb s e r a i stage was the most i n t e n s i v e l y used h a b i t a t at n i g h t . The c o n i f e r s e r a i stage was the second most commonly used cutover h a b i t a t , while the shrub s e r a i stage was the t h i r d . No use was made of f e r n or newly logged s e r a i stages by radio-tagged deer during s p r i n g . Summer In summer, daytime use of the Vaccinium-Skunk Cabbage a s s o c i a t i o n was again g r e a t e r than the use of other f o r e s t e d p l a n t a s s o c i a t i o n s i n the C o a s t a l Western Hemlock Zone ( F i g . 25). T h i s high use of the Vaccinium-Skunk Cabbage a s s o c i a t i o n was mainly due t o h o r i z o n t a l migrator 0FL71 ( F i g . 26). However, r e s i d e n t deer OFL62 a l s o used t h i s a s s o c i a t i o n . In summer, use was s t i l l made of Ama b i l i s F ir-Western Hemlock, Western Hemlock- 129 F i g u r e 26. Percent use of f o r e s t e d p l a n t a s s o c i a t i o n s and s e r a i stages d u r i n g summer by a l t i t u d i n a l and h o r i z o n t a l m i g r a t o r s , and r e s i d e n t s . Unshaded histograms are daytime use, shaded histograms are nig h t t i m e use. Number of deer from which the percent use of f o r e s t e d and cut o v e r h a b i t a t s i n each season was c a l c u l a t e d are i n d i c a t e d above the histograms f o r f o r e s t e d h a b i t a t s . F o r e s t e d p l a n t a s s o c i a t i o n s : VS = Vaccinium - Skunk Cabbage, SC = Sword Fern - Western Bed Cedar, DW = Deer Fern - Western Hemlock, WP = Western Hemlock - Plagiothecium, AW = Am a b i l i s F i r - Western Hemlock, SD = S a l a l - D o u g l a s - f i r , SW = S a l a l - Western Hemlock, AT = Amabilis F i r - Twisted S t a l k , MC = Mountain Hemlock - Copperbush . Immature S e r a i Stages : N = Newly Logged, H = Herb, F = Fern, S = Shrub, C = C o n i f e r . altitudinal day n = 4 night n = 3 1 3 0 40- 20- T 1 1 r - , — q - 1 604 r- LU 40 O t r LU 20H 0- horizontal day n * 1 night n = 1 -1—q— L f* 60H 40-̂ 20H resident day n = 2 night n = 2 T r 1 4- VS SC DWWP AW SD SW Coastal Western Hemlock Zone AT MC Mountain Hemlock Zone N H F S C Serai Stages 131 P l a g i o t h e c i u m , and Salal-Western Hemlock a s s o c i a t i o n s . Most daytime use of these a s s o c i a t i o n s r e s u l t e d from the r e s i d e n t deer ( F i g . 26). Two plant a s s o c i a t i o n s used i n summer, but not i n s p r i n g , were the Amabilis F i r - T w i s t e d S t a l k and Mountain Hemlock-Copperbush a s s o c i a t i o n s ( F i g . 25) . Use of these a s s o c i a t i o n s i n the subalpine Mountain Hemlock Zone was mainly due t o a l t i t u d i n a l migrators ( F i g . 26) . Nighttime use of f o r e s t e d p l a n t a s s o c i a t i o n s i n summer was s i m i l a r t o t h a t i n s p r i n g . Use of f o r e s t e d p l a n t a s s o c i a t i o n s was g e n e r a l l y l e s s at n i g h t than during day and the same a s s o c i a t i o n s were used duri n g both p e r i o d s . S e r a i stages were used i n d i f f e r e n t i n t e n s i t i e s i n summer than i n s p r i n g ( F i g . 25). The c o n i f e r s e r a i stage, i n which almost 40% of the daytime use i n s p r i n g occurred, had l e s s than 5% of the daytime use i n summer. Some of t h i s drop i n use o f the c o n i f e r s e r a i stage was a r e s u l t of the l a c k of o l d s e r a i stages at high e l e v a t i o n s . Thus, the a l t i t u d i n a l migrators di d not have access to t h i s s e r a i stage i n summer. However, the decrease i n use of the c o n i f e r s e r a i stage i s not wholly due t o movement of deer away from the c o n i f e r s e r a i stage. OFL62 i s a r e s i d e n t deer with access to the c o n i f e r s e r a i stage during s p r i n g and summer. Use of the c o n i f e r s e r a i stage by t h i s deer was high i n s p r i n g but much lower i n summer (Table X), suggesting other f a c t o r s are r e s p o n s i b l e f o r the r e d u c t i o n i n use of the c o n i f e r s e r a i stage. Daytime use of the herb s e r a i stage was l e s s i n summer than i n s p r i n g . Use of the f e r n s e r a i stage r e s u l t e d from only one deer, OFL71. Although the cutover c l a s s i f i e d as a f e r n s e r a i stage was used by 0FL71, she used the area near Croman Creek more 132 Table X. Daytime use of the conifer serai stage by resident deer OFL62, during spring and summer. X2=9.64, p<.05 Spring Summer Conifer Serai Stage 1 3 3 Other Habitats 1 6 3 3 Number of Locations 29 3 6 % in Conifer 8 , Serai Stage 134 i n t e n s i v e l y than the r e s t o f the c u t o v e r . T h i s stream bank area was g r e a t e r i n shrub and herb cover than were c e n t r a l p o r t i o n s of the cut o v e r . Trends i n nighttime use of s e r a i stages were s i m i l a r t o tr e n d s i n daytime use, although the i n t e n s i t y of use was much gre a t e r ( P i g . 2 5 ) . As i n daytime, n i g h t t i m e use of the f e r n s e r a i stage r e s u l t e d s o l e l y from 0FL71 (Fig. 2 6 ) . The c o n i f e r s e r a i stage was not used at n i g h t i n summer by radio-tagged deer. T h i s c o n t r a s t s markedly with the high use i t r e c e i v e d i n s p r i n g . Use of herb and f e r n s e r a i s t a g e s was high e r i n summer than s p r i n g , while use of the shrub s e r a i stage was lower. Winter In w i n t e r , daytime use was g r e a t e s t i n Am a b i l i s Fir-Western Hemlock and Salal-Western Hemlock a s s o c i a t i o n s ( F i g . 2 5 ) . Secondary use was made of S a l a l - D o u g l a s - f i r , Western Hemlock- Plagiothecium, and Sword Fern-Western Bed Cedar a s s o c i a t i o n s , but use of these h a b i t a t s was much l e s s than t h a t of the former two a s s o c i a t i o n s . Use of the Sword Fern-Western Red Cedar a s s o c i a t i o n was due t o 0FL71 when she migrated i n t o the v a l l e y bottom along the Davie R i v e r near Hoomak Lake ( F i g . 14). T h i s a s s o c i a t i o n was not an important type of h a b i t a t f o r deer i n the Croman and Mount Cain s e c t o r s o f the study area. The Vaccinium- Skunk Cabbage a s s o c i a t i o n was used only o c c a s i o n a l l y d u r i n g winter. T h i s low use c o n t r a s t s s h a r p l y with the high use i t r e c e i v e d d u r i n g s p r i n g and summer. The a s s o c i a t i o n s i n the sub a l p i n e Mountain Hemlock Zone were used i n c i d e n t a l l y d u r i n g winter i n c o n t r a s t t o the high use they r e c e i v e d during summer. 135 Although use of f o r e s t e d h a b i t a t s a t n i g h t was g e n e r a l l y l e s s than t h a t i n daytime, trends i n use of p l a n t a s s o c i a t i o n s at n i g h t were s i m i l a r to those i n the day. Daytime use of cutovers d u r i n g winter d i f f e r e d from t h a t i n summer by the higher use of shrub and c o n i f e r s e r a i s t a g es. Nighttime use of herb and f e r n s e r a i stages i n winter was l e s s than t h a t i n summer. The c o n i f e r s e r a i stage was used more at ni g h t i n winter than i n summer. Herb, shrub, and c o n i f e r s e r a i stages r e c e i v e d about the same amount of use i n wint e r and d i d not e x h i b i t the l a r g e d i f f e r e n c e s apparent during s p r i n g and summer. 136 4. D i s c u s s i o n 4.1. S i z e Of Home Eanges B l a c k - t a i l e d deer i n h a b i t i n g c o a s t a l f o r e s t environments i n B r i t i s h Columbia were found t o have three primary seasonal home ranges c o r r e s p o n d i n g t o the s p r i n g , summer, and winter, although summer and winter home ranges have been observed i n a non- migratory p o p u l a t i o n of b l a c k - t a i l e d deer (Dasmann and Taber 1956), the e x i s t e n c e of seasonal home ranges f o r migratory deer are not c o n s i s t e n t with e x i s t i n g concepts of migratory behaviour f o r b l a c k - t a i l e d deer t h a t were proposed by K l e i n (1965). Home ranges were l a r g e s t i n summer and the mean 100% home range s i z e was 165 ha , s i m i l a r t o the estimate p r e d i c t e d by Harestad and Bu n n e l l ( i n p r e s s ) . Home range s i z e i s r e l a t e d to the animal's energy requirements and h a b i t a t p r o d u c t i v i t y (McNab 1963, Schoener 1968, Harestad and Bun n e l l , i n p r e s s ) . The v a r i a b i l i t y i n home range s i z e i s l i k e l y a r e s u l t of d i f f e r e n c e s i n body s i z e and s p a t i a l d i f f e r e n c e s i n food abundance. Home ranges d u r i n g winter were s m a l l e r than they were i n summer. T h i s decrease of home range s i z e d u r i n g winter has been observed i n other North American c e r v i d s (Leopold e t aJL. 1951, Sparrow and Spr i n g e r 1970, Van Ballenberghe and Peek 1971, Alexander 1973, Craighead et a l . 1973, P h i l l i p s et a l . 1973). The decrease i s a t t r i b u t e d by Harestad and Bu n n e l l (in press) to the ruminant's lower apparent energy requirements (Nordon e t a l . 1970) and lower r a t e o f food p r o c e s s i n g d u r i n g winter because of reduced q u a l i t y o f t h e i r f o r a g e (Cameron et al.. 1975, Person et a l . . 1975),. 