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Foraging ecology and nutrition of Stone’s sheep Seip, Dale R. 1983

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FORAGING ECOLOGY AND NUTRITION OF STONE'S SHEEP by DALE ROY SEIP B . S c , U n i v e r s i t y of Western O n t a r i o , 1976 M.Sc, Simon F r a s e r U n i v e r s i t y , 1980 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Department of F o r e s t r y ) we accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 1983 © D.R. Seip, 1983 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date DE-6 (3/81) ABSTRACT This study compared the foraging behaviour and n u t r i t i o n of Stone's sheep (Ovis d a l l i stonei) which had access to burned range to that of sheep on unburned range throughout the year. In winter, sheep were r e s t r i c t e d to areas with less than 25-30 cm of snow. For most sheep this meant windswept, alpine ridges, but one small population used a burned, subalpine slope. Grazing pressure was high on these r e s t r i c t e d winter ranges, p a r t i c u l a r l y during a severe winter, resulting in removal j of a l l the forage from alpine range, and leaving only very poor q u a l i t y forage on the subalpine range. The poor winter n u t r i t i o n was re f l e c t e d in low fecal nitrogen and DAPA level s and high Protostronqylus counts. In spring, sheep used either natural or fire-induced subalpine clearings to obtain early new plant growth. Forage quantity was much lower on unburned ranges, but b i t i n g rate and foraging time were the same as on burned ranges with high forage biomass. Quality of available forage and food intake were also s i m i l a r . The foraging behaviour of Stone's sheep appeared to be similar to domestic sheep in that intake rate was primarily dependent on grass length rather than forage density. Sheep moved to higher e l e v a t i o n s as the season pr o g r e s s e d which p r o v i d e d them with access to the high e r q u a l i t y a l p i n e forage. Regular use of m i n e r a l l i c k s i n summer a p p a r e n t l y s a t i s f i e d t h e i r sodium requirement. Grasses and sedges were the most important foods throughout the year although f o r b s and browse were important i n the summer. Adul t m o r t a l i t y r a t e s were low. Lamb pro d u c t i o n was low f o l l o w i n g severe w i n t e r s , presumably due to poor n u t r i t i o n . An e x p l a n a t i o n f o r changes i n lamb p r o d u c t i o n based on density-dependent s e l e c t i v e f e e d i n g was developed. Burned ranges were of l i m i t e d value to Stone's sheep because they were u s u a l l y u n a v a i l a b l e as winter range, d i d not p r o v i d e s u p e r i o r s p r i n g range and were not used i n summer. Horn growth, however, appeared to be s l i g h t l y b e t t e r on burned ranges. A model of n u t r i e n t i n t a k e i s developed to i n v e s t i g a t e the seasonal p a t t e r n of n u t r i t i o n on burned and unburned ranges. TABLE OF CONTENTS PAGE Abstract i i Table of Contents i - v L i s t of Tables v i i i L i s t of Figures x i i L i s t of Appendices x v i i i Acknowledgements xix Introduction 1 Stone's sheep 3 Nutrition of ruminants 4 Food s e l e c t i v i t y 6 Intake rate 7 Population condition and population dynamics .. 9 Study area 11 Methods 17 Range use patterns and group composition counts 17 Range analysis 18 S o i l analysis . 19 Fecal analysis 20 TABLE OF CONTENTS PAGE Food habits 20 Parasitology 21 Foraging behaviour 21 Capturing and measurements .... 24 Results - 26 Range use patterns 26 Winter range 26 Spring range 33 A l t i t u d i n a l migration to summer range .... 37 F a l l range 39 S p a t i a l separation of sexes 42 Forage production and biomass on Stone's sheep ranges 43 Pattern of production 43 Winter range 48 Forage q u a l i t y 51 Winter forage 51 Spring-summer forage 56 Food habits 65 Winter food habits 69 Spring food habits 71 Summer food habits 72 F a l l food habits 72 N u t r i t i o n a l indices of the sheep 73 v i TABLE OF CONTENTS PAGE Food s e l e c t i v i t y 7 9 Selection of species 7 9 Species selected against 7 9 Species selected for 80 Selection of graminoids versus forbs 80 Selection of superior q u a l i t y food 82 Mineral n u t r i t i o n 84 S o i l mineral concentrations 84 Forage mineral concentrations 86 Behaviour at mineral l i c k s 88 Mineral l i c k s 89 Foraging behaviour 91 B i t i n g rate 91 Daily pattern 91 Sex and age differences 91 Seasonal pattern 92 Foraging time 92 Length and number of foraging bouts 99 Parasitology 102 Horn growth of rams 104 Population parameters 107 Population numbers 107 Lamb and yearling counts 109 Survival rates I l l Group size • 113 TABLE OF CONTENTS PAGE Discussion H 5 Seasonal pattern of n u t r i t i o n 115 A model of food and energy intake for mountain sheep 115 Implications of the model 119 Protein n u t r i t i o n 126 Summary of seasonal n u t r i t i o n patterns . . . 126 Selective feeding 130 Range selection 130 Selection of forage species 132 Selection of superior q u a l i t y food 133 Selecting a mixed diet 134 Sexual differences in s e l e c t i v i t y 134 Summary of food s e l e c t i v i t y 136 Intake rate 137 Animal condition and growth 146 Population dynamics 148 Management of Stone's sheep 155 Conclusions 160 References Cited 163 Appendices v i i i LIST OF TABLES PAGE 1. Average c l i m a t i c data f o r Muncho Lake, B r i t i s h Columbia (1955-1978) 14 2. S p e c i e s composition (% cover) of s e v e r a l Stone's sheep s p r i n g ranges (May-June) i n n o r t h e a s t e r n B r i t i s h Columbia (1980-1982) .... 36 3. S p e c i e s composition (% cover) of s e v e r a l Stone's sheep summer ranges (June-July) i n n o r t h e a s t e r n B r i t i s h Columbia (1980-1982) .... 41 4. I_n v i t r o dry matter d i g e s t i b i l i t y (%) of graminoids and fo r b s from Stone's sheep ranges i n n o r t h e a s t e r n B r i t i s h Columbia ( 1980-1 982) 55 5. Q u a l i t y a n a l y s i s of browse s p e c i e s on Stone's sheep ranges i n s p r i n g and summer in n o r t h e a s t e r n B r i t i s h Columbia (1980-1982) .... 62 6. Food h a b i t s of Stone's sheep on unburned range i n n o r t h e a s t e r n B r i t i s h Columbia (1980-1982) determined by rumen a n a l y s i s 66 ix LIST OF TABLES PAGE 7. Food habits of Stone's sheep on subalpine burned range in northeastern B r i t i s h Columbia (1980-1982) determined by fecal analysis....... 67 8. Food habits of Stone's sheep on unburned range in northeastern B r i t i s h Columbia (1980-1982) determined by fe c a l analysis 68 9. Seasonal changes in fe c a l ash content of Stone's sheep on burned and unburned ranges in northeastern B r i t i s h Columbia (1980-1982)... 74 10. Proportion of forbs versus graminoids in the diet of Stone's sheep compared to a v a i l a b i l i t y on the range 81 11. Mineral concentrations and pH of s o i l s and mineral l i c k s in the Toad River area 85 12. Mineral concentrations in forages from Stone's sheep ranges in northeastern B r i t i s h Columbia (1980-1982) compared to requirements of domestic sheep 87 13. B i t i n g rate of Stone's sheep ewes under LIST OF TABLES PAGE di f f e r e n t range c h a r a c t e r i s t i c s (April-June)... 93 Time budget and calculated bites/day for Stone's sheep ewes and yearlings (February-May). 94 Time budget and calculated bites/day for Stone's sheep rams (February-May) 95 Protostrongylus larvae counts in feces of Stone's sheep on burned and unburned range in northeastern B r i t i s h Columbia (1982).... 103 Maximum da i l y count of sheep on F e r t i l i z e r • Mountain each month (1980-1982) 108 Number of sheep using C h u r c h i l l mine l i c k and adjacent areas in summer ( 1980-1982) 110 Lamb/ewe and yearling/ewe counts of Stone's sheep on F e r t i l i z e r Mountain and at the Chur c h i l l mine ( 1980-1982). 112 Digestible energy requirements of sheep under d i f f e r e n t physiological conditions 116 x i LIST OF TABLES PAGE 21. Protein a v a i l a b i l i t y in forage on Stone's sheep ranges compared to protein requirements of domestic sheep 128 22. Estimated foraging time of a Stone's sheep ewe in d i f f e r e n t seasons assuming a constant intake rate 141 23. Forage a v a i l a b i l i t y of several Stone's sheep ranges compared to estimated sheep requirements 144 x i i LIST OF FIGURES PAGE 1 . L o c a t i o n and map of the study area 12 2. Windswept, a l p i n e winter range i n the Yedhe area (February 1982). 27 3. Burned, subalpine winter range ( F e r t i l i z e r Mountain) i n a year of high s n o w f a l l (February 1 982), 29 4. Use of winter range (January-March) on F e r t i l i z e r Mountain i n a year of h i g h s n o w f a l l ( 1 982). 32 5. T y p i c a l unburned s p r i n g range i n Yedhe v a l l e y (May 1982) 3 4 6. Burned, subalpine s p r i n g range on Toad Mountain (May 1982) . 35 7. E l e v a t i o n of range use (mode ± range) by Stone's sheep i n n o r t h e a s t e r n B r i t i s h Columbia ( 1 980-1982) throughout the year. 38 x i i i LIST OF FIGURES PAGE 8. R e l a t i o n s h i p between t i l l e r l e n g t h of new grass (X~ ± 95% C.I.) and range use by Stone's sheep i n s p r i n g and summer 4 0 9. Seasonal p a t t e r n of graminoid p r o d u c t i o n (X ± standard d e v i a t i o n ) on Stone's sheep ranges i n n o r t h e a s t e r n B r i t i s h Columbia (1980-1982)... 4 4 10. R e l a t i o n s h i p between mean t i l l e r l e ngth and mean t i l l e r weight of grasses on Stone's sheep, s u b a l p i n e , s p r i n g ranges 4 5 11. Seasonal p a t t e r n of f o r b p r o d u c t i o n (X ± standard d e v i a t i o n ) on Stone's sheep ranges in n o r t h e a s t e r n B r i t i s h Columbia (1980-1982)... 4 7 12. Boundary between h e a v i l y grazed area and snow-covered,ungrazed area on subalpine winter range ( F e r t i l i z e r Mountain 1982) 50 13. Seasonal p a t t e r n of ADF c o n c e n t r a t i o n s i n graminoids (X ± 90% C.I.) on d i f f e r e n t Stone's sheep ranges i n n o r t h e a s t e r n B r i t i s h Columbia ( 1980-1982). 52 xiv LIST OF FIGURES PAGE 14. Seasonal pattern of crude protein concentrations in graminoids (X ± 90% C.I.) on d i f f e r e n t Stone's sheep ranges in northeastern B r i t i s h Columbia (1980-1982) 53 15. Seasonal pattern of l i g n i n concentrations in graminoids (X ± 90% C.I.) on d i f f e r e n t Stone's sheep ranges in northeastern B r i t i s h Columbia ( 1980-1 982) 54 16. Seasonal pattern of ADF concentrations in forbs (X ± 90% C.I.) on d i f f e r e n t Stone's sheep ranges in northeastern B r i t i s h Columbia ( 1980-1982) 57 17. Seasonal patterns of crude protein concentrations in forbs (X ± 90% C.I.) on di f f e r e n t Stone's sheep ranges in northeastern B r i t i s h Columbia (1980-1982) 58 18. Seasonal pattern of l i g n i n concentrations in forbs (X ± 90% C.I.) on d i f f e r e n t Stone's sheep ranges in northeastern B r i t i s h Columbia ( 1980-1982) 59 XV LIST OF FIGURES PAGE 19. Relationship between t i l l e r length and crude protein concentrations of new grasses on Stone's sheep ranges (May-July) in northeastern B r i t i s h Columbia (1980-1982) 60 20. Calculated values for dry matter d i g e s t i b i l i t y (DMD) of graminoids on di f f e r e n t Stone's sheep ranges in northeastern B r i t i s h Columbia (1980-1982) 63 21. Summary of seasonal food habits for Stone's sheep determined by fecal analysis on burned and unburned ranges in northeastern B r i t i s h Columbia (1980-1982) 70 22. Seasonal pattern of fecal protein levels (corrected for ash content) for Stone's sheep on burned and unburned ranges (X.± 95% C.I.) in northeastern B r i t i s h Columbia ( 1 980- 1 982)# # , 75 23. Seasonal pattern of DAPA concentrations for Stone's sheep on burned and unburned range in northeastern B r i t i s h Columbia (1980-1982) 78 24. Relationship between protein concentrations xvi LIST OF FIGURES PAGE of the a v a i l a b l e forage and the f e c a l p r o t e i n c o n c e n t r a t i o n s of Stone's sheep ( s t a n d a r d i z e d to 15% ash content) 83 25. R e l a t i o n s h i p between snow depth and percentage o f - f o r a g i n g time spent d i g g i n g (X ± standard d e v i a t i o n ) by Stone's sheep 98 26. T y p i c a l d a i l y time budgets of Stone's sheep ram groups compared to ewe/yearling groups i n March and May 100 27. Comparison of annual horn increments of Stone's sheep rams on burned versus unburned range CR" ± 95% C.I.) i n n o r t h e a s t e r n B r i t i s h Columbia ( 1980-1982).. 105 28. Comparison of horn l e n g t h s from t i p to annulus of Stone's sheep rams shot on burned range and unburned range (X ± 95% C.I.) i n n o r t h e a s t e r n B r i t i s h Columbia (1980-1982). 106 29. R e l a t i o n s h i p between d i g e s t i b i l i t y of the food and the d a i l y i n t a k e of sheep when d i g e s t i v e c a p a c i t y i s l i m i t i n g 118 x v i i LIST OF FIGURES P A G E 30. Relationship between d i g e s t i b i l i t y of the food and the model's prediction of maximum possible d a i l y energy intake of sheep 1 2 0 31. Seasonal pattern of da i l y energy intake and energy requirements of a 50 kg ewe predicted by the model 1 2 2 32. Relationship between body weight of sheep and the model's prediction of minimum adequate forage d i g e s t i b i l i t y adequate to meet maintenance requirements 1 2 7 33; The relationship^between d a i l y energy intake of ewes in winter and predicted values for peri-natal lamb mortality and summer lamb/ewe ra t i o (2-year-old and older ewes). 1 5 0 x v i i i LIST OF APPENDICES I. Birds and mammals sighted in the Toad River area . I I . Body weights and measurements of Stone's sheep I I I . The e f f e c t of burning and f e r t i l i z a t i o n on Stone's sheep ranges x i x ACKNOWLEDGEMENTS Dr. Fred Bunnell i n i t i a t e d t h i s project and provided guidance and support throughout. Drs. M. P i t t , J . Kimmins, A. S i n c l a i r , and L. Larson were the other members of my advisory committee. L e s l i e Gilmore, Robert Dulfer, Ray Rasker, and Andy Derocher provided f i e l d assistance. Pat M i l l s typed the thesis and Engel Rahs prepared the graphics. Dr. John E l l i o t t proposed the research problem and helped me to get started. Dr. W. Samuel provided the services of his laboratory for the parasitology analyses and Dr. T.M. Ballard provided the laboratory analyses of mineral l e v e l s . Members of the Guide O u t f i t t e r s Association of B r i t i s h Columbia, p a r t i c u l a r l y Ed-and Dave Wiens and Blaine Southwick, provided information and assistance in conducting the study. E s s e n t i a l l y everyone in the Toad River area, p a r t i c u l a r l y Bruce and Donna Powell and the Price family, regularly helped me out. My thanks to a l l of you. Funding for this work was provided by the Canadian National Sportsmen's Fund, the Guide-Outfitters Association of B r i t i s h Columbia, the Foundation for North American Wild Sheep, and the A r c t i c and Alpine Research Committee (UBC). 1 INTRODUCTION The concept of an animal p o p u l a t i o n being food l i m i t e d i m p l i e s t h a t i f the p o p u l a t i o n grows too l a r g e the animals eat most of the food, cannot f i n d enough to eat and s t a r v e to death or forego r e p r o d u c t i o n . Mountain sheep (Ovis  spp.) eat g r a s s . Because there i s u s u a l l y a l o t of grass around, i t may seem strange to suggest that mountain sheep are food l i m i t e d . Even on h e a v i l y used winter ranges, mountain sheep u s u a l l y consume onl y 50 to 80% of the standing crop of grass by the end of the winter (Luckhurst 1973, S t e l f o x 1976, Hoefs and Brink 1978). S i m i l a r l y , deer (Odocoileus spp.) are u s u a l l y surrounded by abundant amounts of browse and moose (Al c e s a l c e s ) never eat the l a s t s t a nding willow shrub. But we know that sheep and other w i l d ungulates are n u t r i t i o n a l l y s t r e s s e d , p a r t i c u l a r l y i n winter. Bighorn sheep (0. canadensis) r e g u l a r l y s u f f e r massive d i e - o f f s when o v e r g r a z i n g leads to malnourished sheep ( S t e l f o x 1976). V i a b l e lamb p r o d u c t i o n of mountain sheep i s c o r r e l a t e d with winter n u t r i t i o n (Hoefs and Brink 1978; S t e l f o x 1976) and can be improved by supplemental f e e d i n g (Ramsay 1980) or by h a r v e s t i n g ewes to reduce c o m p e t i t i o n (Smith and Wishart 1978). S i m i l a r n u t r i t i o n a l problems are known f o r other ungulates ( S i n c l a i r 1977, McCullough 1979). Yet i n almost a l l cases of n u t r i t i o n a l s t r e s s 2 there i s s t i l l food a v a i l a b l e . The problem the animal faces i s not simply to o b t a i n enough food but r a t h e r to o b t a i n enough food of s u i t a b l e q u a l i t y . I t i s w e l l known that ungulates can d i e of s t a r v a t i o n with a stomach f u l l of l o w - q u a l i t y food (Pearson 1969). The animal's e f f i c i e n c y i n o b t a i n i n g a h i g h l y n u t r i t i o u s d i e t w i l l have a major impact on i t s c o n d i t i o n and f i t n e s s . T h e r e f o r e , one would expect that animals w i l l be w e l l adapted to forage e f f i c i e n t l y . The i n t e r a c t i o n s between the range c h a r a c t e r i s t i c s and the f o r a g i n g behaviour of a s p e c i e s c o n s t i t u t e s the f o r a g i n g ecology of that s p e c i e s . ThejDptimum f o r a g i n g behaviour w i l l vary depending on the c h a r a c t e r i s t i c s of the f o r a g i n g environment. Animals should a l t e r t h e i r f o r a g i n g behaviour a c c o r d i n g l y to optimize t h e i r n u t r i t i o n a l i n t a k e . That i s the focus of t h i s t h e s i s . Range burning i s widely used i n northern B r i t i s h Columbia i n an e f f o r t t o improve w i l d l i f e h a b i t a t . F i r e c o n v e r t s subalpine spruce and poplar f o r e s t i n t o g r a s s l a n d which i s o f t e n used by Stone's sheep (0. da11i s t o n e i ) . T h i s a l t e r a t i o n of h a b i t a t provided an o p p o r t u n i t y to study how Stone's sheep modify t h e i r f o r a g i n g behaviour i n response to a change i n range c h a r a c t e r i s t i c s . In a d d i t i o n , I t r i e d to determine the e f f e c t of.range burning on the n u t r i t i o n and p o p u l a t i o n dynamics of Stone's sheep 3 p o p u l a t i o n s i n order to e v a l u a t e the b e n e f i t s of range burning f o r the management of Stone's sheep. STONE'S SHEEP Mountain sheep i n North America are d i v i d e d i n t o two s p e c i e s , the bighorns (Ovis canadensis) i n the south and the t h i n h o r n s (Ovis d a l l i ) i n the n o r t h . The t h i n h o r n s are f u r t h e r d i v i d e d i n t o two subspecies, the a l l - w h i t e D a l l ' s sheep (O.d. d a l l i ) and the dark-bodied Stone's sheep (O.d. s t o n e i ) . The two subspecies i n t e r b r e e d to produce an intermediate form know as Fannin's sheep i n the c e n t r a l Yukon where t h e i r ranges meet. Stone's sheep i n h a b i t mountainous areas of northern B r i t i s h Columbia and the southern Yukon. T h i s subspecies has been l i t t l e s t u d i e d i n the p a s t . G e i s t (1971) c o n c e n t r a t e d on the s o c i a l behaviour of these animals, Luckhurst (1973) conducted a range study and E l l i o t (1978) d i s c u s s e d the e f f e c t of range burning on horn growth of Stone's sheep. In a d d i t i o n to s t u d y i n g the f o r a g i n g ecology of these animals, the present study p r o v i d e d an o p p o r t u n i t y to l e a r n more about the g e n e r a l ecology of t h i s important big-game animal. 4 NUTRITION OF RUMINANTS Stone's sheep are ruminants. An understanding of the f o r a g i n g ecology of the s p e c i e s i s impossible u n l e s s one c o n s i d e r s both the advantages and the c o n s t r a i n t s that being a ruminant e n t a i l s . The major advantage of being a ruminant i s the a b i l i t y t o d i g e s t h e m i c e l l u l o s e and c e l l u l o s e i n p l a n t m a t e r i a l that would be l a r g e l y u n d i g e s t i b l e f o r a non-ruminant. In a d d i t i o n , the rumen m i c r o f l o r a can manufacture u s e f u l p r o t e i n s from r e c y c l e d n i t r o g e n wastes and a l s o produce v a r i o u s e s s e n t i a l v i t a m i n s f o r the animal (Church 1980). The l i m i t i n g f a c t o r t o the e f f i c i e n c y of the ruminant d i g e s t i v e system i s the r a t e a t which food can be processed. The maximum forage intake i n ruminants i s l i m i t e d by the passage r a t e through the gut ( B l a x t e r et a l . 1961, Conrad et a l . 1964). Passage rate through the gut i s r e l a t i v e l y c o n s t a n t but d e c l i n e s somewhat when more f i b r o u s forage i s consumed ( P h i l l i p s o n and Ash 1965). Because passage r a t e i s r e l a t i v e l y c onstant, the onl y way that i n t a k e can i n c r e a s e i s f o r more of the food to be d i g e s t e d . The gross energy content of most forages i s r e l a t i v e l y c onstant and averages 4.4 kcal/gm (Maynard et a l . 1979). How much of t h i s c a l o r i c energy i s usable by the animal depends on how d i g e s t i b l e the forage i s because there i s a 5 near 1:1 r e l a t i o n s h i p between dry matter d i g e s t i b i l i t y and energy d i g e s t i b i l i t y (Moir 1961). Because forage d i g e s t i b i l i t y i n f l u e n c e s both the maximum forage i n t a k e and the d i g e s t i b l e energy content of that food, changes i n d i g e s t i b i l i t y have a m u l t i p l i c a t i v e e f f e c t on the animal's energy i n t a k e . T h e r e f o r e , data on the d i g e s t i b i l i t y of forage allow us to make important p r e d i c t i o n s about the n u t r i e n t intake of ruminants. One o b j e c t i v e of t h i s study was to c o l l e c t forage samples throughout the year f o r d i g e s t i b i l i t y and p r o t e i n a n a l y s e s . Because g r a z i n g animals feed s e l e c t i v e l y , q u a l i t y a n a l y s i s of a v a i l a b l e herbage may not represent the q u a l i t y of the food that the animal a c t u a l l y e a t s . I t i s a very f r u s t r a t i n g task to d e c i d e what items of the t o t a l p l a n t biomass are a c t u a l l y food f o r Stone's sheep. I t i s much more s a t i s f a c t o r y i f one can measure the q u a l i t y of the food a c t u a l l y s e l e c t e d by the animal. I attempted t h i s by a n a l y s i n g f e c a l samples f o r p r o t e i n and d i a m i n o p i m e l i c a c i d (DAPA) content, two v a r i a b l e s which are c o r r e l a t e d with the q u a l i t y of food consumed by a ruminant (Hebert 1973; Nelson et a l . 