UBC Theses and Dissertations

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UBC Theses and Dissertations

Computer simulation of Rangifer energetics Russell, Donald Edmund 1976

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COMPOTES S I M U L A T I O N OF H & N G I F E R E N E R G E T I C S b y DONALD EDMUND R U S S E L L B . S . F . U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1 9 7 2 h T H E S I S S U B M I T T E D I N P A R T I A L F U L F I L M E N T OP T H E E E Q U I B E M E N T S FOR THE D E G R E E G F MASTER OF F O R E S T R Y IM T H E F A C U L T Y OF F O R E S T R Y we a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE U N I V E R S I T Y OF B R I T I S H COLOMBIA F E B R U A R Y , 1976 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an advanced degree a t the U n i v e r s i t y o f E r i t i s h C o l u m b i a , I agree t h a t t h e l i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g cf t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head of toy Department c r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l net be a l l o w e d w i t h o u t my w r i t t e n p e r m i s i o n . De Fa r t ment o f .... .Fpf §^t,ry The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada Date . ^ P?-^. ,2^; »^^» ABSTRACT With i n c r e a s i n g demands on and d e v e l o p m e n t o f n o r t h e r n m i n e r a l r e s o u r c e s , a b a s i c u n d e r s t a n d i n g o f t h e w i l d l i f e p r o d u c t i v i t y i s r e q u i r e d f o r t h e c a r e f u l management o f any s p e c i e s . B a r r e n - g r o u n d c a r i b o u , R a n g i f e r t a r a n d u s ( R i c h a r s o n ) , has been an i n t e g r a l p a r t o f t h e s e n o r t h e r n r e g i o n s and t h e c u l t u r e o f t h e n a t i v e s f o r c e n t u r i e s . W i t h t h e use o f s i m u l a t i o n m o d e l i n g much o f t h e d i v e r s e d a t a c o n c e r n i n g c a r i b o u was i n t e g r a t e d and e v a l u a t e d i n t o two model s t r u c t u r e s . Model BIOEN examined t h e w i n t e r b i o e n e r g e -t i c s o f c a r i b o u w h i l e model ACTIVE examined t h e r o l e o f b i t i n g i n s e c t s i n t h e summer e n e r g e t i c s o f c a r i b o u . D u r i n g t h e c o n -s t r u c t i o n o f t h e s e models much d a t a c o l l e c t e d on u n g u l a t e s o t h e r t h a n c a r i b o u were i n c o r p o r a t e d when c o m p a r a t i v e d a t a f o r c a r i b o u were a v a i l a b l e . M odel BIOEN p r o p o s e s a c r i t i c a l e n v i r o n m e n t f o r a 100 Kg male c a r i b o u under two n u t r i t i o n a l r e g i m e s . S i m u l a t e d e f f e c t s o f snow c o v e r on e n e r g y b a l a n c e a p p e a r i m p o r t a n t and d e s e r v e more r e s e a r c h a t t e n t i o n . Two a r e a s , one i n t h e t u n d r a and one i n t h e b o r e a l r e g i o n , were examined i n terms o f w i n t e r -i n g p o t e n t i a l f o r c a r i b o u . I n t h e y e a r s s i m u l a t e d , t h e b o r e a l r e g i o n p r o v e d more f a v o u r a b l e i n terms o f w e i g h t l o s s t o t h e a n i m a l . However, i t was r e v e a l e d t h r o u g h s e n s i t i v i t y a n a l y s e s t h a t s m a l l e r r o r s i n t h e measurement o f d i g e s t i b i l i t y , g r o s s e n e r g y c o n t e n t o f the f o r a g e , f o o d i n t a k e r a t e o r g r a z i n g i n t e n s i t y have a s i g n i f i c a n t e f f e c t on w e i g h t p r o j e c t i o n s d u r i n g t h e w i n t e r . i i i Model ACTIVE incorporated data from Prudhoe Bay, Alaska to examine the r o l e of insects i n the summer energy budgets of caribou. Results ind i c a t e d that insects caused a s i g n i f i c a n t increase i n heat production (51.8 Kcal/Kg /day). A p r e d i c t i v e regression equation i s presented r e l a t i n g t o t a l heat production (kcal/Kg/day) to the number of hours of moderate and no ins e c t harassment per day for an adult male or non-lactating female. i v TABLE OF CONTENTS ABSTRACT i i TABLE OF CONTENTS i v FIGURES v i i TABLES ........ i x ACKNOWLEDGEMENTS x INTRODUCTION 1 EANGIFER ENERGETICS - LITERATURE REVIEW ..................... 4 I n t r o d u c t i o n 4 W i n t e r . 5 Heat p r o d u c t i o n 5 Heat l o s s 7 Energy i n t a k e 9 Summer ................................................. 10 Heat p r o d u c t i o n i l Energy i n t a k e 12 Summary .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13' BIOEN - A MODEL OF THE ENERGETICS OF RANGIFEE IN SINTER . . . 1 5 S p e c i f i c o b j e c t i v e s ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Summary o f t h e model ................................... 15 I n p u t v a r i a b l e s 16' I n t e r m e d i a t e v a r i a b l e s -18 V a l i d a t i o n f o r i n t e r m e d i a t e v a r i a b l e s .....18 Output v a r i a b l e s 19 V a l i d a t i o n f o r ou t p u t v a r i a b l e s ... < Q................. 19 D e s c r i p t i o n and d i s c u s s i o n o f t h e model ................ 20 Heat l o s s e s ..,20 V Harming of food and d r i n k i n g water .. 21 Heat of v a p o r i z a t i o n of water vapour 2 2 S e n s i b l e heat l o s s 2 2 Energy p r o d u c t i o n f o r Eancjif er ...................... 27 Basal m e t a b o l i c r a t e ... 2 7 S p e c i f i c dynamic e f f e c t .......................... 30 Energy c o s t of a c t i v i t y 3 0 Energy i n t a k e .37 A b i o t i c v a r i a b l e s 41 D i s c u s s i o n of model output 41, C r i t i c a l environment ,'4i, The e f f e c t of snow depth .