137 The s p r i n g home ranges of b l a c k - t a i l e d deer were s m a l l e r than both the summer and winter home ranges. Energy and p r o d u c t i v i t y r e l a t i o n s h i p s with home range s i z e can a l s o e x p l a i n these s m a l l s p r i n g home ranges. The s p r i n g home ranges were l o c a t e d i n h a b i t a t s with g r e a t e r amounts of food than the h a b i t a t s used d u r i n g winter, a l s o during s p r i n g the new growth at the lower e l e v a t i o n s would be higher i n g u a l i t y than the food a v a i l a b l e i n win t e r . The abundance o f high q u a l i t y food d u r i n g s p r i n g would r e s u l t i n a s m a l l e r area being needed t o o b t a i n energy and n u t r i e n t s than would be necessary d u r i n g winter. Although the amounts of food a v a i l a b l e on s p r i n g and summer home ranges are s i m i l a r , home range s i z e i n c r e a s e d i n summer. The decrease i n food q u a l i t y over time from s p r i n g to summer would mean a decrease i n the amounts of energy and other n u t r i e n t s a v a i l a b l e to deer on these areas. F u r t h e r , not onl y would the d e n s i t y of energy and n u t r i e n t s a v a i l a b l e to deer be lower i n summer than i n s p r i n g but the deer's energy and n u t r i e n t requirements would be i n c r e a s i n g because of growth, f a t d e p o s i t i o n , l a t e f o e t a l growth, and l a c t a t i o n . These changes i n requirements, and a v a i l a b i l i t y o f energy and n u t r i e n t s , would r e s u l t i n the expansion of home ranges d u r i n g the summer from the s m a l l home ranges used during the s p r i n g . The tren d s i n s i z e s of sea s o n a l home ranges i n t h i s study are c o n s i s t e n t with the energy : p r o d u c t i v i t y home range model proposed f o r mammals by Harestad and B u n n e l l ( i n press) . 138 4.2. Seasonal Movements and N u t r i t i o n A l t e r a t i o n s of home range s i z e i s one way by which deer can respond t o environmental changes. However there appears to be a maximum l i m i t t o the extent which home range s i z e can be i n c r e a s e d (Covich 1976, Harestad and B u n n e l l , i n p r e s s ) . Another way by which deer can respond to environmental changes i s by a l t e r i n g the p o s i t i o n of t h e i r home ranges. In the study area t h r e e p a t t e r n s of s e a s o n a l movement were observed; a l t i t u d i n a l m i g r a t i o n , h o r i z o n t a l m i g r a t i o n , and r e s i d e n c y . Together, these p a t t e r n s p r o v i d e a ge n e r a l d e s c r i p t i o n of the s e a s o n a l movements of the b l a c k - t a i l e d deer p o p u l a t i o n i n h a b i t i n g the study a r e a . B l a c k - t a i l e d deer wintered i n f o r e s t e d h a b i t a t s on s i d e h i l l s at low e l e v a t i o n s u s i n g nearby cutover h a b i t a t s when they were a v a i l a b l e . During s p r i n g deer moved down i n t o the v a l l e y bottoms or used the cutovers nears t h e i r winter home ranges more i n t e n s i v e l y . In summer, some deer remained at low e l e v a t i o n s but changed the i n t e n s i t y of use of p o r t i o n s of t h e i r home ranges; other deer migrated t o m i d - e l e v a t i o n s or high e l e v a t i o n s ; s t i l l o ther deer migrated i n t o t r i b u t a r y v a l l e y s . Although there are d i f f e r e n c e s i n the proximate f a c t o r s i n d u c i n g the s e a s o n a l movements of North American ungulates, the u l t i m a t e f a c t o r i s g e n e r a l l y accepted as seasonal f l u c t u a t i o n i n food a v a i l a b i l i t y (Orr 1970, p. 24). In the study area, b l a c k - t a i l e d deer used d i f f e r e n t seasonal home ranges during s p r i n g , summer, and winter. Movements of b l a c k - t a i l e d deer between these s e a s o n a l home ranges are proposed t o occur because of h a b i t a t s e l e c t i o n r e s u l t i n g from the r e l a t i v e abundance of food s u p p l i e s i n h a b i t a t s encompassed by the home ranges. Where food 139 a v a i l a b i l i t y f a i l s t o account f o r p a t t e r n s of s e a s o n a l movements, other f a c t o r s are suggested which c o u l d c o n t r i b u t e to the r e l a t i v e f a v o u r a b i l i t y of h a b i t a t s . Winter During winter, snow a f f e c t s food a v a i l a b i l i t y by b u r i a l of food s o u rces and through locomotory r e s t r i c t i o n s on deer. The b u r i a l of food items by snow can be d i r e c t or snow can cause downward displacement of the forage and permit t h e i r b u r i a l by subsequent s n o w f a l l s . At high e l e v a t i o n s (above 900 m) , the snowpack was deep enough by l a t e November to reduce food a v a i l a b i l i t y . T h i s r e d u c t i o n i n a v a i l a b i l i t y o c c u r r e d f o r both herbs and shrubs. Herbs were covered s u f f i c i e n t l y by 8 cm of snow to e l i m i n a t e t h i s f orage component from d i e t s of white- t a i l e d deer, 0. y i r g i n i a n u s (Zimmermann) (Coblentz 1970). S i m i l a r e f f e c t s may be imposed on b l a c k - t a i l e d deer because no evidence of deer d i g g i n g through the snowpack was observed i n the study area. Besides herbs, the snowpack was deep enough to bury d i r e c t l y the s h o r t e r shrub stems. I f the e f f e c t of bending of shrub stems i s a l s o c o n s i d e r e d , then the amount of food a v a i l a b l e a t high e l e v a t i o n s would be l e s s than t h a t at low e l e v a t i o n s . Food a v a i l a b i l i t y d uring winter a l s o depends on the e f f e c t of snow on deer m o b i l i t y . Snow depths at which the m o b i l i t y of b l a c k - t a i l e d deer i s hampered can be estimated from o b s e r v a t i o n s of the m o b i l i t y of Bocky mountain mule deer and w h i t e - t a i l e d deer i n snow. In these s p e c i e s , snow depths of over 40 to 60 cm s e r i o u s l y hampered or prevented locomotion (Hosely 1956, 140 L o v e l e s s 1967, K e l s a l l 1969, G i l b e r t et a^U 1970), while shallower snow depths (25 t o 35 cm) reduced m o b i l i t y (Hepburn 1959, L o v e l e s s 1967). K e l s a l l (1969) observed t h a t snow depths of g r e a t e r than 70% of the chest height of moose ( Rices a l e e s (Linnaeus)) and w h i t e - t a i l e d deer s e r i o u s l y impeded t h e i r movements, assuming t h i s same r e l a t i o n s h i p f o r b l a c k - t a i l e d deer, then with t h e i r average chest h e i g h t s between 50 and 58 cm (Jones 1975), the depth at which t h e i r m o b i l i t y would be s e r i o u s l y impeded i s about 37 cm. Snow depths were f r e q u e n t l y g r e a t e r than 37 cm at mid and high e l e v a t i o n s of the study area over most of the winter. Snow d e n s i t y determines the degree t o which snow depth a f f e c t s deer m o b i l i t y . Snow d e n s i t i e s decrease with i n c r e a s i n g e l e v a t i o n ( F i t z h a r r i s 1975), so high e l e v a t i o n s would be more l i k e l y to have d e n s i t i e s of snow t h a t would not support deer and so r e s t r i c t t h e i r movement. T h i s decrease of deer m o b i l i t y would r e s u l t i n i n c r e a s e d energy c o s t s f o r movements while f o r a g i n g i n areas o f deep snow (Jacobsen 1973). The b u r i a l o f food and the deer's reduced m o b i l i t y i n areas of deep snow would r e s u l t i n a decreased d e n s i t y of a v a i l a b l e food, and an i n c r e a s e d energy c o s t of o b t a i n i n g food. For migratory deer, these snow-dependent e f f e c t s on f o r a g i n g e f f i c i e n c y mean t h a t winter home ranges with shallow snow or snow-free areas would be more f a v o u r a b l e than the summer home ranges i n winter with deep snow cover. Resident deer would a l s o experience lowered food d e n s i t i e s on t h e i r summer home ranges d u r i n g winter. T h i s r e d u c t i o n would occur because of the c h a r a c t e r i s t i c s of food p l a n t s on summer home ranges, and d i f f e r e n c e s i n snow depth and d e n s i t y between 141 f o r e s t s and c u t o v e r s . Use of c u t o v e r s by r e s i d e n t deer was g r e a t e r i n summer than i n winter ( F i g . 