1982). T h i s i n f o r m a t i o n d e s c r i b e s the seasonal p a t t e r n of food q u a l i t y . Comparison of forage q u a l i t y , f e c a l p r o t e i n , and DAPA l e v e l s between burned and unburned ranges p r o v i d e d a t e s t of the hypotheses: 6 i ) Forage q u a l i t y ( d i g e s t i b i l i t y and p r o t e i n ) i s s u p e r i o r on burned ranges. i i ) Sheep fee d i n g on burned ranges have a higher q u a l i t y of food intake than sheep using unburned ranges. A n a l y s i s of mineral c o n c e n t r a t i o n s i n forage and s o i l s was a l s o conducted i n an e f f o r t t o determine i f the sheep encountered any s e r i o u s mineral d e f i c i e n c i e s . M i n e r a l l i c k behaviour was s t u d i e d to see how the animals d e a l t with the problem of mineral n u t r i t i o n . FOOD SELECTIVITY Ungulates s e l e c t i v e l y feed on those items which are most n u t r i t i o u s f o r them. T h i s s e l e c t i v i t y occurs at s e v e r a l d i f f e r e n t l e v e l s : i ) s e l e c t i o n of range, i i ) s e l e c t i o n of p a r t i c u l a r p l a n t s on that range, i i i ) s e l e c t i o n of p l a n t p a r t s (Jarman and S i n c l a i r 1979). Ruminants are more e f f i c i e n t at s e l e c t i n g a n u t r i t i o u s d i e t when f r e e - r a n g i n g than when presented with processed r a t i o n s ( B a i l e and Forbes 1974). T h i s o b s e r v a t i o n i n d i c a t e s that the animals do not de t e c t the n u t r i e n t q u a l i t y d i r e c t l y but ra t h e r d e t e c t cues which are p o s i t i v e l y c o r r e l a t e d with q u a l i t y such as low f i b r e content or new growth versus dead m a t e r i a l . A r n o l d (1966) 7 demonstrated that smell and t a s t e are the most important senses used i n s e l e c t i v e f e e d i n g by sheep. I examined s e l e c t i v e f e e d i n g of Stone's sheep by o b s e r v i n g seasonal p a t t e r n s of range use and by comparing food h a b i t s with s p e c i e s a v a i l a b i l i t y . T h i s i n f o r m a t i o n , i n c o n j u n c t i o n with forage q u a l i t y data, was used to t e s t the h y p o t h e s i s : i i i ) Stone's sheep s e l e c t ranges and food items which p r o v i d e the best n u t r i t i o n a v a i l a b l e . E stimates of food q u a l i t y based on f e c a l p r o t e i n a n a l y s e s were compared to forage q u a l i t y to t e s t the h y p o t h e s i s : i v ) Q u a l i t y of food eaten i s s u p e r i o r to the average q u a l i t y of a v a i l a b l e herbage due to s e l e c t i v e f e e d i n g . INTAKE RATE In a d d i t i o n t o s e l e c t i n g h i g h q u a l i t y food, the g r a z i n g ungulate must a l s o maintain an adequate intake r a t e . Presumably there i s an i n v e r s e r e l a t i o n s h i p between s e l e c t i v i t y and i n t a k e r a t e . An animal s e l e c t i n g only h i g h q u a l i t y items w i l l probably have a lower intake r a t e than an animal f e e d i n g n o n - s e l e c t i v e l y , and an animal t h a t i s too s e l e c t i v e may not be a b l e to o b t a i n enough food. 8 T h e r e f o r e , the animal should modify i t s f o r a g i n g behaviour to achieve the optimum t r a d e - o f f between these two f a c t o r s . Optimum f o r a g i n g theory (Schoener 1971) would p r e d i c t t h a t : v) Sheep feed i n such a way as to maximize t h e i r net energy intake r a t e . The optimum s t r a t e g y w i l l vary with d i f f e r e n t range c o n d i t i o n s and may vary with sex and body s i z e of i n d i v i d u a l s . T e s t i n g t h i s h y p o t h e s i s r e q u i r e s i n f o r m a t i o n on f a c t o r s i n f l u e n c i n g the intake r a t e of sheep. I t may seem l o g i c a l t h a t intake r a t e would go up as the q u a n t i t y of forage i n c r e a s e s . However, i n g r a z i n g domestic sheep, intake r a t e remains constant over a wide range of p l a n t d e n s i t i e s but i s g r e a t l y i n f l u e n c e d by grass t i l l e r l e n g t h which determines the b i t e s i z e ( A l l d e n and Whittaker 1970). I t i s not p o s s i b l e to measure d i r e c t l y the i n t a k e r a t e of f r e e - r a n g i n g w i l d ungulates. D e t a i l e d s t u d i e s of ungulate f o r a g i n g behaviour w i l l probably have to r e l y on c a p t i v e or semi-tame animals. However, there are some components of the f o r a g i n g behaviour of f r e e - r a n g i n g animals t h a t can be measured and which we would expect to be r e l a t e d to intake r a t e . I recorded b i t i n g r a t e and d a i l y f o r a g i n g time of sheep under d i f f e r e n t range types 9 and c o n d i t i o n s t o t e s t some hypotheses r e l a t i n g t o the e f f e c t of range c h a r a c t e r i s t i c s and range burning on intake r a t e : v i ) F o r a g i n g time and b i t i n g r a t e a re r e l a t e d t o forage q u a n t i t y and/or grass t i l l e r l e n g t h . v i i ) F o r a g i n g time i s l e s s and b i t i n g r a t e of sheep i s h i g h e r on burned range than on unburned range. The i n f o r m a t i o n on f o r a g i n g r a t e s was i n t e g r a t e d with the forage q u a l i t y data and e v a l u a t e d i n the context of the optimal f o r a g i n g hypothesis i . e . , maximization of net energy i n t a k e r a t e . POPULATION CONDITION AND POPULATION DYNAMICS If food l i m i t a t i o n of sheep p o p u l a t i o n s does not mean that the animals eat a l l the food, what does i t mean? Heavy s e l e c t i v e g r a z i n g by sheep can g r a d u a l l y degrade the q u a l i t y of the remaining forage on the range i n a d e n s i t y -dependent manner (Arnold 1960a). The process w i l l be most pronounced d u r i n g the non-growing season when grazed v e g e t a t i o n i s not being r e p l a c e d by new growth. For mountain sheep at normal p o p u l a t i o n d e n s i t i e s , winter i s probably the only time when g r a z i n g can s i g n i f i c a n t l y . degrade the a v a i l a b l e forage q u a l i t y . In t h i s study data were c o l l e c t e d t o t e s t the h y p o t h e s i s : 10 v i i i ) S e l e c t i v e g r a z i n g by Stone's sheep i n winter removes hi g h q u a l i t y forage and thereby degrades the q u a l i t y of the range that w i n t e r . Ungulates faced with a p r o g r e s s i v e l y d e t e r i o r a t i n g food source would be f o r c e d to s e l e c t a p r o g r e s s i v e l y poorer d i e t . Below a c e r t a i n forage d i g e s t i b i l i t y the animal would be unable to compensate by e a t i n g more because of gut c a p a c i t y . The r e s u l t a n t decrease i n n u t r i e n t i n t a k e would be expected to have a n e g a t i v e e f f e c t on the growth r a t e s , c o n d i t i o n , and p o p u l a t i o n dynamics of the animals. For Stone's sheep I attempted to t e s t the hypotheses: ix) Horn and body growth, lamb p r o d u c t i o n , and p a r a s i t e l e v e l s are r e l a t e d to winter n u t r i t i o n . x) Horn growth, body growth, and lamb p r o d u c t i o n are g r e a t e r and p a r a s i t e l e v e l s are lower i n sheep using burned range compared to sheep using unburned range. STUDY AREA The study was conducted i n the v i c i n i t y of Toad R i v e r , B r i t i s h Columbia (59°N, 125°W) near M i l e 422 of the Alaska Highway (F i g u r e 1). The study area i n c l u d e d p a r t s of the Muskwa Range and the Stone Range of the northern Rocky Mountains and extended i n t o the Rocky Mountain f o o t h i l l s . Geology of the area was d i s c u s s e d by T a y l o r and S t o t t (1973). The area i s composed of bands of f o l d e d and f a u l t e d sedimentary rocks ( s h a l e s , conglomerates, sandstones, and limestones) ranging i n age from Precambrium i n the southwest t o T r i a s s i c i n the n o r t h e a s t . The Precambrium formations i n the southwestern p a r t of the study area c o n t a i n numerous igneous d i k e s , one of which was the s i t e of a now abandoned copper mine. Topography ranges from steep, p r e c i p i t o u s , g l a c i e r -topped peaks in the southwest to more r o l l i n g country i n the n o r t h e a s t . E l e v a t i o n s range from 750 m to 2,500 m. Mountains have been e x t e n s i v e l y g l a c i a t e d and e x h i b i t c i r q u e s and U-shaped v a l l e y s . T a l l u s slopes and a l l u v i a l fans c r e a t e numerous open areas along f o r e s t e d s l o p e s . S o i l s i n the area were d e s c r i b e d by V a l e n t i n e et a l . (1978). G e n e r a l l y the v a l l e y bottoms c o n t a i n d y s t r i c and e u t r i c b r u n i s o l s , f o r e s t e d mountain slopes are composed of humo-ferric podzols and the a l p i n e peaks have r e g o s o l s o i l s . 12 Figure 1. Location and map of the study area. Elevations in meters. 13 There i s a permanent weather s t a t i o n maintained by the F e d e r a l Government w i t h i n the study area at Muncho Lake. Long term, average weather data are summarized i n Table 1. The b i o g e o c l i m a t i c zones ( K r a j i n a 1976) of the area i n c l u d e the B o r e a l White and Black Spruce Zone which extends up to about 1400 m, the Spruce-Willow-Birch Zone between 1400 and 1600 m, and the A l p i n e Tundra Zone above 1600 m. White spruce (Picea qlauca) and black spruce (P. mariana) form the climax f o r e s t type at low e l e v a t i o n s , but f i r e has induced the establishment of lodgepole pine (Pinus c o n t o r t a ) , p o p l a r s (Populus  tremuloides and P. b a l s a m i f e r a ) and/or g r a s s l a n d i n many areas depending on the f i r e frequency (Parminter 1981). Bearberry ( A r c t o s t a p h y l o s u v a - u r s i ) and mountain c r a n b e r r y (Vaccinium v i t i s - i d a e a ) are common ground cover at low e l e v a t i o n , and Labrador tea (Ledum groenlandicum), b u f f a l o - b e r r y (Sheperdia c a n a d e n s i s ) , high-bush c r a n b e r r y (Viburnum e d u l e ) , willows ( S a l i x spp.), a l d e r s (Alnus  spp.), and rose (Rosa a c i c u l a r i s ) are common shrubs. The Spruce-Willow-Birch Zone i s a t r a n s i t i o n zone from spruce f o r e s t t o a shrubby zone dominated by scrub b i r c h ( B e t u l a glandulosa) and w i l l o w s . The A l p i n e Zone i s dominated by mountain avens (Dryas i n t e g r i f o l i a ) , sedges (Carex spp.), n e t - v e i n e d willow ( S a l i x r e t i c u l a t a ) , and Table 1. Average climatic data for Muncho Lake, British Columbia (1955-1978). Month J F M Daily Maximum Temperature * -13.0 -7.3 -2.0 Daily Minimum Temperature -24.4 -19.8 -16.3 Average Daily Temperature -18.7 -13.6 -9.2 Rainfall** 0.9 0.0 0.4 Snowfall 27.4 27.0 17.0 Total Precipitation 35.2 33.3 19.9 Days with Precipitation 12 9 9 * temperatures in C. **rain and snow in mm of water A M J J A 6.7 13.4 18.2 20.2 18.7 6.1 0.6 5.7 7.7 6.1 0.3 7.1 12.0 14.0 12.5 0.8 35.7 59.7 78.0 58.3 6.1 4.7 0.4 1.0 0.0 6.8 43.0 60.2 79.4 58.3 4 7 11 13 13 S 0 N D Total 13.6 6.9 -2.5 -10.1 -2.1 -2.9 -12.2 -20.6 -7.9 2.1 -7.4 -15.4 -38.5 15.5 5.7 0.4 293.9 0.9 9.8 21.2 28.6 144.1 39.0 23.8 27.3 32.8 459.0 13 10 9 10 120 15 numerous l i c h e n s and f o r b s . T h i s zone i s d i s c u s s e d i n d e t a i l i n the r e s u l t s s e c t i o n . A p a r t i a l p l a n t c o l l e c t i o n f o r the area was made by Gilmore (1981) and i s l o c a t e d i n the U n i v e r s i t y of B r i t i s h Columbia herbarium. A more complete c o l l e c t i o n by A. Chiska i n 1982 i s l o c a t e d i n the B.C. P r o v i n c i a l Museum Herbarium. Sheep p o p u l a t i o n s i n p a r t s of the Toad R i v e r , Racing R i v e r , and Sulphur Creek area ( F i g u r e 1) have access to e x t e n s i v e areas of burned range. Sulphur Creek v a l l e y was i n t e n t i o n a l l y burned by the B.C. F i s h and W i l d l i f e Branch i n 1978. A n a l y s i s of f i r e s c a r s on t r e e s i n d i c a t e d that the Toad and Racing R i v e r v a l l e y s have experienced r e g u l a r f i r e s over the past 80 years at an i n t e r v a l of about every 9 years (Parminter, p e r s . comm.). Most of these f i r e s were i n t e n t i o n a l l y s t a r t e d to c r e a t e rangeland and s e v e r a l f i r e s were s t a r t e d d u r i n g the course of t h i s p r o j e c t . Sheep i n the Yedhe and Delano v a l l e y area are p r i m a r i l y found on unburned range except f o r a small (5 km2) recent burn i n the Delano v a l l e y . Otherwise the area shows no evidence of f i r e f o r at l e a s t the past 120 years (Parminter, p e r s . comm.). Other l a r g e ungulates i n the study area i n c l u d e moose (A l c e s a l c e s ) , c a r i b o u (Ranqifer tarandus), e l k (Cervus  c a n a d e n s i s ) , mule deer (Odocoileus hemionus), and mountain 16 goats (Oreamos americanus). A b i r d and mammal l i s t i s located in the Appendices. 17 METHODS RANGE USE PATTERNS AND GROUP COMPOSITION COUNTS Sheep were r e g u l a r l y l o c a t e d by h i k i n g and c l i m b i n g throughout the area. These o b s e r v a t i o n s were supplemented with s e v e r a l h e l i c o p t e r and fixed-wing surveys throughout the season: May, 1980 f i x e d wing August, 1980 h e l i c o p t e r March, 1981 f i x e d wing A p r i l , 1981 f i x e d wing J u l y , 1981 h e l i c o p t e r October, 1981 h e l i c o p t e r February, 1982 h e l i c o p t e r A p r i l , 1982 f i x e d wing November, 1982 f i x e d wing Conversations with l o c a l r e s i d e n t s , o u t f i t t e r s , and John E l l i o t t of B.C. F i s h and W i l d l i f e Branch were h e l p f u l i n l e a r n i n g where to l o c a t e the sheep. Counts and l o c a t i o n s of sheep were recorded along with as complete a c l a s s i f i c a t i o n as was p o s s i b l e under s p e c i f i c c o n d i t i o n s . For the unburned area, I used only lamb:yearling:ewe r a t i o s which were c o l l e c t e d i n J u l y at a major m i n e r a l l i c k ( C h u r c h i l l mine) where a l a r g e sample s i z e c o u l d be observed r e p e a t e d l y ( F i g u r e 1). For the 18 burned range, the only composition counts i n which I had c o n f i d e n c e were winter counts which c o u l d be taken r e p e a t e d l y from a group which remained on the same slope ( F e r t i l i z e r Mountain) throughout winter and s p r i n g . The winter count was a l s o the only one f o r which I c o u l d be c o n f i d e n t that the counted sheep had used burned range i n w i n t e r . For counts on a l p i n e summer range i t was im p o s s i b l e t o know where the sheep had wintered. RANGE ANALYSIS Forage biomass of ranges was measured by c l i p p i n g a l l the p l a n t m a t e r i a l from 6-10 randomly s e l e c t e d p l o t s . Most p l o t s were 0.25 m2 but o c c a s i o n a l l y 1 m2 p l o t s were used i n a l p i n e areas with very low biomass. The samples were s o r t e d i n t o l i v e f o r b s , l i v e graminoids, and standing dead m a t e r i a l and then a i r d r i e d f o r s e v e r a l days u n t i l a constant weight was maintained. These samples were weighed to the nearest 0.1 g. Some samples (n = 53) were then oven-dried at 100°C and then weighed. From t h i s i n f o r m a t i o n a c o r r e c t i o n f a c t o r equal to 92.5% ± 0.41 (SE) was c a l c u l a t e d t o convert a i r dry weight i n t o oven dry weight. T i l l e r l e n g t h of grasses and sedges was measured by randomly s e l e c t i n g 10 or more i n d i v i d u a l t i l l e r s and measuring to the nearest mm the l e n g t h from the ground to 19 the t i p of the longest l e a f . S p e c i e s composition of ranges was measured by a m o d i f i e d p o i n t t r a n s e c t method. A p o i n t e r was dropped at random i n t e r v a l s along a t r a n s e c t and the p l a n t s p e c i e s h i t by the p o i n t e r was recorded. The procedure was continued f o r 50-100 p o i n t s / t r a n s e c t . The procedure was repeated u n t i l the average of the pooled data f o r a l l the t r a n s e c t s s t a b i l i z e d and a d d i t i o n a l t r a n s e c t s had no great e f f e c t on the average v a l u e s . Samples of graminoids, f o r b s , and browse were c o l l e c t e d throughout the season f o r q u a l i t y a n a l y s i s . Only leaves were c o l l e c t e d from browse p l a n t s but f o r graminoid and f o r b samples, a l l the p l a n t p a r t s were i n c l u d e d . Samples were a i r d r i e d f o r storage. I_n v i t r o d i g e s t i b i l i t y , proximate a n a l y s i s , and p r o t e i n a n a l y s i s was conducted by the W i l d l i f e H a b i t a t Lab., Washington St a t e U n i v e r s i t y , Pullman. I_n v i t r o d i g e s t i b i l i t y was determined by the two-stage T i l l e y and T e r r y (1963) method u t i l i z i n g rumen f l u i d from domestic sheep. M i n e r a l a n a l y s i s of forage samples was done by the Department of S o i l Science, U n i v e r s i t y of B r i t i s h Columbia. 20 c o l l e c t e d . A n a l y s i s was c a r r i e d out by the Department of S o i l S c i e n c e s , U n i v e r s i t y of B r i t i s h Columbia. Exchangeable Ca, Mg, and K were determined by d e s o r p t i o n in 1 N N H 2OAc. T o t a l carbon was determined using the Walkley-Black technique and phosphorous was determined using the Bray technique. FECAL ANALYSIS F e c a l samples were a i r d r i e d a f t e r c o l l e c t i o n . N i t r o g e n , ash, and DAPA a n a l y s i s was done at the W i l d l i f e H a b i t a t Lab., Pullman. DAPA i s a peptide found i n the c e l l w a l l s of rumen b a c t e r i a that i s not absorbed by ruminants. The amount of DAPA i n the feces i s thus r e l a t e d to the r a t e of rumen m i c r o b i a l a c t i o n and c o r r e l a t e d with d i g e s t i b l e energy intake (Nelson et a l . 1982). FOOD HABITS Food h a b i t a n a l y s i s i n c l u d e d f e c a l fragment a n a l y s i s , rumen a n a l y s i s , and d i r e c t o b s e r v a t i o n . The rumen samples were c o l l e c t e d from 5 animals that d i e d from a c c i d e n t s . Rumen samples were s t o r e d i n f o r m a l i n and f e c a l samples were a i r d r i e d . A n a l y s i s of rumen and f e c a l samples was done at the W i l d l i f e H a b i t a t Lab., Pullman. The technique f o r both rumen and f e c a l samples i n v o l v e s p r e p a r i n g a 21 Rumen samples were s t o r e d i n f o r m a l i n and f e c a l samples were a i r d r i e d . A n a l y s i s of rumen and f e c a l samples was done a t the W i l d l i f e H a b i t a t Lab., Pullman. The technique for both rumen and f e c a l samples i n v o l v e s p r e p a r i n g a s l i d e from a s o l u t i o n of the m a t e r i a l , s t a i n i n g the s l i d e , and i d e n t i f y i n g p l a n t m a t e r i a l at 300 random p o i n t s on the s l i d e u s i n g c h a r a c t e r i s t i c s of epidermal t i s s u e . For d e t a i l s see Nelson and D a v i t t (undated). In a d d i t i o n , some i n f o r m a t i o n on food h a b i t s was c o l l e c t e d by observing sheep f e e d i n g . I t was u s u a l l y very d i f f i c u l t to see what an animal was e a t i n g when i_t was g r a z i n g but i t was easy to determine which p l a n t s were being browsed. PARASITOLOGY F e c a l samples were c o l l e c t e d from burned and unburned ranges i n mid-winter and e a r l y s p r i n g . 1 Samples were a i r d r i e d f o r storage. P a r a s i t e counts were done by the l a b of Dr. W. Samuels, U n i v e r s i t y of A l b e r t a , Edmonton using the Baermann technique f o r recovery of f i r s t - s t a g e l a r v a e . FORAGING BEHAVIOUR Time budget i n f o r m a t i o n was c o l l e c t e d by scanning the p o p u l a t i o n every 5 or 10 minutes and r e c o r d i n g the behaviour of each i n d i v i d u a l . Observations were made at 22 d i s t a n c e s ranging from 500 m to 5 km using 20-40X t e l e s c o p e s . Observations extended from dawn to dusk. Days with incomplete data caused by l o s i n g s i g h t of the animals f o r long p e r i o d s of time were excluded from a n a l y s i s . Loss of v i s i b i l i t y was r e g u l a r l y caused by weather or animal movement. Most scans were done at a 5-minute i n t e r v a l except f o r s e v e r a l done i n the winter of 1982 when I was doing daylong scans alone and i t was too c o l d to maintain a 5-minute i n t e r v a l . For most scans, two observers worked a l t e r n a t i n g 2-hour s h i f t s . On each scan, behaviour of each i n d i v i d u a l was c l a s s e d as: i ) f o r a g i n g : head down and f e e d i n g or d i g g i n g f o r food w i t h i n approximately 3 seconds of s p o t t i n g the animal. i i ) r e s t i n g : l y i n g down, o f t e n ruminating. i i i ) s t a n d i n g : standing with head up f o r more than 3 seconds a f t e r being s p o t t e d . i v ) t r a v e l l i n g : head up and moving f o r more than 3 seconds a f t e r being s p o t t e d . These four behaviours accounted f o r the v a s t m a j o r i t y of the o b s e r v a t i o n s . Other a c t i v i t i e s (e.g., s o c i a l i n t e r a c t i o n s , comfort movements) comprised an i n s i g n i f i c a n t amount of time i n the day of a Stone's 23 sheep. Behaviour of rams was recorded s e p a r a t e l y from behaviour of ewes and y e a r l i n g s . Ewe and y e a r l i n g data were aggregated because these c l a s s e s o c c u r r e d together i n fee d i n g groups and i t was not always p o s s i b l e to d i s t i n g u i s h a c c u r a t e l y between the two c l a s s e s given the o b s e r v a t i o n c o n d i t i o n s and time c o n s t r a i n t s imposed by m a i n t a i n i n g a 5-minute scanning i n t e r v a l . In winter, a l a r g e p a r t of the f o r a g i n g time was spent d i g g i n g through the snow. Digging time i n d i f f e r e n t snow depths was measured by observing i n d i v i d u a l sheep f o r 3-4 minute f o r a g i n g p e r i o d s and r e c o r d i n g the amount of time spent d i g g i n g . Snow depth was estimated by comparing the snow l e v e l to nearby sheep used f o r s c a l e ( G e i s t 1971). B i t i n g r a t e was determined by o b s e r v i n g an i n d i v i d u a l ewe f o r a g i n g f o r repeated 1-2 minute i n t e r v a l s and co u n t i n g the number of b i t e s taken. A b i t e was i d e n t i f i e d by a d i s t i n c t j e r k i n g motion of the sheep's head which accompanied each b i t e . The counts were recorded on a tape recorder and t r a n s c r i b e d l a t e r . F oraging behaviour recorded d u r i n g time budget o b s e r v a t i o n s i n c l u d e d s e a r c h i n g and chewing i n a d d i t i o n to a c t u a l f e e d i n g time. The p r o p o r t i o n of time a c t u a l l y spent f e e d i n g was determined from the b i t i n g r a t e tapes by t i m i n g the time spent b i t i n g compared to the t o t a l f o r a g i n g time. 24 I n i t i a l l y , b i t i n g r a t e was recorded once every 5 minutes f o r the same sheep throughout the e n t i r e day. However, a n a l y s i s of these data showed no s i g n i f i c a n t change throughout the day or during a f o r a g i n g bout (see R e s u l t s ) . T h e r e f o r e , f o r subsequent counts, the o b s e r v a t i o n s were made over approximately a one hour p e r i o d around mid-day. CAPTURING AND MEASUREMENTS The only p l a c e that I c o n s i d e r e d a f e a s i b l e l o c a t i o n to capture sheep was an abandoned copper mine s i t e which was e x t e n s i v e l y used by sheep as a m i n e r a l l i c k i n summer. In excess of 100 sheep used t h i s area i n June and J u l y and were q u i t e easy to approach. Sheep were captured i n l a t e June and e a r l y J u l y of 1981 and 1982. In 1981 a cage t r a p was c o n s t r u c t e d of lumber and f i s h i n g net. The t r a p door was h e l d up by a rope which c o u l d be r e l e a s e d by hand to drop the door. The t r a p was b a i t e d with s a l t . Captured sheep were manually r e s t r a i n e d and b l i n d f o l d e d . Measurements of hind foot l e n g t h , chest g i r t h , chest h e i g h t , shoulder h e i g h t , and horn l e n g t h were taken f o r a l l animals. Lambs and y e a r l i n g s were weighed by suspending them from a s p r i n g balance, but a d u l t ewes s t r u g g l e d too much to be handled e a s i l y . Numbered c o l l a r s were atta c h e d to a d u l t ewes. 25 In 1982 sheep were captured in rope leg snares. Rope snares were laid out on the ground and sheep were baited into the area with salt. When one stepped into the noose the rope was pulled up by hand thereby catching the leg. The sheep were then wrestled to the ground. Measurements were taken as in 1981 except that adult ewes were tranquilized with 1 ml (4 mg/kg) of Rompun (xylazine hydrochloride) to allow weighing. Horn growth data were obtained from B.C. Fish and Wildlife Branch compulsory reporting forms for hunter killed sheep in the area from 1976-1981. 26 RESULTS RANGE USE PATTERNS WINTER RANGE Most Stone's sheep i n the study area used windswept mountain peaks and r i d g e s as winter range ( F i g . 2 ) . Surveys of the Yedhe, Delano, and Racing R i v e r areas i n February 1982, March 1981, and A p r i l 1982 found almost a l l the sheep (n = 140) to be using such ranges. These ranges were at e l e v a t i o n s ranging from 1500 to 2200 m. The primary c h a r a c t e r i s t i c of these areas appeared to be t h e i r tendency to be blown f r e e of snow. Such h a b i t a t s appeared to be q u i t e l i m i t e d . In a survey area exceeding 1000 km2, a l l the sheep l o c a t e d were u s i n g a t o t a l of l e s s than 3 km 2. Most areas that were blown c l e a r of snow and appeared to be s u i t a b l e c o n t a i n e d sheep or sheep t r a c k s . No sheep were l o c a t e d on slopes with high snow accumulations. The one example of t r a c k s i n such areas was a s i n g l e - f i l e t r a i l through a v a l l e y l e a d i n g from one windswept peak to another. In March of 1981, 5 sheep were spo t t e d i n the Delano burn u s i n g areas that had melted c l e a r of snow. However, i n the winter of 1982, no sheep or t r a c k s were seen i n the Delano burn, presumably due to high snow accumulation (> 1 m). Figure 2. Windswept, alpine winter range in the Yedhe area (February 1982). 28 The Toad V a l l e y c o n t a i n s l a r g e areas of f i r e - i n d u c e d , s u b a l p i n e g r a s s l a n d . In March of 1981, these subalpine s l o p e s were snow-free and were used by about 40 sheep. However, i n the winter of 1982 ( J a n u a r y - A p r i l ) , most of these s l o p e s were snow-covered and unused by the sheep. Rather, the sheep were r e g u l a r l y s p o t t e d (102 s i g h t i n g s ) u s i n g the windswept peak of Toad Mountain. S i m i l a r l y , i n the Sulphur Creek v a l l e y , the l a r g e areas of burned range were snow-covered and unused and the sheep were l o c a t e d (n = 11) on the snow-free peaks of adjacent mountains. The exc e p t i o n was one slope on F e r t i l i z e r Mountain which was a s u b a l p i n e , burned slope which remained p a r t i a l l y snow-free throughout the winter due to i t s p a r t i c u l a r combination of steepness, s o u t h - f a c i n g aspect, and p a r a l l e l o r i e n t a t i o n and exposure to the p r e v a i l i n g winds ( F i g . 