^45 Comparison of tundra and b o r e a l w i n t e r i n g areas ..... 45 ACTIVE - A MODEL OF SUMMER ACTIVITY AND ENERGY EXPENDITURE 51 I n t r o d u c t i o n 51 S p e c i f i c o b j e c t i v e s ....,51 Summary of model 52 Ba s i c model s t r u c t u r e 52 Input v a r i a b l e s 53 Intermediate v a r i a b l e s 54! V a l i d a t i o n data f o r i n t e r m e d i a t e v a r i a b l e s 56 Model output v a r i a b l e s .............................. 56 V a l i d a t i o n data f o r output ........................... 57 D e s c r i p t i o n and d i s c u s s i o n of model 5 7 Distance walked and d i s t a n c e from coast ............. 61 Energy c o s t s a s s o c i a t e d with a c t i v i t y p a t t e r n s ...... 61 F a s t i n g metabolic r a t e ...... ... .................. 63 S p e c i f i c dynamic e f f e c t , . 6 3 v i E n e r g y c o s t s o f a c t i v i t y 64 A c t i v i t y s u b r o u t i n e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 D i s c u s s i o n o f model o u t p u t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 SUMMARY . ,83 BIBLIOGRAPHY ... 86 FIGURES v i i F i g u r e L l . G e n e r a l r e l a t i o n s h i p s c o n s i d e r e d i n t h e model BIOEN 17 F i g u r e 2. S i m u l a t e d e f f e c t o f a i r t e m p e r a t u r e on s k i n t e m p e r a t u r e i n s t i l l a i r 28 F i g u r e 3. S i m u l a t e d m o d i f i c a t i o n o f s k i n s u r f a c e t e m p e r a t u r e due t o wind speed 28 F i g u r e 4. S i m u l a t e d e f f e c t o f snow d e p t h on e n e r g y e x p e n d i t u r e w h i l e w a l k i n g 35 F i g u r e 5. S i m u l a t e d e f f e c t o f snow d e p t h on d i g g i n g movements p e r day 35 F i g u r e 6. P o s t u l a t e d r e l a t i o n s h i p between snow d e p t h and p r o p o r t i o n o f day s p e n t d i g -g i n g 36 F i g u r e 7 . Assumed r e l a t i o n s h i p between v o l u n t a r y f o o d i n t a k e and d i g e s t i b l e e n e r g y o f t h e f o o d 39 F i g u r e 8. S i m u l a t e d c r i t i c a l e n v i r o n m e n t 43 F i g u r e 9. Components o f h e a t l o s s due t o r a d i a t i o n and c o n v e c t i o n v e r s u s wind speed .43 F i g u r e 10. E n e r g y r e l a t i o n s o f R a n g i f e r i n t h e two s e l e c t e d y e a r s i n t u n d r a and b o r e a l w i n t e r r a n g e s 47 1 F i g u r e 11. B a s i c r e l a t i o n s h i p s and s e q u e n c e o f r u l e s f o r change i n t h e model ACTIVE 55 F i g u r e 12. R e l a t i o n s h i p o f i n t e n s i t y o f i n s e c t h a r a s s m e n t on c a r i b o u w i t h ambient temp-e r a t u r e and wind speed 60 F i g u r e 13. S i m u l a t e d r e l a t i o n s h i p between t h e com-p u t e d i n d e x o f i n s e c t h a r a s s m e n t ( I s ) and d i s t a n c e from c o a s t 62 v i i i F i g u r e 14. S i m u l a t e d t r a n s i e n t o f t h e s p e c i f i c dynamic e f f e c t o f f o o d d i g e s t i o n f o l -l o w i n g t h e o n s e t o f an e a t i n g p e r i o d ^65 F i g u r e 15. S i m u l a t e d i n f l u e n c e on t h e d u r a t i o n o f t h e e a t i n g p e r i o d on t h e s p e c i f i c dynamic e f f e c t o f d i g e s t i o n 67 F i g u r e 16. S i m u l a t e d r e l a t i o n s h i p between t h e d u r a -t i o n o f t h e i n t e r - g r a z i n g p e r i o d and t h e d u r a t i o n o f e a t i n g 67 F i g u r e 17.. s i m u l a t e d e f f e c t o f i n s e c t h a r a s s m e n t on g r a z i n g i n t e n s i t y 69 F i g u r e ,18. E f f e c t o f i n s e c t h a r a s s m e n t on w a l k i n g s p e e d '69 F i g u r e 19. S i m u l a t e d i n f l u e n c e o f w a l k i n g v e l o c i t y and d i s t a n c e on t i m e between g r a z i n g p e r i o d s 73 F i g u r e 20.. C o m p a r i s o n o f s i m u l a t e d p r o j e c t i o n s w i t h f i e l d r e s u l t s t o i l l u s t r a t e t h e e f f e c t s o f i n s e c t h a r a s s m e n t on d a i l y a c t i v i t y p a t e r n s 79 TABLES T a b l e I. i Summary o f p a r a m e t e r v a l u e s and l i t e r -a t u r e s o u r c e s u s e d i n E q n s . 2 - 7 . 2 9 T a b l e I I . Mean p e r c e n t a g e o f t i m e t h e r e i n d e e r spend on d i f f e r e n t a c t i v i t i e s e a ch month (from Thomson, 1973) 32 T a b l e I I I . E s t i m a t e s o f i n t a k e d u r i n g t h e w i n t e r . . . 32 T a b l e IV. S i m u l a t e d e f f e c t o f snow d e p t h on h e a t p r o d u c t i o n and t o t a l m e t a b o l i z a b l e e n e r g y i n t a k e 46 T a b l e V. S i m u l a t e d w e i g h t l o s s a t F t . Simpson and C o n twayto Lake 4 9 T a b l e V I . R e s u l t s o f component s e n s i t i v i t y a n a l -y s e s on f i n a l w e i g h t i n t u n d r a and b o r e a l r a n g e s 4 9 -T a b l e V I I . C o m p a r i s o n o f s i m u l a t e d a c t i v i t y bud-g e t s f o r i n s e c t - f r e e days w i t h f i e l d o b s e r v a t i o n s 76 T a b l e V I I I . S i m u l a t e d e s t i m a t e s o f e n e r g y expen-d i t u r e f o r c a r i b o u w e i g h i n g 100 Kg 7-7• T a b l e IX. S i m u l a t e d e s t i m a t e s o f e n e r g y expend-i t u r e f o r a d u l t n o n - l a c t a t i n g c a r i b o u w e i g h i n g 100 Kg w i t h m o d i f i e d w a l k i n g speeds 77 T a b l e X. R e g r e s s i o n summary u s i n g p a r a m e t e r s i i i F i g . 