24). In summer, most of the food i n these c u t o v e r s was i n the form of herbs. In winter, herbs were dormant or dead and t h e i r a v a i l a b i l i t y reduced or e l i m i n a t e d by even shallow snowdepths. Fo r e s t e d areas have more food a v a i l a b l e s i n c e food here i s mainly shrubs which are l e s s a f f e c t e d by shallow snow depths. Cutovers have snowpacks of g r e a t e r depths than nearby f o r e s t e d areas and have higher energy c o s t s f o r locomotion (Jones 1975). At low e l e v a t i o n s under the observed snow c o n d i t i o n s , f o r e s t e d areas have g r e a t e r food d e n s i t i e s than most c u t o v e r s and energy c o s t s f o r locomotion are lower. Winter home ranges o f r e s i d e n t deer, being predominantly f o r e s t e d h a b i t a t s , are more f a v o u r a b l e i n winter than t h e i r summer home ranges which have g r e a t e r amounts of cutovers and poorer snow c o n d i t i o n s . As with summer home ranges i n winter, d i f f e r e n c e s i n snow depths between the winter and s p r i n g home ranges modify the amount of food a v a i l a b l e t o deer and t h e i r energy c o s t of locomotion. Spring home ranges of most deer were l o c a t e d i n v a l l e y bottoms. These areas had snowpacks t h a t accumulated to g r e a t e r depths and p e r s i s t e d f o r lon g e r p e r i o d s than d i d the snowpacks i n winter home ranges on adjacent low e l e v a t i o n s i d e h i l l s . Spring home ranges a l s o i n c l u d e d l a r g e p o r t i o n s of cuto v e r . Snow depths i n the v a l l e y bottom were f r e q u e n t l y deeper than the 37 cm depth estimated to r e s t r i c t locomotion of b l a c k - t a i l e d deer. Although b u r i a l by snow of forage on s p r i n g home ranges would not be as g r e a t as on summer home ranges, more forage would be covered on s p r i n g home ranges than on winter 142 home ranges. On s p r i n g home ranges, the herb component i n the amount of food a v a i l a b l e during winter would be much l e s s than t h a t a v a i l a b l e i n summer or s p r i n g . Given the absence of herbs and the higher c o s t s of locomotion on s p r i n g home.ranges d u r i n g winter, winter home ranges would be the most f a v o u r a b l e h a b i t a t s . although d i f f e r e n c e s between i n d i v i d u a l deer were observed, the l o c a t i o n s of seasonal home ranges were s i m i l a r i n t h e i r snow c h a r a c t e r i s t i c s . Winter home ranges were i n areas subjected to l e s s s n o w f a l l and p e r i o d i c snow cover of s h o r t e r d u r a t i o n than were ot h e r s e a s o n a l home ranges. Abundance and a v a i l a b i l i t y of food d u r i n g winter . are a f u n c t i o n of both the amount of food present and the snowpack. On winter ranges snow accumulation i s l e s s and more food i s a v a i l a b l e than on the other s e a s o n a l h a b i t a t s . The winter ranges are the only h a b i t a t s where food i s a v a i l a b l e and the energy c o s t of locomotion i s low. A l t i t u d i n a l m i g r a t i o n s from summer home ranges to winter home ranges c o i n c i d e d with, or occurred soon a f t e r , the f i r s t s n o w f a l l s of 12 cm or more. Snowfalls of 3 and 5 cm were not s u f f i c i e n t t o cause m i g r a t i o n . Thus, the winter migration was not a d i r e c t response to the a v a i l a b i l i t y of food. T h i s i s a l s o i m p l i e d by the o b s e r v a t i o n t h a t deer d i d not move to e l e v a t i o n s j u s t below the lower extent of snow, but moved d i r e c t l y to t h e i r winter home ranges w e l l below the snow l i n e . The c o i n c i d e n c e of s n o w f a l l and winter m i g r a t i o n i s common i n North American ungulates (Edwards and E i t c e y 1956, Blood 1963, Capp 1968, P h i l l i p s e t al._ 1973, LeEesche 1974, Sweeney 1975, Hoskinson and Mech 1976, Leege and Hickey 1977). Other 143 s t u d i e s observed winter migrations c o r r e l a t e d with c l i m a t i c f a c t o r s such as temperature and humidity (Wright and Swift 1942, McCullough 1964), and water a v a i l a b i l i t y ( A s h c r a f t 1961). A s h c r a f t (1961) and McCullough (1964) observed m i g r a t i o n s o c c u r r i n g up t o s e v e r a l weeks before a c t u a l s n o w f a l l s . The occurrence of winter m i g r a t i o n s before the food supply i s reduced t o d e n s i t i e s below t h a t on winter ranges does not mean t h a t food a v a i l a b i l i t y i s not the u l t i m a t e f a c t o r i n d u c i n g m i g r a t i o n . Adaptation t o u n p r e d i c t a b l e or h i g h l y v a r i a b l e f a c t o r s may i n c l u d e e i t h e r an immediate or premature response (Cohen 1967). Ungulate p o p u l a t i o n s t h a t make t h e i r winter m i g r a t i o n before snow covers t h e i r food supply may only be r e a c t i n g t o the p r o b a b i l i t y t h a t a s n o w f a l l may occur which w i l l cover t h e i r food as w e l l as prevent t h e i r m i g r a t i o n to winter range (Bergerud 1974). In p l a c e s where deer migrations occur before the f i r s t s n o w f a l l s , d i s t a n c e s between summer and winter ranges may be up to 160 km. In these s i t u a t i o n s , the p r o b a b i l i t y of an e a r l y s n o w f a l l deep enough t o impede migrati o n may be s u f f i c i e n t t o s e l e c t f o r deer t h a t are s e n s i t i v e to environmental v a r i a b l e s which are p r e c u r s o r s of snow. In s i t u a t i o n s where d i s t a n c e s between summer and winter home ranges are s h o r t , s n o w f a l l i s i m p l i c a t e d as the t r i g g e r f o r mi g r a t i o n . In only one area i s a winter m i g r a t i o n of deer d e s c r i b e d t h a t occurs s e v e r a l months before the f i r s t winter s n o w f a l l s (Dealy 1959, McCullough 1964). In t h i s apparent anomaly, n i g h t counts were made only on the summer range. Changes i n deer abundance were i n t e r p r e t e d as m i g r a t i o n s . Although i n l a t e summer there was a d e c l i n e i n deer numbers, a 144 m i g r a t i o n to the winter range was not demonstrated. McCullough (1964) was unable t o de t e c t i n c r e a s e s i n deer abundance i n oth e r p o r t i o n s of h i s study area, and i n t e r p r e t e d the d e c l i n e i n deer p o p u l a t i o n as an e a r l y m i g r a t i o n t o the winter range. In n e a r l y a l l other s t u d i e s i n areas where there i s snow duri n g the winter, snow i s reported as the i n i t i a t o r o f the winter migra t i o n ( E u s s e l l 1932, Dixon 1934, Leopold e t al.. 1951, Longhurst et a l . 1952, G r u e l l 1958, Moir 1976, Bertram and Rempel 1977). Depending on the r i s k s and b e n e f i t s of these movements, s e l e c t i o n would favour deer t h a t were s e n s i t i v e to f a c t o r s which induce m i g r a t i o n s before they are necessary from a f o r a g i n g p e r s p e c t i v e . Over long d i s t a n c e s , the chances of being trapped on the summer range may be s u f f i c i e n t t o outweigh the l o s s i n f i t n e s s imposed by not s t a y i n g on the summer ranges as lon g as i s p o s s i b l e (Cohen 1967). Spring During s p r i n g , when winter and s p r i n g home ranges are snow- f r e e , and thus not su b j e c t e d to the b u r i a l of for a g e and locomotory r e s t r i c t i o n s of deer by snow, s p r i n g home ranges would have g r e a t e r d e n s i t i e s of a v a i l a b l e food than winter home ranges. Snow melts on s p r i n g home ranges e a r l y i n s p r i n g and uncovers new sources of food. Use of these s p r i n g home ranges with higher d e n s i t i e s of food r e s u l t s i n movement of deer from t h e i r winter home ranges. During s p r i n g , summer home ranges would s t i l l be covered with snow. Locomotion would t h e r e f o r e be impeded, and although the snowpack c o u l d be l e s s than the snow-free h e i g h t s of shrubs. 145 the snowpack on summer ranges s t i l l covers shrubs because of stem displacement. T h i s displacement and consequent b u r i a l of shrubs r e s u l t i n d e n s i t i e s o f a v a i l a b l e food on summer home ranqes during s p r i n g t h a t would be l e s s than those on s p r i n g home ranges. In t h i s study, l o c a t i o n s of deer i n s p r i n g were d i f f e r e n t from t h e i r l o c a t i o n s i n winter. T h i s c o n t r a s t s with the r e s u l t s o f Dasmann and Taber (1956) who do not r e c o g n i z e s p r i n g home ranges as s p a t i a l l y d i f f e r e n t from winter home ranges, but do d e s c r i b e " s e a s o n a l d r i f t s " of the deer p o p u l a t i o n d u r i n g the s p r i n g . Some authors s t a t e or imply t h a t m i g r a t i o n s must be of a c e r t a i n magnitude (Einarsen 1946, Longhurst et a l . 1952). T h i s assumption has l e d to d i s c u s s i o n s of "seasonal d r i f t s " , when a c t u a l l y s h o r t d i s t a n c e s e a s o n a l movements were observed. Lack of r e c o g n i t i o n of s p r i n g home ranges by e a r l i e r s t u d i e s probably r e s u l t s because seasonal movements have been determined u s u a l l y from changes i n the seasonal d i s p e r s i o n o f the deer p o p u l a t i o n , r a t h e r than from l o c a t i o n s of i n d i v i d u a l animals. Summer Energy i s a major f a c t o r i n f l u e n c i n g the s i z e of home range (McNab 1963, Schoener 1968, Harestad and B u n n e l l , i n press) and the use of h a b i t a t s ( K l e i n 1965, Jarman 1974). Foraging models p r e d i c t t h a t animals should forage i n h a b i t a t s where the d e n s i t y of a v a i l a b l e energy i s g r e a t e s t (MacArthur and Pianka 1966, Schoener 1971, Pyke e t a l . 