3). T h i s small snow-free area of about 5 h e c t a r e s supported about 33 sheep throughout the w i n t e r . Thus, the general p a t t e r n of winter range use was that Stone's sheep sought out low-snow or snow-free areas and avoided deep snow are a s . In most p l a c e s t h i s meant using h i g h windswept mountain peaks. Low e l e v a t i o n s l o p e s , i n c l u d i n g burned s l o p e s , were g e n e r a l l y u n a v a i l a b l e as winter range due to h i g h snow accumulation except i n low-snowfall years or i n a t y p i c a l l o c a t i o n s . When f l y i n g over Stone's sheep country i n winter, the o v e r a l l impression was of immense 29 F igu re 3 . Bu rned , suba lp ine w i n t e r range ( F e r t i l i z e r Mountain) i n a y e a r o f h i gh s n o w f a l l (February 1982) . 30 areas of empty, barren mountains covered i n deep snow with the sheep r e s t r i c t e d to s m a l l , s c a t t e r e d patches of d e s o l a t e , snow-free mountain-tops. The v e g e t a t i o n atop the wind-swept, a l p i n e peaks used as winter range was very sparse and l a r g e l y composed of l i c h e n s ( A l e c t o r i a spp., C e t r a r i a spp., C l a d i n a spp.), sedges (Carex spp.) and some grass e s ( p r i m a r i l y Festuca  a l t a i c a and Poa spp.). The v e g e t a t i o n on the s u b a l p i n e , burned s l o p e s was p r i m a r i l y ryegrass (Elymus innovatus) with l e s s e r amounts of other g r a s s e s (Aqropyron, Poa) and f o r b s ( A r t e m i s i a f r i g i d a , O x y t r o p i s spp., V i c i a spp.). The e f f e c t of snow on sheep d i s t r i b u t i o n was most e a s i l y observed on F e r t i l i z e r mountain which was v i s i b l e from my camp. In 1982 the slope was used by approximately 26 sheep. For most of the time a f t e r I a r r i v e d i n l a t e February the e n t i r e slope was snow-free and sheep ranged over the e n t i r e area (115 s i g h t i n g s ) . When the slope was snow-covered f o r 2 days f o l l o w i n g a snowstorm i n e a r l y A p r i l a l l the sheep r e s t r i c t e d t h e i r a c t i v i t y to small areas of the t o t a l range, p r i m a r i l y along rocky outcrops and c l i f f edges on which snow shedding and m e l t i n g was a c c e l e r a t e d . Use of the e n t i r e range resumed immediately a f t e r snow melt. In the winter of 1982 most of the slope was covered i n deep snow except f o r a small area that remained blown c l e a r of snow. One c o u l d see bare exposed 31 ground on t h i s area even immediately f o l l o w i n g major snowstorms. L o c a t i o n s of sheep were observed twice each day throughout February and are shown on F i g u r e 4. F o l l o w i n g snowstorms, the sheep would r e t r e a t t o the c e n t r a l p a r t of t h i s area which would be e s s e n t i a l l y snow-f r e e . They would i n i t i a l l y feed i n t h i s area and then g r a d u a l l y r a d i a t e outwards by d i g g i n g through the snow to feed. T h i s a c t i v i t y l e f t a packed area behind as the fe e d i n g sheep slowly advanced through the snow. From a d i s t a n c e i t appeared as i f the sheep are e a t i n g the snow o f f the mountain i n a slowly expanding r e g i o n . T h i s a c t i v i t y continued u n t i l they reached areas i n which the snow was q u i t e deep so they ceased d i g g i n g and ret u r n e d t o feed again i n the packed area. Thus, the c e n t r a l p a r t of t h i s area was grazed over r e p e a t e d l y throughout the w i n t e r . The snow depth (X ± S.E.) at the edge where the sheep ceased d i g g i n g f o r food was 32.4 ± 1.9 cm (range 23-40 cm). Snow depth beyond t h i s boundary which was unused by sheep ranged from 23 to > 100 cm. The average snow depth w i t h i n the area t h a t was used by the sheep was 16.5 ± 2.1 cm (range 0-26 cm). Thus i t appeared that Stone's sheep were r e s t r i c t e d to areas with l e s s than 25-30 cm of snow i n w i n t e r . Figure 4. Use of winter range (January-March) on Fertilizer Mountain in a year of high snowfall (1982). Density of dots corresponds to intensity of use. 33 SPRING RANGE The sheep used low e l e v a t i o n (1,200 - 1,500 m) areas f o r s p r i n g range. In the Delano and Yedhe area, sheep p r i m a r i l y used n a t u r a l s u b a l p i n e c l e a r i n g s i n c l u d i n g streamsides, r o c k s l i d e s , t a l l u s s l o p e s , and avalanche chutes ( F i g . 5 ) . In a d d i t i o n , the subalpine burn i n Delano v a l l e y was a l s o used by sheep i n s p r i n g . The a r r i v a l of the sheep on these low e l e v a t i o n ranges from the a l p i n e winter range o c c u r r e d i n l a t e A p r i l . S i m i l a r l y , sheep on Toad Mountain which wintered i n the a l p i n e moved down to the sub a l p i n e burned range ( F i g . 6) at about the same time. The sheep on F e r t i l i z e r Mountain which wintered on subalpine burned slopes remained on the same slope throughout the s p r i n g although they ranged more widely once the snow no longer r e s t r i c t e d t h e i r movement. They a l s o o c c a s i o n a l l y moved to areas of the slope s e v e r a l hundred meters lower than those used i n w i n t e r . The s p e c i e s composition of the s p r i n g ranges i s summarized i n Table 2. Forage q u a n t i t y and q u a l i t y are d i s c u s s e d i n subsequent c h a p t e r s . Sheep a l s o s e l e c t e d s p r i n g range at a more f i n e -g r a i n e d l e v e l . The sheep on the burned, s u b a l p i n e range avoided areas with high amounts of winter c a r r y o v e r i n s p r i n g and fed i n areas t h a t were l a r g e l y f r e e of c a r r y o v e r . Some of these areas l a c k e d v e g e t a t i o n because 3 4 Figure 5. Typical unburned spring range in Yedhe valley (May 1982). 35 Figure 6. Burned, subalpine spring range on Toad Mountain (May 1982). 36 Table 2. Species composition (% cover) of several Stone's sheep spring ranges (May-June) in northeastern British Columbia (1980-1982). Subalpine burned slopes: Delano Creek Elymus innovatus 401 Populus spp A 11% Arctostaphylos uva-ursi 10% Rosa acicularis 101 Epilobium angustofolium 5% bare s o i l 18% Galium. Achillea. trace Shepherdia.Zygadenus F e r t i l i z e r Mountain Graminoids 57% (primarily Elvmus^ Artemisia spp. 15% Oxytropis spjL 9% Aster spp. 7% Thalictrum spp. 5% Potentilla spp. 41 Galium. Vicia, trace Solidago. Rosa Subalpine natural clearings: Delano Creek 1 Arctostaphylos uva-ursi 75% Juniperus spp. 10% Elymus innovatus 10% Qxytropis, F r a p a r i a, trace Saxifraga. P o t P n t i l l f i Delano Creek 2 Dryas i n t e g r i f o l i a 44% Arctostaphylos uva-ursi 24% Graminoids 9% Betula glandulosa 9% Potentilla fruticosa 5% Arctostaphylos rubra 5% Arnica. Shepherdia, trace Silene 37 i t was removed by heavy g r a z i n g the p r e v i o u s winter whereas other areas lacked v e g e t a t i o n because they were n a t u r a l l y unproductive (e.g., c l i f f edges, o u t c r o p s ) . These areas c o u l d be v i s u a l l y i d e n t i f i e d from a d i s t a n c e by the dark c o l o u r compared to the golden brown of areas covered i n senescent g r a s s . Such areas had almost no c a r r y o v e r compared to 145 ± 17.2 (S.E.) g/m2 on the unused a r e a s . A scan survey of sheep f e e d i n g on F e r t i l i z e r Mountain i n s p r i n g found 27 sheep f e e d i n g i n areas with low amounts of c a r r y o v e r and 0 f e e d i n g i n areas with abundant c a r r y o v e r . ALTITUDINAL MIGRATION TO SUMMER RANGE Movement from s p r i n g range to summer range was a g r a d u a l p r o c e s s . In the Delano and Yedhe area the sheep moved from s u b a l p i n e c l e a r i n g s i n May to s i m i l a r c l e a r i n g s i n s p r u c e - w i l l o w - b i r c h zone v a l l e y s i n e a r l y June and to h i g h a l p i n e peaks by J u l y ( F i g . 7). S i m i l a r l y , i n the Toad R i v e r a r e a , sheep moved from low e l e v a t i o n burned s l o p e s i n May to the s p r u c e - w i l l o w - b i r c h zone i n June and the h i g h a l p i n e i n J u l y ( F i g . 7). The m i g r a t i o n corresponded to the onset of green-up at p r o g r e s s i v e l y higher e l e v a t i o n s . The l o c a t i o n of sheep d u r i n g t h i s p e r i o d corresponded to areas where new grass had reached a h e i g h t of approximately 10 cm. By the time 2500n Figure 7. Elevation of range use (mode ± range) by Stone's sheep in northeastern British Columbia (1980-1982) throughout the year. 39 the grass had grown longer the sheep had moved to higher s l o p e s where p r o d u c t i o n began l a t e r ( F i g . 8 ) . T h i s movement continued u n t i l J u l y at which time the sheep were found on high a l p i n e peaks and r i d g e s and there were no hi g h e r ranges a v a i l a b l e . E x c e p t i o n s to t h i s g e n e r a l p a t t e r n seemed to be r e l a t e d to movements to mi n e r a l l i c k s which r e s u l t e d i n the animals being i n areas f o r reasons other than f o r a g i n g . T h i s phenomenon i s d i s c u s s e d l a t e r ( M i n e r a l N u t r i t i o n ) . The s p e c i e s composition of the summer ranges i s d e s c r i b e d i n Table 3. FALL RANGE Range use was extremely v a r i a b l e d u r i n g the f a l l with sheep being l o c a t e d from h i g h a l p i n e peaks t o low, su b a l p i n e burned s l o p e s i n October and November. In November 1982, 54 sheep were s i g h t e d on hi g h a l p i n e peaks i n the Yedhe/Delano area but d u r i n g the same survey 20 sheep were u s i n g the Delano burn and an a d d i t i o n a l 44 sheep were using burned sl o p e s along the Racing R i v e r . On Toad Mountain 14 sheep were u s i n g the top r i d g e while 32 were using burned, s u b a l p i n e s l o p e s . O v e r a l l i t appeared t h a t sheep with access to burned, subalpine s l o p e s made ex t e n s i v e use of them i n f a l l whereas sheep without access to burns used the a l p i n e . 40 40 n May June July August M O N T H Figure 8. Relationship between t i l l e r length of new'grass (X ± 951 C.I.) and range use by Stone's sheep in spring and summer. Star indicates area where most sheep are located at that time of the year. 41 Table 3. Species composition (% cover) of several Stone's sheep summer ranges (June-July) in northeastern British Columbia (1980-1982). . Spruce-Willow-Birch Zone: Toad Mountain Dryas in t e g r i f o l i a 241 Rhododendron lapponicum 171 Betula spp. Graminoids 121 10% These species form the ground cover between Betula and Salix stands which cover 70-90% of Vaccinium spp. 7% the area. Lupinus arcticus 7% Arctostaphylos uva-ursi 6% Ledum groenlandicura 41 Potentilla, Pvrola trace Alpine Zone: Magnum Creek F e r t i l i z e r Mountain Dryas in t e g r i f o l i a 40% Lichens 28% Salix reticulata 11% Dryas integr i f o l i a 17% Carex spp. 9% Carex spp_. 15% Lupinus arcticus 8% Lupinus arcticus 8% Festuca a l t a i c a 5% mosses 8% Anemone spp. •;5% Salix spp_. 7% Polygonum spp. 4% Vaccinium spp_. 3% Astragalus, Potentilla. trace Pedicularis, Potentilla, trace Cassiope, Silene, Poa, Equisetum, Delphinium Phyllodoce 42 Use of n a t u r a l subalpine c l e a r i n g s i n f a l l was not observed. Most of the sheep u s i n g subalpine burns i n f a l l were i n areas adjacent to important a l p i n e w i n t e r i n g areas which were used when deep snow accumulated on the sub a l p i n e s l o p e s . SPATIAL SEPARATION OF SEXES S p a t i a l s e p a r a t i o n of sexes was not apparent i n the present study. Although rams tended to be in groups segregated from ewes and y e a r l i n g s , both types of groups foraged on the same range. For example, the w i n t e r / s p r i n g range on F e r t i l i z e r Mountain supported 16 ewes, 8 lambs, and 9 rams i n 1982. Although the group of 9 rams tended to stay together, they r e g u l a r l y foraged i n the same area as the ewes and o f t e n the groups became completely i n t e r -mixed. S i m i l a r l y , most patches of a l p i n e winter range c o n t a i n e d both rams and ewes l i v i n g together on the same small a r e a s . One extreme example was a larg e ram and a ewe alone together on an i s o l a t e d peak i n w i n t e r . Ram and ewe groups a l s o used the same ranges i n s p r i n g and summer and o f t e n i n t e r - m i x e d . O v e r a l l , there was no reason to b e l i e v e t h a t s p a t i a l s e p a r a t i o n of sexes was a common phenomenon i n these Stone's sheep. 43 FORAGE PRODUCTION AND BIOMASS ON STONE'S SHEEP RANGES PATTERN OF PRODUCTION The onset of major green-up of graminoids on s u b a l p i n e , burned s l o p e s i n the area ranged from l a t e A p r i l i n 1980 to about May 5 i n 1982. However, there was a l i m i t e d amount of new p r o d u c t i o n long before t h i s time. In p a r t i c u l a r , s c a t t e r e d O x y t r o p i s and A r t e m i s i a p l a n t s had begun growing by mid-March i n 1981. Green-up on n a t u r a l s u b a l p i n e c l e a r i n g s o c c u r r e d at the same time as on s u b a l p i n e burns ( F i g u r e s 8 and 9 ) . T h e r e f o r e , sheep using these n a t u r a l c l e a r i n g s c o u l d o b t a i n new p r o d u c t i o n as e a r l y as sheep on burned ranges. However, the q u a n t i t y of new v e g e t a t i o n a v a i l a b l e i n May on these n a t u r a l c l e a r i n g s was much l e s s than t h a t a v a i l a b l e on burned slo p e s ( F i g . 9 ) . The grass p l a n t s on the n a t u r a l c l e a r i n g s were as t a l l as those on burned s l o p e s ( F i g . 8) but the d e n s i t y of p l a n t s was much l e s s . T i l l e r d e n s i t y was c a l c u l a t e d by d i v i d i n g the s t a n d i n g crop of g r a s s by the w e i g h t / t i l l e r which was estimated from the r e l a t i o n s h i p between t i l l e r l e n g t h and t i l l e r weight ( F i g . 10). The t i l l e r d e n s i t i e s i n May c a l c u l a t e d i n t h i s way were: 30 t i l l e r s / m 2 on n a t u r a l s u b a l p i n e c l e a r i n g s compared to 180 t i l l e r s / m 2 on burned s u b a l p i n e s l o p e s . ISO 140 130 H MONTH Figure 9. Seasonal pattern of graminoid production (X ± standard deviation) on sheep ranges in northeastern British Columbia (1980-1982) . 45 G R A S S TILLER L E N G T H (cm) Figure 10. Relationship between mean t i l l e r length and mean t i l l e r weight of grasses on Stone's sheep subalpine spring ranges. 46 E a r l y f o r b p r o d u c t i o n on the s l o p e s used as s p r i n g range i n c l u d e d O x y t r o p i s , F r a g a r i a , P o t e n t i l l a , A c h i l l e a , and E p i l o b i u m . By l a t e May, T h a i i c t r u m , V i c i a , A s t r a g a l u s , Solidaqo, and E r i q e r o n p l a n t s were a l s o growing. The f o r b s p e c i e s were s i m i l a r on both n a t u r a l c l e a r i n g s and burned s u b a l p i n e s l o p e s (Table 2) but as with g r a s s , the biomass of f o r b s was much higher on burned s l o p e s ( F i g u r e 11). Dryas i n t e g r i f o l i a was not i n c l u d e d i n the measurement of f o r b s because although i t o f t e n formed a complete ground cover, p a r t i c u l a r l y i n the a l p i n e a r e a s , i t was only a minor component i n the d i e t of the sheep. Dryas was a l s o extremely d i f f i c u l t to c o l l e c t and s o r t . The amount of Dryas on p l o t s that were c l i p p e d was up to 30-40 g/m2 f o r areas where i t formed complete ground cover. Leaf emergence on p o p l a r s (Populus tremuloides) and cottonwoods (P. b a l s a m i f e r a ) began d u r i n g the l a t t e r h a l f of May on subalpine s l o p e s . Browse biomass was not measured s i n c e i t was e s s e n t i a l l y u n l i m i t e d f o r any sheep which chose to feed on browse. When the sheep moved upwards from the subalpine burns t o the Spruce-Willow-Birch Zone i n e a r l y June they were moving to an area of lower forage q u a n t i t y and s h o r t e r t i l l e r l e n g t h ( F i g s . 8 and 9). Sheep moving up from the 1101 100-90-fr 80-E CD 70-0) 60-fD OC O 50-u. UJ 40-> ZJ 30-20-10-a SUBALPINE CLEARING • SUBAIPIME BURN O SPRUCE-WlllOW-BIRCH • ALPINE September Figure 11. Seasonal pattern of forb production (X ± standard deviation) on Stone's sheep ranges in northeastern British Columbia (1080-1982). 48 n a t u r a l s ubalpine c l e a r i n g s were a l s o moving to an area of s h o r t e r grass but forage q u a n t i t y was s i m i l a r . Leaf emergence on willows ( S a l i x ) and b i r c h e s ( B e t u l a  glandulosa) i n t h i s area o c c u r r e d i n mid-June. When the sheep moved i n t o the h i g h a l p i n e i n J u l y , they were once again moving to an area of short grasses and sedges and lower forage biomass. Peak standing c r o p o c c u r r e d i n e a r l y J u l y i n the su b a l p i n e and l a t e J u l y i n the a l p i n e . The subalpine burns had by f a r the g r e a t e s t q u a n t i t y of forage but at t h i s time the sheep were feeding on the sparse v e g e t a t i o n i n the a l p i n e . A v a i l a b l e green forage d e c l i n e d on a l l ranges a f t e r t h i s time as v e g e t a t i o n g r a d u a l l y matured. By October, a l l v e g e t a t i o n had ceased growing and sheep had to feed on dormant v e g e t a t i o n f o r the d u r a t i o n of the win t e r . WINTER RANGE Dormant v e g e t a t i o n was abundant on subalpine burned s l o p e s i n February-March (162.0 ± 17.5 g/m2) (X ± SE, n = 23). However, because these areas were u s u a l l y snow-covered, t h i s food u s u a l l y was not a v a i l a b l e to the sheep. During the winter of low snow accumulation (1981) the sheep on F e r t l i z e r Mountain were ab l e to feed i n areas of hi g h forage q u a n t i t y . However, i n 1982, r e s t r i c t i o n of 49 the sheep to a s m a l l area by snow r e s u l t e d i n them consuming v i r t u a l l y a l l of the forage from that s l o p e . Immediately adjacent areas which had been snow-covered d u r i n g the winter s t i l l had 97.6 ± 14.5 g/m2 (n = 5) of s t a n d i n g dead v e g e t a t i o n remaining i n s p r i n g . T h i s heavy g r a z i n g of snow-free areas i s obvious i n F i g u r e 12. Sheep w i n t e r i n g on windswept a l p i n e r i d g e s began with a much lower a v a i l a b l i t y of p l a n t forage ( F i g u r e s 9 and 11), p l u s an undetermined q u a n t i t y of l i c h e n s . Heavy g r a z i n g on these r e s t r i c t e d r i d g e s i n the Delano and Yedhe area had removed e s s e n t i a l l y a l l the v e g e t a t i o n by l a t e February of 1982. There was so l i t t l e v e g e t a t i o n l e f t t h a t i t was d i f f i c u l t to c o l l e c t a few grams of p l a n t m a t e r i a l f o r l a b o r a t o r y a n a l y s i s . When these sheep moved down to n a t u r a l subalpine c l e a r i n g s i n the s p r i n g they encountered 24.8 ± 3.9 g/m2 (n = 5) of s t a n d i n g dead v e g e t a t i o n i n a d d i t i o n to whatever new growth was p r e s e n t . 50 F igu re 12. Boundary between h e a v i l y g razed a rea and snow-covered, ungrazed area on suba lp ine w i n t e r range ( F e r t i l i z e r Mounta in 1982) . 51 FORAGE QUALITY WINTER FORAGE Winter forage was h i g h i n f i b r e (ADF) and l i g n i n and low i n p r o t e i n and d i g e s t i b i l i t y ( F i g u r e s 13 - 15, Table 4 ) . S t a t i s t i c a l comparisons were based on comparison of the c o n f i d e n c e i n t e r v a l s i n the graphs. There was no d i f f e r e n c e (P > 0.1) between the q u a l i t y of a l p i n e and s u b a l p i n e winter forage; i t was e q u a l l y poor i n both a r e a s . There was an i n d i c a t i o n t h at the winter forage remaining on the h e a v i l y grazed areas was poorer i n q u a l i t y than the forage on ungrazed areas t h a t had been covered i n snow and u n a v a i l a b l e to the sheep. Remaining forage i n the h e a v i l y grazed areas was lower i n p r o t e i n , d i g e s t i b i l i t y , and c e l l c o n t e n t s and h i g h e r i n f i b r e (ADF) and l i g n i n than forage from ungrazed a r e a s . Although these d i f f e r e n c e s were not s t a t i s t i c a l l y s i g n i f i c a n t , they do suggest t h a t heavy g r a z i n g r e s u l t e d i n a decreased q u a l i t y of the forage remaining f o r the animals. Most of t h i s remaining m a t e r i a l i n areas of heavy g r a z i n g was hard stems compared to dry l e a f y m a t e r i a l a v a i l a b l e i n the ungrazed a r e a s . 50 a SUBALPINE CLEARING • SUBALPINE BURN O SPRUCE-WILLOW-BIRCH M a r c h April May June July August M O N T H on Figure 13. Seasonal pattern of ADF concentrations in graminoids (X ± 90% C.I.) on different Stone's sheep ranges in northeastern British Columbia (1980-1982). 25 n Z UJ r— o oc 0 . UJ O OC UJ a 2 < H 15^ i < H • SUBALPINE CLEARING • SUBALPINE BURN O SPRUCE-WILLOW-BIRCH • ALPINE 5^ UNGRAZED HEAVILY GRAZED March Apri l May June July August M O N T H Figure 14. Seasonal pattern of crude protein concentrations i n graminoids (X ± 90% C.I.) on different Stone's sheep ranges in northeastern B r i t i s h Columbia (1980-1982). 5 O SUBALPINE CLEARING • SUBALPINE BURN O SPRUCE-WILLOW-BIRCH • ALPINE T — 1 1 I * I * , March Apri l May June July August M O N T H Figure 15. Seasonal pattern of lignin concentrations in graminoids (X ± 90% C.I.) on different Stone's sheep ranges in northeastern British Columbia (1980-1982). 55 Table 4. In vi t r o dry matter d i g e s t i b i l i t y {%) of graminoids and forbs from Stone's sheep ranges in northeastern B r i t i s h Columbia (1980-1982). Location Graminoids Forbs (X + SE) n ( X + SE) n Winter Range: subalpine burned -heavily grazed 3 6 . 5 + 2 . 6 4 -ungrazed 3 9 . 8 + 3 . 7 5 alpine 32.1 1 Spring Range: subalpine burn -May 25 65.1+ 0.4 3 -June 3 51.9+ 3.7 3 53.2 1 June 25 4 3 . 3 + 5 . 2 3 subalpine clearings May 15 56.2 1 June 25 48.0 2 • spruce-willow-birch June 7 50.5 1 48.4 1 June 25 57.0+ 0.2 4 Summer Range: alpine June 25 Carex 5 3 . 8 + 1 . 8 4 5 9 . 7 + 2 . 6 3 June 25 Festuca 55.3 2 August 1 57.0+ 2.5 7 66.5+ 2.1 8 56 SPRING-SUMMER FORAGE The appearance of new p r o d u c t i o n i n s p r i n g p r o v i d e d a dramatic i n c r e a s e i n the q u a l i t y of forage a v a i l a b l e to Stone's sheep. There was no d i f f e r e n c e i n forage q u a l i t y between the burned, s u b a l p i n e ranges and n a t u r a l , s u b a l p i n e c l e a r i n g s used by sheep i n May ( F i g u r e s 13-15). As the growing season progressed, there was an o v e r a l l tendency f o r p r o t e i n l e v e l s to decrease and f i b r e and l i g n i n l e v e l s t o i n c r e a s e i n both graminoids and forbs ( F i g u r e s 13-18). The decrease i n n u t r i t i o n a l q u a l i t y of g r a s s e s throughout the growing season was a l s o shown by the negative r e l a t i o n s h i p between grass t i l l e r l e n g t h and p r o t e i n content ( F i g u r e 19). Compared t o the p h e n o l o g i c a l l y o l d e r subalpine v e g e t a t i o n , v e g e t a t i o n at higher e l e v a t i o n s s t a r t e d to grow l a t e r i n the season and t h e r e f o r e , was more n u t r i t i o u s i n the summer months. F i b r e (ADF) ( F i g u r e s 13 and 16) was s i g n i f i c a n t l y lower (P < 0.1) a t h i g h e l e v a t i o n s compared to subalpine s l o p e s d u r i n g J u l y and August f o r f o r b s and from June-August i n graminoids. P r o t e i n l e v e l s ( F i g u r e s 14 and 17) i n J u l y were s i g n i f i c a n t l y higher (P < 0.1) f o r both graminoids and f o r b s a t h i g h e l e v a t i o n s compared to the s u b a l p i n e . L i g n i n ( F i g u r e 18) l e v e l s of f o r b s from h i g h e l e v a t i o n s were s i g n i f i c a n t l y lower (P < 0.1) than l e v e l s f o r s u b a l p i n e f o r b s d u r i n g J u l y and August. L i g n i n l e v e l s i n 57 May June July August M O N T H Figure 16. Seasonal pattern of ADF concentrations in forbs (X ± 901 C.I.) on different Stone's sheep ranges in northeastern B r i t i s h Columbia (1980-1982). 58 35 30-1 25H 20 15 10 • SUBALPINE BURN O SPRUCE-WILLOW-BIRCH • ALPINE July August May June MONT H Figure 17. Seasonal patterns of crude protein concentrations in forbs (X ± 90% C.I.) on different Stone's sheep ranges in northeastern Br i t i s h Columbia (1980-1982). 59 r-Z LU o OC LU a • SUBALPINE BURN O SPRUCE-WILLOW-BIRCH • ALPINE H May June July August M O N T H Figure 18. Seasonal pattern of lignin concentrations in forbs (X ± 90% C.I.) on different Stone's sheep ranges in northeastern B r i t i s h Columbia (1980-1982). t 60 GRASS TILLER LENGTH Ccm) Figure 19. Relationship between t i l l e r length and crude protein concentrations of new grasses on Stone's sheep ranges in northeastern Br i t i s h Columbia (1980-1982). 61 graminoids were extremely v a r i a b l e and d i f f i c u l t to i n t e r p r e t ( F i g . 