12 8 1 X ACKNOWLEDGEMENTS The study was funded p r i m a r i l y by the U. S. International B i o l o g i c a l Program, Tundra Biome and a grant from A r c t i c and Alpine Research. Canadian Forest products provided a fellowship for the 1973 - 1974 academic year. The Faculty of Forestry provided computer funds during the project. Dr. Fred Bunnell provided valuable supervision during the i n i t i a t i o n , development and completion of the t h e s i s . The knowledge and assistance of Drs. R. G. White and R. Hudson were gr e a t l y appreciated. T. Skogland and B. Thomson provided much data and assistance i n the development of many of the functional r e l a t i o n s h i p s that appear i n the t h e s i s . I am indebted to Drs. Bunnell, White, Hudson, Strang, and S i n c l a i r and S. Russell for reviewing the manuscript and providing many h e l p f u l suggestions. Penny Lewis typed the bibliography and Sharon Russell helped i n the preparation..of the figures and table s . SIMULATION MODELING OF BANGIFEB ENERGETICS INTRODUCTION B a r r e n - g r o u n d c a r i b o u , R a n g i f e r t a r , a h d i j s ( R i c h a r d s o n ) , c o n s t i t u t e a w i l d l i f e r e s o u r c e o f n a t i o n a l i m p o r t a n c e i n C a n a d a . T h e s e v a s t h e r d s o f m i g r a t o r y , s o m e t i m e s n o m a d i c r u m i n a n t s h a v e c o n t r i b u t e d i m p o r t a n t l y t o t h e c u l t u r e and economy o f t h e n o r t h e r n p e o p l e s and a r e i n e x t r i c a b l y l i n k e d w i t h p a s t and p r e s e n t d e v e l o p m e n t o f n o r t h e r n r e s o u r c e s . I n 1949, o v e r 100,000 c a r i b o u were h a r v e s t e d i n Canada t o p r o v i d e f o o d , c l o t h i n g a n d s h e l t e r f o r n o r t h e r n r e s i d e n t s and t h e i r s l e d d o g s ( K e l s a l l , 1963) . As n o r t h e r n d e v e l o p m e n t i n t e n s i f i e d and n a t i v e h u n t i n g e f f i c i e n c y i m p r o v e d , a marked d e c l i n e i n l o c a l c a r i b o u p o p u l a t i o n s was o b s e r v e d . I t h a s been r e c o r d e d t h a t c a r i b o u p o p u l a t i o n s i n t h e e a r l i e r p a r t o f t h i s c e n t u r y numbered b e t w e e n two t o t h r e e m i l l i o n ( C l a r k e , 1 9 4 0 ) . S u r v e y s i n 1948 a n d 1967 r e v e a l e d l e v e l s o f 670,000 and 385,000 r e s p e c t i v e l y ( P a r k e r , 1 9 7 1 ) . T h e s e f i g u r e s h a v e b e e n q u e s t i o n e d r e c e n t l y a n d t h e r e i s some d o u b t a s t o t h e i r a c c u r a c y . Due t o t h e i n c r e a s i n g c o n c e r n o v e r t h i s a p p a r e n t d e c l i n e . 2 the Canadian W i l d l i f e Service i n i t i a t e d studies i n 1948 to inventory caribou resources and to elucidate the ecology of the species. Continuing studies on winter range, population structure, mortality factors, reproductive success, growth and n u t r i t i o n revealed a low productivity compared to other native ungulates. Recently t h i s low productivity has caused considerable concern. Within the l a s t f i v e years, resource exploitation i n the north, through o i l exploration, d r i l l i n g and pipeline construction has placed increasing pressure to provide hasty solutions to resolve resource c o n f l i c t s . To f a c i l i t a t e c a r e f u l management of caribou, a framework i s needed within which data can be integrated and evaluated to guide both research e f f o r t and management strategies. Such a framework should f a c i l i t a t e the testing of data for i n t e r n a l consistency, generality and examine the r e l a t i v e s e n s i t i v i t y of s p e c i f i c measures to productivity of Rangifer herds. Simulation modeling techniques have proven useful f o r incorporating data into t h i s kind of framework. M i l l e r , C o l l i e r and Bunnell (1973) discuss the use of simulation models i n the evaluation of research p r i o r i t i e s within the U. S. Tundra Biome of the International B i o l o g i c a l Program. Simulation models can be useful for the evaluation of management strategies when used as an "ecological laboratory" (Walters and Bunnell, 1971; Bunnell, 1974). The re s u l t s of various management p o l i c i e s can be explored quickly, without a l t e r i n g the r e a l world. Reviews and examples of mathematical models i n the l i f e sciences are available ( S t i b i t z , 1966; J e f f e r s , 1971; Patten, 1971; deWitt 3 and Goudriaan, 1974). The basic objective of the thesis i s to examine, integrate and t e s t the exis t i n g information on energetics u t i l i z i n g computer simulation techniques.. This thesis constructs a framework for a portion of the data necessary to management, based primarily on l i t e r a t u r e . As the data base for Bangifer i s very broad but r e l a t i v e l y shallow, the thesis provides a detailed examination of only two aspects of Bangifer ecology -summer and winter energetics. An i n i t i a l search of the l i t e r a t u r e (section 2) reveals the need for a detailed examination of both summer and winter energetics to provide a sounder basis f o r the study of the o v e r a l l productivity of the species. In the construction of these models various assumptions had to be made when appropriate data were lacking. I t i s hoped that as further data become available the models can be updated and refined. The general format i s a review of the l i t e r a t u r e on Bangifer energetics and a presentation of two models of energetic r e l a t i o n s h i p s . 