1977). For ruminants, the c a l o r i c need i s a primary one t o which requirements of other n u t r i e n t s are l i n k e d ( B l a x t e r 1962, Oldemeyer 1974) and the a v a i l a b l e 146 energy i n forage i s i n d i c a t i v e of i t s n u t r i t i v e value (Swift 1957, Hardison 1959, Ee i d 1968)^ Given the r e l a t i o n s h i p s between energy, f o r a g i n g behaviour, and home ranges, i t f o l l o w s t h a t s easonal movements should p l a c e deer i n h a b i t a t s where the d e n s i t y of a v a i l a b l e energy and n u t r i e n t s would be greater than i n h a b i t a t s used i n the p r e v i o u s season. Thus s e l e c t i o n of seasonal h a b i t a t s should be based on the r e l a t i v e a v a i l a b i l i t y o f energy and n u t r i e n t s . Estimates o f d i g e s t i b l e energy were not a v a i l a b l e f o r the major f o r a g e types used by b l a c k - t a i l e d deer i n the study area. However, d i g e s t i b l e dry matter values were a v a i l a b l e from R o c h e l l e ( i n prep.) and used i n pl a c e o f d i g e s t i b l e energy. D i g e s t i b l e dry matter i s d i r e c t l y p r o p o r t i o n a l to d i g e s t i b l e energy with r 2 of .98 (Moir 1961) and .93 (Rittenhouse et a l . 1971). T h i s c o r r e l a t i o n i s supported by s t u d i e s of w i l d ruminants (Ammann e t a l . 1973, Hebert 1973). D i g e s t i b l e dry matter i s a l s o p r o p o r t i o n a l to the p r o t e i n content of a f o r a g e , s i n c e f o r a g e s h i g h i n p r o t e i n are u s u a l l y low i n crude f i b r e (Crampton and H a r r i s 1969) . Because of these i n t e r r e l a t i o n s h i p s the d e n s i t y of d i g e s t i b l e dry matter of the a v a i l a b l e food was used t o e v a l u a t e home ranges, and i s an ex p r e s s i o n of the d e n s i t y o f energy and n u t r i e n t s a v a i l a b l e t o deer. During summer, the amount of energy and n u t r i e n t s a v a i l a b l e to deer on t h e i r s e a s o n a l home ranges was estimated i n terms of the d e n s i t y of d i g e s t i b l e dry matter. The mean d e n s i t y of d i g e s t i b l e dry matter per l o c a t i o n was c a l c u l a t e d f o r the t h r e e se a s o n a l home ranges o f each deer, under c o n d i t i o n s o f the summer food supply f o r the a p p r o p r i a t e h a b i t a t t y p es l i s t e d i n 147 Table I I . Mean d e n s i t i e s of d i g e s t i b l e dry matter f o r the day and night l o c a t i o n s were weighted a c c o r d i n g to average l e n g t h of day and n i g h t at 50°N between June and October ( L i s t 1966), and a mean d a i l y d e n s i t y of d i g e s t i b l e dry matter per l o c a t i o n c a l c u l a t e d (Table XI) . The l o c a t i o n s of radio-tagged deer i n summer were s i t u a t e d i n h a b i t a t s s i g n i f i c a n t l y g r e a t e r (p < .05) i n d e n s i t y of d i g e s t i b l e dry matter than t h e i r winter ranges contained i n summer (Table XI) . For only one out of the seven radio-tagged deer was the h a b i t a t s used d u r i n g summer l e s s abundant i n d i g e s t i b l e dry matter than h a b i t a t s t h i s deer would have encountered had i t stayed on i t s winter home range d u r i n g summer. T h i s deer, OFL62, was a r e s i d e n t and the lower d e n s i t y of d i g e s t i b l e dry matter f o r h i s summer home range was due to h i s g r e a t e r use of the Western Hemlock - Plagiothecium a s s o c i a t i o n d u r i n g summer than i n winter. D e n s i t i e s of d i g e s t i b l e dry matter a v a i l a b l e on summer and s p r i n g home ranges were not s i g n i f i c a n t l y d i f f e r e n t (p < .20). Three o f the f o u r migratory deer encountered g r e a t e r d e n s i t i e s o f d i g e s t i b l e dry matter by moving to t h e i r summer home ranges than they would have encountered had they stayed on t h e i r s p r i n g home ranges f o r summer. The f o u r t h migratory deer and the two r e s i d e n t deer used h a b i t a t s i n summer th a t had lower d e n s i t i e s of d i g e s t i b l e dry matter than h a b i t a t s they used i n s p r i n g . In one r e s i d e n t deer, the sample s i z e of l o c a t i o n s was smal l and d e n s i t y o f d i g e s t i b l e dry matter on the s p r i n g home range may have been overestimated. Part of the s p r i n g home ranges of the other two deer i n c l u d e d the Vaccinium-Skunk Cabbage a s s o c i a t i o n . 148 Table XI. Mean d e n s i t y o f d i g e s t i b l e dry matter per l o c a t i o n a v a i l a b l e d u r i n g summer on seasonal home ranges. Wilcoxon signed ranks t e s t . H 0: summer < winter ; T=1, n=7, p<.01 H„: summer < s p r i n g ; T=6, n=6, p<.20 H 0: s p r i n g < winter ; T=3, n=6, p<.05 149 OS o E H « (—I En Z w Q M CO w PC 0 F L 6 1 OFL68 OFL67 0 F L 6 0 0 F L 7 1 * OFL58 0 F L 6 2 Food Available On Seasonal Home Ranges During Summer ( k g digestible dry matter ha ) Spring Range 3 6 0 . 4 1 9 7 . 8 9 9 . 2 1 6 3 . 8 2 8 8 . 8 1 9 0 . 6 Summer Range 1 4 4 . 9 2 0 8 . 5 5 0 3 . 6 2 5 6 . 9 3 2 6 . 2 2 1 0 . 0 1 2 6 . 4 Winter Range 1 0 6 . 1 1 6 6 . 2 1 7 9 . 8 1 4 2 . 8 1 2 4 . 6 1 7 2 . 0 1 4 2 . 8 * horizontal migrator 150 T h i s a s s o c i a t i o n has a high d e n s i t y of d i g e s t i b l e dry matter but i s small i n area r e l a t i v e to other types of f o r e s t e d p l a n t a s s o c i a t i o n s . M i g r a t i o n of deer away from the Vaccinium-Skunk Cabbage a s s o c i a t i o n and r e d u c t i o n i n use of t h i s h a b i t a t by r e s i d e n t deer may r e s u l t from the c o n c e n t r a t i o n of deer i n s p r i n g and use of t h i s h a b i t a t throughout the year by Roosevelt e l k { Cervus elaphus r o o s e v e l t i Merriam). T h i s c o n c e n t r a t i o n and a s s o c i a t e d f e e d i n g by deer and elk may reduce the amounts of food a v a i l a b l e i n s p r i n g h a b i t a t s . While the e f f e c t of f e e d i n g i n s p r i n g h a b i t a t s could reduce food d e n s i t y , another p o t e n t i a l f a c t o r , t h a t c o u l d e x p l a i n why deer l e a v e the s p r i n g h a b i t a t s and go to summer home ranges, i s p r e d a t i o n . I f deer p r e d a t o r s s e l e c t e d t h e i r hunting h a b i t a t s on the b a s i s of prey d e n s i t y and f o r a g i n g e f f i c i e n c y , then d u r i n g s p r i n g they would focus t h e i r hunting i n deer s p r i n g ranges. Not on l y are the deer concentrated on the s p r i n g range but fawns are born i n June adding f u r t h e r to the prey a v a i l a b l e t o pr e d a t o r s . Risk of p r e d a t i o n would be l e s s on high e l e v a t i o n summer ranges because wolves ( Canis l u p u s Linnaeus) are t i e d t o den s i t e s at t h i s time (B. S c o t t , p e r s o n a l communication) and black bears (Orsus americanus P a l l a s ) are t i e d t o low e l e v a t i o n h a b i t a t s because of t h e i r dependence on v e g e t a t i v e f o od. A t t r a c t i o n of predators to s p r i n g ranges would i n c r e a s e the r i s k of p r e d a t i o n to deer i n h a b i t i n g these areas and make s p r i n g home ranges l e s s f a v o u r a b l e than summer home ranges. I f deer moved o f f s p r i n g home ranges and i n t o the much l a r g e r area of summer range when i t was snowfree, the r i s k of p r e d a t i o n may be reduced because of lower prey d e n s i t i e s (Tinbergen et a l . 1967). 151 Movement from s p r i n g to summer home ranges c o i n c i d e with the melting of the snowpack and the uncovering of f o r a g e on summer ranges. For migratory deer, t h i s movement was not immediate but o c c u r r e d up to s e v e r a l weeks a f t e r the f i r s t bare patches of ground appear. Short term v i s i t s t o the summer home ranges p r i o r to permanent s e a s o n a l occupancy were observed i n some migratory b l a c k - t a i l e d deer and have been r e p o r t e d by Bertram and Eempel (1977) f o r C a l i f o r n i a mule deer (Pli Jli. c a l i f o r n i c us (Canton)) and by Hoskinson and Mech (1976) f o r w h i t e - t a i l e d deer. O c c a s i o n a l v i s i t s t o suboptimal h a b i t a t s are proposed as f u n c t i o n i n g to keep an animal aware of changes i n the food supply of p o t e n t i a l h a b i t a t s (Smith and Sweatman 1974, Davies 1977). These v i s i t s suggest that b l a c k - t a i l e d deer r e c o n n o i t r e t h e i r summer home ranges and provide a mechanism through which t h e i r summer home ranges can be occupied when they are more f a v o u r a b l e . Short term v i s i t s provide deer with an up- to-date assessment of c o n d i t i o n s on t h e i r summer home ranges. E a r l y s t u d i e s i m p l i c a t e d both the abundance of food and i t s n u t r i e n t content as f a c t o r s i n m i g r a t i o n s of mule deer (McLean 1930, R u s s e l l 1932, Dixon 1934, Leopold et a l ^ 1951, Longhurst et a l . 