15). Although the q u a l i t y of a l p i n e forage tended to be s u p e r i o r to forage from the inte r m e d i a t e s p r u c e - w i l l o w - b i r c h zone, these d i f f e r e n c e s were not s t a t i s t i c a l l y s i g n i f i c a n t . On the ranges that the sheep were using, p r o t e i n l e v e l s of f o r b s were s i g n i f i c a n t l y higher (P < 0.1) than l e v e l s i n graminoids i n May and June. ADF l e v e l s of f o r b s were s i g n i f i c a n t l y lower (P < 0.1) than l e v e l s i n graminoids from June t o August. The l i m i t e d data on browse q u a l i t y a l s o show that the p r o t e i n l e v e l of high e l e v a t i o n w i l l o w s tended t o be highe r than the l e v e l i n the poplar browse a v a i l a b l e at suba l p i n e e l e v a t i o n s (Table 5). Data on j j i v i t r o dry matter d i g e s t i b i l i t y (DMD) were too sparse to make v a l i d comparisons (Table 4 ) . T h e r e f o r e , v a l u e s f o r DMD were c a l c u l a t e d based on values f o r p r o t e i n and ADF l e v e l s u s i n g the equ a t i o n : % DMD = 67.05 + 0.23 (% p r o t e i n ) - 0.66 (%ADF), which was c a l c u l a t e d from the data and had r 2 = 0.86, S.E. = 3.5, n = 42. These c a l c u l a t e d v a l u e s a re presented i n F i g u r e 20. Although the d i f f e r e n c e s were not s t a t i s t i c a l l y s i g n i f i c a n t , the data suggest the same p a t t e r n of g r a d u a l l y d e c l i n i n g forage q u a l i t y throughout the growing season with h i g h e l e v a t i o n forage being s u p e r i o r to Table 5. Quality analysis of browse species on Stone's sheep ranges in spring and summer in northeastern British Columbia (1980-1982). Source Cell Contents ADF Lignin Protein In vi t r o DMD ** % % % % % SWB Salix 73.7 8.2 2.2 16.2 * SWB= spruce-willow-birch zone ** DMD = dry matter d i g e s t i b i l i t y n June 5 SWB Salix * 72.0 19.7 2.9 24.6 - 1 SWB Betula 80.6 13.0 1.7 25.4 - 1 SWB Arctostaphylos 80.7 7.1 3.1 16.5 - 1 June 25 alpine Salix 78.1-79.0 15.8-16.7 5.0-5.3 23.9 46.4-60.6 SWB Salix 78.1 17.2 5.9-6.1 21.7-22.1 46.2-47.7 subalpine Pormlus 76.9-77.1 15.4-15.6 6.2 17.0-18.0 46.8 2 July 17 alpine Salix 77.0 15.3 1.1 30.7 1 1 601 55-• SUBALPINE CLEARING • SUBALPINE BURN O SPRUCE-WILLOW-BIRCH • ALPINE Q Ul r-< 50" 3 O _J < o f-z ui o QC Ul a 45 40-35-March Apri l May June July August M O N T H Figure 20. Calculated values for dry matter digestibility (DMD) of graminoids on different Stone's sheep ranges in northeastern British Columbia (1980-1982). 64 subalpine forage in summer. The differences in forage q u a l i t y between ranges appeared to decline as f a l l approached and by winter there was no difference between alpine and subalpine forage. 65 FOOD HABITS There are s e v e r a l problems which d e t r a c t from the accuracy of the f e c a l fragment a n a l y s i s data on food h a b i t s . The major problem i s that d i f f e r e n t i a l d i g e s t i b i l i t y of d i f f e r e n t p l a n t s p e c i e s can r e s u l t i n the p r o p o r t i o n of d i f f e r e n t p l a n t s p e c i e s i n the feces d i f f e r i n g from the p r o p o r t i o n i n the d i e t . Some re s e a r c h e r s have developed c o r r e c t i o n f a c t o r s to c o r r e c t f o r d i f f e r e n t i a l d i g e s t i b i l i t i e s of p l a n t types but these values may not be accurate when e x t r a p o l a t e d to an e n t i r e l y new s i t u a t i o n . Rumen a n a l y s i s of food h a b i t s i s more ac c u r a t e because there i s l e s s o p p o r t u n i t y f o r d i f f e r e n t i a l d i g e s t i b i l i t y to a l t e r the p r o p o r t i o n of p l a n t fragments. Comparison of food h a b i t s of the same animals by both rumen and f e c a l a n a l y s i s (Tables 6 and 8) showed t h a t although the r e s u l t s d i d not agree e x a c t l y , there was no c o n s i s t e n t p a t t e r n to the d e v i a t i o n . For example, i n three cases f e c a l a n a l y s i s underestimated t o t a l g r a s s and sedges compared to rumen a n a l y s i s whereas i n two other cases i t overestimated t o t a l grass and sedges. Comparison of f e c a l a n a l y s i s data from A p r i l 21, 1981 to data from two rumen samples c o l l e c t e d at the same time showed that the f e c a l data tended to f a l l between the v a l u e s from the two rumen an a l y s e s suggesting that the e r r o r i n the f e c a l a n a l y s i s technique was l e s s than the 6 6 Table 6 . Food habits of Stone's sheep on unburned range in northeastern Br i t i s h Columbia (1980-1982) determined by rumen analysis. March 23 Apr i l 21 April 21 June 20 June 25 1981 1981 1981 1981 1981 alpine subalpine subalpine alpine alpine 1 % % % % Carex 38.6 8.8 2 .3 6.5 10.8 Elymus 3.8 25.7 42 .0 8.0 1.1 Poa 12.2 8.8 8 .3 19.7 19.5 Festuca 0.6 0.9 0 .0 0.0 0.0 Other grass 0.0 0.4 1 .6 0.0 0.0 TOTAL GRAMINOIDS 55.2 44.6 54, .2 34.2 31.4 Oxytropis 0.0 0.0 0, .0 0.0 48.0 Lupinus 0.0 1.4 7, .8 18.0 2.7 Dryas 0.0 0.0 1. .0 0.0 0.0 Astragalas 0.0 2.3 0. ,0 0.0 0.0 Other forbs 0.0 5.0 8. .7 18.9 12.5 TOTAL FORBS 3.8 8.7 17. ,5 36.8 63.2 Conifers 0.6 2.6 0. 2 0.0 0.0 Salix 0.0 3.8 1. 9 16.4 1.6 Vaccinium 0.0 5.8 1. 6 0.0 0.0 Rosa 0.0 2.2 0. 0 1.2 0.0 Populus 0.0 3.8 3. 8 0.0 0.0 Betula 0.0 4.2 5. 2 0.0 0.0 Other browse 0.0 0.0 0. 0 9.4 3.7 TOTAL BROWSE 2.4 22.4 12. 7 27.0 5.3 Lichen 38.6 9.0 12. 8 1.8 0.1 Moss 0.0 15.3 2. 8 0.0 0.0 Table 7. Food habits of Stone's sheep on subalpine burned range i n northeastern British Columbia (1980-1982) determined by fecal analysis. February 24 March 19 April 6 April 22 May 7 May 13 May 18 June 22 November 1982 1981 1982 1982 1982 i 9 8 1 i 9 8 0 1980 1982 Carex 7.7 9.0 12.6 7.7 7.2 13.0 0.6 1.3 3.8 Elvmus 29.6 13.9 26.3 19.3 23.3 46.5 - - 31.8 Poa 49.4 26.8 29.9 16.4 36.9 16.7 - - 31.1 Agronvron 0.0 3.6 0.0 4.4 0.0 4.0 - - 0.0 Festuca 0.0 3.1 0.0 2.3 0.0 3.7 - - 0.0 Other grasses (LO 0J) 0 J ) CUD 3.2 0.0 - - 0.0 TOTAL GRAMINOIDS S O S O 6X7 5 0 7076 8X9 7 0 4(570 WJ Artemisia - 0.0 - 0.0 - 0.0 - - 12.2 Achillea - 0.0 - 30.4 - 0.0 - - 0.0 Lupinus - 3.0 - 2.9 - 2.3 2.1 4.3 5.8 Dryas - 0.0 - 2.0 - 0.0 3.0 6.4 0.0 Astragalus - 12.3 - 0.0 - 2.0 - - 0.0 Other forbs - 14.7 - 3.0 7 . 4 - 5.5 TOTAL FORBS 1373 3 0 2 0 3773 2973 H77 1476" 27715 2 3 3 Conifers 0.0 1.5 0.0 2.1 0.0 3.3 0.0 0.0 0.0 Other browse 0.0 2^9 3.4 5.0 0.0 0.4 10.3 23.0 0.0 TOTAL BROWSE O O 371 771 07T5 3T7 T073 237TJ 07(7 Lichen 0.0 9.2 0.0 5.5 0.0 0.7 0.8 3.0 0.0 A dash (-) indicates that the proportion of the food type is lumped with others for that group. Table 8. Food habits of Stone's sheep on unburned range in northeastern B r i t i s h Columbia (1980-19821 determined by fecal analysis. February 1982 March 23 1981 April 21 1981 May 13 1982 May 18 1981 May 22 1982 May 28 1980 June 5 1981 June 20 1981 June 25 1982 June 25 1982 July 3 1980 July 12 1981 August 1980 Carex Elymus Poa Festuca Other grasses 3S.0 6.3 25.0 0.0 1.2 37.0 5.3 2.2 0.0 0.0 5.4 . 33.6 7.3 2.9 0.2 3.7 23.0 61.6 0.0 0.0 10.4 25.9 29.7 2.2 2.1 8.5 21.8 42.4 0.0 4.7 12.9 12.8 0.0 10.0 1.5 2.9 22.4 0.0 14.6 5.2 0.4 rams 12.5 0.0 10.1 0.0 0.0 ewes 7.9 2.0 13.0 0.0 0.0 30.6 27.4 0.5 7.8 1.1 0.0 6.0 TOTAL GRAMINOIDS 67.5 44.8 49.4 88.3 70.3 77.4 63.4 27.2 42.6 22.6 22.9 48.3 36.8 53.6 Oxytroois Luninus Dryas Astragalus Other forbs 0.0 9.7 3.0 7.1 4.9 0.0 1.4 0.0 0.0 6.3 0.0 4.0 0.0 0.0 7.1 0.0 0.0 0.0 0.0 8.0 0.0 4.1 0.0 0.0 7.7 5.9 0.0 0.0 0.0 6.9 3.2 2.9 13.4 0.0 2.8 4.2 11.8 4.0 0.0 7.0 1.3 3.4 2.2 24.9 3.2 0.0 3.9 34.1 45.9 1.6 0.0 1.0 16.9 7.1 4.4 18.5 0.0 6.6 3.0 10.5 4.1 2.6 1.8 19.2 TOTAL FORBS 24.7 7.7 11.1 8.0 11.8 12.8 19.5 22.8 13.9 66.1 65.4 30.0 24.2 23.6 Conifers Salix Vaccinium Rosa Arctostaphylos Populus Other browse 0.0 0.0 0.0 0.0 0.0 0.0 0.9 1.5 1.8 1.8 1.0 1.1 0.0 1.9 3.5 2.0 2.0 3.2 2.3 0.0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 1.5 0.0 0.0 0.0 1.9 2.2 0.0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 4.5 0.0 4.2 17.8 7.7 0.0 2.0 8.6 6.2 1.7 17.7 6.5 1.7 2.1 4.3 8.5 0.0 8.1 0.0 0.0 0.0 0.0 1.0 0.0 5.5 0.0 0.0 0.0 0.0 3.0 0.0 4.4 14.6 4.8 1.5 2.5 2.7 4.1 0.0 TOTAL BROWSE 0.9 12.0 20.3 1.5 14.7 4.5 11.7 46.5 42.5 9.1 8.5 16.5 34.6 7.4 Lichen Mosses 6.9 0.0 35.5 0.0 15.6 3.6 2.2 0.0 3.2 0.0 5.3 0.0 5.4 0.0 3.5 0.0 1.0 0.0 2.2 0.0 3.2 0.0 5.2 0.0 3.4 1.0 15.4 0.0 A dash (-) indicates that the proportion of that food type is lumped with others for that group. 69 v a r i a b i l i t y i n rumen samples from d i f f e r e n t animals. Another problem was t h a t the f e c a l a n a l y s i s was based on one pooled sample from a c e r t a i n c o l l e c t i o n p e r i o d . T h e r e f o r e , there was no measure of v a r i a n c e f o r the samples. Given these problems, i t would be unwise to put much s i g n i f i c a n c e on small d i f f e r e n c e s ( i . e . , < 10%) i n the data on food h a b i t s . Rather, I analysed the data l o o k i n g f o r broad p a t t e r n s i n the food h a b i t s throughout the year. WINTER FOOD HABITS Sheep using a l p i n e s l o p e s i n winter (February, March) were fee d i n g h e a v i l y on sedges (Carex) (Table 8, F i g u r e 21). In the February samples, blue grass (Poa) was very important whereas i n the March sample l i c h e n was very high i n both the rumen and f e c a l samples. O v e r a l l , grasses and sedges made up most of the d i e t with f o r b s making up a sma l l e r p a r t and browse being q u i t e unimportant. Sheep using burned, subalpine slopes i n winter were fe e d i n g p r i m a r i l y on rye grass (Elymus) and blue grass (Poa) (Table 7 ) . Forbs made up a smal l e r amount of the d i e t and browse and l i c h e n were unimportant food items. UNBURNED RANGE: ~ 100 E 80 ^ 60 i § 40 20 winter alpine lichen forbs grasses, primarily Poa Carex A p r i l subalpine lichen forbs browse other grasses Elymus May subalpine browse forbs Elymus Poa June spruce-willow-birch Carex grasses, p r i m a r i l y Poa other forbs Lupinus other browse S a l i x sunmer alpine other forbs Oxytropis other browse S a l i x grasses, primarily Poa Carex BURNED SUBALPINE RANQE: 3 80 1 u. 60 o C 40 g 20 winter forbs other grasses. Elymus Poa A p r i l other forbs A c h i l l e a Carex Elymus Poa May forbs other grasses Carex Poa Elymus June November moss other forbs Arternesia Elymus Poa Figure 21. Summary of seasonal food habits for Stone's sheep determined by fecal analysis on burned and unburned ranges in northeastern British Columbia (1980-1982). o 71 SPRING FOOD HABITS The descent of sheep from a l p i n e areas to s u b a l p i n e c l e a r i n g s i n A p r i l was e v i d e n t i n the decrease i n sedges and l i c h e n i n the d i e t and the heavy use of subalpine g r a s s e s , p a r t i c u l a r l y Elymus, and browse s p e c i e s i n c l u d i n g c o n i f e r s . The onset of new s p r i n g growth r e s u l t e d i n the sheep f e e d i n g p r i m a r i l y on new grasses (Elymus and Poa) throughout May on both burned and n a t u r a l s l o p e s . One sample ( A p r i l 22, 1982) from the burned range i n d i c a t e d t h a t the most important food was yarrow ( A c h i l l e a ) , a f o r b which began growing very e a r l y on the s p r i n g range. Movement to higher e l e v a t i o n s i n June was a s s o c i a t e d with a decrease i n grasses and an i n c r e a s e i n f o r b s i n the d i e t . Locoweed (Oxytropis) was the s i n g l e most important food item at t h i s time. Heavy use of shrubs, e s p e c i a l l y w i l l o w s , at t h i s time corresponded to new l e a f p r o d u c t i o n on shrubs. Sheep were observed to browse e x t e n s i v e l y on willow at t h i s time of the year. Poplars were used i n e a r l y June but by l a t e June the sheep had migrated above the upper a l t i t u d i n a l l i m i t of p o p l a r s . 72 SUMMER FOOD HABITS Sedges were the most important food item of sheep on a l p i n e summer range. In a d d i t i o n , a wide assortment of f o r b and browse s p e c i e s were a l s o taken. Willows were a major food source and sheep were r e g u l a r l y observed browsing on willows at t h i s time of year. FALL FOOD HABITS Information on f a l l food h a b i t s i s only a v a i l a b l e f o r sheep using burned, subalpine range. Grasses (Poa and Elymus) made up the bulk of the d i e t but f o r b s , p a r t i c u l a r l y A r t e m i s i a were a l s o eaten. 73 NUTRITIONAL INDICES OF THE SHEEP The sample v a r i a n c e f o r f e c a l p r o t e i n v a l u e s c o u l d be g r e a t l y reduced by c o r r e c t i n g f o r the ash content of the f e c e s , that i s , c a l c u l a t i n g the p r o t e i n content of the non-ash p o r t i o n of the f e c e s . T h i s c o r r e c t i o n was p a r t i c u l a r l y important i n samples c o l l e c t e d near m i n e r a l l i c k s i n which f e c e s o f t e n c o n t a i n e d up to 88% m i n e r a l m a t e r i a l and averaged up to 45% (Table 9). Samples with h i g h ash content had abnormally low p r o t e i n content compared to other samples; c o r r e c t i n g f o r ash content r e s u l t e d i n a much lower v a r i a b i l i t y i n the samples. For example, i n a group of samples i n which ash content v a r i e d from 14-47%, c o r r e c t i n g f o r the ash content reduced the standard d e v i a t i o n of the f e c a l p r o t e i n v a l u e s from 5.46 t o 3.46. T h e r e f o r e , u n l e s s otherwise s t a t e d , a l l f u r t h e r d i s c u s s i o n of f e c a l p r o t e i n l e v e l s r e f e r to v a l u e s c o r r e c t e d f o r ash. F i g u r e 22 shows the f e c a l p r o t e i n values f o r sheep i n the Yedhe/Delano area compared to sheep i n the Toad R i v e r a r e a . Lowest va'lues (10-12%) o c c u r r e d i n winter with a dramatic i n c r e a s e d u r i n g green-up i n May. Peak v a l u e s (30%) were a t t a i n e d on a l p i n e range i n l a t e June and then g r a d u a l l y decreased throughout the autumn r e a c h i n g low winter v a l u e s by November. F e c a l p r o t e i n v a l u e s f o r sheep on a l p i n e range i n February were s i g n i f i c a n t l y g r e a t e r (P 74 Table 9. Seasonal changes in fecal ash content of Stone's sheep on burned and unburned ranges in northeastern B r i t i s h Columbia (1980-1982). Delano/Yedhe area Toad Mountain area (X + SD) n (K + SD) n February 15.8 + 3.5 13 12.1 + 0.9 8 March - 15.5 + 5.5 11 early April - 14.6 + 3.0 14 late A p r i l - 16.9 + 4.6 8 early May 10.3 + 1.6 12 16.4 + 7.2 12 late May 13.8 20.2 + + 1.3 10.3* 5 9 16.9 + 2.1 5 early June 23.8 + 13.5* 16 45.9 + 14.9 3 late June 22.6 + 4.7* 20 21.9 + 10.0 4 early July 33.6 + 21.1* 10 -late August 14.2 + 2.2* 5 21.0 + 8.9 3 November - 15.5 + 5.6 7 * samples collected at a mineral l i c k . 35 '1 1 i l l i l i i l1 l i I i J F M A M J J A S O N D MONTH F igure 22. Seasonal p a t t e r n o f f e c a l p r o t e i n l e v e l s ( co r rec ted f o r ash content ) f o r S tone ' s sheep on burned and unburned ranges (X ± 95% C . I . ) i n no r t heas te rn 1 / 1 B r i t i s h Columbia (1980-1982). 76 < 0.05) than v a l u e s f o r sheep on the subalpine burned range of F e r t i l i z e r Mountain. T h i s o b s e r v a t i o n was s u r p r i s i n g because the a l p i n e range c o n t a i n e d almost no food compared to the sub a l p i n e range. F e c a l p r o t e i n v a l u e s from February of 1982 when the sheep were r e s t r i c t e d to a s m a l l , h e a v i l y grazed area of the t o t a l range were not d i f f e r e n t from winter values of 1981 when the e n t i r e range was being used. S i m i l a r l y the valu e s from A p r i l 1982, when l a r g e areas of p r e v i o u s l y u n a v a i l a b l e range became a v a i l a b l e because of snow melt, were not s i g n i f i c a n t l y d i f f e r e n t from the February v a l u e s when the sheep were con c e n t r a t e d i n a small a r e a . The l a t t e r two p o i n t s are c o n t r a r y to the hypothesis that heavy g r a z i n g r e s u l t s i n a decrease i n the q u a l i t y of food i n t a k e by the sheep. During May, although f e c a l p r o t e i n values of sheep i n c r e a s e d d r a m a t i c a l l y on both burned and unburned range i t appeared t h a t the i n c r e a s e was 7-10 days e a r l i e r f o r sheep on burned range. Values f o r sheep i n the Yedhe v a l l e y on May 20, 1982 were s i g n i f i c a n t l y l e s s (P < 0.05) than the v a l u e s f o r sheep on F e r t i l i z e r Mountain two days e a r l i e r which demonstrates that f e c a l p r o t e i n v a l u e s on unburned range lagged behind values f o r sheep on burned range. F e c a l n i t r o g e n v a l u e s throughout the summer were s i m i l a r i n both p o p u l a t i o n s which was not s u r p r i s i n g 77 because both p o p u l a t i o n s were u t i l i z i n g s i m i l a r a l p i n e h a b i t a t at t h a t time of the year. DAPA v a l u e s (Figure 23) showed s i m i l a r p a t t e r n s and r e l a t i o n s h i p s to f e c a l p r o t e i n but lack of r e p l i c a t e s p r e c l u d e d s t a t i s t i c a l a n a l y s i s . Figure 23. Seasonal pattern of DAPA concentrations for Stone's sheep on burned and unburned ranges in northeastern British Columbia (1980-1982). 79 FOOD SELECTIVITY SELECTION OF SPECIES There was a large amount of variance in both the estimates of food a v a i l a b i l i t y and food habits which made any analysis of plant species selection d i f f i c u l t . Therefore, I r e s t r i c t e d the analysis to major differences between use and a v a i l a b i l i t y . Species Selected Against Lichens covered up to 30% of alpine ranges (Table 3) and in winter they sometimes became the only vegetation on alpine ranges. However, they usually comprised only a very small proportion of the diet (about 5%). This small amount could have been consumed accidently while feeding on sedges and forbs tangled in lichen. Dryas i n t e g r i f o l i a and Arctostaphylos uva-ursi were the dominant ground cover plants on alpine and subalpine areas respectively (Tables 2 and 3). However, they were only found in trace amounts in the diet (< 5%). Sheep were not always on ranges with access to conifers but in spring when they were, conifers were not extensively used even though they were e s s e n t i a l l y unlimited to any sheep which chose to feed on them. 80 B e t u l a g landulosa was about as abundant as willows on the range i n June but was not eaten whereas willows were h e a v i l y used at t h i s time (Table 8 ) . Lupinus a r c t i c u s was a common food (Table 8) but the p r o p o r t i o n i n the d i e t was f a r l e s s than i t s a v a i l a b i l i t y on a l p i n e ranges ( u s u a l l y 50-80% of f o r b biomass). Species S e l e c t e d For The o n l y s p e c i e s which appeared to be h e a v i l y s e l e c t e d f o r year-round were Poa spp. which was an important food on s u b a l p i n e and a l p i n e ranges ( F i g u r e 21) even though i t was s p a r s e l y d i s t r i b u t e d . At p a r t i c u l a r times of the s p r i n g and summer, v a r i o u s f o r b s p e c i e s i n c l u d i n g A c h i l l e a and O x y t r o p i s were taken f a r i n excess of t h e i r a v a i l a b i l i t y . SELECTION OF GRAMINOIDS VERSUS FORBS S e l e c t i o n f o r graminoids versus f o r b s d i d not d i f f e r from a v a i l a b i l i t y on s p r i n g ranges (Table 10). There appeared t o be s e l e c t i o n a g a i n s t f o r b s i n favour of graminoids on a l p i n e range i n summer. 81 Table 10. Proportion of forbs versus graminoids in the diet of Stone's sheep compared to availability on the range. Proportion of Diet {%) Availability ( g / m ) Graminoids : Forbs Graminoids : Forbs Burned subalpine, May 70 (4.7 15 1) 20 (4 5 1) Alpine, June-July 45 : 30 (1.5 : 1) 5 : 10 (0.5 : 1) 82 SELECTION OF SUPERIOR QUALITY FOOD The p r o t e i n content of the food intake was c a l c u l a t e d based on the p r o t e i n content of grasses, f o r b s , and browse and the p r o p o r t i o n of these items i n the d i e t based on the f e c a l a n a l y ses data (Figure 24). F e c a l p r o t e i n values ( u n c o r r e c t e d f o r ash) have an almost 1:1 r e l a t i o n s h i p t o crude p r o t e i n i n the d i e t of mountain sheep (Hebert 1973). F e c a l p r o t e i n v a l u e s ( c o r r e c t e d f o r ash) were reduced by 15% to make them comparable to the u n c o r r e c t e d f e c a l p r o t e i n l e v e l s i n Hebert's study because the ash l e v e l i n the f e c e s of sheep not using l i c k s i s about 15% (Table 9). These values were compared with the estimated p r o t e i n content of the food i n F i g u r e 24. F e c a l p r o t e i n v a l u e s were higher than forage p r o t e i n v a l u e s when the animals were fee d i n g on winter v e g e t a t i o n . In s p r i n g the i n c r e a s e i n f e c a l p r o t e i n v a l u e s lagged behind the i n c r e a s e i n food q u a l i t y by about 10 days. By summer, f e c a l p r o t e i n v a l u e s were s i m i l a r to the estimated food p r o t e i n l e v e l s . I f sheep were being h i g h l y s e l e c t i v e f o r more n u t r i t i o u s p a r t s of the forage, the f e c a l p r o t e i n values should have been higher than the p r o t e i n v a l u e s of forage samples c o l l e c t e d at random. The data d i d not appear to support t h i s h y p o t h e s i s . The food intake of the sheep d i d not appear to be any higher i n p r o t e i n than the average food a v a i l a b l e t o them on the range. 83 UN BURNED RANGE 28T l i • Apri l May June July M O N T H Figure 24. Relationship between protein concentrations of the available forage and the fecal protein concentrations of Stone's sheep (standardized to 15% ash content). 84 MINERAL NUTRITION SOIL MINERAL CONCENTRATIONS S o i l m i neral c o n c e n t r a t i o n s a re presented i n Table 11. T o t a l n i t r o g e n c o n c e n t r a t i o n s were lower i n the two t a l l u s slope areas (Yedhe, Delano) than i n the s o i l s from the more s t a b l e areas. These t a l l u s slopes were used as s p r i n g range by sheep i n these two areas. The car b o n : n i t r o g e n r a t i o s i n a l l the s o i l s were low enough to ensure that a net gain i n n i t r o g e n m i n e r a l i z a t i o n was o c c u r r i n g (Thompson and Troeh 1978). However s o i l n i t r a t e c o n c e n t r a t i o n s were undetectable (< 1 ppm). The abundance of n i t r o g e n - f i x i n g p l a n t s i n the area (Shepherdia, Lupinus, O x y t r o p i s , A s t r a g a l u s and other legumes) a l s o i n d i c a t e d a s o i l d e f i c i e n t i n a v a i l a b l e n i t r o g e n even though t o t a l n i t r o g e n c o n c e n t r a t i o n s were reasonably h i g h . The low n i t r a t e c o n c e n t r a t i o n s may r e s u l t from low r a t e s of n i t r i f i c a t i o n c h a r a c t e r i s t i c of c o l d , s u b a r c t i c s o i l s ( M i t c h e l l and O f f n e r 1982). Phosphorous c o n c e n t r a t i o n s were extremely low i n a l l s o i l s except f o r F e r t i l i z e r mountain. Otherwise, a l l the other n u t r i e n t c o n c e n t r a t i o n s (Ca, Mg, K) were not l i k e l y to be s e v e r e l y l i m i t i n g to p l a n t growth (T. B a l l a r d p e r s . comm.). The major s o i l n u t r i e n t c o n c e n t r a t i o n s (N, P, K) tended to be higher on F e r t i l i z e r Mountain than from Table 11. Mineral concentrations and pH of soils and mineral licks in the Toad River area. pH total C C:N P Ca Mg K Na S N % % ppm ppm ppm ppm ppm ppm Yedhe 7.5 0.10 1.17 11.7 u 3026 73.0 39.0 u -• Delano 6.0 0.08 1.43 17.9 u 1202 145.9 78.0 u -Tower 6.2 0.44 1.81 4.1 u 2645 340.5 78.0 u -Magnum 7.0 0.89 16.25 18.3 2.1 8958 681.0 78.0 u -F e r t i l i z e r 6.8 0.52 3.23 6.2 16.6+3.1* 3968 425.6 117.3 u 7.5+1.2* X + SD 6.7+0.6 0.4+0.3 4.8+6.5 11.6+6. 5 3959+2965 333+241 78.0+27.6 u -Mineral Licks: Churchill mine 8.1 0.01 0.10 10.0 u 3387 133.8 117.3 92.0 -Toad Bridge 8.8 0.08 0.72 9.0 u 3447 1252.4 39.0 23.0 -Toad Mountain 7.6 0.12 0.67 5.6 u 4329 389.1 39.0 23.0 -X - SD 8.2+0.6 0.1+0.06 0.5+0.3 8.2+2. ,3 u 3721+527 592+586 65+45 46+40 -* Y - SD, n=8 u = undetectible, less than 0.1 ppm for phosphorus and less than 23.0 ppm for sodium. 86 other s i t e s which suggested that the frequent burning in this area had no detrimental effect on s o i l nutrients and may even have been b e n e f i c i a l . FORAGE MINERAL CONCENTRATIONS Forage mineral concentrations are compared to the mineral requirements of domestic sheep (NRC 1975, Maynard et a l . 