4 JilGIFES ENESGETICS - A STATE OF THE KNOWLEDGE INTRODUCTION The study of animal productivity involves the study of animal energetics - the combination of energy intake, heat production, and heat l o s s . A thorough understanding of t h i s f i e l d i s a prerequisite to ef f e c t i v e management of any species. Such knowledge i s p a r t i c u l a r i l y important for the management of IilJ13if§I a species that must cope with c l i m a t i c extremes, short growing seasons, and low primary productivity. The o v e r a l l energetics of the barren ground caribou i n North America are l i t t l e known. Effects of external factors, b i o t i c and a b i o t i c , on the productivity of an i n d i v i d u a l animal are v i r t u a l l y unknown. The domestication of Rancjifer. iJirandus herds i n Scandinavia and the Soviet Union has enabled workers to study the species far more intensively than could researchers of native North American herds. The introduction of reindeer into North America at the turn of the century permitted early investigators to conduct intensive studies of the species cn t h i s continent <Palmer, 1934} . It soon became evident that the natural history of and problems encountered by native herds could be considered circumboreal. In constructing an energetics framework for barren-ground caribou i t i s possible to u t i l i z e research on Bangifer tarandus conducted i n Scandinavian countries and the Soviet Union, combined with s p e c i f i c projects i n North America. In addition, where gaps occur i n the data, studies on domestic ruminants other than Sanaifer provide p r i n c i p l e s that have been exploited. 5 I t i s t h e p u r p o s e o f t h i s s e c t i o n t o r e v i e w t h e p e r t i n e n t l i t e r a t u r e on e n e r g e t i c s o f H a n j g i f e r . W i n t e r W h e t h e r t h e y m i g r a t e t o t h e t a i g a r e g i o n s o r r e m a i n i n t h e open b a r r e n s t o o v e r w i n t e r , h e r b i v o r e s p e c i e s i n t h e n o r t h e r n e n v i r o n m e n t e n c o u n t e r many p r o b l e m s p e c u l i a r t o t h e n o r t h . How S l l i a i J S f t a r a n d u s h a s a d a p t e d t o an e n v i r o n m e n t where snow i s p r e s e n t f o r 8 months o f t h e y e a r and where t e m p e r a t u r e s may a v e r a g e -40 d e g r e e s C e n t i g r a d e i n c e r t a i n months o f t h e w i n t e r , h a s been a g u e s t i o n a s k e d by many r e s e a r c h e r s ( J a c o b i , 1 9 3 1; F o r m a z o v , 1946; B a n f i e l d , 1954; N a s i m o v i c h , 1955; K e l s a l l , 1 9 6 8 ) . W i n t e r c o n d i t i o n s p r e s e n t p r o b l e m s o f e n e r g y b a l a n c e , a f f e c t i n g h e a t p r o d u c t i o n , h e a t l o s s a n d e n e r g y i n t a k e . H e a t P r o d u c t i o n H e a t p r o d u c t i o n o f r u m i n a n t s i s t h e sum o f b a s a l m e t a b o l i s m , t h e s p e c i f i c d y n a m i c e f f e c t o f n u t r i e n t m e t a b o l i s m , e n e r g y c o s t s o f a c t i v i t i e s , a n d , u n d e r e x t r e m e l y c o l d c o n d i t i o n s , t h e r m o g e n e s i s . T h e r e a r e many f a c t o r s w h i c h r e g u l a t e t h e m a g n i t u d e o f t h e s e e x p e n d i t u r e s . Some w i l d r u m i n a n t s i n c l u d i n g R a n g i f e r h a v e t h e p h y s i o l o g i c a l a b i l i t y t o r e d u c e t h e i r m e t a b o l i c r a t e d u r i n g t h e c o l d w i n t e r months ( S i l v e r , e t a l , 1969; c f . McEwan, 1970 and S e g a l , 1 9 6 2 ) . E s t i m a t e s f o r w i n t e r f a s t i n g m e t a b o l i c r a t e h a v e been o b t a i n e d f o r r e i n d e e r (HcEwan, 1970) w h i c h r e v e a l h i g h e r v a l u e s t h a n i n t h e g e n e r a l i z e d mouse t o e l e p h a n t c u r v e p r e s e n t e d by K l e i b e r ( 1 9 6 1 ) . 6 A n o t h e r component o f t o t a l h e a t p r o d u c t i o n i s t h e s p e c i f i c d y n a m i c e f f e c t o f n u t r i e n t m e t a b o l i s m , SDE, d e f i n e d by B l a x t e r (1962) a s t h e " i n c r e a s e i n h e a t p r o d u c t i o n w h i c h o c c u r s when an amount o f n u t r i e n t w i t h a c a l o r i f i c v a l u e e g u a l t o t h e f a s t i n g m e t a b o l i s m i s g i v e n i n a s i n g l e m e a l . " T h u s , SDE i s t h a t e n e r g y p r o d u c e d by t h e d i g e s t i o n and m e t a b o l i s m o f f o o d . B l a x t e r (1962) e x a m i n e d SDE f o r s h e e p on f a s t i n g , m a i n t e n a n c e and f u l l f e e d d i e t s . To d a t e no r e s e a r c h h a s c o n s i d e r e d t h e m a g n i t u d e o f t h e e n e r g y p r o d u c t i o n v i a SDE f o r R a n g i f gr.-The e n e r g y e x p e n d i t u r e o f v a r i o u s a c t i v i t i e s h a s b een d e t e r m i n e d f o r many r u m i n a n t s ( W h i t e and L u i c k , 1973; Y o u n g , 1966; Young and C o r b e t t , 1 9 7 2 ) . T h e s e r e s e a r c h e r s c o n s i d e r e d t h e e n e r g y e x p e n d i t u r e s o f w a l k i n g , t r o t t i n g , r u n n i n g - , l y i n g , s t a n d i n g and e a t i n g r o u g h a g e . G i v e n a d a i l y a c t i v i t y b u d g e t f o r an i n d i v i d u a l o r a h e r d , i t i s p o s s i b l e t o e s t i m a t e h e a t p r o d u c t i o n a s s o c i a t e d w i t h t h e s e a c t i v i t i e s . I n Norway, r e s e a r c h e r s h a v e b e e n m o n i t o r i n g w i n t e r a c t i v i t y b u d g e t s o f w i l d r e i n d e e r i n H a r d a n g e r v i d d a f o r some y e a r s ( G a a r e , S k o g l a n d , Thomson, 