1952). Where n u t r i t i o n a l f a c t o r s are suggested as important i n causing seasonal movements, p r o t e i n content i n the f o r a g e was proposed as the i n d u c i n g agent (Dealy 1959, Hebert 1973). although p r o t e i n i s necessary f o r growth and body maintenance, i t a l s o f a c i l i t a t e s i n c r e a s e d forage d i g e s t i b i l i t y and food i n t a k e and thus the b e n e f i t s of high p r o t e i n d i e t s to ruminants are mainly i n terms of energy (Jones 1972, Verme and U l l r e y 1972, B a i l e and Forbes 1974). R e l a t i v e a v a i l a b i l i t y of 152 energy and n u t r i e n t s on s e a s o n a l home ranges of migratory animals depend on both the q u a l i t y and q u a n t i t y of f o r a g e . Studies r e l a t i n g seasonal movements to p r o t e i n content of forage (Dealy 1959, K l e i n 1965, Hebert 1973) have found n u t r i t i v e d i s p a r i t i e s between seasonal ranges, but since food abundance was not assessed, e v a l u a t i o n of the advantages of migratory behaviour cannot be made. The n u t r i t i v e value of the forage cannot be s i n g l e d out as the d r i v i n g v a r i a b l e i n m i g r a t i o n . Both q u a n t i t y and q u a l i t y of the forage combine to g i v e a d e n s i t y of d i g e s t i b l e dry matter and i t i s t h i s d e n s i t y of d i g e s t i b l e dry matter to which b l a c k - t a i l e d deer appear t o respond. In c o a s t a l areas where summers are wet and moisture d e f i c i e n c i e s do not cause e a r l y senescence of the forage p l a n t s at low e l e v a t i o n s , a l t i t u d i n a l d i f f e r e n c e s i n the n u t r i t i v e content of forage would not d i f f e r as much as i t does i n d r i e r i n t e r i o r and a l p i n e areas. In the study area on Vancouver I s l a n d , the p r i n c i p a l forages of deer are herbs and shrubs. These c l a s s e s of forage maintain t h e i r n u t r i t i v e q u a l i t y over a l o n g e r p o r t i o n of the p h e n o l o g i c a l c y c l e than do grasses (Cook 1972). Both the summer-long succulence of herbs and shrubs and t h e i r prolonged high q u a l i t y would r e s u l t i n l e s s n u t r i t i o n a l d i f f e r e n c e i n the forage between a l t i t u d e s on the coast than would be observed i n i n t e r i o r areas. I f only d i f f e r e n c e s i n q u a l i t y , and not q u a n t i t y , of the f o r a g e were r e s p o n s i b l e f o r the seasonal movements of b l a c k - t a i l e d deer i n the study area, then s e v e r a l major d i f f e r e n c e s would be expected from the observed p a t t e r n s of movements. I f b l a c k - t a i l e d deer were e x p l o i t i n g a p h e n o l o g i c a l s t a t e of t h e i r 153 forage i n order to maximize t h e i r i n t a k e of some n u t r i e n t , such as p r o t e i n , then a slow p r o g r e s s i v e m i g r a t i o n would be observed. Deer would be expected t o l e a v e t h e i r s p r i n g home ranges and move upwards i n e l e v a t i o n o r i n t o t r i b u t a r y v a l l e y s f o l l o w i n g the best p h e n o l o g i c a l c o n d i t i o n of the forage. T h i s p a t t e r n of movement was not observed. The f i n a l m i g r a t i o n of b l a c k - t a i l e d deer from t h e i r s p r i n g t o summer home ranges was not a gradual process over many days, but occu r r e d i n a p e r i o d of l e s s than a day. I f b l a c k - t a i l e d deer were mi g r a t i n g i n order to e x p l o i t some p h e n o l o g i c a l stage o f t h e i r forage, then the deer p o p u l a t i o n would be concentrated w i t h i n the area where t h i s stage o c c u r s . On Mount Cain, the p o p u l a t i o n would be expected to be i n a h o r i z o n t a l s t r i p that moves a l t i t u d i n a l l y i n response to the changing p h e n o l o g i c a l s t a t e of the forage. T h i s p a t t e r n was not observed. Both r a d i o - t e l e m e t r y and ni g h t count o b s e r v a t i o n s i n d i c a t e t h a t some deer move from low e l e v a t i o n s i n t o mid- e l e v a t i o n s and remain there throughout summer. Other deer, whose home ranges were at high e l e v a t i o n s , remained on t h e i r low e l e v a t i o n s p r i n g ranges u n t i l the high e l e v a t i o n h a b i t a t s were snowfree and p l a n t growth had begun. Under the observed system of migratory behaviour, deer l e f t the s p r i n g ranges where they were concentrated and spread out over the h a b i t a t made a v a i l a b l e d u r i n g summer with the melting o f the snowpack. I f deer were migrating i n order to e x p l o i t a p a r t i c u l a r p h e n o l o g i c a l stage of t h e i r f o rage, then s i n c e n u t r i t i o n a l advantages would e x i s t f o r migratory deer, non-migratory deer would be s e l e c t e d a g a i n s t . Hence, a t h i r d e x p e c t a t i o n i s t h a t i f 154 b l a c k - t a i l e d deer were responding t o s o l e l y a n u t r i t i o n a l f a c t o r , the p o p u l a t i o n should be p r i m a r i l y migratory and few r e s i d e n t deer would occur. T h i s e x p e c t a t i o n i s not confirmed by my o b s e r v a t i o n s . There are s u b s t a n t i a l numbers of r e s i d e n t deer. Rather than n u t r i t i o n a l f a c t o r s being invoked f o r e x p l a i n i n g some m i g r a t i o n s and forage a v a i l a b i l i t y invoked f o r ot h e r s , my approach can be used as the b a s i s f o r a s i n g l e model of s e a s o n a l movements t h a t focuses on energy, n u t r i e n t s , and s e c u r i t y f a c t o r s . By addressing these f a c t o r s , assessment of seas o n a l home ranges i n terms of the b e n e f i t s and c o s t s to the animal's f i t n e s s permits a more g e n e r a l e x p l a n a t i o n of s e a s o n a l movements made by b l a c k - t a i l e d deer. 4.3. Seasonal Movements And S o c i a l O r g a n i z a t i o n Mammalian s o c i e t i e s are complex systems i n f l u e n c e d and modified by e x t e r n a l environmental v a r i a b l e s and s p e c i e s parameters (Crook e t al,. 1976). Crook et a l . (1 976) argue t h a t p a r t i c u l a r s o c i a l s t r u c t u r e s a r i s e because they provide an op t i m a l context w i t h i n which the i n d i v i d u a l s comprising them c a r r y out v i t a l f u n c t i o n s i n c l u d i n g p r i m a r i l y : r esource e x p l o i t a t i o n , predator avoidance, mating, and r e a r i n g of young. The importance of the s p a t i o - t e m p o r a l d i s t r i b u t i o n of reso u r c e s to the s o c i a l o r g a n i z a t i o n of ungulates i s d i s c u s s e d by Este s (1974), Jarman (1974), and G e i s t (1974), and i s r e l e v a n t to the se a s o n a l movements of b l a c k - t a i l e d deer. In t h i s study, the use of home ranges r a t h e r than t e r r i t o r i e s by b l a c k - t a i l e d deer confirm p r e d i c t i o n s of G e i s t (1974) concerning the s p a t i a l o r g a n i z a t i o n of ungulates i n environments with seasonal 155 f l u c t u a t i o n s i n a v a i l a b i l i t y o f r e s o u r c e s . Group s i z e i s one of the p r i n c i p l e s o c i a l systems v a r i a b l e s used to d e s c r i b e s o c i a l o r g a n i z a t i o n s (Crook e t a l . 1976). In " c h a p a r r a l " h a b i t a t s , b l a c k - t a i l e d deer form s m a l l groups f o r most of the year (Dasmann and Taber 1956). These groups c o n s i s t mainly of mothers and young or up t o three a d u l t males. During the r u t more males become s o l i t a r y and more male-female groups are observed. The " c h a p a r r a l " h a b i t a t would be c l a s s e d as a c l o s e d h a b i t a t by Jarman (1974) , who observed a ne g a t i v e c o r r e l a t i o n between group s i z e v i s u a l d e n s i t y of the h a b i t a t . F o r e s t e d and c o n i f e r s e r a i stage h a b i t a t s are a l s o c l o s e d h a b i t a t s so s m a l l groups s i z e s would be expected. In the study area deer occurred mainly i n s m a l l groups or were s o l i t a r y , s i m i l a r t o those d e s c r i b e d by Dasmann and Taber (1956) and agree with the p r e d i c t i o n s made by Jarman (1974). In cu t o v e r s which have l i t t l e l a t e r a l cover (newly logged, herb, f e r n , and shrub s e r a i s t a g e s ) , the h a b i t a t would be more open and group s i z e s would be l a r g e r than i n the v i s u a l l y dense h a b i t a t s (Jarman 1974, H i r t h 1977). The i n c r e a s e d use of the more open h a b i t a t s by b l a c k - t a i l e d deer during s p r i n g and summer should r e s u l t i n l a r g e r s i z e d aggregations i n these seasons than i n winter. These aggregations would a f f e c t other aspects of s o c i a l behaviour such as i n t e r a c t i o n r a t e s and a c t i v i t y . The seasonal movements of b l a c k - ' t a i l e d deer would impose f u r t h e r i n f l u e n c e s on t h e i r s o c i a l o r g a n i z a t i o n . In a p o p u l a t i o n where some members are migratory, the seasonal c o n c e n t r a t i o n and spacing out of deer would a f f e c t s t a b l e h i e r a r c h i c a l r e l a t i o n s h i p s because of the a d d i t i o n and l o s s of s o c i a l 156 p a r t n e r s . Seasonal movements by a p o r t i o n of the p o p u l a t i o n to summer home ranges a t high e l e v a t i o n s or to t r i b u t a r y v a l l e y s would r e s u l t i n the breaking of s o c i a l r e l a t i o n s h i p s t h a t were e s t a b l i s h e d between i n d i v i d u a l s during winter and s p r i n g . A f t e r the summer m i g r a t i o n , new r e l a t i o n s h i p s would have to be e s t a b l i s h e d with the u n f a m i l i a r deer encountered on the summer home range. Even on low e l e v a t i o n areas i n h a b i t e d by r e s i d e n t deer some s o c i a l d i s r u p t i o n would occur. M i g r a t i o n away from the low e l e v a t i o n s by migratory deer would r e s u l t i n the l o s s of some p a r t i c i p a n t s and t h i s would a l t e r r e l a t i o n s h i p s between the remaining s o c i a l p a r t n e r s . The r u t occurs i n November and e a r l y December (Thomas 1970) , and o v e r l a p s with the winter m i g r a t i o n p e r i o d . The s h u f f l e of the deer p o p u l a t i o n r e s u l t i n g from the winter migration would a f f e c t the dominance h i e r a r c h y among the males and so have d i r e c t r e p e r c u s s i o n s on the mating system of deer (Kucera 1978). Mixing of migratory and non-migratory deer would r e s u l t i n a l e s s s t a b l e male h i e r a r c h y . The s o c i a l o r g a n i z a t i o n of b l a c k - t a i l e d deer i n the study area would be based on t r a n s i e n t h i e r a r c h i c a l r e l a t i o n s h i p s r a t h e r than on s t a b l e s o c i a l r e l a t i o n s h i p s such as i n r e s i d e n t p o p u l a t i o n s d e s c r i b e d by Dasmann and Taber (1956) and M i l l e r (1970). 