1979) in Table 12. These values are for maintaining sheep in good condition and probably exceed the needs for basic s u r v i v a l . Winter forage was d e f i c i e n t in nitrogen, phosphorous, potassium, zinc, and possibly copper. Sulphur lev e l s were low but probably adequate considering the low nitrogen intake at thi s time. Levels of calcium, magnesium, iron, and manganese were adequate to meet the the requirements of sheep. Levels of the five d e f i c i e n t minerals, p a r t i c u l a r l y potassium, tended to be higher in the subalpine winter forage than the alpine forage but the data are too scant for s t a t i s t i c a l comparisons. New spring grasses from a l l s i t e s met or came quite close to sheep requirements for a l l minerals (Delano was s l i g h t l y low in zinc and sulphur). The calcium: phosphorous r a t i o was also close to the optimum of 2:1. Sim i l a r l y , summer grasses and sedges contained adequate level s of a l l minerals except phosphorous. The sedges Table 12. Mineral concentrations in forages from Stone's sheep ranges in northeastern B r i t i s h Columbia (1980-1982) compared to requirements of domestic sheep. N P Ca Mg K Fe Zn Mn Al Cu B S % % % % % ppm ppm ppm ppm ppm ppm X Subalpine winter forage: Fertilizer mountain 0.73 0.09 0.83 0.11 0.43 63.0 17.0 24.0 50.0 3.0 7.64 0.11 Toad mountain 0.58 0.07 0.83 0.75 0.54 28.0 18.0 5.0 20.0 6.0 7.52 0.09 Alpine winter forage: Delano 0.40 0.04 0.73 0.90 0.18 63.0 5.0 74.0 60.0 1.0 5.70 0.09 Toad 0.52 0.06 0.70 0.85 0.12 43.0 11.0 16.0 30.0 1.0 5.20 0.09 Magnum 0.58 0.03 0.71 0.95 0.09 64.0 9.0 38.0 60.0 1.0 5.40 0.10 Mean 0.50 0.04 0.71 0.90 0.13 56.7 8.3 42.7 30.0 1.0 5.40 0.09 Subalpine spring range: Delano 3.43 0.27 0.77 0.13 - 119.0 15.0 43.0 190.0 8.0 5.50 0.11 Fertilizer mountain 2.92 0.31 0.46 0.13 2.45 112.0 35.0 49.0 130.0 6.0 7.80 0.21 Magnum 3.50 0.27 0.50 0.17 2.78 140.0 61.0 37.0 190.0 8.0 4.80 0.24 Mean 3.28 0.28 0.58 0.14 2.62 123.0 37.0 43.0 170.0 7.3 6.00 0.19 Alpine range (July): Magnum creek 2.50 0.20 0.47 0.17 1.76 160.0 55.0 34.0 60.0 111.0 8.80 0.22 Tower mountain 2.40 0.18 0.34 0.17 1.96 60.0 26.0 61.0 10.0 2.0 6.40 0.21 Subalpine range (July): Fertilizer mountain 1.90 0.23 0.43 0.11 2.60 48.0 25.0 20.0 10.0 4.0 4.10 0.15 Yedhe creek 2.30 0.14 0.48 0.15 2.65 37.0 11.0 36.0 10.0 4.0 4.40 0.18 Delano 2.20 0.17 0.30 0.12 3.55 46.0 9.0 53.0 20.0 6.0 4.70 0.17 Mean 2.13 0.18 0.40 0.13 2.93 43.7 15.0 36.3 13.3 4.7 4.40 0.17 Alpine Salix (June) 3.60 0.31 0.75 0.30 1.43 188.0 101.0 31.0 333.0 8.0 20.00 0.30 SHEEP REQUIREMENTS: 1.60 0.25 0.25-0.50 0.06 0.50 25-40 20-30 16-40 0.0 5.0 0.0 0.18 oo 88 from Magnum V a l l e y with the high copper l e v e l s i n J u l y were c o l l e c t e d adjacent to the abandoned copper mine. Summer willow leaves c o n t a i n e d m i n e r a l l e v e l s exceeding sheep requirements f o r a l l m i n e r a l s . BEHAVIOUR AT MINERAL LICKS Use of m i n e r a l l i c k s by sheep o c c u r r e d p r i m a r i l y from A p r i l to J u l y but use of a l i c k i n November was a l s o observed. Deep snow prevented the sheep from u s i n g many of the s i t e s , i n c l u d i n g the C h u r c h i l l mine, d u r i n g much of the winter u n t i l l a t e May. Sheep were o f t e n observed q u i c k l y approaching a l i c k from s e v e r a l k i l o m e t r e s away i n a manner which suggested a strong d e t e r m i n a t i o n to get to the l i c k . At the l i c k the animals became obsessed with l i c k i n g and e x h i b i t e d a reduced l e v e l of c a u t i o n , o f t e n a l l o w i n g people to approach w i t h i n 2-3 metres before moving away. The sheep e i t h e r l i c k e d the ground with t h e i r tongue or took i n a mouthful of s o i l and chewed i t . The i n t e n s i t y of mineral l i c k use d u r i n g the summer was r e f l e c t e d i n the f a c t t h a t the feces of some sheep d u r i n g t h i s time c o n t a i n e d up to 88% mineral m a t e r i a l and averaged up to 45% (Table 9). I n d i v i d u a l sheep u s u a l l y spent from 1-4 hours l i c k i n g before moving o f f to feed or r e s t . Most l i c k i n g took p l a c e d u r i n g mid-day. There were u s u a l l y no sheep at the C h u r c h i l l mine e a r l y i n the 89 morning but they began to move i n about 0800 and l e f t the area by 1800. The frequency of use of l i c k s by i n d i v i d u a l sheep i s not w e l l known but of 6 c o l l a r e d sheep u s i n g the C h u r c h i l l l i c k , frequency of use by known i n d i v i d u a l s ranged from 1 to 6 days out of a 10-day o b s e r v a t i o n p e r i o d or an average use of once every 2-3 days. S i g h t i n g s of sheep i n subalpine areas d u r i n g the summer were u s u a l l y r e l a t e d to the animals u s i n g subalpine m i n e r a l l i c k s . Sheep were observed moving q u i c k l y down from a l p i n e areas to use the l i c k on Toad Mountain and at M i l e 475 of the Ala s k a Highway but they then returned to a l p i n e a r e a s . MINERAL LICKS Many d i f f e r e n t forms of mineral l i c k s were u t i l i z e d i n the area i n c l u d i n g : 1) s o i l l i c k s exposed along creek beds and road c u t s , i i ) weathered, rocky outcrops, and i i i ) man-made sources, p a r t i c u l a r l y the C h u r c h i l l copper mine s i t e and m i l l s i t e . On Toad Mountain the sheep have c r e a t e d a small cave extending about 1.5 m i n t o the s i d e of the mountain by e a t i n g the s o i l . S o i l from mineral l i c k s (Table 11) had lower t o t a l n i t r o g e n and carbon l e v e l s than other s o i l s i n the area due to the l a c k of o r g a n i c matter. The higher pH i s the expected v a l u e f o r c a l c i u m carbonate mineral m a t e r i a l without the a c i d i f y i n g e f f e c t s of organic a c i d s present i n 9 0 other s o i l s . Levels of phosphorous, calcium, magnesium, and potassium were not d i f f e r e n t from other s o i l samples from the area. S o i l l e v e l s of these elements were lower than the l e v e l s found in forage samples. Sodium was the only element which was higher in mineral l i c k samples which suggests that i t was the mineral a t t r a c t i n g sheep to these areas . Sodium was undetectable (< 23 ppm) in a l l the samples except for the three mineral l i c k samples. The sheep also became f r a n t i c in t h e i r e f f o r t s to get access to the s a l t blocks we used as bait for trapping indicating a strong drive to obtain sodium. 91 FORAGING BEHAVIOUR BITING RATE D a i l y P a t t e r n On the 2 oc c a s i o n s i n A p r i l 1982 when the b i t i n g r a t e of i n d i v i d u a l ewes was observed throughout the d a y l i g h t hours, there was no t r e n d i n the b i t i n g r a t e e i t h e r throughout the day or du r i n g i n d i v i d u a l f o r a g i n g bouts. T h e r e f o r e , I concluded that i t was not necessary t o conduct day-long o b s e r v a t i o n s but r a t h e r a sample at any time of the day would be r e p r e s e n t a t i v e of the b i t i n g r a t e throughout the day. Sex and Age D i f f e r e n c e s On the one day when the b i t i n g r a t e of rams and y e a r l i n g s was determined, there was no s i g n i f i c a n t d i f f e r e n c e (P < 0.05) between the b i t i n g r a t e of rams (30 ± 1.8 (S.E.) b i t e s / m i n u t e ) , y e a r l i n g s (30 ± 1.2 (S.E.) b i t e s / m i n u t e ) , and ewes (34.2 ± 2.4 (S.E.) bites/minute) f e e d i n g on the same range. 92 Seasonal P a t t e r n The b i t i n g r a t e remained r e l a t i v e l y constant throughout the spring-summer season under a wide v a r i e t y of range types and forage d i s t r i b u t i o n s (Table 13). There was no d i f f e r e n c e between the b i t i n g r a t e of sheep on burned versus n a t u r a l s u b a l p i n e s p r i n g range. O v e r a l l i t appeared t h a t Stone's sheep maintained a r e l a t i v e l y c o nstant b i t i n g r a t e averaging about 30-35 bites/minute and t h a t t h i s r a t e was not o b v i o u s l y a f f e c t e d by the range c h a r a c t e r i s t i e s . FORAGING TIME The p r o p o r t i o n of d a y l i g h t hours spent f o r a g i n g remained constant throughout the w i n t e r - s p r i n g p e r i o d f o r both ewe/yearling groups and ram groups (Tables 14 and 15). On average, ewe/yearling groups spent about 13% more of the d a y l i g h t hours f o r a g i n g than d i d rams. A l s o the p r o p o r t i o n of time spent f o r a g i n g was more v a r i a b l e from day t o day f o r rams than f o r ewes/yearlings. The one a t y p i c a l day of ewe/yearling a c t i v i t y (May 19) when f o r a g i n g time was only 50% may have been due t o a preponderance of y e a r l i n g s on t h a t day (6 y e a r l i n g s , 2 ewes). T h i s d i s t o r t i o n was caused by a d u l t ewes moving from the main slope to lambing c l i f f s at t h i s time of ye a r . These data represent a wide range of c o n d i t i o n s 93 Table 13. Biting rate of Stone's sheep ewes under different range characteristics (April-June). Date Biting Rate Number of Range Type Forage Grass T i l l e r observations* Biomass Length 2 (g/m ) cm April 9 35.0 + 1.2 44 subalpine burn 162 dead -A p r i l 20 26.0 + 0.6 90 subalpine burn 162 dead trace l i v e -May 5 28.0 + 1.0 22 subalpine burn 14 liv e grass 8 May 11 29.4 + 1.2 35 subalpine burn 14 liv e grass 9 May 13 34.8 + 2.6 11 subalpine clearing 1.5 live grass 10 May 20 34.2 + 1.5 24 subalpine burn 20 liv e grass 13 May 22 34.8 + 1.7 12 subalpine clearing 1.6 liv e grass 11 May 24 31.8 + 2.2 11 subalpine burn 34.2 grass 15.4 forbs 13 June 28 37.7 + 1.2 15 alpine 3.7 sedges 13.5 forbs 12 1 observation equals a 1-2 minute period of observation. Table 14. Time budget and calculated bites/day for Stone's sheep ewes and yearlings (February-May). Date Number of observations Resting % PERCENTAGE OF DAYLIGHT TIME Travelling Foraging 4 % Standing 1 Observation period (hours) Daylight hours foraging Estimated bites/day Feb. 8 1907 17.5 2.7 62.6 17.7 10 6.2 9600 Feb. 14 1767 21.0 2.0 67.0 10.0 10 6.7 10375 March 16 1965 32.0 2.0 62.0 4.0 12 7.4 13480 March 17 1807 21.0 5.0 67.0 6.0 12 8.0 14573 March 18 1677 21.0 7.0 69.0 4.0 12 8.2 14940 March 24 2341 24.0 4.0 70.0 3.0 13 9.1 16580 March 31 1696 27.0 1.0 64.0 8.0 13 8.3 15123 A p r i l 4 1744 34.0 2.0 60.0 4.0 14 8.4 15305 Ap r i l 20 70 30.0 5.0 61.0 4.0 14 8.5 15487 May 5 2859 26.0 4.0 64.0 5.0 16 10.2+ 18584+ May 7 954 29.0 4.0 61.0 6.0 17 10.4+ 18950+ May 10 2322 30.0 3.0 63.0 5.0 18 11.3+ 20590+ May 12 1925 25.0 6.0 60.0 9.0 18 10.8+ 19675+ May 12* 918 30.0 1.0 63.0 5.0 18 11.3+ 20590+ May 19** 1465 42.0 2.0 50.0 6.0 18 9.0+ 16400+ May 25 935 32.0 1.0 64.0 3.0 18 11.5+ 20955+ Mean Standard Deviation 26.6 4.4 3.3 1.9 63.8 3.1 6.3 3.8 sheep on natural subalpine clearing, a l l other data i s for sheep on subalpine burned range. ** predominately yearlings — dashed line separates periods of feeding on senescent forage from periods of feeding on new production. Table 15. Time budget and calculated bites/day for Stone's sheep rams (February-May). Date Number of PERCENTAGE OF DAYLIGHT TIME Observation Daylight Estimated S r v a S o n s Period hours bites/day Resting Travelling Foraging Standing foraging Feb. 8 Feb. 14 Feb. 16 Feb. 17 Mean 410 34.6 2.8 40.0 21.2 10 4.0 547 41.0 2.0 56.0 1.0 10 5.6 204 56.0 5.0 37.0 3.0 12 4.4 298 34.0 6.0 46.0 14.0 12 5.5 505 42.0 1.0 49.0 8.0 14 6.9 1586 28.0 4.0 58.0 10.0 16 9.3+ 6195 8673 6814 8518 A p r i l 4 505 Z.U I U H 3.U „ . „ 12572 May 5 - • - - - - , n C D n 1 n n l f i g 3 + 1 6 9 4 5 + May 9 May 10 May 12* May 12 May 19 May 19 May 25 401 42.0 4.0 49.0 5.0 18 8.8+ 16035 2150 38.0 1.0 56.0 5.0 18 10.1+ 18402+ 362 34.5 2.5 56.9 6.0 18 10.2+ 18584+ 1885 38.0 3.0 54.0 4.0 18 9.7+ 17675+ 231 38.0 2.0 53.0 7.0 18 9.5+ 17300+ 248 35.0 4.0 58.0 3.0 18 10.4+ 18950+ 1461 39.0 4.0 50.0 7.0 18 9.0+ 16400+ 38.0 3.2 51.0 7.3 Standard Deviation 6.7 1.5 6.8 5.4 * c W n on natural subaloine clearing. A l l other data i s for sheerj on subalpine burned range. -- S£ nSiyS^ SriS o/feeding on senescent forage from periods of feeding on new production. 96 including cratering through the snow in February, snow-free slopes with dead grass in March-April and new production in May. S i m i l a r l y , there was no difference in proportion of time spent foraging between sheep feeding on subalpine burned range and sheep feeding on a natural subalpine clearing in May. The proportion of daylight hours spent foraging remained constant even though the amount of daylight almost doubled from February to May. It appeared that in the winter the sheep were not foraging during darkness and thus the observation period included a l l or most of the to t a l time spent foraging. This conclusion i s based on the fact that the sheep were usually seen bedding down in the evening and were often seen bedded in the same spot the following morning. In fact, in winter the sheep often remained bedded down for up to an hour after l i g h t was adequate to begin observations. In spring, the observation period did not include the entire day's foraging a c t i v i t y since most of the sheep usually began foraging before l i g h t was adequate to see them. Although most sheep usually had bedded down before darkness prevented further observation some foraging s t i l l continued beyond the observation period. The occurrence of a major foraging bout at dawn and dusk in conjunction with bedding a c t i v i t y at dusk suggested that extensive 97 f o r a g i n g d i d not occur d u r i n g the s e v e r a l hours of darkness i n the s p r i n g . Thus, the o b s e r v a t i o n p e r i o d d e f i n i t e l y d i d not i n c l u d e the e n t i r e f o r a g i n g p e r i o d i n s p r i n g but probably came c l o s e i f i n f a c t f o r a g i n g d i d not occur d u r i n g the peak of darkness. The time spent f o r a g i n g f o r ewe/yearling groups went from 6.2 hours i n February to 12+ hours i n May and f o r rams went from 4-5 hours i n February t o 10+ hours i n May. Not a l l of the f o r a g i n g time was spent a c t i v e l y f e e d i n g , p a r t i c u l a r l y i n winter when much of the f o r a g i n g p e r i o d was spent d i g g i n g through snow to reach the food. The amount of time spent d i g g i n g was dependent on the snow depth ( F i g . 25) and averaged 15 - 20% d u r i n g February of 1982. In a d d i t i o n , throughout the year o n l y 92% of the f o r a g i n g time was spent a c t i v e l y f e e d i n g with the remaining 8% of the time spent s e a r c h i n g , chewing, e t c . T h i s value i s based on the d i f f e r e n c e between f o r a g i n g time and a c t i v e b i t i n g time determined d u r i n g b i t i n g r a t e o b s e r v a t i o n s (n = 264). The numbers of b i t e s / d a y i n T a b l e s 14 and 15 were c a l c u l a t e d by reducing the f o r a g i n g time i n February by 15% t o account f o r c r a t e r i n g and then reducing a l l v a l u e s of f o r a g i n g time by an a d d i t i o n a l 8% t o account f o r non-f e e d i n g time. The r e s u l t a n t values f o r f e e d i n g time was then m u l t i p l i e d by the average b i t i n g r a t e of 33 99 b i t e s / m i n u t e . LENGTH AND NUMBER OF FORAGING BOUTS D e t a i l e d day-long o b s e r v a t i o n s of two ewes i n A p r i l showed that both animals had four f o r a g i n g bouts throughout the day ranging from 60 minutes to g r e a t e r than 240 minutes separated by r e s t p e r i o d s ranging from 40 to 150 minutes. In both animals the f i r s t f o r a g i n g bout began before d a y l i g h t and the l a s t f o r a g i n g bout continued i n t o the darkness. T h e r e f o r e , the exact d u r a t i o n of these bouts i s unknown. In both cases the longest f o r a g i n g bout of the day (160+ and 240+ minutes) was the one preceding darkness. The time budget data lumped f o r ewes/yearlings and f o r rams showed a s i m i l a r p a t t e r n of four f o r a g i n g bouts/day throughout May ( F i g . 26). However, i n February and March, the animals o n l y had three f o r a g i n g bouts/day. Both times of the year showed major dawn and dusk feeding bouts with the d i f f e r e n c e being the number of i n t e r v e n i n g bouts. The f a c t t h a t the p a t t e r n i s q u i t e d i s t i n c t even i n the aggregated data demonstrates t h a t there was a great d e a l of synchrony i n the behaviour of animals w i t h i n a f o r a g i n g group. However, i t can a l s o be seen from F i g u r e 26 that behaviour of rams compared to ewes/yearlings was o f t e n asynchronous, with rams f e e d i n g while the 100 MARCH 17, EWES • • 1107 MARCH 17. RAMS I s 211 TIME OF DAY OrO standing and travelling resting foraging Figure 26. Typical daily time budgets of Stone's sheep ram groups compared to ewe/yearling groups in March and May. 101 ewes/yearlings were resting etc. 1 02 PARASITOLOGY Lungworm larvae counts for winter and spring fecal samples are presented in Table 16. Most larvae belonged to Protostrongylus spp. but in addition some samples contained up to 33 larvae/gram of dorsal-spined larvae, most l i k e l y Muellerius  spp. (W. Samuel, pers. comm.). Lungworm counts from sheep using unburned range (Delano) were higher than samples from burned subalpine range in both winter and spring. However, the high spring count for the Delano samples probably resulted from a build-up occurring on the alpine winter range rather than r e f l e c t i n g on the qual i t y of the spring range. In both areas the spring counts were higher than the winter counts indicating that parasite loads continued to build up throughout the winter. 103 Table 16. Prbtbstrbngylus larvae counts in feces of Stone's sheep on burned and unburned range i n northeastern B r i t i s h Columbia (1982). number of larvae/g feces Location and X SE range n Season Delano alpine, 417 171 34-992 February" F e r t i l i z e r subalpine, 38 10 17-65 February Delano subalpine, 824 567 192-3087 May Fe r t i l i z e r subalpine, 220 May 71 42-385 4 1 04 HORN GROWTH OF RAMS The maximum increment i n ram horn l e n g t h o c c u r r e d d u r i n g the second year of l i f e (annulus 1-2) and subsequently d e c l i n e d with age ( F i g u r e 27). Horn growth of rams with access to burned range was s i g n i f i c a n t l y g r e a t e r (P < 0.05) than on unburned range f o r y e a r l i n g s but there was no d i f f e r e n c e f o r o l d e r ages. Despite t h i s d i f f e r e n c e i n y e a r l i n g growth, there was no s i g n i f i c a n t d i f f e r e n c e i n t o t a l horn l e n g t h between rams with access to burned range compared to unburned range ( F i g . 28). The l o s s of the e a r l y horn growth advantage by sheep from burned range appeared to r e s u l t from an i n c r e a s e d r a t e of brooming (amount broomed i s estimated by rec o r d e r on r e p o r t i n g form) i n these animals (58.5 mm ± 12.3 (S.E.)) compared to rams on unburned range (30.8 mm ± 7.9 ( S . E . ) ) . T h i s d i f f e r e n c e was not s t a t i s t i c a l l y s i g n i f i c a n t but i t was s u f f i c i e n t to n u l l i f y the d i f f e r e n c e i n horn growth between ranges. Although rams from burned range d i d not have longer horns, they may have scored higher as t r o p h i e s because the t h i n t i p was not i n c l u d e d i n the remaining horn. E E Hi 5 UJ QC O QC O 2201 200-180-160-140-120-100-80-60-40-20-• BURNED RANGE • UNBURNED RANGE 10 HORN A N N U L U S Figure 27. Comparison of annual horn increments of Stone's sheep rams on burned versus unburned range (X ± 95% C.I.) in northeastern British Columbia (1980-1982). o HORN A N N U L U S Figure 28. Comparison of horn lengths from tip to annulus of Stone's sheep rams shot on burned range and unburned range (X ± 95% C.I.) in northeastern British Columbia (1980-1982). o ON 107 POPULATION PARAMETERS POPULATION NUMBERS The f o l l o w i n g p o p u l a t i o n numbers are minimum counts. In a d d i t i o n , because most of the area was continuous sheep h a b i t a t , any boundary used t o d e f i n e a p o p u l a t i o n would have been q u i t e a r b i t r a r y . The best counts are f o r the number of sheep w i n t e r i n g on the subalpine s l o p e s of F e r t i l i z e r Mountain (Table 17). T h i s group appeared t o be d i s c r e t e from other w i n t e r i n g groups and the numbers remained q u i t e constant throughout the w i n t e r . However, numbers were q u i t e v a r i a b l e a f t e r the snow melted and animals c o u l d move around more e a s i l y . Approximately 15-20 sheep used the a l p i n e peaks of adjacent Toad Mountain i n the wint e r , and s p r i n g counts u s u a l l y found from 5-16 sheep on the s u b a l p i n e s l o p e s . Winter a e r i a l surveys of the Sulphur Creek area found 14-17 sheep on adjacent a l p i n e peaks. In a d d i t i o n , another 22 animals were spotted on other mountains i n the Toad R i v e r area t h a t were not immediately adjacent t o burned s l o p e s . O v e r a l l , the Toad River/Sulphur Creek area r supported at l e a s t 90 sheep i n an area of about 900 km2 f o r a minimum d e n s i t y estimate of 1 sheep/10 km 2. 10 Table 17. Maximum daily count of sheep on F e r t i l i z e r Mountain each month (1980-1982). Date Ewes Yearlings Rams Total May 1980 March 1981 Ap r i l 1981 May 1981 February 1982 Ap r i l 1982 May 1982 Apr i l 1983 8 7 12 27 11 6 9 26 11 8 5 24 16 8 16 40 16 8 9 33 16 8 9 33 14 7 6 27 19 8 15 42 109 Winter a e r i a l surveys i n the Yedhe/Delano area l o c a t e d from 40-50 animals on windswept a l p i n e r i d g e s . May counts i n Delano v a l l e y ranged from 25-40 animals. Summer counts (June-July) at the C h u r c h i l l mine s i t e p r o v i d e d the best o p p o r t u n i t y to o b t a i n r e p l i c a t e counts over many days (Table 18). In 1982 e i g h t c o l l a r e d sheep r e g u l a r l y used t h i s m i n e r a l l i c k but on any one day o n l y 2-5 of these i n d i v i d u a l s would be s p o t t e d at the l i c k . T h e r e f o r e , the t o t a l count on any day probably only i n c l u d e d from 25-65% of the t o t a l number of animals using the l i c k . Thus, i t was l i k e l y t h a t a t o t a l of 100-125 sheep used t h i s l i c k d u r i n g the summer. The s i z e of the area from which animals were drawn to t h i s m ineral l i c k was not known. The t o t a l area of adjacent watersheds from which these sheep appeared to be coming t o t a l e d about 800 km2. T h i s p r o v i d e d a rough estimate of 1 sheep/7-8 km 2. LAMB AND YEARLING COUNTS I t was d i f f i c u l t t o o b t a i n a c c u r a t e lamb counts i n the Toad R i v e r area because by the time the lambs were born the sheep were i n small groups d i s p e r s e d widely i n the s p r u c e - w i l l o w - b i r c h zone. Counts of 9-month-old lambs (sh o r t y e a r l i n g s ) on F e r t i l i z e r Mountain were probably more r e l i a b l e due to the d i s c r e t e n e s s of the p o p u l a t i o n 110 Table 18. Number of sheep using Churchill mine l i c k and adjacent areas i n summer (1980-1982) . Date Number June 1980 52 July 1980 49 June 1981 36-49 July 1981 39-102 June 1982 24-76 111 and the o p p o r t u n i t y to o b t a i n r e p l i c a t e counts. I t was a l s o d i f f i c u l t t o o b t a i n lamb counts immediately a f t e r lambing i n the Delano/Yedhe area, p r i m a r i l y due to access problems. The most r e l i a b l e counts were taken l a t e r i n the summer at the mine s i t e where l a r g e , r e p l i c a t e samples were o b t a i n e d . In 1980 the lamb/ewe r a t i o was h i g h i n both the F e r t i l i z e r Mountain and C h u r c h i l l p o p u l a t i o n s f o l l o w i n g an e a r l y s p r i n g with subalpine s l o p e s being snow-free by e a r l y March (Table 19). In 1981 the lamb/ewe r a t i o was almost four times g r e a t e r near Toad R i v e r than at C h u r c h i l l f o l l o w i n g an e s s e n t i a l l y snow-free winter on the burned, s u b a l p i n e slopes but a high snow winter i n the a l p i n e . The 1982 lamb/ewe r a t i o was low i n both p o p u l a t i o n s f o l l o w i n g a severe winter with deep s n o w f a l l g r e a t l y r e s t r i c t i n g the a v a i l a b l e range i n both a r e a s . Thus high lamb pr o d u c t i o n appeared to be r e l a t e d to winter snow accumulation. SURVIVAL RATES The only d i r e c t data which gave any i n d i c a t i o n of s u r v i v a l r a t e s were: 1) A minimum of e i g h t a d u l t ewes out of 10 c o l l a r e d i n the summer of 1981 s u r v i v e d the winter and were seen i n the 112 Table 19. Lamb/ewe and yearling/ewe counts of Stone's sheep on F e r t i l i z e r Mountain and at the Churchill mine (1980-1982) Location and Date Lambs/ewe #lambs Yearlings/ewe #yearlings counted counted F e r t i l i z e r mountain area: June, 1982 June, 1980 0.60 64 March, 1981 November, 1982 0.35 March, 1983 0.53 17 June, 1981 0.74 17 March, 1982 - - °- 5 0 0.38 20 Churchill Mine: July,1980 . 0.49 64 0.28 23 July 1981 0.18 22 0.27 32 0.26 90 0.19 66 113 summer of 1982. 