1970; Thomson, 1971; S k o g l a n d , 1 9 7 4 ) . T h e s e s t u d i e s r e v e a l t h a t w i n t e r d i s t r i b u t i o n o f a n i m a l s c a n be a c c o u n t e d f o r by snow c o n d i t i o n s and r e i n d e e r l i c h e n d i s t r i b u t i o n - t h e p r i n c i p a l f o o d s o u r c e f o r w i n t e r i n g B a n g i f e r . A l t h o u g h a c t i v i t y b u d g e t s o f c a r i b o u i n w i n t e r h a v e been c o n s i d e r e d ( B a n f i e l d , 1954; K e l s a l l , 1968; M i l l e r , 1970) no d e t a i l e d s t u d y h a s been made i n N o r t h A m e r i c a . I t h a s b een s u g g e s t e d t h a t snow c h a r a c t e r i s t i c s a f f e c t t h e e n e r g y b u d g e t o f R a n j i f e r i n w i n t e r , P r u i t t (1959) d e t e r m i n e d l e v e l s o f snow h a r d n e s s , d e n s i t y and d e p t h b e y o n d w h i c h c a r i b o u 7 w o u l d n o t c r a t e r f o r l i c h e n s u n d e r t h e snow. The amount o f t i m e and e n e r g y s p e n t c r a t e r i n g u n d e r t h e snow h a s n e v e r been a c c u r a t e l y r e s e a r c h e d . Some d a t a e x i s t f o r t h e r e l a t i o n s h i p s b e t w e e n snow d e p t h and c r a t e r i n g . The number o f p a w i n g movements p e r m i n u t e o f f e e d i n g a p p e a r s d i r e c t l y p r o p o r t i o n a l t o c r a t e r (snow) d e p t h and snow d e n s i t y ( S k o g a n d , 1974) . D a t a f r o m D a v y d o v (1965) i n d i c a t e a c u r v i l i n e a r r e l a t i o n s h i p b e t w e e n snow d e p t h and t h e number o f d i g g i n g movements p e r day. F u r t h e r r e s e a r c h ( S a b l i n a , 1962) h a s e x a m i n e d t h e d u r a t i o n o f d i g g i n g v e r s u s n o n -d i g g i n g a c t i v i t i e s u n d e r v a r y i n g snow c o n d i t i o n s . E x i s t i n g d a t a s u g g e s t t h a t snow d e p t h a l s o h a s a m e a s u r a b l e e f f e c t o n e n e r g y e x p e n d e d w h i l e w a l k i n g . U s i n g a mask t e c h n i g u e M a k a r o v a and S e g a l (1958) measured o x y g e n c o n s u m p t i o n o f r e i n d e e r w a l k i n g t h r o u g h snow. The d e r i v e d e n e r g y e x p e n d i t u r e c a n be c o m p a r e d t o h e a t p r o d u c t i o n o f r e i n d e e r w a l k i n g u n d e r s n o w - f r e e c o n d i t i o n s and a t r e s t (Hammel e t a l , 1 9 6 2 ) . Heat l o s s The c o l d t e m p e r a t u r e s , s t r o n g w i n d s and l o w n u t r i t i o n a l p l a n e o f r e i n d e e r and c a r i b o u a t many t i m e s d u r i n g t h e w i n t e r c a n r e s u l t i n h e a t l o s s b e i n g g r e a t e r t h a n h e a t p r o d u c t i o n and t h e n e c e s s i t y t o p r o d u c e a d d i t i o n a l e n e r g y t h r o u g h t h e r m o g e n e s i s . The a n i m a l i s s a i d t o be i n a c r i t i c a l e n v i r o n m e n t when h e a t l o s s i s g r e a t e r t h a n e n e r g y i n t a k e a n d n o r m a l h e a t p r o d u c t i o n . The a v e n u e s o f h e a t l o s s a r e c o n v e c t i o n , c o n d u c t i o n ^ r a d i a t i o n , e v a p o r a t i o n a n d warming o f f o o d a n d w a t e r . A c c u r a t e m e a s u r e m e n t s o f t h e s e c o m p o n e n t s r e g u i r e s p e c i a l i z e d c h a m b e r s a s w e l l a s v e r y c o o p e r a t i v e s u b j e c t s . Few h e a t l o s s s t u d i e s h a v e been c o n d u c t e d on R a n g j . f e r t a r a n d u s . Most o f t h e work on h e a t l o s s h a s b e e n i n i t i a t e d w i t h d o m e s t i c s t o c k u n d e r l a b o r a t o r y c o n d i t i o n s . B l a x t e r (1962) p r e s e n t s an e x c e l l e n t r e v i e w o f h e a t l o s s i n c l u d i n g some o f t h e e a r l i e r p r e d i c t i v e e g u a t i o n s . The p a r t i t i o n i n g o f h e a t l o s s i n s h e e p i s a f f e c t e d by e n v i r o n m e n t a l t e m p e r a t u r e and f l e e c e l e n g t h (Graham e t a l , 1963; B l a x t e r e t a l , 1963a; B l a x t e r e t a l , 1 9 6 3 b ) . E n e r g y m e t a b o l i s m i n s t e e r s a l s o h a s been m e a s u r e d ( B l a x t e r and Wainman, 1 9 6 0 ) . T h e i r r e s e a r c h s u b s e q u e n t l y e x a m i n e d t h e e f f e c t o f wind on h e a t p r o d u c t i o n and e m i s s i o n i n s t e e r s ( B l a x t e r and Wainman, 1 9 6 4 ) . R a d i a n t e f f e c t s a l s o i n f l u e n c e t h e m a g n i t u d e o f h e a t l o s s u n d e r v a r y i n g w i n d and t e m p e r a t u r e r e g i m e s ( J o y c e and B l a x t e r , 1 9 6 4 ) . The n u t r i t i o n a l p l a n e o f s t e e r s d e t e r m i n e d t h e c r i t i c a l e n v i r o n m e n t i n s t u d i e s o f c o l d o u t d o o r e n v i r o n m e n t s ( W e b s t e r , 1 9 7 1 ) . , R e c e n t s t u d i e s on w h i t e t a i l d e e r u t i l i l i z e d an e n v i r o n m e n t a l s i m u l a t o r t o p r o v i d e d e t a i l e d p r e d i c t i v e e g u a t i o n s f o r h e a t l o s s u n d e r v a r y i n g e n v i r o n m e n t a l c o n d i t i o n s ( S t e v e n s , 1972; Moen, 1 9 7 3 ) . T h e s e r e s u l t s s u g g e s t t h a t t h e p r o c e s s o f h e a t l o s s i n a n i m a l s f o l l o w s u n i v e r s a l p h y s i c a l l a w s o f h e a t e x c h a n g e a n d f l o w . I t i s t h e r e f o r e p o s s i b l e t o c o n s t r u c t a model w h i c h c a n p r e d i c t h e a t l e s s f o r R a n g i f e r p r o v i d i n g c e r t a i n b a s i c p a r a m e t e r s