4.4. Model Of Seasonal Movements A more s u c c i n c t statement of the seasonal movements and h a b i t a t use by b l a c k - t a i l e d deer can be made through a c o n c e p t u a l model ( F i g . 27). T h i s model i s d e r i v e d from o b s e r v a t i o n s of deer movements and the f a c t o r s proposed to 157 Figure 27. Model of seasonal movements and habitat s e l e c t i o n . f— Benefits To Fitness - ENERGY quantity and quality of food, requirements, expenditures. HABITATS AVAILABLE Habitat Evaluation - experience - habitat predictability - exploration - natural selection for surrogates of fitness 1 Costs To Fitness - PREDATION security cover, mobility, other prey. NATURAL SELECTION FOR GREATER FITNESS HABITATS SELECTED HABITATS USED Seasonal Movements •CD Seasonal Environmental Changes depth and density of snow, growth and dormancy of vegetation. 159 e l i c i t these movements. The model i l l u s t r a t e s the process of h a b i t a t s e l e c t i o n by b l a c k - t a i l e d deer i n the study area. In t h i s model, seasonal movements are a response by deer t o 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 o f d i f f e r e n t h a b i t a t s . Given a number of h a b i t a t s which are a v a i l a b l e t o deer, the use of these h a b i t a t s can be evaluated on the b a s i s of the b e n e f i t s and c o s t s to the user's f i t n e s s . The b e n e f i t s t o f i t n e s s of a h a b i t a t are repr e s e n t e d by a s i n g l e parameter, net energy a c q u i s i t i o n . T h i s parameter i n t e g r a t e s the e f f e c t s of n u t r i e n t requirements, weather, c o m p e t i t i o n , locomotion, and f o r a g i n g c o s t s o c c u r r i n g w i t h i n a p a r t i c u l a r h a b i t a t . The c o s t s to f i t n e s s express the e f f e c t s o f changes to the r i s k of p r e d a t i o n w i t h i n a h a b i t a t and i n c o r p o r a t e s the impacts of a l t e r a t i o n s i n prey d e n s i t y , s e c u r i t y cover, and predator avoidance. Among heterogeneous h a b i t a t s p o t e n t i a l l y a v a i l a b l e to deer, some w i l l be more f a v o u r a b l e than o t h e r s . This f a v o u r a b i l i t y i s evaluated i n terms of the deer's f i t n e s s . The e v a l u a t i o n can be based on the deer's experience, s e l e c t i o n f o r the a p p r o p r i a t e behaviour, or p o s s i b l y even d i r e c t e v a l u a t i o n . Experience c o u l d provide deer with a means to a n t i c i p a t e imminent environmental changes (Bouckhout 1972). No c o n s c i o u s a n t i c i p a t i o n i s needed as long as deer respond a p p r o p r i a t e l y to the environmental s i g n a l s . T r a d i t i o n may a l s o c o n t r i b u t e t o t h i s "experience". In b l a c k - t a i l e d deer, t r a d i t i o n probably helps t o maintain migratory or r e s i d e n t behaviour i n i n d i v i d u a l s once t h e i r s e a s o n a l movement p a t t e r n s have been e s t a b l i s h e d . 160 H a b i t a t e v a l u a t i o n can a l s o be made by migratory e x p l o r a t i o n s to' p o t e n t i a l h a b i t a t s . T h i s process may be o c c u r r i n g i n b l a c k - t a i l e d deer and c o u l d e x p l a i n t h e i r s h o r t v i s i t s t o summer and winter home ranges p r i o r to t h e i r seasonal occupancy of these h a b i t a t s . When h a b i t a t s have been e v a l u a t e d , then those t h a t are the most f a v o u r a b l e can be s e l e c t e d . Although some h a b i t a t s may have d i f f e r e n t b e n e f i t s and c o s t s to f i t n e s s , they may have the same net c o n t r i b u t i o n t o the deer's f i t n e s s , and thus more than one type of h a b i t a t may be used by deer. These d i f f e r e n c e s would be observed as v a r i a b i l i t y i n the p a t t e r n s of h a b i t a t use. As h a b i t a t s are e v a l u a t e d , deer s e l e c t and use the more f a v o u r a b l e ones. Depending on the l o c a t i o n of these h a b i t a t s the observed p a t t e r n s of seasonal movements could occur. The use of these new h a b i t a t s would continue u n t i l t h e i r food and cover resources were a l t e r e d . These a l t e r a t i o n s would be p r i m a r i l y a f u n c t i o n of snow and p h e n o l o g i c a l changes i n the food sources. In the study area these processes are s e a s o n a l and thus change the r e l a t i v e f a v o u r a b i l i t y of the h a b i t a t s . As h a b i t a t s are a l t e r e d , f u r t h e r h a b i t a t s e l e c t i o n would occur and the response observed as another s e a s o n a l movement. The movements of b l a c k - t a i l e d deer from one seasonal home range to another as a response to the b e n e f i t s and c o s t s to f i t n e s s accrued through e x p l o i t i n g the most f a v o u r a b l e h a b i t a t s i s an e x p l a n a t i o n c o n s i s t e n t with the observed p a t t e r n s of s e a s o n a l movements. The causal d i f f e r e n c e s between v e r t i c a l and h o r i z o n t a l m i g r a t i o n s as w e l l as seasonal s h i f t s i n use of d i f f e r e n t h a b i t a t s w i t h i n home ranges of r e s i d e n t deer can be 161 r e s o l v e d by t h i s model of h a b i t a t s e l e c t i o n . The model has broader a p p l i c a t i o n than j u s t accounting f o r the behaviour of b l a c k - t a i l e d deer i n the study area. The seasonal movements of mule deer throughout i t s g e o g r a p h i c a l range can be a t t r i b u t e d t o the seasonal a v a i l a b i l i t y of food. T h i s v a r i a t i o n i n food a v a i l a b i l i t y i s l a r g e l y due to the e f f e c t s of p r e c i p i t a t i o n i n the form of both r a i n and snow. Four c l i m a t i c r e g i o n s based on the amount of r a i n and the depth and d u r a t i o n of the snowpack e x i s t w i t h i n the g e o g r a p h i c a l range of mule deer i n North America. Among these c l i m a t i c r e g i o n s the p a t t e r n s of seasonal movements are between extremes of completely r e s i d e n t p o p u l a t i o n s to completely migratory p o p u l a t i o n s . In the dry south-west there i s l i t t l e i f any s n o w f a l l and p r e c i p i t a t i o n i s low, o c c u r r i n g mostly i n winter. In areas away from ground water t h i s p a t t e r n of p r e c i p i t a t i o n r e s u l t s i n the d r y i n g and senescence of forage d u r i n g the summer with green forage o c c u r r i n g i n winter. At the beginning of summer deer do not migrate up i n t o the mountains but i n s t e a d move down i n t o the v a l l e y bottoms where green f o r a g e i s a v a i l a b l e i n the r i p a r i a n h a b i t a t s and i r r i g a t e d a g r i c u l t u r a l l a n d (McLean 1930, Longhurst and C h a t t i n 1941, Longhurst e t a l . 1952). A f t e r the winter r a i n s and growth of f o r a g e i n the areas away from the v a l l e y bottoms the deer leave these areas and migrate i n t o the surrounding h a b i t a t s where they remain u n t i l the dry summer. In moister p a r t s of C a l i f o r n i a , Oregon, and Washington where there i s l i t t l e s n o w f a l l , mule deer tend t o be mainly r e s i d e n t (Dasmann 1953, Dasmann and Taber 1956, Brown 1961, 162 Lauckhart 1948). The food supply although s e a s o n a l l y changing does not have the extreme s p a t i a l d i f f e r e n c e s i n q u a n t i t y and q u a l i t y as occurs i n the dry or hiqh s n o w f a l l a r e a s . In t h i s r e g i o n deer make seasonal s h i f t s of t h e i r home range c e n t r e s (Dasmann 1953) hut there are few migratory deer. The preponderance of r e s i d e n t deer occurs because t h e i r requirements are met w i t h i n t h e i r heme ranges f o r the whole year and t h e r e are not more s e a s o n a l l y a t t r a c t i v e h a b i t a t s nearby. The t h i r d c l i m a t i c r e g i o n i n the range of mule deer has deep snowpacks during the winter i n high e l e v a t i o n s and low r a i n f a l l d u r i n g the summer. These c o n d i t i o n s occur i n i n t e r i o r areas l i k e Colorado, Utah, eastern C a l i f o r n i a , and p a r t s of Washington and Oregon. . In t h i s c l i m a t i c r e g i o n t h e r e i s a downward a l t i t u d i n a l m i g r a t i o n i n winter c o i n c i d i n g with s n o w f a l l s i n h i g h e r e l e v a t i o n s and t h i s migration i s a t t r i b u t e d to the c o v e r i n g of forage by snow. In s p r i n g t h e r e i s an upward migration which occurs because the food i n the lower e l e v a t i o n s matures and d r i e s out by summer and so the forage i n the high e l e v a t i o n s becomes more n u t r i t i o u s r e l a t i v e t o t h a t a t the low e l e v a t i o n s . Deer i n t h i s c l i m a t i c r e g i o n are p r i m a r i l y migratory ( R u s s e l l 1932, Dixon 1934, Leopold et a l . 