2) A l l of the 33 animals using F e r t i l i z e r Mountain i n January, 1982 s u r v i v e d u n t i l A p r i l , 1982. These two p o i n t s i n d i c a t e t h a t i n g e n e r a l , n a t u r a l a d u l t m o r t a l i t y r a t e s were q u i t e low. Crude estimates of lamb winter m o r t a l i t y were made by comparing lamb/ewe r a t i o s with the yearling/ewe r a t i o s f o r the f o l l o w i n g year (Table 19) and adding an a d d i t i o n a l 10% to account f o r a d u l t ewe m o r t a l i t y . On F e r t i l i z e r Mountain, estimated lamb m o r t a l i t y was 22% d u r i n g the m i l d winter of 1981 and 42% d u r i n g the severe winter of 1982. In the C h u r c h i l l area, the estimated lamb m o r t a l i t y f o r 1981, a severe winter i n the a l p i n e , was 55%. The estimate f o r the winter of 1982 was unreasonable ( i . e . , more y e a r l i n g s than lambs) due to a q u e s t i o n a b l y low lamb/ewe r a t i o f o r 1981. The average f o r the three reasonable estimates of winter lamb m o r t a l i t y was 40%. GROUP SIZE The average group s i z e was 4.8 ± 3.0 (S.D.) (n - 71). Most groups ranged from 3-6 i n s i z e but i t was not unusual to see s i n g l e sheep or p a i r s . Large groups of sheep (50+) o f t e n c o n c e n t r a t e d around m i n e r a l l i c k s i n summer. In wi n t e r , l a r g e groups (20+) sometimes o c c u r r e d i n areas 1 where many sheep were r e s t r i c t e d to a small area by snow 1 1 5 DISCUSSION SEASONAL PATTERN OF NUTRITION A MODEL OF FOOD AND ENERGY INTAKE FOR MOUNTAIN SHEEP Within the model I assume that a sheep w i l l consume enough food t o meet i t s energy requirements u n l e s s i n t a k e i s l i m i t e d to some lower l e v e l by passage r a t e through the gut. T h i s g e n e r a l p a t t e r n i s observed i n domestic sheep ( D i n i u s and Baumgardt 1970), cows (Conrad et a l . 1964), and deer (Ammann et a l . 1973). Mountain sheep have a d a i l y maintenance metabolic requirement of about 110 k c a l / W ° - 7 s (Chappel and Hudson 1978) which i s almost i d e n t i c a l t o the value f o r domestic sheep (NRC 1975). T h i s value corresponds to a d a i l y d i g e s t i b l e energy requirement of 128 kcal/W° - 7 S . Hebert (1973) r e p o r t e d d a i l y d i g e s t i b l e energy requirements ranging from 112 - 156 k c a l / W 0 - 7 5 f o r bighorn sheep. A c t u a l energy requirements of an i n d i v i d u a l w i l l o f t e n exceed the maintenance requirement depending on the p h y s i o l o g i c a l s t a t e (Table 20). The energy c o s t of g r a z i n g i n domestic sheep i s about 1.25 times the maintenance requirements of penned sheep ( O s u j i 1974). However, the energy requirements of mountain sheep i n maintenance t r i a l s tend to be c l o s e r t o v a l u e s f o r g r a z i n g 116 Table 20. Digestible energy requirements of sheep under different physiological conditions.  Physiological Digestible Energy Multiple of Minimum ^ State Reauirements Maintenance Adequate DMD k c a l / l V 7 5 % Maintenance 128* 1.0 48.0 Early gestation 140* 1.1 49.0 Late gestation 232* 1.8 60.0 Lactation 319* 2.5 69.0 Lamb growth 339* 2.7 79.0 Adult weight gain of 0.02 g/day 140** 1.1 49.0 Adult weight loss of 0.02 g/day 115** 0.9 47.0 Maintenance + Thermoregulation below -20°C 178*** 1.4 54.0 * NRC 1975 **Garrett et a l . 1959 ***Chappel and Hudson 1978 1 calculated from model 117 domestic sheep than to penned domestic sheep, possibly due to the stress associated with c a p t i v i t y of mountain sheep compared to docile domestic sheep. Therefore, an energy expenditure for grazing was not added to the maintenance l e v e l . Gross energy content of most mountain sheep forages i s about 4.3 - 4.4 kcal/g (Hebert 1973). The d i g e s t i b l e energy content of forage can be estimated by multiplying the gross energy value by the dry matter d i g e s t i b i l i t y (DMD) of the forage. Therefore, the food requirement of a mountain sheep can be calculated by the equation: Food requirement (g/day) = (a) (128) (W 0- 7 5) (4.4) (DMD) where: a = multiple of maintenance requirement from Table 20, W = body weight in kg, and DMD = dry manner d i g e s t i b i l i t y expressed as a proportion. The maximum l e v e l of forage intake in ruminants i s limi t e d by the passage rate through the gut (Blaxter et a l . 1961, Conrad et a l . 1964). Because outflow from the animal i s r e l a t i v e l y constant ( P h i l l i p s o n and Ash 1965), the only way that food intake can increase i s i f more of 118 i t i s digested. Therefore, intake increases as forage d i g e s t i b i l i t y increases u n t i l energy requirements are met. Data on intake rate versus forage d i g e s t i b i l i t y when gut capacity i s l'imiting are presented for domestic sheep and bighorn sheep in Figure 29. The linear regression was calculated excluding the four low outlying points for which intake appeared to be well below the gut capacity. This r e l a t i o n s h i p i s used in the model to calculate maximum intake capacity. The maximum possible energy intake w i l l be the product of the maximum capacity and the d i g e s t i b l e energy content of the food. Since DMD influences both of these values, changes in DMD have a m u l t i p l i c a t i v e effect on energy intake when the digestive system i s at capacity (Figure 30). Therefore, small changes in DMD can have quite major e f f e c t s on the energy intake of the animal. In the model I assume that the actual food intake of the animal w i l l be whichever value, food requirement or maximum capacity, i s l e a s t . That i s , the sheep w i l l feed to meet i t s energy requirements unless r e s t r i c t e d to a lower consumption by gut capacity. The value for food requirements w i l l depend on body weight, physiological state of the animal, and the DMD of the food. Maximum capacity i s a function of body weight and the DMD of the food. Figure 29. Relationship between digestibility of the food and the daily intake of sheep when digestive capacity is limiting. MAXIMUM ENERGY INTAKE Lacta t ion Rcquirtmtnt model's prediction 121 IMPLICATIONS OF THE MODEL The value f o r DMD at which the c a l c u l a t e d maximum energy intake ( c a p a c i t y l i m i t ) equals the energy requirements represents the minimum forage DMD that w i l l p r o v i d e the animal's energy needs ( F i g u r e 30). C a p a c i t y i s a f u n c t i o n of body weight and forage DMD. The minimum forage d i g e s t i b i l i t y on which a 50 kg sheep can meet i t s maintenance requirements i s estimated to be 48%. At lower forage d i g e s t i b i l i t i e s gut c a p a c i t y w i l l l i m i t i n t a k e below the food requirement l e v e l . As e n e r g e t i c requirements i n c r e a s e , the minimum q u a l i t y of forage r e q u i r e d to meet demands w i l l a l s o i n c r e a s e ( F i g u r e 30). The annual p a t t e r n of energy requirements f o r a 50 kg a d u l t ewe are presented i n F i g u r e 31 based on the data i n Table 19. Winter requirements were c a l c u l a t e d assuming that about 25% of the days are below -20°C and r e q u i r e energy f o r the r m o r e g u l a t i o n . The maximum p o s s i b l e energy i n t a k e w i l l depend on the d i g e s t i b i l i t y of the forage being consumed by the animal. Although forage q u a l i t y measurements were c o l l e c t e d throughout the season, f e c a l p r o t e i n v a l u e s ( c o r r e c t e d f o r ash) were used as a measure of food q u a l i t y from May to November because they i n d i c a t e what the animal consumed r a t h e r than what was a v a i l a b l e . The DMD of the food was c a l c u l a t e d from May to November from the f e c a l p r o t e i n ra ra o sc O oc UJ z LU 111 _J CD (0 UJ O 8000 7000 H 6000-1 5000 H 4000 3000 2000 1000+ MONTH Figure 31. Seasonal pattern of daily energy intake and energy requirements of a 50 kg ewe predicted by the model. T = Thermoregulation, G = Gestation, L - Lactation 123 data u s i n g the r e g r e s s i o n equation presented by Lambourne and Reardon (1963). However, f e c a l p r o t e i n v a l u e s d i d not seem to p r e d i c t reasonable v a l u e s f o r food q u a l i t y when q u a l i t y was very low. In the winter, even when the sheep a t e a l l the forage, f e c a l p r o t e i n d i d not d e c l i n e below an average of 10% even though forage p r o t e i n was only 4% (F i g u r e 24). T h i s d i s p a r i t y probably r e s u l t s from a decreased d i g e s t i b i l i t y of p r o t e i n at very low crude p r o t e i n l e v e l s (Mould and Robbins 1981). T h e r e f o r e , f e c a l p r o t e i n does not d i s t i n g u i s h between poor and very poor f o r a g e s . T h i s problem e x p l a i n s why f e c a l p r o t e i n v a l u e s f a i l e d to d i f f e r e n t i a t e sheep c o n d i t i o n between m i l d and severe winters and between a l p i n e and sub a l p i n e winter range. Because sheep consumed v i r t u a l l y a l l the forage a v a i l a b l e d u r i n g a severe w i n t e r , the d i g e s t i b i l i t y of the a v a i l a b l e forage r e p r e s e n t s the d i g e s t i b i l i t y of the food eaten. T h i s v a l u e was used as the forage d i g e s t i b i l i t y f o r the winter months. Given the DMD of the food, the maximum p o s s i b l e energy i n t a k e was c a l c u l a t e d u s i n g the values f o r maximum c a p a c i t y ( F i g u r e 29) and d i g e s t i b l e energy content of food ( i . e . k c a l / g = 4.4 x DMD). Requirements exceeded the supply i n winter but were l e s s than the supply i n summer and e a r l y f a l l ( F i g u r e 31). Over the season, the 124 c a l c u l a t e d energy d e f i c i t i n winter (200,000 k c a l ) was balanced by the summer-fall s u r p l u s (215,000 k c a l ) . The d a i l y winter d e f i c i t of 1200 kcal/day would r e s u l t i n a d a i l y weight l o s s of about 106 g/day ( G a r r e t t et a l . 1959), f o r a t o t a l of about 12-13 kg over the w i n t e r . T h i s value i s comparable to the 18-22% overwinter weight l o s s r e p o r t e d f o r bighorn sheep d u r i n g severe winters ( S t e l f o x 1976). The energy s u r p l u s i n summer and f a l l would a l l o w the animals to put on f a t f o r the next w i n t e r . C a p t i v e mountain sheep and deer with access to h i g h q u a l i t y food ad l i b i t u m e x h i b i t a v o l u n t a r y r e d u c t i o n i n food intake d u r i n g the winter r e s u l t i n g i n weight s t a s i s i n . sheep and weight d e c l i n e s i n deer (Chappel and Hudson 1978, Nordan e t a l . 1968). T h i s phenomenon suggests that the metabolic p a t t e r n of w i l d ungulates i s g e n e t i c a l l y programmed to correspond to the energy a v a i l a b l e i n the w i l d . I t i s u n l i k e l y t h a t w i l d ungulates v o l u n t a r i l y reduce t h e i r i n t a k e i n the w i l d as suggested by Mautz (1978) but r a t h e r that they eat as much as they can given the l i m i t a t i o n s imposed by t h e i r d i g e s t i v e c a p a c i t y . V o l u n t a r y r e d u c t i o n i n c a p t i v e animals i s p o s s i b l y an anomaly r e s u l t i n g from a v a i l a b l e food q u a l i t y g r e a t l y exceeding demands which are programmed to correspond to n a t u r a l food q u a l i t y . 125 I t may seem unusual that an animal does not have the c a p a b i l i t y of using abnormally abundant food energy when i t i s a v a i l a b l e . However, non-growing ungulates i n winter have a maintenance metabolic r a t e below the l e v e l of animals which are p h y s i o l o g i c a l l y geared to grow ( S i l v e r et a l . 1969, H o l t e r et a l . 1977). T h i s decrease i s r e l a t e d to winter decreases i n t h y r o x i n e and growth hormone l e v e l s (Bahnak et a l . 1981). T h e r e f o r e , m a i n t a i n i n g the p h y s i o l o g i c a l a b i l i t y to u t i l i z e s u r p l u s energy f o r growth i n winter would e n t a i l a g r e a t e r energy d e f i c i t under the usual winter c o n d i t i o n s of a negative energy balance. E l k and moose do not e x h i b i t a weight l o s s i n winter when pro v i d e d with h i g h q u a l i t y food i n c a p t i v i t y (Hudson p e r s . comm.) which suggests that they are not programmed to l o s e weight i n wint e r , presumably because winter forage i n the w i l d i s adequate to meet t h e i r maintenance metabolic requirements. Larger ruminants can meet t h e i r requirements on lower q u a l i t y forage because as body s i z e i n c r e a s e s , the c a p a c i t y of the d i g e s t i v e t r a c t i n c r e a s e s at a g r e a t e r r a t e than the metabolic r a t e . The model p r e d i c t s a minimum forage d i g e s t i b i l i t y of 42% to meet the maintenance requirements of a 200 kg e l k and 39% to meet the requirements of a 400 kg moose. I t i s l i k e l y t h a t they can o b t a i n food of t h i s q u a l i t y i n wi n t e r . 126 Another aspect to t h i s r e l a t i o n s h i p between body s i z e and forage q u a l i t y requirements i s the importance of lambs growing to an adequate s i z e to s u r v i v e the winter (Bunnell 1980). The model p r e d i c t s t h at a 30 kg lamb can meet maintenance needs on 50% d i g e s t i b l e forage compared to 52% d i g e s t i b i l i t y f o r a 20 kg lamb ( F i g u r e 32). When DMD i s below the maintenance requirement, small lambs w i l l l o s e weight more q u i c k l y than l a r g e r lambs. S i m i l a r l y , large, rams w i l l be able to s u r v i v e on l e s s d i g e s t i b l e forage than ewes. PROTEIN NUTRITION The seasonal crude p r o t e i n requirements f o r sheep are compared to the crude p r o t e i n content a v a i l a b l e i n the forage and the p r o t e i n content of food p r e d i c t e d from f e c a l p r o t e i n v a l u e s i n Table 21. P r o t e i n supply i n forage was l e s s than requirements d u r i n g winter and e a r l y s p r i n g but forage crude p r o t e i n content exceeded requirements d u r i n g the summer months when new p r o d u c t i o n was a v a i l a b l e . The f e c a l p r o t e i n v a l u e s were probably a dependable measure of food p r o t e i n i n the summer but they, o v e r e s t i m a t e d food p r o t e i n i n winter f o r reasons d i s c u s s e d p r e v i o u s l y . l-i CD O J ts) MINIMUM DMD (%) TO PROVIDE M A I N T E N A N C E R E Q U I R E M E N T S o l -h PO O CD H. I—1 p p TO r+ fD H -O CL 3 H - </) TO 3 * fD H -C/l " 3 cr fD H ' fD r+ fD 5" — CL cr - o c t £ fD fD M -r r T O o sr fD O fD i -h r t t/i 3 =r-P5 CD H * CD n- „ CD P 3 3 3 n fD 2 2 CD 3 a-CD C H -l-i I 3* r t t/l CD • a. n r+ o 3 o H i 3 H -3 3 00 O a •< m o z 7? ca to O w o o Ul . o o o o os. o LIX 128 Table 21. Protein a v a i l a b i l i t y in forage on Stone's sheep ranges compared to protein requirements of domestic sheep. Requirements Crude Protein Protein for Crude Protein i n Available Content of in Diet* a. Forage Food Intake** Winter: Early gestation 9.0 Ram maintenance 8.9 4.0 4.0 Spring: Late gestation 9.3 18.0 8.7 - 20.0 Summer: Lactation Lamb growth 10.4 16.0 18.0 - 25.0 18.0 - 25.0 21.0 21.0 * NRC 1975 ** estimated from fecal protein using the equation from Hebert (1973): Crude Protein i n Diet= -0.94 + 1.034 x Fecal Protein 129 SUMMARY OF SEASONAL NUTRITION PATTERNS Stone's sheep in winter were forced to eat forage which was too low in d i g e s t i b i l i t y to meet energy requirements and was d e f i c i e n t in protein and many essen t i a l mineral elements. The animals were forced to rely on stored reserves for winter s u r v i v a l . The onset of new production in the spring provided high q u a l i t y forage which exceeded the immediate requirements of the animals throughout the summer and allowed them to accumulate reserves for the next winter. The seasonal n u t r i t i o n a l regime was mirrored by fecal protein and DAPA values. 1 30 SELECTIVE FEEDING RANGE SELECTION In winter, when Stone's sheep faced the most severe n u t r i t i o n a l problems, they a l s o faced the most severe r e s t r i c t i o n s of a v a i l a b l e range. Sheep were r e s t r i c t e d to ranges with snow accumulations of l e s s than 25-30 cm. T h i s r e s t r a i n t dominated any p o s s i b l e s e l e c t i o n f o r areas with more or b e t t e r food. Sheep used both a l p i n e and subalpine ranges i n winter so long as they were not covered i n deep snow. The r o l e of snow i n r e s t r i c t i n g range use of sheep i s a l s o r e p o r t e d by G e i s t (1971), Hoefs and Cowan (1979), and Simmons et a l . (1981). S e l e c t i o n of ranges i n winter was thus s e l e c t i o n f o r a v a i l a b l e food r a t h e r than f o r areas with abundant but snow-covered forage. Avoidance of areas with high snow depths would a c t to reduce energy expenditures f o r locomotion. Mountain sheep are p a r t i c u l a r l y p o o r l y adapted f o r movement through snow given t h e i r low chest height and h i g h f o o t - l o a d i n g ( T e l f e r and K e l s a l l 1971). A l s o , i f t h e i r food i s covered by deep snow they must spend a l a r g e amount of time d i g g i n g to reach i t (Figure 25). The i n f l u e n c e of snow depth was the major f a c t o r which l i m i t e d the value of range burning f o r Stone's sheep. Abundant forage on the burned s l o p e s was 131 u s u a l l y u n a v a i l a b l e to the animals at the c r i t i c a l time of the year. Movement to subalpine areas i n s p r i n g provided the sheep with n u t r i t i o u s new p r o d u c t i o n f a r e a r l i e r than i t was a v a i l a b l e on a l p i n e ranges ( F i g u r e s 8 and 9). The gradual movement to higher e l e v a t i o n s throughout June and e a r l y J u l y c o n t i n u e d to p r o v i d e sheep with the best forage a v a i l a b l e . In summer, the a l p i n e range used by sheep p r o v i d e d more n u t r i t i o u s forage than was a v a i l a b l e on the su b a l p i n e s l o p e s . In f a l l , when forage q u a l i t y was d e c l i n i n g on a l l ranges, sheep were the l e a s t s e l e c t i v e and used a great v a r i e t y of range types. The n u t r i t i o n a l b e n e f i t s of the a l t i t u d i n a l m i g r a t i o n of mountain sheep were s t u d i e d i n d e t a i l by Hebert (1973). During the a l t i t u d i n a l m i g r a t i o n the sheep are u s u a l l y moving from areas of abundant low q u a l i t y food t o areas of sparse but high q u a l i t y food. Use of m i n e r a l l i c k s i n summer had important e f f e c t s on the range use p a t t e r n s of the sheep i n t h i s and other s t u d i e s (Simmons 1982). Sheep are u s u a l l y found c l o s e to mi n e r a l l i c k s i n summer. Although some sheep used su b a l p i n e l i c k s i n summer, they returned to the a l p i n e range f o r f o r a g i n g . Sheep appeared to use l i c k s t o o b t a i n sodium as i n other s t u d i e s of ungulate m i n e r a l l i c k i n g ( F r a s e r et a l . 1980). Most forages do not c o n t a i n 132 adequate amounts of sodium t o meet body needs (Maynard et a l . 1979) and l i c k i n g behaviour appeared to s a t i s f y t h i s need. Requirements f o r other e s s e n t i a l elements c o u l d be s u p p l i e d by summer forage which were higher i n these elements than the mineral l i c k s . O v e r a l l , the seasonal p a t t e r n of movements by Stone's sheep r e s u l t e d i n the animals f e e d i n g i n areas with the most n u t r i t i o u s a v a i l a b l e food while a l s o s a t i s f y i n g t h e i r sodium demands i n summer. SELECTION OF FORAGE SPECIES Stone's sheep avoided e a t i n g s e v e r a l p l a n t s p e c i e s which c o n s t i t u t e d a l a r g e amount of the t o t a l a v a i l a b l e . forage biomass. P l a n t s which were avoided a p p a r e n t l y were not l e s s n u t r i t i o u s than other foods (see B e t u l a and A r c t o s t a p h y l u s , Table 5) but r a t h e r had c h a r a c t e r i s t i c s which made them u n p a l a t a b l e . These mechanisms were not q u a n t i f i e d but i n c l u d e d waxy and/or l e a t h e r y c u t i c l e s on A r c t o s t a p h y l o s , Dryas, and c o n i f e r s , and s t i c k y s e c r e t i o n s on B e t u l a q l a n d u l o s a . Forbs were u s u a l l y more n u t r i t i o u s than graminoids (lower f i b r e , higher p r o t e i n ) on s p r i n g and summer ranges. However, sheep d i d not appear t o s e l e c t f o r b s p r e f e r e n t i a l l y over grasses i n s p r i n g and s e l e c t e d a g a i n s t f o r b s i n summer. T h i s i s c o n t r a r y to the optimal f o r a g i n g 133 h y p o thesis but may be due to higher l e v e l s of secondary compounds i n f o r b s compared to graminoids which make them l e s s p a l a t a b l e . There were numerous for b s on the ranges which are known to be t o x i c i n c l u d i n g Lupinus, Aconitum, Delphinium, and Zigadenus (Stephens 1980). Most of these p l a n t s can be consumed in small q u a n t i t i e s but are t o x i c when a l a r g e amount i s eaten. L e v e l s of t o x i c compounds tend to be lower i n new p l a n t s than i n mature ones (F r e e l a n d and Janzen 1974). T h e r e f o r e , the s e l e c t i o n a g a i n s t f o r b s i n summer may have been due to h i g h l e v e l s of t o x i c compounds i n many s p e c i e s of f o r b s . SELECTION OF SUPERIOR QUALITY FORAGE Comparison of food q u a l i t y (estimated from f e c a l p r o t e i n values) with the q u a l i t y of forage which was c o l l e c t e d at random suggested that the sheep were not s e l e c t i n g b e t t e r than average q u a l i t y food, at l e a s t i n terms of p r o t e i n . The lack of a d i f f e r e n c e suggests that forage on a range may be q u i t e homogeneous i n q u a l i t y and t here was no need to be h i g h l y s e l e c t i v e . A l t e r n a t i v e l y , sheep may have been unable to d i s t i n g u i s h between d i f f e r e n c e s i n q u a l i t y at that l e v e l . 134 SELECTING A MIXED DIET Accor d i n g to the food q u a l i t y data, Stone's sheep c o u l d have fed on only willow shrubs i n the summer and o b t a i n e d a very n u t r i t i o u s d i e t . The same c o u l d be s a i d f o r other food types at t h i s and other times of the year. Although sheep d i d feed h e a v i l y on p a r t i c u l a r food types at c e r t a i n times of the year, they always maintained a v a r i e d d i e t . Westoby (1978: 627-628) d i s c u s s e d the b i o l o g i c a l bases of v a r i e d d i e t s : i ) A r e d u c t i o n of search c o s t s w i l l r e s u l t from t a k i n g s e v e r a l foods of equal v a l u e . i i ) If the optimal food type changes with time, the d i e t w i l l c o n t a i n a mixture of these foods. i i i ) Animals may have to sample a v a r i e t y of foods t< determine the optimal food. i v ) I f d i f f e r e n t foods are the best source of d i f f e r e n t n u t r i e n t s (or non-sources of negative compounds) the optimum d i e t w i l l be mixed. A l l of these reasons may apply to Stone's sheep. SEXUAL DIFFERENCES IN SELECTIVITY D i f f e r e n c e s i n body s i z e and e n e r g e t i c demands might be expected t o cause d i f f e r e n c e s i n forage s e l e c t i v i t y between rams and ewes. The model p r e d i c t s that a 70 kg ram can meet maintenance requirements on 46% d i g e s t i b l e 135 forage compared to 48% f o r 50 kg ewes. G e i s t and Petocz (1977) suggested that d i f f e r e n t i a l range use between sexes i n bighorn sheep maybe r e l a t e d to d i f f e r e n c e s i n f o r a g i n g s t r a t e g y . However, Shank (1982) s t u d i e d the same p o p u l a t i o n and concluded that i t was u n l i k e l y t h a t t h i s s p a t i a l s e p a r a t i o n arose from d i f f e r e n t i a l d i e t p r e f e r e n c e s . In the present study, s p a t i a l s e p a r a t i o n of sexes onto d i s t i n c t ranges d i d not occur. Over sho r t p e r i o d s of time, ram groups were o f t e n s p a t i a l l y separate from ewe groups but i n a l l seasons they r e g u l a r l y made use of the same areas of the range. T h e r e f o r e , s p a t i a l s e p a r a t i o n of rams and ewes was not due to d i f f e r e n t i a l range p r e f e r e n c e s . A l t e r n a t i v e l y , one might p r e d i c t t hat rams would eat lower q u a l i t y food than ewes because they can meet t h e i r requirements with l e s s d i g e s t i b l e f o r a g e . Shank (1979) found no d i f f e r e n c e between food q u a l i t y of rams and ewes i n w i n t e r . The lack of a d i f f e r e n c e might have been expected because both sexes were below maintenance i n winter and should have s e l e c t e d the best food a v a i l a b l e . However, i n summer, rams might be expected to s e l e c t poorer forage, i f i t was very abundant a l l o w i n g them t o meet t h e i r requirements i n l e s s time than by being h i g h l y s e l e c t i v e . In f a c t , t here was no d i f f e r e n c e i n the food h a b i t s or the food q u a l i t y as measured by f e c a l p r o t e i n 136 and DAPA l e v e l s between rams and ewes in summer. Therefore, there was no reason to believe that sexual differences in food s e l e c t i v i t y exist in Stone's sheep. The lack of a difference i s further evidence that sheep do not have to be highly sel e c t i v e when feeding in summer. There was no lack of high q u a l i t y food once the animals had selected the best range. SUMMARY OF FOOD SELECTIVITY Stone's sheep selected the range which contained the most nu t r i t i o u s available forage. Certain foods were avoided, probably because of plant c h a r a c t e r i s t i c s which made them unpalatable. Beyond these i n i t i a l l e v e l s of s e l e c t i v i t y , sheep did not seem to select forage which was any more nu t r i t i o u s than the average food a v a i l a b l e . Apparently once the sheep had selected the best range and avoided unpalatable foods, there was no need or opportunity to feed more s e l e c t i v e l y . 