u n i g u e t o R a n g i f e r c a n be e s t i m a t e d . Hammel e t a l (1962) m easured deep body t e m p e r a t u r e s o f r e i n d e e r w h i l e McEwan (1970) p r o v i d e d c o m p a r a t i v e d a t a f o r c a r i b o u . R a n g i f e r s p e c i e s have a t h i c k , w e l l - i n s u l a t e d w i n t e r c o a t w h i c h r e d u c e s h e a t l o s s due t o c o n d u c t i o n a nd c o n v e c t i o n (Hammel, 1955; S c h o l a n d e r e t a l , 1 9 5 0 ) . R e i n d e e r h a v e t h e 9 a b i l i t y t o c o n t r o l e v a p o r a t i v e h e a t l o s s b e n a v i o u r a l l y by p a r t i a l l y c o o l i n g e x h a l e d a i r b e f o r e e x p e l l i n g i t (Hammel e t a l , 1 9 6 2 ) . The o n l y i n d i r e c t d e t e r m i n a t i o n o f c r i t i c a l e n v i r o n m e n t f o r c a r i b o u was c o n d u c t e d by H a r t e t a l (1961) when s h i v e r i n g r e s p o n s e s were n o t e d i n newborn c a l v e s w i t h wet a n d d r y c o a t s u n d e r v a r y i n g w i n d and t e m p e r a t u r e v a l u e s . E n e r g y I n t a k e The n e t b a l a n c e o f m e t a b o l i z a b l e e n e r g y i n t a k e and h e a t p r o d u c t i o n r e s u l t s i n e i t h e r w e i g h t l o s s , m a i n t e n a n c e o r w e i g h t g a i n t o t h e a n i m a l . E o t h c a r i b o u and r e i n d e e r r e l y h e a v i l y on l i c h e n s a s an e n e r g y s o u r c e d u r i n g w i n t e r . The d e t e r m i n a t i o n o f t o t a l m e t a b o l i z a b l e e n e r g y i n t a k e r e q u i r e s e s t i m a t e s o f f o o d i n t a k e , f o r a g e d i g e s t i b i l i t y and g r o s s e n e r g y c o n t e n t o f t h e f o r a g e . V e r y l i t t l e work h a s b een c o n d u c t e d on e n e r g y i n t a k e o f E a n g i f e r . E n e r g y r e q u i r e m e n t s o f R a n j i f e r have been d o c u m e n t e d i n a f e w i n d o o r e x p e r i m e n t s and e x t r a p o l a t e d t o f r e e r a n g i n g i n d i v i d u a l s ( S t e e n , 1 9 6 8 ) . T h e r e a p p e a r s t o be a r e d u c t i o n i n v o l u n t a r y f o o d i n t a k e o f c a r i b o u i n w i n t e r (McEwan and W h i t e h e a d , 1 9 7 0 ) . T h e r e i s a d e f i n i t e b r e a k i n t h e g r o w t h c u r v e d u r i n g w i n t e r , e v e n i n t h o s e i n d i v i d u a l s f e d a d l i b i d u m ( H c l w a n , i n p r e s s ) . E s t i m a t e s a r € a l s o a v a i l a b l e on e n e r g y i n t a k e ( g r o s s , d i g e s t i b l e and m e t a b o l i z a b l e ) and r e t e n t i o n d u r i n g t h e w i n t e r months u n d e r l a b o r a t o r y c o n d i t i o n s . W h i t e (1974) c i t e s u n p u b l i s h e d s t u d i e s t h a t i n d i c a t e " g r o w t h c e s s a t i o n may be r e g u l a t e d by p h a g i c b e h a v i o r , f o r when g i v e n f o o d o f h i g h ( 1 8 % ) , medium ( 1 2 % ) , and l o w (1%) c r u d e p r o t e i n , weaned r e i n d e e r c a l v e s 10 t e n d t o r e g u l a t e a t a c o n s t a n t d r y m a t t e r i n t a k e . " S i n c e l i t t l e f i e l d work h a s been done on w i n t e r e n e r g y i n t a k e , i n d i r e c t m ethods must be e m p l o y e d t o d e t e r m i n e g r o s s e n e r g y i n t a k e d u r i n g t h i s t i m e . G a a r e , S k o g l a n d , and Thomson (1970) and W h i t e e t a l (1975) p r o v i d e d a t a on d r y m a t t e r i n t a k e p e r m i n u t e o f e a t i n g t i m e i n c o m m u n i t i e s o f d i f f e r e n t b i c m a s s l e v e l s on summer r a n g e s . B e c e n t work ( W h i t e , pers.comm.) r e v e a l s t h a t d a t a on f o o d i n t a k e i n l i c h e n c o m m u n i t i e s f i t s t h e c u r v e p u b l i s h e d f o r summer v e g e t a t i o n . R e i n d e e r l i c h e n s p r o v i d e a r i c h e n e r g y s o u r c e d u r i n g t h e w i n t e r m o n t h s , b e i n g c o m p r i s e d p r i m a r i l y o f r e a d i l y s o l u b l e c a r b o h y d r a t e s . S c c t t e r (1964) d e t e r m i n e d t h e c h e m i c a l c o m p o s i t i o n o f many C l a d o n i a s p e c i e s and o t h e r w i n t e r f o o d s o u r c e s . G r o s s e n e r g y c o n t e n t s o f l i c h e n s a r e a l s o r e p o r t e d by J a c o b s e n and S k j e n n e b e r g (1975) a n d K l e i n ( 1 9 7 0 ) . One o f t h e most v a r i a b l e f a c t o r s d e t e r m i n i n g d i g e s t i b l e e n e r g y i n t a k e by R a n g i f e r i s t h e d i g e s t i b l i t y o f t h e f o r a g e . W h i t e e t -aj. (1975) and J a c o b s e n and S k j e n n e b e r g (1975) f o u n d w i d e v a r i a b i l i t y i n l i c h e n d i g e s t i b i l i t y . Summer A f t e r c a l v i n g , n u r s e r y bands j o i n o r f o l l o w t h e b u l l s t o r i v e r v a l l e y s a n d c o a s t a l p l a i n s a l o n g t h e a r c t i c c o a s t , t h e summer r a n g e f o r t h e b a r r e n - g r o u n d c a r i b o u . C a r i b o u t r a v e l e x t e n s i v e l y d u r i n g t h e summer, g r a z i n g p r i m a r i l y on s e d g e , g r a s s a n d s h r u b c o m m u n i t i e s . W i t h t h e a d v e n t o f warm w i n d l e s s d a y s i n J u l y and A u g u s t , numerous b i t i n g and s u c k i n g i n s e c t s c a u s e t h e c a r i b o u t o move t o r e l i e f a r e a s s u c h a s r i v e r b e d s , 11 w i n d y b l u f f s and c o a s t a l s a n d d u n e s . I t i s d u r i n g t h i s c r u c i a l p e r i o d , when c a r i b o u a r e s t i l l a t t e