1951, Longhurst et a l . 1952, Robinette 1966, Loveless 1967, Bertram and Rempel 1977). The f o u r t h c l i m a t i c r e g i o n i s i n the n o r t h - c o a s t a l areas and represented by t h i s study. Here r a i n f a l l i s abundant and occurs throughout the year, snowpacks are deep at high e l e v a t i o n s but low e l e v a t i o n s are snowfree o r have shallow snowpacks. The r a i n a l l o w s green forage throughout the summer at a l l e l e v a t i o n s . In w i n t e r , snow covers forage a t high e l e v a t i o n s 163 and the low e l e v a t i o n s are the only h a b i t a t s where food i s a v a i l a b l e . Under these c l i m a t i c c o n d i t i o n s deer p o p u l a t i o n s have both r e s i d e n t and migratory components. The r e s i d e n t deer stay i n the low s n o w f a l l areas throughout the year but make sea s o n a l s h i f t s i n t h e i r home range c e n t r e s . The migratory deer move from winter ranges t o summer h a b i t a t s t h a t were u n a v a i l a b l e d u r i n g the winter. They r e t u r n to the winter ranges a f t e r the i n i t i a l s n o w f a l l s on t h e i r summer ranges. The seasonal movements of mule deer i n the f o u r c l i m a t i c r e g i o n s can be e x p l a i n e d by the h a b i t a t s e l e c t i o n model. Although the p a t t e r n s of movements are d i f f e r e n t , the reasons f o r them appear to be the same. 4.5. Seasonal H a b i t a t s and F o r e s t Harvesting The concept of s e a s o n a l movements and subsequent h a b i t a t use as a f u n c t i o n of energy and n u t r i e n t a v a i l a b i l i t y and p r e d a t i o n i s u s e f u l i n e v a l u a t i n g f o r e s t management p r a c t i c e s with regard to the abundance of b l a c k - t a i l e d deer . In f o r e s t types where t h e r e i s l i t t l e shrub and herb food , removal o f the f o r e s t canopy r e s u l t s i n an i n c r e a s e of forage and i s thought to be b e n e f i c i a l t o deer (Einarsen 1946, Leopold 1950, Brown 1961, Gates 1968, Hines 1973). In the study a r e a , some f o r e s t e d summer range h a b i t a t s have equal or g r e a t e r food d e n s i t i e s than i s found i n adjacent c u t o v e r s ( F i g . 5). A l s o , these f o r e s t e d h a b i t a t s are more ex t e n s i v e i n area than are the cutovers and are used by deer d u r i n g day and n i g h t . F o r e s t h a b i t a t s thus rep r e s e n t a l a r g e amount of the p o t e n t i a l summer f o r a g i n g area f o r deer. Because of g r e a t e r food abundance i n high e l e v a t i o n and some v a l l e y bottom f o r e s t types ( F i g . 5) , the b e n e f i t s to 164 deer of l o g g i n g i n the study area are l i k e l y not as g r e a t as those enjoyed by deer i n r e g i o n s f u r t h e r south or with lower s n o w f a l l . In the study area removal of the f o r e s t canopy at high e l e v a t i o n s probably does not a f f e c t deer abundance to any great extent, s i n c e food can be provided by e i t h e r f o r e s t e d or logged h a b i t a t s . On summer ranges, where food can be provided by e i t h e r f o r e s t e d or cutover areas, the use of these h a b i t a t s by deer w i l l depend upon s a t i s f a c t i o n of the deer's other h a b i t a t requirements (Bunnell and Eastman 1976). Although i n i t i a l l y l o g g i n g u s u a l l y r e s u l t s i n the l a c k or r e d u c t i o n of cover f o r the f i r s t 15 t o 20 years a f t e r the f o r e s t i s removed, some h a r v e s t i n g p r a c t i c e s c o u l d be employed which would provide the deer with cover. One obvious way to provide cover i n the summer ranges would be to l e a v e patches of old-growth. Since these patches are only intended to pr o v i d e cover, non-merchantable stands would s u f f i c e . Logging of low e l e v a t i o n f o r e s t s could e i t h e r b e n e f i t or c o n s t r a i n deer p o p u l a t i o n s depending upon the season i n which the e v a l u a t i o n i s made. In summer, l o g g i n g may appear b e n e f i c i a l t o deer. However, s i n c e e x t e n s i v e summer ranges already e x i s t at high e l e v a t i o n s i n the study a r e a , replacement of f o r e s t s by cutovers a t low e l e v a t i o n s may only r e s u l t i n the r e d i s t r i b u t i o n o f the deer p o p u l a t i o n . Logging i n low e l e v a t i o n f o r e s t s e s s e n t i a l l y r e s u l t s i n the p r o v i s i o n of summer ranges a d j a c e n t t o winter ranges. P r o v i s i o n of t h i s h a b i t a t may encourage an i n c r e a s e i n the p r o p o r t i o n of the r e s i d e n t component, but not n e c e s s a r i l y i n an i n c r e a s e of the t o t a l deer p o p u l a t i o n . 165 In winter, f o r e s t h a r v e s t i n g a t low e l e v a t i o n s may have a d e t r i m e n t a l e f f e c t on the deer p o p u l a t i o n (Edwards 1956, Robinson 1956, Jones 1974 and 1975, Bloom 1978). The magnitude of t h i s e f f e c t w i l l depend upon the s e v e r i t y of the winter , the f o r e s t type t h a t i s logged, and the a v a i l a b i l i t y of other winter h a b i t a t . Some low e l e v a t i o n , f o r e s t e d p l a n t a s s o c i a t i o n s p rovided l i t t l e a v a i l a b l e d i g e s t i b l e dry matter f o r deer ( F i g . 9) and were used i n c i d e n t a l l y d u r i n g winter ( F i g . 25). Logging i n these f o r e s t types should not be d e t r i m e n t a l to the deer p o p u l a t i o n and the cutovers c r e a t e d may provide f o r a g i n g areas which deer c o u l d use during low snow depth or snow-free p e r i o d s i n winter. The value of these cutovers as winter f o r a g i n g areas would be g r e a t e s t once they had reached the shrub and c o n i f e r s e r a i stages ( F i g . 9) . Other f o r e s t e d p l a n t a s s o c i a t i o n s a t low e l e v a t i o n s p r o v i d e deer with g r e a t e r d e n s i t i e s of a v a i l a b l e d i g e s t i b l e dry matter ( F i g . 9) and reduced snow depths d u r i n g p e r i o d s of deep snow i n winter. Dse of f o r e s t e d winter ranges by b l a c k - t a i l e d deer i n deep s n o w f a l l r e g i o n s was observed by Robinson (1956). He noted t h a t d u r i n g p e r i o d s with deep snowpacks, deer were i n old-growth f o r e s t s . Robinson (19 56) suggested t h a t i n deep s n o w f a l l r e g i o n s l o g g i n g of these f o r e s t e d winter ranges would be d e t r i m e n t a l to the deer p o p u l a t i o n . Edwards (1956) observed t h a t deep snow was a f a c t o r i n a d i e - o f f of b l a c k - t a i l e d deer and re c o g n i z e d the importance of f o r e s t e d winter ranges. The value of f o r e s t e d winter ranges t o b l a c k - t a i l e d deer was apparent i n the e x t e n s i v e l y logged Sayward F o r e s t where only deer i n h a b i t i n g the small patches of remaining old-growth s u r v i v e d the winter 166 (Edwards 1956). The n e c e s s i t y of old-growth f o r e s t as winter h a b i t a t f o r b l a c k - t a i l e d deer was f u r t h e r acknowledged by Cowan and Guiguet (1965) and Alaska Dept. F i s h and Game (1973). Jones (1974,1975) and Bloom (1978) were more s p e c i f i c about the types of f o r e s t h a b i t a t t h a t were used by deer d u r i n g winter. The h a b i t a t s they i d e n t i f i e d are s i m i l a r to those used by r a d i o - tagged deer i n t h i s study. In r e c e n t years p r e s e r v a t i o n o f " c r i t i c a l winter range" has taken p r i o r i t y i n deer h a b i t a t management. The assumption i s t h a t p r e s e r v a t i o n of " c r i t i c a l winter range" means p r e s e r v a t i o n of the deer p o p u l a t i o n . T h i s i s not n e c e s s a r i l y t r u e s i n c e " c r i t i c a l winter range" i s not an i s o l a t e d component of the h a b i t a t reguirements of b l a c k - t a i l e d deer and other s e a s o n a l h a b i t a t s may be important i n p r o v i d i n g deer with adequate energy r e s e r v e s with which they can s u r v i v e the winter (Mautz 1978). I t does not f o l l o w t h a t i f a l l " c r i t i c a l winter range" i s preserved then the deer p o p u l a t i o n w i l l be maintained. The importance of severe winter ranges may be overestimated because even though severe winter ranges have g r e a t e r deer d e n s i t i e s , mild winter ranges may provide the p o p u l a t i o n with a g r e a t e r t o t a l number of deer days of use. During p e r i o d s of shallow snow depths mild winter ranges can have g r e a t e r food d e n s i t i e s than some f o r e s t e d p l a n t a s s o c i a t i o n s used as severe winter range. In e v a l u a t i n g an area as winter range, c o n s i d e r a t i o n should be given to the c o n t r i b u t i o n of the h a b i t a t towards meeting the winter energy and n u t r i e n t requirements of the deer p o p u l a t i o n , and not j u s t the d e n s i t y of deer i n t h a t h a b i t a t . 