137 INTAKE RATE Both b i t i n g r a t e and f o r a g i n g time were independent of a v a i l a b l e forage biomass. T h i s p o i n t was p a r t i c u l a r l y e v i d e n t i n the lack of any d i f f e r e n c e i n the s p r i n g between sheep on burned range compared to n a t u r a l c l e a r i n g s . Although the grass l e n g t h was s i m i l a r on both areas, burned ranges had a much higher forage biomass due to a g r e a t e r d e n s i t y of grass t i l l e r s . The r e s u l t s are c o n s i s t e n t with data f o r domestic sheep i n which b i t i n g r a t e and intake r a t e are p r i m a r i l y dependent on the t i l l e r l e n g t h r a t h e r than the t i l l e r d e n s i t y ( A l l d e n and Whittaker 1970, A r n o l d 1975). B i t e s i z e of domestic sheep d e c l i n e s at short t i l l e r l e n gths ( A l l d e n and Whittaker 1970). Smaller b i t e s i z e i s p a r t i a l l y compensated f o r by an i n c r e a s e d b i t i n g r a t e and by longer f o r a g i n g p e r i o d s but t h i s compensation i s incomplete when grass t i l l e r l e n g t h i s very short r e s u l t i n g i n a decreased d a i l y i n t a k e . T h i s p a t t e r n i s s i m i l a r to that r e p o r t e d f o r g r a z i n g cows (Chacon and Stobbs 1976) but d i f f e r s from r e i n d e e r i n which b i t e s i z e remains q u i t e constant and i n t a k e r a t e i s determined by the b i t i n g r a t e which i n c r e a s e s as forage biomass i n c r e a s e s ( T r u d e l l and White 1981). I t was not p o s s i b l e to i n v e s t i g a t e the r e l a t i o n s h i p between t i l l e r l e n g t h and b i t i n g r a t e of Stone's sheep because the a l t i t u d i n a l m i g r a t i o n of the 138 sheep r e s u l t e d i n them always f e e d i n g i n areas where the t i l l e r l e n g t h was about 8 - 12 cm (Fi g u r e 8 ) . When the sheep were on s p r i n g range, the model p r e d i c t e d a maximum d a i l y food c a p a c i t y of a ewe fe e d i n g on 65% d i g e s t i b l e forage t o be about 1837 grams. D i v i d i n g t h i s value by the number of b i t e s / d a y (23000) g i v e s an estimated b i t e s i z e of 0.08 grams. T h i s value i s almost i d e n t i c a l to the value f o r domestic sheep feeding on 8,-10 cm long grass ( A l l d e n and Whittaker 1970). I t i s a l s o c l o s e to the weight of an i n d i v i d u a l grass p l a n t of th a t l e n g t h (Figure 10) suggesting that most b i t e s c o n s i s t of an i n d i v i d u a l s m a l l grass t i l l e r . The estimated intake r a t e i s about 2.7 g/minute i f they were consuming t h e i r maximum c a p a c i t y of food. I t i s i n t e r e s t i n g to note that domestic sheep can a t t a i n t h e i r maximum r a t e of intake on 8 - 10 cm grass with a b i t e s i z e of 0.08 g ( A l l d e n and Whittaker 1970, Ar n o l d 1975). These o b s e r v a t i o n s suggest that by f o l l o w i n g the zone of 10 cm grass Stone's sheep were ab l e to maximize intake r a t e while simultaneously f e e d i n g on the hig h e s t q u a l i t y of grass a v a i l a b l e ( F i g u r e 19). Such behaviour i s c o n s i s t e n t with the optimal f o r a g i n g h y p othesis i . e . , maximization of net energy in t a k e r a t e (Schoener 1971). However, the c a l c u l a t e d i n t a k e r a t e of the sheep was only about h a l f the maximum re p o r t e d f o r domestic sheep ( A l l d e n and Whittaker 1970). 139 The d i f f e r e n c e r e s u l t e d from Stone's sheep b i t i n g at only about h a l f the r a t e (33 compared t o 60 b i t e s / m i n u t e ) . By fe e d i n g f o r almost twice as long (700 vs 400 minutes) Stone's sheep took about the same number of b i t e s / d a y as the domestic sheep s t u d i e d by A l l d e n and Whittaker (1970). T h i s d i f f e r e n c e between domestic sheep and Stone's sheep may i n d i c a t e that Stone's sheep on n a t u r a l range were unable t o a t t a i n the same b i t i n g r a t e as domestic sheep on p l a n t e d p a s t u r e . A l t e r n a t i v e l y i t may r e s u l t from sheep redu c i n g t h e i r b i t i n g r a t e t o a more r e l a x e d l e v e l when they are not pressed to feed q u i c k l y . The l a t t e r h y p o t h e s i s i s supported by the f a c t that domestic sheep do not u s u a l l y forage at the maximum p o s s i b l e r a t e but ra t h e r vary the r a t e depending on t h e i r needs. A r n o l d and B i r r e l i (1977) found that f a t sheep and t h i n sheep on good pasture both foraged f o r the same l e n g t h of time but that the t h i n sheep had a higher intake over that time (2.2 vs 1.8 g/minute). S i m i l a r l y A r n o l d (1975) found that l a c t a t i n g sheep foraged s l i g h t l y longer than dry sheep but tha t the most important f a c t o r a l l o w i n g them to i n c r e a s e t h e i r d a i l y i n t a k e was a g r e a t e r intake r a t e (2.17 vs 1.82 g/minute). T h e r e f o r e , sheep do not u s u a l l y feed at the maximum ra t e p o s s i b l e but slow down to a more r e l a x e d r a t e i f they can. Thus sheep are not "time m i n i m i z e r s " when f o r a g i n g . A c t u a l l y there i s no reason t o expect sheep to 140 eat at a f r a n t i c r a t e only to p r o v i d e more time f o r r e s t i n g . The energy expenditure r e q u i r e d f o r t h i s r a p i d f o r a g i n g may w e l l be as great or g r e a t e r than energy saved by r e s t i n g . Thus a c o n s e r v a t i v e r a t e of f o r a g i n g may a c t u a l l y be a s t r a t e g y of "energy maximization". The r a t h e r constant b i t i n g r a t e of Stone's sheep under d i f f e r e n t c o n d i t i o n s suggests that t h i s was the "comfortable" rate f o r them to m a i n t a i n . F o r a g i n g time then becomes a f u n c t i o n of the d a i l y food intake of the animals which i n t u r n i s determined by requirements or c a p a c i t y . Because the seasonal intake of the sheep i s roughly c o r r e l a t e d with the amount of d a y l i g h t ( i . e . , low i n t a k e i n winter, h i g h i n summer), a constant i n t a k e r a t e would r e s u l t i n the animals f e e d i n g f o r about the same p r o p o r t i o n of the d a y l i g h t hours (Table 22). F o r a g i n g a c t i v i t y which covers 60-70% of the d a y l i g h t hours i s q u i t e standard f o r domestic sheep under good range c o n d i t i o n s but sheep which are unable to meet t h e i r needs w i l l forage f o r a much g r e a t e r p r o p o r t i o n of d a y l i g h t (Arnold 1960b; A l l d e n and Whittaker 1970). O v e r a l l , there appears to be a great d e a l of s i m i l a r i t y between the f o r a g i n g behavior of Stone's sheep and domestic sheep. The most important p o i n t i s t h a t Stone's sheep can maintain an adequate intake r a t e on ranges which are very low i n p l a n t biomass because intake 141 Table 22. Estimated foraging time of a Stone's sheep ewe in different seasons assuming a constant intake rate. February May DMD 0.4 0.7 Estimated intake (g)* 900 2025 Foraging time (minutes)** 360 810 Daylength (minutes) 600 1320 Proportion of daylight foraging 0.6 0.6 * calculated from model ** assuming constant intake rate of 2.5 g/minute. 142 r a t e i s i n f l u e n c e d p r i m a r i l y by grass l e n g t h . A range which i s poor f o r sheep i s one on which g r a z i n g has r e s u l t e d i n very short grass (< 5 cm). Mountain sheep ranges may have very sparse grass cover but the grass i s u s u a l l y long enough to allow a h i g h intake r a t e . For t h i s reason, n a t u r a l subalpine c l e a r i n g s appeared to allow the same intake r a t e as burned ranges i n s p r i n g . The c o n s i s t e n t l y lower p r o p o r t i o n of d a y l i g h t time spent fee d i n g by rams compared to ewes co u l d be due to a g r e a t e r i n t a k e r a t e or a lower food requirement. In the winter when the l a r g e rams have a g r e a t e r food requirement, the d i f f e r e n c e i s probably due to a g r e a t e r intake r a t e r e s u l t i n g from a l a r g e r mouth s i z e . A l l d e n and Whittaker (1970) found that l a r g e r sheep had a g r e a t e r intake r a t e when food was abundant. However, i n the s p r i n g when the intake r a t e would be l a r g e l y l i m i t e d by the small s i z e of new green p l a n t s a l a r g e mouth would not l i k e l y p r o v i d e an advantage. T h e r e f o r e , the s p r i n g d i f f e r e n c e may r e f l e c t a d i f f e r e n c e i n the food requirements of rams compared to ewes (1106 g/day f o r ram growth vs 1406 g/day f o r l a t e g e s t a t i o n ) . The d i f f e r e n c e i n f o r a g i n g time between ewes and rams may e x p l a i n why they forage i n separate groups. Even without any a c t i v e avoidance between sexes, d i f f e r e n c e s i n f o r a g i n g time w i l l l e a d to separate f o r a g i n g groups. Ram and ewe groups 143 o f t e n foraged or r e s t e d t o g e t h e r . However, the ewes soon became s p a t i a l l y separated because they would move away while f o r a g i n g , l e a v i n g the r e s t i n g rams behind. A l a r g e biomass of dead forage appeared to have a n e g a t i v e e f f e c t on f o r a g i n g on s p r i n g ranges. Sheep on burned s p r i n g range avoided areas with l a r g e amounts of dead g r a s s , presumably because i t i n t e r f e r e d with t h e i r a c cess to n u t r i t i o u s new p r o d u c t i o n . T h i s phenomenon i s s i m i l a r to the s i t u a t i o n i n which small A f r i c a n antelope forage on h i g h l y n u t r i t i o u s small p l a n t s which are exposed a f t e r l a r g e r antelope remove the bulk of the forage biomass ( V e s e y - F i t z g e r a l d 1960). Moderate g r a z i n g by c a t t l e i s a l s o thought t o improve range f o r mule deer by exposing new growth (Wilms et a l . 1979). Food supply was not a problem f o r Stone's sheep i n s p r i n g and summer when forage p r o d u c t i o n on a l l ranges exceeded the requirements of the sheep (Table 23). However, winter ranges d i d not c o n t a i n enough food i n w i n t e r s of h i g h s n o w f a l l to meet the requirements or even the c a p a c i t y l i m i t a t i o n s bf sheep (Table 23). By l a t e w i n t e r , sheep had e s s e n t i a l l y no food to e a t . For most of the year the sheep appeared to have no problem g e t t i n g enough food but r a t h e r endeavour to o b t a i n h i g h q u a l i t y food. The a l t i t u d i n a l movements from a h i g h -biomass of low q u a l i t y food to areas of sparse, h i g h Table 23. Forage availability of several Stone's sheet) ranges compared to estimated sheep requirments. Winter Range Type and Location Alpine (ridge above Churchill mill) Subalpine, Burned (Fertilizer mountain) high snow winter (1982) low snow winter (1981) Available Forage kg 2000 8000 80,000 Number of Sheep 15 30 30 Winter Forage Requirements* kg/100 days 13,000 27,000 27,000 Spring Range Type and Location Graminoid Production kg/day Number of Sheeo Forage Requirements'1 kg/day Subalpine, Burned (Fertilizer mountain) Natural Subalpine Clearings (slope shown i n Figure 5) 900 90 25 10 45 18 * Requirements calculated from model, winter requirements calculated for 100 days assuming intake limited by capacity. quality food served this objective. 146 ANIMAL CONDITION AND GROWTH Poor winter n u t r i t i o n of mountain sheep i s c o r r e l a t e d with h i g h lungworm l e v e l s which can l e a d t o major d i e - o f f s ( S t e l f o x 1976). The poor winter n u t r i t i o n of Stone's sheep, p a r t i c u l a r l y of a l p i n e sheep, was r e f l e c t e d i n f a i r l y h i g h lungworm l e v e l s . R e s t r i c t i o n by snow of sheep to s m a l l areas d u r i n g the winter may a l s o have l e d to i n c r e a s e d t r a n s m i s s i o n of the p a r a s i t e s . However, these l e v e l s were not as h i g h as those l e a d i n g to d i e - o f f s (> 1,400 larvae/g) i n bighorns. A l s o , sheep were never observed to be coughing as i n h e a v i l y a f f e c t e d p o p u l a t i o n s (W. Samuel p e r s . comm.). Death due to lungworm was probably not a major cause of m o r t a l i t y i n these Stone's sheep p o p u l a t i o n s but the d i f f e r e n c e i n lungworm l e v e l s between a l p i n e and burned subalpine winter range suggests s u p e r i o r n u t r i t i o n on subalpine burns. In f a c t lungworm l e v e l s may be a b e t t e r i n d i c a t o r of animal c o n d i t i o n than the f e c a l p r o t e i n or DAPA l e v e l s d u r i n g w i n t e r . Burning may a l s o reduce lungworm l e v e l s by k i l l i n g s n a i l s on the range which are the a l t e r n a t i v e host to the p a r a s i t e . Data on body weights and measurements were inadequate to examine seasonal and i n t e r - p o p u l a t i o n d i f f e r e n c e s . A summary of these data i s presented i n Appendix I I . 147 Horn growth data showed that yearling rams had superior horn growth on burned range. Horn growth of rams i s primarily dependent on spring n u t r i t i o n (Bunnell 1978). Because other indicators of spring range qu a l i t y showed no major difference between burned and unburned range, the poorer horn growth of yearling rams may have been due to the sheep from alpine winter range coming onto the spring range in much poorer, condition. Yearlings from the alpine winter range appeared to be smaller than yearlings from subalpine winter range. The horn growth of older rams did not d i f f e r between ranges and the i n i t i a l d i s p a r i t y due to better yearling growth had been lost by the time the animals were shot by hunters. Although the horns from burned range were no longer, they may have been better trophies since they tended to have more t i p broomed o f f . Therefore, range burning may have a s l i g h t b e n e f i c i a l e f f e c t on the production of trophy rams. 148 POPULATION DYNAMICS Ad u l t s u r v i v a l r a t e s appeared to be q u i t e high based on the small sample of c o l l a r e d animals (minimum s u r v i v a l of 80%) and the 100% s u r v i v a l of ewes throughout the winter of 1982 on F e r t i l i z e r Mountain. Low m o r t a l i t y r a t e s f o r a d u l t mountain sheep (< 15%) are common (Simmons et a l . 1981, Hoefs and Cowan 1979, G e i s t 1971). T y p i c a l l y , annual l o s s e s to p r e d a t i o n and other m o r t a l i t y causes are very low (< 10%) f o r prime aged sheep but m o r t a l i t y r a t e s i n c r e a s e f o r old-aged a d u l t s (> 8 years o l d ) . Low lambtewe counts were the most obvious f a c t o r l i k e l y to a f f e c t p o p u l a t i o n growth. I t i s not s u r p r i s i n g that lamb pr o d u c t i o n i s o f t e n q u i t e low c o n s i d e r i n g the poor n u t r i t i o n of the pregnant ewes d u r i n g w i n t e r . Poor n u t r i t i o n d u r i n g g e s t a t i o n r e s u l t s i n the b i r t h of un d e r s i z e d lambs which experience a high m o r t a l i t y r a t e even under i d e a l c o n d i t i o n s f o l l o w i n g b i r t h (McClymont and Lambourne 1958). A s i m i l a r s i t u a t i o n occurs i n deer and e l k (Thorne et a l . 1976; Verme 1977). Heimer (1983) r e p o r t e d lower f e t u s weights a s s o c i a t e d with a reduced lamb:ewe r a t i o i n D a l l ' s sheep. The experimental data which are most comparable to mountain sheep are presented by McClymont and Lambourne (1958). Sheep were p l a c e d on poor n u t r i t i o n d u r i n g g e s t a t i o n u n t i l 4 weeks pre-partum 149 and then given high q u a l i t y f e ed. . Ewes that had l o s t 22% of t h e i r body weight produced lambs which experienced a 26% p e r i - n a t a l m o r t a l i t y whereas ewes which had l o s t 25% body weight l o s t 41% of t h e i r lambs a t b i r t h . Based on the model, these v a l u e s f o r weight l o s s correspond to d a i l y d i g e s t i b l e i n t a k e s of 63.8 kcal/W° 7 5 and 56.0 kcal/W° 7 5 r e s p e c t i v e l y . Under b e t t e r n u t r i t i o n a l c o n d i t i o n s , P r i o r and C h r i s t e n s o n (1976), found that ewes r e c e i v i n g 120 kcal/W° 7 5 d i g e s t i b l e energy throughout pregnancy s u f f e r e d 10% p e r i - n a t a l lamb m o r t a l i t y compared to only 2% lamb l o s s f o r ewes r e c e i v i n g 200 kcal/W° 7 5 d i g e s t i b l e energy. T h i s r e l a t i o n s h i p i s shown i n F i g u r e 33. In the w i l d , an average lamb m o r t a l i t y of 18% would u s u a l l y be added t o these p e r i - n a t a l l o s s e s before most re p o r t e d lambiewe counts are made (Hoefs and Cowan 1979). A l s o , many s t u d i e s , i n c l u d i n g t h i s one, i n c l u d e d 2-year-o l d ewes i n the count. Y e a r l i n g females do not breed i n most sheep p o p u l a t i o n s (Hoefs and Cowan 1979). I d i d not observe any 2-year-old ewes with lambs i n the present study. Lamb/ewe counts which do not d i s t i n g u i s h 2-year-o l d ewes w i l l underestimate the lamb/adult ewe by about 15%. These data were used to generate a h y p o t h e t i c a l r e l a t i o n s h i p between winter n u t r i t i o n of the ewes and subsequent lamb:ewe r a t i o s i n the summer (F i g u r e 33). 3 -J 50-1 < DAILY DIGESTIBLE ENERGY INTAKE OF E W E S IN WINTER ( k c a l / W 7 5 ) £ o Figure 33. Relationship between daily energy intake of ewes in winter and the predicted values for peri-natal mortality and summer lamb/ewe ratio (2-year-old and older ewes). 151 These p r e d i c t e d values cover the normal range of r e p o r t e d lambrewe r a t i o s (Hoefs and Cowan 1979). The lowest values (45-50 lambs/100 ewes) correspond to an estimated forage d i g e s t i b i l i t y of about 35% whereas v a l u e s of 60 lambs/100 ewes correspond to an estimated forage d i g e s t i b i l i t y of about 40%. These d i g e s t i b i l i t y v a l u e s were the v a l u e s f o r h e a v i l y grazed versus ungrazed areas of Stone's sheep winter range. Domestic sheep and cows s i m i l a r l y degrade the q u a l i t y of t h e i r range over time by removing the best forage and l e a v i n g only poor forage remaining (Arnold 1960a, Chacon and Stobbs 1976). Heavy g r a z i n g which degrades the q u a l i t y of the a v a i l a b l e forage i n winter would be expected to r e s u l t i n lower lamb crops the subsequent summer due to poorer n u t r i t i o n of the ewes. The impact of g r a z i n g on the range w i l l vary depending on the p o p u l a t i o n s i z e , the i n i t i a l amount of food a v a i l a b l e , and the degree of range l i m i t a t i o n which i s p r i m a r i l y a f u n c t i o n of snow depths. Thus both density-dependent and density-independent f a c t o r s w i l l be o p e r a t i n g . The negative e f f e c t of snow depth on lamb pr o d u c t i o n was obvious i n the present study and was a l s o r e p o r t e d by Smith and Wishart (1978) and N i c h o l s (1978). Hoefs and Brink (1978) found that lamb p r o d u c t i o n appears to be r e l a t e d t o forage q u a n t i t y on the winter range. The negative impact of d e n s i t y on lamb p r o d u c t i o n i s r e p o r t e d 152 by Woodgerd (1964) and Smith and Wishart (1978). The p r e d i c t e d lamb:ewe r a t i o f o l l o w i n g a m i l d winter (60-65/100) d u r i n g which g r a z i n g i n t e n s i t y was low was comparable to the observed v a l u e s f o r 1980 and 1981 on Toad Mountain. The p r e d i c t e d lambiewe r a t i o f o r severe w i n t e r s , when g r a z i n g p r e s s u r e was i n t e n s e , was an overestimate compared to the r e s u l t s f o r F e r t i l i z e r Mountain i n 1982 and C h u r c h i l l i n 1981 and 1982. T h i s d i s p a r i t y may i n d i c a t e t h a t the r e l a t i o n s h i p i n F i g u r e 33 underestimates lamb m o r t a l i t y i n poor c o n d i t i o n s . A l t e r n a t i v e l y , the lower lamb p r o d u c t i o n may i n d i c a t e that the maternal n u t r i t i o n was even poorer than was p r e d i c t e d on the b a s i s of forage d i g e s t i b i l i t y . That s i t u a t i o n c o u l d r e s u l t from the animals being unable to o b t a i n a s u f f i c i e n t q u a n t i t y of food to meet even t h e i r c a p a c i t y -l i m i t e d i n t a k e needs. C o n s i d e r i n g the almost t o t a l removal of forage from winter ranges i n 1982, t h i s p o s s i b i l i t y seems to be q u i t e l i k e l y . O v e r a l l , observed lamb crops i n the study were c o n s i s t e n t with p r e d i c t i o n s based on maternal n u t r i t i o n d u r i n g the p r e v i o u s w i n t e r . The model p r e d i c t s t h at no lamb should be a b l e to s u r v i v e the winter because a forage d i g e s t i b i l i t y of 40% would r e s u l t i n a 30% weight l o s s . Poorer q u a l i t y forage or l a c k of forage r e s u l t i n g from heavy s e l e c t i v e g r a z i n g would make the s i t u a t i o n even worse. Mule deer d i e when 153 they l o s e about 28% of t h e i r body weight ( d e C a l e s t a et a l . 1977). However, a comparison of January weights of B a l l ' s sheep lambs (27-39 kg; B u n n e l l and Olsen 1976) with June weights of Stone's sheep y e a r l i n g s (19.1-30.4 kg) suggests that a 30% winter weight l o s s may be t o l e r a b l e t o lambs because D a l l ' s sheep and Stone's sheep are almost i d e n t i c a l i n s i z e (Appendix I I ) . C e r t a i n l y lambs d i d s u r v i v e the winter although m o r t a l i t y r a t e s were q u i t e h i g h (22-55%). Reported lamb winter m o r t a l i t y r a t e s t y p i c a l l y range from 30-50% (Hoefs and Cowan 1979, Simmons et a l . 1981). Although lamb m o r t a l i t y i s probably at l e a s t p a r t l y d e n s i t y and n u t r i t i o n a l l y dependent, these r e l a t i o n s h i p s are not w e l l q u a n t i f i e d . However, i f we apply an average winter m o r t a l i t y r a t e of 40% to the p r e d i c t e d lamb crop under heavy versus l i g h t g r a z i n g pressure ( i . e . , 50 vs 60 lambs/ewe) the r e s u l t i s 30 versus 36 yearlings/ewe r e s p e c t i v e l y . A subsequent y e a r l i n g m o r t a l i t y r a t e of 10% (Simmons et a l . 1981) would leave 27 versus 32 two-year-o l d s or about 13 versus 16 female r e c r u i t s / 1 0 0 a d u l t ewes. The higher number of r e c r u i t s would r e s u l t i n s l i g h t p o p u l a t i o n growth. The l e s s e r number i s i n s u f f i c i e n t to balance the a d u l t m o r t a l i t y r a t e of 15% and would r e s u l t i n a p o p u l a t i o n d e c l i n e . The d e c l i n e would be even more severe i f an a b s o l u t e l a c k of food i n winter l e d to even 154 lower lamb production. These rough calculations outline the way in which density-dependent selective grazing could regulate population growth by way of ewe n u t r i t i o n during pregnancy. However, t h i s simple pattern w i l l be masked by density-independent v a r i a b i l i t y in winter severity and other regulatory factors. 