m p t i n g t o r e p l e n i s h p r o t e i n and f a t r e s e r v e s d e p l e t e d d u r i n g t h e p r e v i o u s w i n t e r , and when l a c t a f i n g f e m a l e s a r e s t i l l s u c k l i n g t h e i r y oung t h a t i n s e c t h a r a s s m e n t may become c r i t i c a l t o t h e p r o d u c t i v i t y o f t h e h e r d s . I n s e c t h a r a s s m e n t i s b e l i e v e d t o be t h e c a u s e o f i s o l a t e d mass m o r t a l i t y among c a r i b o u . K e l s a l l (1968) w r i t e s o f t h e d e a t h s o f s e v e r a l h u n d r e d c a r i b o u cn two s e p a r a t e o c c a s i o n s , t h e f i r s t i n Tshich " i n s e c t h a r a s s m e n t may have b e e n r e s p o n s i b l e " n e a r B a t h u r s t I n l e t i n 1950 and t h e s e c o n d n e a r t h e T h e l s o n E i v e r t h a t " c o i n c i d e d w i t h t h e h e i g h t o f f l y s e a s o n " . The i m p o r t a n c e o f i n s e c t h a r a s s m e n t h a s been w e l l d o c u m e n t e d i n S c a n d i n a v i a a n d t h e S o v i e t O n i o n ( Z h i g u n o v , 1 9 6 1; B a s k i n , 1970; Thomson, 1971; S k o g l a n d , 1 9 7 4 ) . B e s e a r c h e r s r e p o r t t h a t i n many y e a r s t h e p e r i o d o f f l y h a r a s s m e n t d u r i n g t h e summer c o r r e s p o n d s w i t h a p e r i o d o f w e i g h t l o s s i n B a n q i f e r ( K e l s a l l , 1968; B a s k i n , 1 S 7 0 ) . I t i s t h e r e f o r e v a l u a b l e t o e x a m i n e i n a d e t a i l e d f a s h i o n t h e r o l e o f i n s e c t s i n t h e e n e r g y b u d g e t o f B a n q i f e r t a r a n d u s . The p r o c e s s e s o f h e a t l o s s i n t h e summer a r e n o t c o n s i d e r e d i n t h e t h e s i s due t o t h e l a c k c f a p p r o p r i a t e d a t a . The a b i l i t y o f an a n i m a l t o d i s s i p a t e a h e a t l o a d e f f i c i e n t l y may have i m p o r t a n t c o n s e q u e n c e s i n t e r m s o f e n e r g e t i c s by a l t e r i n g a c t i v i t y a n d f e e d i n g p a t t e r n s , h o w e v e r no d o c u m e n t a t i o n i s a v a i l a b l e . E n e r g y E x p e n d i t u r e D u r i n g t h e summer c a r i b o u and r e i n d e e r g r a z e e x t e n s i v e l y and a r e c o n s t a n t l y on t h e move. Davydov (1965) r e p o r t s t h a t r e i n d e e r t a k e t h r e e t i m e s a s many s t e p s p e r d a y i n summer as i n 12 w i n t e r . A c t i v i t y b u d g e t s d u r i n g t h e i n s e c t - f r e e p e r i o d o f summer i n d i c a t e an i n c r e a s e i n g r a z i n g t i m e and g r a z i n g i n t e n s i t y ( d e f i n e d a s t h e amount o f t i m e s p e n t e a t i n g / t i m e s p e n t g r a z i n g ) c o m p a r e d w i t h w i n t e r a c t i v i t y b u d g e t s ( B a n f i e l d , 1954; Thomson, 197 1 ; S k o g l a n d , 1974; w h i t e e t a l , 1 9 7 5 ) . I t i s u n d e r m o d e r a t e and s e v e r e i n s e c t h a r a s s m e n t (as d e f i n e d by Thomson, 1973) t h a t d i s r u p t i o n o f n o r m a l a c t i v i t y a l t e r s t h e e n e r g y b a l a n c e . D u r i n g s e v e r e a t t a c k s t h e c a r i b o u a r e k e p t on t h e move c o n s t a n t l y i n s e a r c h o f r e l i e f a r e a s , w i t h a r e s u l t a n t d e c l i n e i n e a t i n g t i m e and a s i g n i f i c a n t i n c r e a s e i n r u n n i n g and w a l k i n g t i m e . S t u d i e s a t P r u d h o e B a y , A l a s k a ( W h i t e e t a l , 1975) document t h e d i s r u p t i o n o f a c t i v i t y p e r i o d s by i n s e c t h a r a s s m e n t . I t a p p e a r s t h a t i n s e c t h a r a s s m e n t i n c r e a s e s h e a t p r o d u c t i o n and d e c r e a s e s e n e r g y i n t a k e r e s u l t i n g i n an u n f a v o u r a b l e e n e r g y b a l a n c e f o r t h e a n i m a l . I t i s o n l y a f t e r t h e i n s e c t s e a s o n t h a t t h e a n i m a l s , s l o w l y m e a n d e r i n g i n l a n d i n l o o s e h e r d s , a r e a b l e t o b u i l d up f a t r e s e r v e s f o r t h e w i n t e r . The l e n g t h and s e v e r i t y o f t h e i n s e c t s e a s o n p l a y s an i m p o r t a n t r o l e i n d e t e r m i n i n g t h e p r e w i n t e r i n g c o n d i t i o n o f t h e a n i m a l . E n e r g y I n t a k e C e r t a i n a s p e c t s o f e n e r g y i n t a k e i n summer were d i s c u s s e d u n d e r t h e w i n t e r e n e r g y i n t a k e s e c t i o n . L a t e s p r i n g a n d summer i s t h e t i m e o f maximum w e i g h t g a i n t h r o u g h f a t a n d t i s s u e d e p o s i t i o n i n r e i n d e e r and c a r i b o u . N o n - l a c t a t i n g and l a c t a t i n g f e m a l e s d e p o s i t f a t g r a d u a l l y t h r o u g h t h e summer u n t i l a f t e r t h e 13 r u t w h i l e t h e o l d e r b u l l s a r e a b l e t o d e p o s i t f a t a t v e r y h i g h r a t e s u n t i l r u t , a t w h i c h t i m e t h e y d r a s t i c a l l y r e d u c e f o o d i n t a k e a n d u t i l i z e f a t r e s e r v e s ( B a n f i e l d , 1954; K e l s a l l , 1968; B a s k i n , 1970, McEwan, i n p r e s s ) . H e r d e r s and r e s e a r c h e r s h a v e l o n g r e c o g n i z e d t h e i m p o r t a n c e o f summer f a t t e n i n g p r o g r a m s f o r d o m e s t i c r e i n d e e r . B a s k i n (1970) e m p h a s i z e d t h a t " t h o s e n a t i o n a l g r o u p s w h i c h pay g r e a t e s t a t t e n t i o n t o summer f e e d i n g a n d f a t t e n i n g o f r e i n d e e r . . . p