167 F a i l u r e t o p r o v i d e mild winter range, may be j u s t as d e t r i m e n t a l t o the deer p o p u l a t i o n as f a i l u r e t o provide severe winter range. I f only severe winter range h a b i t a t i s provided f o r deer then during each winter they would be on t h e i r severe winter d i e t f o r the e n t i r e winter. P r o v i s i o n of mild winter ranges which would be a v a i l a b l e d u r i n g p e r i o d s of shallow snow may allow deer t o reduce t h e i r r a t e of energy l o s s or i t may even permit them to secure a p o s i t i v e energy balance, thus i n c r e a s i n g t h e i r chances of over-winter s u r v i v a l . I f mild winter ranges are not provided along with severe winter ranges, then deer would be r e s t r i c t e d to severe winter ranges f o r the e n t i r e winter. T h i s c o n c e n t r a t i o n of the deer p o p u l a t i o n could cause an o v e r - u t i l i z a t i o n o f the forage and l e a d t o a degradation of the severe winter range's c a r r y i n g c a p a c i t y . I f winter range h a b i t a t i s t o be provided f o r b l a c k - t a i l e d deer then i t must i n c l u d e areas o f both mild and severe winter range. Severe winter ranges are d e s c r i b e d by Jones (1974 and 1975) and i n the study area are p r i m a r i l y i n the S a l a l - D o u g l a s - f i r a s s o c i a t i o n . Deer used t h i s a s s o c i a t i o n type mainly dur i n g the more severe p e r i o d s i n winter. When weather was milder and snow depths s h a l l o w e r , deer l e f t the S a l a l - Douglas- f i r a s s o c i a t i o n and moved i n t o S a l a l - Western Hemlock and Ama b i l i s F i r - Western Hemlock a s s o c i a t i o n s . S i n c e deer moved from severe winter ranges d u r i n g mild p e r i o d s i t suggests t h a t mild winter ranges met t h e i r requirements b e t t e r a t these times than d i d the severe winter ranges. Stevenson (1978) has shown t h a t l i c h e n s are more abundant on mild winter ranges than on severe winter ranges. T h i s d i f f e r e n c e i n l i c h e n abundance 168 combined with g r e a t e r amounts of shrubs and c o n i f e r s and g r e a t e r area o f mild winter ranges, would provide deer with a more s u b s t a n t i a l food source than t h a t on severe winter ranges. Because o f t h e i r p o t e n t i a l as f o r a g i n g areas, mild winter ranges may be j u s t as important as severe winter ranges to the over- winter s u r v i v a l of the deer p o p u l a t i o n . 4.6. M i g r a t i o n C o r r i d o r s Jones (1975) proposed t h a t continuous s t r i p s of mature f o r e s t be maintained between s u b a l p i n e summer ranges and low e l e v a t i o n winter ranges i n order to f a c i l i t a t e downward winter migration of deer. These c o r r i d o r s are a l s o suggested by the B r i t i s h Columbia F i s h and W i l d l i f e Branch (1976) who recommend t h a t " l o n g term f i r e b r e a k - deer c o r r i d o r s " extending from v a l l e y bottoms to h e i g h t s of l a n d be e s t a b l i s h e d t o connect winter ranges with summer ranges. The p r o v i s i o n of these c o r r i d o r s i n the management of deer h a b i t a t are implemented by the B. C. F o r e s t S e r v i c e through i t s i n p u t i n t o f o r e s t h a r v e s t i n g plans (Young 1977) . R e s u l t s of t h i s study suggest t h a t the concept of "deer c o r r i d o r s " and t h e i r value i n f a c i l i t a t i n g b l a c k - t a i l e d deer m i g r a t i o n s should be re a s s e s s e d . M i g r a t i o n of some deer from t h e i r summer t o winter home ranges occurred soon a f t e r the f i r s t s n o w f a l l s . These s n o w f a l l s were ephemeral and not deep enough to prevent deer movement. S e v e r a l times d u r i n g the i n i t i a l p a r t of the winter deer moved to t h e i r winter home ranges below the snow l i n e and r e t u r n e d t o t h e i r summer home ranges a few days l a t e r when the snow melted. Great m o b i l i t y i s a l s o e v i d e n t i n t h a t 169 migratory movements were accomplished i n l e s s than 12 hours. Given the s e n s i t i v i t y t o snow by b l a c k - t a i l e d deer , the speed with which m i g r a t i o n can occur, and the s h o r t d i s t a n c e s i n v o l v e d , i t i s u n l i k e l y t h a t s u b s t a n t i a l numbers of b l a c k - t a i l e d deer would be trapped a t high e l e v a t i o n s by deep snow and thus be unable t o move to t h e i r winter ranges, i f no f o r e s t e d c o r r i d o r s e x i s t e d . S e n s i t i v i t y t o weather and e a r l y s n o w f a l l s has been r e p o r t e d i n mule deer ( R u s s e l l 1932, Leopold e t -al.. 1951, Wallmo and G i l l 1971). Although d i e - o f f s o f ungulates on winter ranges have been r e p o r t e d (Severinghaus 1947, Leopold e t a l . 1951, Longhurst e t a l . 1952, R o b i n e t t e et a l . 1952, Edwards 1956, K l e i n and Olsen 1960, Cumming and Walden 1970, Verme and Ozoga 1971), no i n s t a n c e s of mass d i e - o f f s of mule deer caused by entrapment on t h e i r summer ranges have been observed, even i n p o p u l a t i o n s where m i g r a t i o n s of over 80 km are common. The m o b i l i t y of b l a c k - t a i l e d deer and t h e i r s e n s i t i v i t y t o snow suggest t h a t p r o v i s i o n of f o r e s t e d c o r r i d o r s as migratory routes are unnecessary. I f cover f o r m i g r a t i n g deer or h a b i t a t f o r other w i l d l i f e s p e c i e s i s d e s i r e d then i t c o u l d be provided by segmented or staggered f o r e s t e d b l o c k s , or by the a p p r o p r i a t e placement and enhancement of r e s i d u a l s t r i p s . F o r e s t e d c o r r i d o r s were a l s o proposed by Jones (1975) to f u n c t i o n as mild winter range. The p o t e n t i a l f o r winter use of these c o r r i d o r s decreases with i n c r e a s i n g a l t i t u d e . I f the f u n c t i o n of c o r r i d o r s i s t o provide mild w i n t e r range then f o r e s t e d areas a l l o t t e d f o r t h i s purpose would be more e f f e c t i v e i f they were h o r i z o n t a l l y deployed and bordered severe winter 170 ranges. T h i s o r i e n t a t i o n would make mild winter ranges a c c e s s i b l e to a g r e a t e r p r o p o r t i o n of the deer p o p u l a t i o n f o r a l o n g e r time i n winter and be more b e n e f i c i a l than the present c o r r i d o r s between high and low e l e v a t i o n s . 171 5. L i t e r a t u r e ; C i t e d Adams, C.C. 1919. M i g r a t i o n as-a f a c t o r i n e v o l u t i o n : i t s e c o l o g i c a l dynamics. I I . Am. Nat. 53: 55-78. Alaska Dept. 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For e s t e d p l a n t a s s o c i a t i o n s : VS = Vaccinium - Skunk Cabbage, SC = Sword Fern - Western Red Cedar, DW = Deer Fern - Western Hemlock, WP = Western Hemlock - Plagiothecium, AW = A m a b i l i s F i r - Western Hemlock, SD = S a l a l - D o u g l a s - f i r , SW = S a l a l - Western Hemlock, AT = A m a b i l i s F i r - Twisted S t a l k , MC = Mountain Hemlock - Copperbush. Immature S e r a i Stages : N = Newly Logged, H = Herb, F = Fern, S = Shrub, C = C o n i f e r . 182 Annual Growth ( kg ha ) For . L. Various Mean Heights Of Stems < 30 cm Association or Serai Stage Plot No. 0 cm 10 cm 30 cm VS VS VS 7 20 41 974.2 666.3 136.8 1005.7 700.7 156.8 1095.6 8 0 0 . 4 209.4 SC 13 10.1 10.5 11.6 DW 19 16.3 18 .0 2 5 . 2 WP WP 3 39 t 1.1 .1 1.4 .3 2 . 8 AW AW AW AW 10 18 44 45 5.7 4 .6 261.5 154.2 6 .4 5 . 3 269.7 159.8 8 . 8 8 . 0 299.0 182.4 SD SD 2 5 297.4 575.3 359.4 643.9 521.3 823.3 sw sw sw sw sw 4 6 8 17 46 121.8 190.4 239.5 19.6 160.5 218.0 218.1 253.6 21 .4 164.4 471.8 302.0 296.O 2 8 . 6 191.5 183 _1 Annual Growth ( kg ha ) For I ^ A ^ , H A « Various Mean Heights Of Stems < 30 cm or Serai Stage Plot No. 0 cm 10 cm 30 cm AT AT AT 1 28 29 309.5 992.1 263.6 323.5 1018.0 279.4 369 .4 1104.8 331.1 MC MC 32 33 364.4 471.1 406.5 531.0 545.4 727.6 38 5.1 5.4 7.4 H H H H H H H H H H 9 11 14 15 16 21 23 24 30 31 1.5 t t .1 t 13.3 67.3 11.3 7 .2 2.7 5.7 . 3 . 3 .5 t 20.1 83.8 12.1 55.5 3 .3 21 .8 1.6 1 .3 1.7 . 2 5 2 . 9 137.9 17.2 214.0 5 . 8 12 184 Annual Growth ( kg ha ) For Various Mean Heights Of Stems < 30 cm Association or Serai Stage Plot No. 0 cm 10 cm 30 cm S S S S S S 27 34 36 37 40 43 122.8 32.8 .1 7 .4 2.9 268.7 234.0 39.6 .2 7.5 3 . 0 290.0 524.6 62 .2 .5 8.1 3 .5 361.8 C C c c c 22 25 26 35 42 12.5 257.0 306.2 195.7 139.8 12.7 469.4 461.2 515.8 141.3 14 .1 1027.2 866.3 1 3 5 L 7 1 4 6 . 7 t = trace

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