155 MANAGEMENT OF STONE'S SHEEP Stone's sheep h e a v i l y graze t h e i r l i m i t e d winter ranges which r e s u l t s i n severe n u t r i t i o n a l problems and reduced lamb crop. S p r i n g and summer ranges p r o v i d e abundant, high q u a l i t y forage and are not l i m i t i n g . T h e r e f o r e , any h a b i t a t improvement should be d i r e c t e d at improving winter range. Burning of subalpine range produces very p r o d u c t i v e g r a s s l a n d areas which are used by sheep. However, these areas are u s u a l l y u n a v a i l a b l e to sheep i n winter because of deep snow. T h i s problem s e v e r e l y l i m i t s the value of range burning f o r Stone's sheep. In the one e x c e p t i o n a l area where s u b a l p i n e , burned range was wind-blown and a v a i l a b l e t o sheep i n winter, the sheep appeared to b e n e f i t from the abundant food a v a i l a b l e . T h e r e f o r e , f u t u r e burning e f f o r t s should be d i r e c t e d towards areas which w i l l be wind-blown i n w i n t e r . The r a r i t y of such areas compared to the l a r g e areas of range that have a l r e a d y been burned suggests that t h i s may not be a very f e a s i b l e endeavour. Although burned s p r i n g ranges c o n t a i n much more forage than unburned ranges, sheep do not seem to b e n e f i t g r e a t l y from i t . Because the intake r a t e of sheep i s l i m i t e d by b i t e s i z e r a t h e r than the b i t i n g r a t e , ranges with very abundant food are not n e c e s s a r i l y b e t t e r than ranges with very sparse forage so long as the food i s of h i g h q u a l i t y 156 and the a b s o l u t e q u a n t i t y i s not l i m i t i n g . T h e r e f o r e , burning to produce s p r i n g range does not appear to be j u s t i f i e d . Although range burning does not seem to be of any great value to Stone's sheep, i t i s not i n any way d e t r i m e n t a l and probably b e n e f i t s other s p e c i e s such as e l k . I f range burning i s continued i n the ar e a , i t would be a d v i s a b l e to produce smaller burns r a t h e r than burning e n t i r e v a l l e y s . The small burn i n Delano v a l l e y produced super-abundant forage f a r beyond the needs of the sheep and mountain goats which used i t . Even i f range burning was b e n e f i c i a l , t here i s no reason to expect t h a t vast burned areas are s u p e r i o r to small burns. F o r e s t e d areas p r o v i d e h a b i t a t f o r f u r b e a r e r s , b i r d s , e t c . , and may be used as thermal cover by ungulates and p r o v i d e a r b o r e a l l i c h e n s f o r c a r i b o u . T h e r e f o r e , a mixture of f o r e s t and small burns would probably support the g r e a t e s t number and d i v e r s i t y of w i l d l i f e . Improvement of a l p i n e winter range i s probably not f e a s i b l e . F e r t i l i z a t i o n i n the a l p i n e f a i l e d t o i n c r e a s e the q u a n t i t y or q u a l i t y of forage (Appendix I I I ) , probably because p l a n t p r o d u c t i o n or n u t r i e n t c y c l i n g processes are l i m i t e d by c l i m a t i c f a c t o r s . A l s o , the c o s t of any e x t e n s i v e f e r t i l i z a t i o n program would l i k e l y be p r o h i b i t i v e . O v e r a l l , the value of h a b i t a t improvement 157 programs appears to be extremely l i m i t e d f o r Stone's sheep i n t h i s a r e a . H a b i t a t d e s t r u c t i o n i s not a major t h r e a t to most sheep p o p u l a t i o n s with the e x c e p t i o n of h y d r o - e l e c t r i c r e s e r v o i r s which may f l o o d c r i t i c a l s u b a l p i n e , s p r i n g range. Stone's sheep a c c l i m a t i z e very w e l l to d i s t u r b a n c e s such as roads and mines. Such developments are u n l i k e l y to cause any s e r i o u s harm. The major problem i s l i k e l y to be i n c r e a s e d poaching r e l a t e d to improved access to new areas. T h i s problem c o u l d be d e a l t with by s t r i c t law enforcement or p r e f e r a b l y by c o n t r o l l i n g access to the areas. Predator c o n t r o l has been proposed r e c e n t l y to i n c r e a s e Stone's sheep p o p u l a t i o n s i n the a r e a . However, the r e i s no good evidence that p r e d a t o r s have a major e f f e c t on sheep p o p u l a t i o n s . A l l p r e d a t i o n attempts observed d u r i n g t h i s study were u n s u c c e s s f u l because the sheep were ab l e to escape i n t o p r e c i p i t o u s t e r r a i n . A d u l t s u r v i v a l r a t e s appeared t o be high as i n other s t u d i e s of mountain sheep. Lamb p r o d u c t i o n and lamb s u r v i v a l was r e l a t e d to winter s e v e r i t y . The sheep encounter severe n u t r i t i o n a l problems r e l a t e d to high d e n s i t i e s on r e s t r i c t e d winter ranges. T h e r e f o r e , any improvement i n s u r v i v a l r a t e s caused by predator c o n t r o l would on l y i n c r e a s e the negative impacts of h i g h d e n s i t i e s on winter 158 ranges. I t i s u n l i k e l y that the winter ranges can support any more sheep. Trophy hunting of l a r g e rams probably has no s i g n i f i c a n t impact on the p o p u l a t i o n numbers. There are more than enough mature rams to breed a l l the ewes. I am very s k e p t i c a l of the h y p o t h e t i c a l arguments a g a i n s t trophy hunting proposed by G e i s t (1970). T h i s s k e p t i c i s m i s supported by r e s u l t s of Shackleton (1973) and work i n Montana ( J . Ford pers. comm.) which f a i l e d to f i n d d e t r i m e n t a l e f f e c t s r e l a t e d to reduced numbers of l a r g e rams in the p o p u l a t i o n . T h e r e f o r e , hunting r e g u l a t i o n s are p r i m a r i l y d i r e c t e d a t ensuring t h a t p o p u l a t i o n s continue to produce l a r g e trophy rams. T h i s o b j e c t i v e i s being e f f e c t i v e l y met by p r o t e c t i n g small rams f r o n hunting by f u l l - c u r l or g r e a t e r r e g u l a t i o n s . A l s o , o u t f i t t e r quotas are based on the average age of sheep k i l l e d i n the o u t f i t t i n g area the p r e v i o u s year. I t would be more l o g i c a l to base quotas on the s i z e of sheep r a t h e r than the age s i n c e i t i s unreasonable to expect hunters to age f r e e - r a n g i n g sheep a c c u r a t e l y . A l s o , the s i z e of sheep k i l l e d by r e s i d e n t hunters should not be i n v o l v e d i n c a l c u l a t i n g o u t f i t t e r quotas s i n c e r e s i d e n t hunters shoot s i g n i f i c a n t l y smaller and younger rams (Hurd and Masters u n p u b l i s h e d ) . Present demand by hunters i s s u f f i c i e n t l y great that most rams are 159 probably k i l l e d within a year or two of reaching legal s i z e . Therefore, to produce large trophy rams you must protect smaller rams u n t i l they reach that s i z e . The major controversy in setting hunting regulations i s d i v i d i n g the k i l l between residents and guided non-residents. In terms of economic benefits to the area and the province, the value of a sheep taken by a guided non-resident i s far greater than a sheep k i l l e d by residents. However, p o l i t i c a l pressure by resident hunters leads to progressively lower quotas for non-resident hunters. Such a debate i s beyond the role of a w i l d l i f e b i o l o g i s t to decide. 160 CONCLUSIONS - order of c o n c l u s i o n s corresponds to hypotheses presented i n I n t r o d u c t i o n 1) 2) 3) 4) Forage q u a n t i t y was much g r e a t e r on burned ranges but forage q u a l i t y was s i m i l a r on burned and unburned ranges Q u a n t i t y of food i n t a k e was s i m i l a r on burned and unburned ranges f o r most of the year although q u a l i t y began t o i n c r e a s e a few days e a r l i e r on burned s p r i n g range. Sheep s e l e c t e d ranges with the most n u t r i t i o u s a v a i l a b l e forage. A v a i l a b i l i t y was s e v e r e l y r e s t r i c t e d by snow i n w i n t e r . Q u a l i t y of intake was not s u p e r i o r to the average q u a l i t y of a v a i l a b l e herbage on the range. S t r u c t u r a l and chemical f a c t o r s a f f e c t i n g p a l a t a b i l i t y appeared to be more important than q u a l i t y i n determining food s e l e c t i v i t y . 5) A l t i t u d i n a l m i g r a t i o n to areas where t i l l e r l e n g t h 161 was about 10 cm pro v i d e d the o p p o r t u n i t y f o r the sheep t o maintain the maximum intake r a t e of hig h q u a l i t y f o r a g e . However, sheep d i d not appear to feed a t the maximum p o s s i b l e i n t a k e r a t e . F o r a g i n g time and b i t i n g r a t e d i d not vary with changes i n forage q u a n t i t y . F o r a g i n g time and b i t i n g r a t e d i d not d i f f e r between burned and unburned range. Heavy g r a z i n g on winter range removed a l l the a v a i l a b l e forage d u r i n g a severe w i n t e r . Lamb p r o d u c t i o n and P r o t o s t r o n q y l u s l e v e l s were r e l a t e d to winter n u t r i t i o n . Data were inadequate to compare horn and body growth between burned and unburned ranges. Horn growth of y e a r l i n g rams was g r e a t e r on burned range than on unburned range but t h i s e a r l y d i s p a r i t y was l o s t by the time rams were shot by hunters. Lamb p r o d u c t i o n was high e r and p a r a s i t e l e v e l s were lower f o r sheep t h a t wintered on burned range than f o r sheep w i n t e r i n g on a l p i n e r i d g e s , but t h i s s i t u a t i o n was an exception because most burned range unavailable in winter due to deep snow. 163 REFERENCES CITED A l l d e n , W.G., and I.A. McD. Whittaker. 1970. The determinants of herbage i n t a k e by g r a z i n g sheep: The i n t e r r e l a t i o n s h i p of f a c t o r s i n f l u e n c i n g herbage i n t a k e and a v a i l a b i l i t y . Aust. J . A g r i c . Res. 21: 755-766. Ammann, A.P., R.L. Cowan, C L . Mothershead, and B.R. Baumgardt. 1973. 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What are the b i o l o g i c a l bases of v a r i e d d i e t s ? Am. Nat. 112: 627-631. Willms, W., A. McLean, R. Tucker, and R. R i t c e y . 1979. I n t e r a c t i o n s between mule deer and c a t t l e on b i g sagebrush range i n B r i t i s h Columbia. J . Range Manage. 32: 299-304. Woodgerd, W. 1964. P o p u l a t i o n dynamics of bighorn sheep on Wildhorse I s l a n d . J . W i l d l . Manage. 28: 381-391. 176 Appendix I. B i r d s and Mammals S i g h t e d i n the Toad R i v e r A r e a . An a s t e r i c k (*) i s used to denote s p e c i e s wh ich a re beyond t h e i r no rma l l y r epo r t ed range . B i r d s Common l oon Horned grebe W h i s t l i n g swan Canada goose M a l l a r d P i n t a i l Green-winged t e a l Cinnamon t e a l * Amer ican widgeon Shove le r Scaup Ba r row 's goldeneye B u f f l e h e a d Oldsquaw H a r l e q u i n duck S u r f s c o t e r Ruddy duck Common merganser Goshawk Sharp-sh inned hawk R e d - t a i l e d hawk Golden eag le B a l d eag le H a r r i e r Pe reg r i ne f a l c o n K e s t r e l B lue grouse Spruce grouse Ru f fed grouse W i l l o w ptarmigan Sora K i l l d e e r Grea te r y e l l o w l e g s Lesse r y e l l o w l e g s Spo t ted sandp iper Snipe H e r r i n g g u l l Great horned owl Common nighthawk B e l t e d k i n g f i s h e r F l i c k e r P i l e a t e d woodpecker* Y e l l o w - b e l l i e d sapsucker H a i r y woodpecker Nor thern t h r e e - t o e d woodpecker E a s t e r n k i n g b i r d * S a y ' s phoebe E a s t e r n phoebe Leas t f l y c a t c h e r T r a i l l ' s f l y c a t c h e r Horned l a r k Tree swal low Bank swal low Barn swal low V i o l e t - g r e e n swal low C l i f f swal low Gray j a y Raven B lack -capped ch ickadee B o r e a l ch ickadee Dipper Rob in V a r i e d th rush Townsend's s o l i t a i r e Swainson 's t h rush Hermi t t h rush Mountain b l u e b i r d Water p i p i t Cedar waxwing Bohemian waxwing Nor thern s h r i k e S t a r l i n g Y e l l o w wa rb le r Yel low-rumped wa rb le r Townsend's wa rb le r W i l s o n ' s w a r b l e r B l a c k p o l l wa rb le r Ye l low-headed b l a c k b i r d * Rusty b l a c k b i r d Brown-headed cowbird Gray-crowned r o s y f i n c h Common r e d p o l l Hoary r e d p o l l P i ne s i s k i n Savannah sparrow Oregon junco Tree sparrow Ch ipp ing sparrow Golden-crowned sparrow White-crowned sparrow Vesper sparrow Song sparrow 177 Birds cont'd Lapland longspur Smith's lonspur Snow bunting Mammals Little brown bat Snowshoe hare Woodchuck Hoary marmot Red squirrel Least chipmunk Flying squirrel Beaver Deer mouse Jumping mouse Porcupine Wolf Coyote Red fox Black bear Grizzly bear Marten Short-tailed weasel Lynx Cougar* Mule deer Elk Moose Caribou Mountain goat Stone's sheep Myotis lucifugus  Lepus americana  Marmota monax  M. caligata Tamiasciurus hudsoriicus  Eutamias minimus  Glaucomys sabriiTus  Castor canadensis  Peromyscus mamculatus  Zapus hiidsomcus  Erithizon dorsatum  Canis lupus  C. latrans  Vulpes vulpes  Ursus americanus  U. arctos  Martes americana  Mus tela ermmea  Lynx lynx  Felis concolor  Odocoileus hemionus  Cervus canadensis  Alces alces  Rangifer tarandus  Oreamnos americanus Ovis dalli 178 APPENDIX II BODY WEIGHTS AND MEASUREMENTS OF STONE'S SHEEP P u b l i s h e d data on body measurements of Stone's sheep are sparse. Cowan and Guiguet (1978) gave measurements f o r 4 rams and 1 ewe; G e i s t (1971) presented weights and measurements f o r 2 rams and 1 ewe. G e i s t (1971) and B a n f i e l d (1974) suggested that Stone's sheep were l a r g e r than D a l l ' s sheep but noted t h a t unequivocal evidence was l a c k i n g . Weights and measures presented here are from sheep captured i n the l a t e June and e a r l y J u l y at C h u r c h i l l m i n e r a l l i c k . A l s o b i r t h weights of 3 lambs at the Okanagan Game Farm are i n c l u d e d . Comparisons are made to D a l l ' s sheep and r e g r e s s i o n s between l i n e a r measurements and body weights are presented. RESULTS AND DISCUSSION The b i r t h weights of c a p t i v e , Stone's sheep lambs (3.3 ± 0.4 kg, N = 4) were s i m i l a r t o weights of newborn D a l l ' s sheep i n the w i l d (3-4 kg, B u n n e l l and Olsen 1976). In e a r l y J u l y , when the w i l d Stone's lambs were between 4 and 6 weeks of age, t h e i r s i z e s and weight were extremely v a r i a b l e . T h i s v a r i a t i o n was not s o l e l y due to the small sample because many other lambs observed, but not 179 captured, were comparable to extremes of s i z e among the 3 captured lambs. Cause of the v a r i a t i o n i s not known ( d i f f e r e n t ages or d i f f e r e n t growth r a t e s ) , but i t c o u l d r e s u l t i n sm a l l e r s i z e d lambs f a i l i n g t o grow to an adequate s i z e t o s u r v i v e the winter ( B u n n e l l 1980). Female y e a r l i n g s were about 46% of the average weight of a d u l t ewes. Male y e a r l i n g s tended to-be l a r g e r than female y e a r l i n g s i n a l l weights and measurements, but there was a great d e a l of o v e r l a p . A d u l t ewes were about 75% of the weight of the a d u l t Stone's ram (77.3 kg) weighed by G e i s t (1971). B u n n e l l and Olsen (1976) rep o r t e d the f o l l o w i n g measurements f o r a d u l t , D a l l ' s sheep ewes (x, range): weight (48.8 kg, 46.4-50.5), h i n d f o o t l e n g t h (37.1 cm, 35-39), ch e s t g i r t h (108.5 cm, 105-112). Stone's sheep appear n e a r l y i d e n t i c a l i n weight and s i z e t o D a l l ' s sheep (Table 1). Because the D a l l ' s sheep were weighed d u r i n g winter or e a r l y s p r i n g and the Stone's sheep were weighed d u r i n g summer, D a l l ' s sheep may be m a r g i n a l l y h e a v i e r ( a l l o w i n g f o r over-winter weight l o s s ) . However, h i n d f o o t l e n g t h s d i d not d i f f e r between the subspecies. The apparent d i f f e r e n c e i n chest g i r t h measurements was most l i k e l y due to a d i f f e r e n c e i n measurement techniques between s t u d i e s . Table 1. Body measurements of Stone sheep. Weight (kg) length (cm) Hind foot Chest girth Chest height Shoulder ^ g 1 * " " ^ ^"J1?™, engA (cm) (cm) (cm) height (cm) length (on) length (cm) Adult ewes X ± S .D. 49.6 ± 4.5 37.9 ± 1.3 95.6 ± 3.8 49.3 + 3.7 Range n 88.3 ± 6.4 26.4 ± 5.8 25.3 ± 6.5 U.l - S5~8 35 - 40 87 - 101 40 - 54 70 - 95 17.5 - 38.0 17.0 - 39.0 15 15 15 15 15 15 Female yearlings i T i T 22.7 35.9 ± 2.8 73 42.8 ± 2.1 73.5 ± 2.9 6.0 ± 2.9 5.3 ± 3.7 19 1 - 26.3 33 - 39 73 - 73 41 - 45 70 - 77 2.0 - 9.0 1.0 - 10.0 d 4 4 4 Range 2 4 2 Male yearlings *77D" 27.7 + 2.8 36.8 + 1.7 76.3 ± 3.2 45.5 ± 1.0 76.3 ± 3.5 8.1 ± 2.8 8.4 ± 4.4 24.5 - 30.4 35 - 39 73 - 79 45 - 47 72 - 80 4.0 - 10.0 2.0 - 11.2 4 4 4 4 4 Range 4 4 Male lambs (July) X ± S . D . 11.5 ± 5.3 27.3 ± 3.8 52.5 ± 10.1 35.7 ± 4.9 55.7 ± 6.7 Range 5.4 - 15.4 23 - 30 41 - 60 30 - 39 48 - 60 n 3 3 3 Captive lamb birthweights X ± S .D. 3.3 ± 0.4 n 3 Ovis d a l l i d a l l i 48.8 37.1 108.5 Adult ewes 46.4 - 50.5 35 - 39 105 - 112 (from Bunnell and Olsen 1976) 0 3 3 3 3 181 Regressions for Stone's sheep (Table 2) predicted body weight from linear measurements with confidence l i m i t s of less than ± 2.5 kg at the mean. Computed confidence l i m i t s were ± 1.5 kg, ± 1.8 kg, and ± 2.3 kg for chest g i r t h , horn length, and hind foot length, respectively. The re l a t i o n s h i p between hind foot length and body weight was linear for Stone's lambs and yearlings, but there was no re l a t i o n s h i p between these measurements in adult ewes. 182 Table 2. Relationships between body weight and measurements of Stone sheep. Regression equation r2 Sy.x Chest girth (G) W = -37.5 + (0.88)G 0.96 3.15 Longest hom length (HL) W = 18.7 + 1.13 HL 0.91 4.2 Hind foot length (HF) W = -32.8 + 1.64 HF 0.92 2.6 (for lambs and yearlings) 183 REFERENCES CITED IN APPENDIX Banfield, A.W. 1974. The mammals of Canada, University of Toronto Press, Toronto. Bunnell, F.L. 1980. Factors c o n t r o l l i n g lambing period of Dall's sheep. Can. J. Zool. 58: 1027-1031. ., and N.A. Olsen. 1976. Weights and growth of Dall's sheep in Kluane Park, Yukon T e r r i t o r y . Can. F i e l d Nat. 90: 157-162. Cowan, I.McT., and C.J. Guiguet. 1978. The mammals of B r i t i s h Columbia. B.C. Pr o v i n c i a l Museum Handbook, V i c t o r i a , B.C. Geist, V. 1971. Mountain sheep. A study in behavior and evolution. University of Chicago Press. Chicago. 184 APPENDIX III THE EFFECT OF BURNING AND FERTILIZATION ON STONE'S SHEEP RANGES Subalpine g r a s s l a n d ranges are r e g u l a r l y burned d u r i n g the s p r i n g i n the Toad R i v e r area i n an e f f o r t to prevent f o r e s t encroachment and to improve range q u a l i t y . A l s o , some a l p i n e areas have r e c e n t l y been f e r t i l i z e d by the F i s h and W i l d l i f e Branch to improve Stone's sheep range. I attempted t o eva l u a t e the value of these techniques by: i ) m o n i t o r i n g the e f f e c t of a sub a l p i n e g r a s s l a n d f i r e i i ) c o n d u cting a l p i n e f e r t i l i z a t i o n experiments. Burning i n a l p i n e areas i s not a v i a b l e technique because these areas are not able to c a r r y a f i r e . METHODS SUBALPINE BURNING The s u b a l p i n e , g r a s s l a n d slopes of F e r t i l i z e r Mountain were burned by l o c a l r e s i d e n t s i n mid-May, 1981. I s e l e c t e d four unburned areas and four adjacent burned 185: areas on the slop e s and measured p l a n t biomass i n these areas by c l i p p i n g 0.25 m2 p l o t s throughout the summer. Forage samples were c o l l e c t e d f o r p r o t e i n and proximate a n a l y s i s . S o i l samples were c o l l e c t e d (top 10 cm of s o i l ) from these areas and analyzed f o r n i t r a t e , phosphorous, potassium, and sulp h u r . ALPINE FERTILIZATION Experiment J_ In 1980, two 0.25 ha p l o t s i n the a l p i n e zone of F e r t i l i z e r Mountain were f e r t i l i z e d with 34% nirogen f e r t i l i z e r (17% n i t r a t e , 17% ammonium) at a r a t e of 5 g/m2 i n e a r l y June, p r i o r to new p r o d u c t i o n . P l a n t biomass was measured on these areas and adjacent u n f e r t i l i z e d areas i n mid-August by c l i p p i n g 0.25 m2 p l o t s . These areas were sampled again i n 1981 and 1982. Forage samples were analyzed f o r p r o t e i n and f i b r e i n 1980 and 1981. Experiment 2 In 1982, two 500 m2 p l o t s i n the a l p i n e zone of Tower Mountain were f e r t i l i z e d with 27-3-3 f e r t i l i z e r (19.5% water s o l u b l e N, 6.8% water i n s o l u b l e N) at a r a t e of 13 g/m2. Pl a n t biomass was measured by c l i p p i n g 0.25 m2 p l o t s i n e a r l y August. Forage samples were an a l y z e d f o r p r o t e i n and i_n v i t r o dry matter d i g e s t i b i l i t y . S o i l 186 samples (top 10 cm) were c o l l e c t e d and analyzed for t o t a l N, P and K. 187, DISCUSSION SUBALPINE BURNING The s p r i n g f i r e i n i t i a l l y set back the p r o d u c t i o n of graminoids and f o r b s but by l a t e June p l a n t biomass was s i m i l a r on burned and unburned p l o t s (Table 1). At the end of the growing season there was no s i g n i f i c a n t d i f f e r e n c e i n the amount of graminoids and f o r b s on burned versus unburned p l o t s . Forage q u a l i t y (ADF and p r o t e i n ) was not s i g n i f i c a n t l y d i f f e r e n t between burned and unburned p l b t s (Table 2). S i m i l a r l y , s o i l m i neral l e v e l 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 on burned versus unburned p l o t s (Table 3). Burning the winter c a r r y o v e r on these slopes i n s p r i n g would v o l a t i l i z e about 0.6 g of n i t r o g e n / m 2 . The f i r e s u s u a l l y d i d not burn s o i l o r g a n i c m a t e r i a l . Very frequent burning may e v e n t u a l l y d e p l e t e s o i l n i t r o g e n l e v e l s u n l e s s the l o s s can be balanced by n i t r o g e n - f i x a t i o n by legumes. As p r e v i o u s l y mentioned i n the t h e s i s (Table 11), F e r t i l i z e r Mountain s o i l s tended to have higher phosphorous and potassium l e v e l s than s o i l s from other areas i n the v i c i n i t y which may be r e l a t e d to the frequent burning i n t e r v a l on t h i s s l o p e . 188 Table 1. Graminoid and forb production on burned versus unburned plots on F e r t i l i z e r mountain following a spring burn.  2 2 Graminoid biomass (g/m ) Forb biomass (g/m ) X - SE* X - SE burned unburned burned unburned + + 0.0 18.8 + 0.8 May 25 8.7 1.5 18.9 0.9 June 17 37.7 + 8.7 38.9 + 6.8 20.1 - 6.9 35.5 + 11.5 July 4 62.8 + 17.6 66.0 + 10.0 52.0 - 17.2 30.8 + 6.0 July 26 58.4 + 9.7 44.0 + 5.9 20.0 - 11.2 34.8 + 8.0 August 12 55.5 + 13.7 53.0 + 9.9 16.0 - 4.7 26.3 + 7.9 * n = 4 for a l l samples Table 2. Protein and ADF levels in graminoids on burned versus unburned plots on F e r t i l i z e r mountain following a spring burn.  May 25 July 4 July 26 Crude Protein (I) J - SE burned unburned 21.6 14.0 - 1.9 9.7 - 1.1 n 2 4 4 19.9 13.5 - 3.1 7.9 - 0.3 n 2 4 ADF (4) J - SE burned unburned 23.9 32.2 - 1.5 32.1 - 0.9 n 2 4 4 29.3 - 0.7 30.1 - 2.2 33.4 - 0.8 Table 3. Comparison of s o i l nutrient levels on burned versus unburned subalpine plots and f e r t i l i z e d versus unfertilized alpine plots. (X + SE).  total N nitrate K n Subalpine burned unburned u u 17.0 - 2.5 16.7 - 1.7 370 - 99.1 393 - 78.0 7.8 - 0.64 7.1 - 0.62 4 4 Alpine f e r t i l i z e d 0.65 - 0.1 unfertilized 0.43 - 0.1 0.8 - 0.5 u 70 - 39.0 70 - 39.0 4 4 u = undetectible, less than 1.0 ppm. 00 o 190 O v e r a l l , the e f f e c t of s p r i n g burning of subalpine ranges was not c l e a r l y b e n e f i c i a l or d e t r i m e n t a l to range q u a l i t y . However, i t does maintain the areas as g r a s s l a n d by k i l l i n g encroaching p o p l a r s . Caution should be e x e r c i s e d by not burning too f r e q u e n t l y i n order to prevent n i t r o g e n d e p l e t i o n of the s o i l s . Even i f burning d i d improve range q u a l i t y , i t would be i m p o s s i b l e to improve c r i t i c a l areas of Stone's sheep winter range because the areas which were h e a v i l y grazed i n winter ( F i g u r e 4 i n t h e s i s ) d i d not c o n t a i n enough f u e l i n s p r i n g to c a r r y a f i r e . These areas remained unburned whereas the dead c a r r y o v e r i n the ungrazed areas was adequate to support the f i r e . ALPINE FERTILIZATION F e r t i l i z e d p l o t s d i d not produce s i g n i f i c a n t l y more graminoids or f o r b s than u n f e r t i l i z e d p l o t s i n e i t h e r experiment (Table 4 ) . Forage q u a l i t y was not s i g n i f i c a n t l y d i f f e r e n t between f e r t i l i z e d and u n f e r t i l i z e d p l o t s i n e i t h e r experiment although q u a l i t y tended to be s u p e r i o r on f e r t i l i z e d p l o t s i n experiment 2 (Table 5 ) . In experiment 2 , s o i l m i n e r a l l e v e l s were not s i g n i f i c a n t l y h i g h e r i n the f e r t i l i z e d p l o t s but n i t r o g e n and phosphorous tended to be higher (Table 3 ) . Although 191 Table 4. Graminoid and forb production on f e r t i l i z e d and unfertilized alpine plots (X * SE).  Graminoid Biomass (g/m2) Forb Biomass (g/m ) f e r t i l i z e d unfertilized f e r t i l i z e d unfertilized Experiment 1 August 1980, plot A 16.1 + 1.8 21.4 + 2.9 22.6 + 3.7 18.7 + 6.3 plot B 10.5 + 3.4 16.2 + 3.8 35.7 + 7.6 39.8 + 6.2 August 1981, plot A 8.4 + 3.3 7.0 3.6 23.1 + 9.3 19.1 + 4.8 plot B 6.9 + 1.6 19.3 + 2.6 26.2 + 3.6 12.6 + 5.1 August 1982, plot A 7.4 + 3.9 5.1 + 2.0 23.9 + 7.6 22.2 + 2.4 Experiment 2 August 1982, plot A 5.4 + 0.7 8.9 + 3.1 24.7 + 6.7 13.3 + 4.6 plot B 6.1 + 3.1 13.4 + 2.4 53.4 + 21.2 20.5 + 5.9 n = 5 for a l l samples Table 5. Forage quality_of graminoids from f e r t i l i z e d and unfertilized alpine plots. (X - S5)  Experiment 1 Crude Protein (t) _X__1%1 August 1980, f e r t i l i z e d 10.0 + 0.5 26.8 unfertilized 9.0 + 0.4 29.1 August 1981 f e r t i l i z e d 10.5 + 0.9 27.3 unfertilized 11.4 0.4 25.2 + Experiment 2 Crude protein (t) In vitroJMD (t) August 1982 f e r t i l i z e d 11.1 - 0.9 60.8 * 2.2 unfertilized 9.6 - 0.2 54.2 - 3.7 n » 4 for a l l samples 1 9 3 the data i s inconclusive, i t suggests that the l e v e l of f e r t i l i z a t i o n in Experiment 2 was beginning to increase s o i l nutrient le v e l s and forage q u a l i t y but not forage production. This minor response was probably not adequate to be a s i g n i f i c a n t benefit to the sheep using the range. 

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