o s s e s s t h e most v i a b l e and p r o d u c t i v e a n i m a l s " . C a r i b o u a p p e a r t o f o l l o w t h e f l u s h o f v e g e t a t i o n ( W h i t e e t a l , 1 9 7 5 ) , t h u s e n s u r i n g a h i g h p r o t e i n c o n t e n t i n t h e d i e t . A n a l y s e s o f summer d i e t i n d i c a t e h i g h u se o f s e d g e s , g r a s s e s and s m a l l s h r u b s ( S a b l i n a , 1962; B a s k i n , 1970; S k o g l a n d , 1974; W h i t e e t a l , 1975). V a r i o u s methods h a v e b e e n a t t e m p t e d t o d e t e r m i n e d r y m a t t e r i n t a k e by B a n g i f e r i n t h e summer ( W h i t e e t a l , 1974). W h i t e e t a l (1975) s u m m a r i z e i n t a k e e s t i m a t e s i n grams d r y m a t t e r / K g O ? V d a y . I n summer, c a r i b o u a p p e a r t o s e l e c t t h o s e p l a n t s p e c i e s h i g h i n c a l o r i c c o n t e n t ( K l e i n , 1970; W h i t e e t a l , 1975). I n v i t r o d i g e s t i b i l i t i e s o f p l a n t s p e c i e s consumed by c a r i b o u i n d i c a t e a wide v a r i a b i l i t y b e t w een and w i t h i n p l a n t s p e c i e s . I t a p p e a r s t h a t an e s t i m a t e o f e n e r g y i n t a k e w o u l d be somewhat u n r e l i a b l e due t o t h e h i g h v a r i a b i l i t y o b s e r v e d i n d r y m a t t e r i n t a k e , c a l o r i c c o n t e n t o f p l a n t s c o n s u m e d , and d i g e s t i b i l i t i e s o f p l a n t s i n g e s t e d . Summary C e r t a i n a s p e c t s o f B a n g i f e r e n e r g e t i c s s h o u l d be c o n s i d e r e d 14 i n g r e a t e r d e t a i l t o g a i n a c l e a r e r i n s i g h t i n t o t h e p r o d u c t i v i t y o f t h e a n i m a l on a y e a r l y b a s i s . D u r i n g t h e w i n t e r , f o r e x a m p l e , t h e d i s t r i b u t i o n and ab u n d a n c e o f R a n q i f e r t a r a n d u s i s a l t e r e d by t h e " d e p t h and c o n d i t i o n o f t h e snow and t h e p r e s e n c e o f l i c h e n " ( S a b l i n a , 1962). The o v e r a l l e n e r g y b a l a n c e i s a l m o s t s u r e l y a f f e c t e d by h e a t l e s s d u r i n g c e r t a i n t i m e s o f t h e w i n t e r . M o d e l BIOEN was c o n s t r u c t e d t o e x a m i n e t h e e f f e c t s o f snow c o v e r o n e n e r g y e x p e n d i t u r e a n d , i n c o m b i n a t i o n w i t h w i n d a n d t e m p e r a t u r e , on h e a t l o s s d u r i n g w i n t e r . The o v e r a l l e n e r g y b a l a n c e w i l l be used t o e x a m i n e p a t t e r n s o f w e i g h t c h a n g e d u r i n g w i n t e r and compare t o a c t u a l f i e l d e s t i m a t e s . I n summer t h e most i m p o r t a n t f a c t o r s i n t h e d i s t r i b u t i o n o f c a r i b o u and r e i n d e e r a r e t h e " p r e s e n c e o f g r e e n v e g e t a t i o n and b l o o d - s u c k i n g i n s e c t s " ( S a b l i n a , 1962). The e f f e c t o f i n s e c t s on t h e e n e r g y b u d g e t o f c a r i b o u i s e x p l o r e d i n t h e summer model -ACTIVE. The r o l e o f g r e e n v e g e t a t i o n was n o t e x p l o r e d i n t h e summer m o d e l due t o t h e l a c k o f d e t a i l e d i n f o r m a t i o n . 15 " 1 J G D E I OF THE J I C E N E E G E T I C S OF HAJNGIIER IN WINTER The a b i l i t y o f R a n g i f e r t a r a n d u s t o s u r v i v e t h e c l i m a t i c e x t r e m e s o f t h e t u n d r a and b o r e a l r e g i o n s h a s i n t e r e s t e d r e s e a r c h e r s f o r some t i m e . However, i n t e n s i v e r e s e a r c h i n t o w i n t e r e n e r g e t i c s and a c t i v i t y o f R a n a i ^ e r has r e c e i v e d l i t t l e a t t e n t i o n c n t h e N o r t h A m e r i c a n c o n t i n e n t . T h i s m o d e l a t t e m p t s t o p r o v i d e a u s e f u l f r a m e w o r k f o r t h e i n t e g r a t i o n o f much o f t h e s c a t t e r e d and d i v e r s e d a t a on w i n t e r b i c e n e r g e t i c s o f R a n a i f e r , s p e c i f i c a l l y r e g a r d i n g h e a t l o s s , h e a t p r o d u c t i o n and e n e r g y i n t a k e . S£ecific O b j e c t i v e s T h i s m o d e l e m b o d i e s t h r e e b a s i c o b j e c t i v e s : 1. To p r o j e c t r e a l i s t i c a l l y e n e r g y r e l a t i o n s o f R a n a i f e r d u r i n g t h e w i n t e r . 2. To p r o j e c t w e i g h t l o s s d u r i n g w i n t e r and d e t e r m i n e management i m p l i c a t i o n s . 3. To e x a m i n e known w i n t e r i n g a r e a s and s t u d y e n e r g y r e l a t i o n s on t h e s e a r e a s and c o n s e g u e n t management i m p l i c a t i o n s . Summary o f t h e M o d e l The model i s s t a t e - o r i e n t e d and p r o j e c t s e n e r g y r e l a t i o n s o v e r d a i l y i n t e r v a l s t h r o u g h o u t t h e w i n t e r months. A d i s c u s s i o n o f m o d el t y p e s , i n c l u d i n g s t a t e - o r i e n t e d m o d e l s , i s f o u n d i n B u n n e l l ( 1 9 7 4 ) , A f t e r i n i t i a l i z i n g p a r a m e t e r s and v a r i a b l e s a r e r e a d i n , i n t e r m e d i a t e v a r i a b l e s a r e c a l c u l a t e d . H e i g h t i s u p d a t e d d a i l y , b a s e d on t h e e n e r g y b u d g e t f o r t h a t day. 16 C o m p u t a t i o n s p e r f o r m e d by t h e model f o r a n y g i v e n day a r e s t r a i g h t f o r w a r d . At t h e b e g i n n i n g o f e a c h day o r t i m e - s t e p , t h e m o d e l c o m p u t e s e n e r g y i n t a k e and h e a t p r o d u c t i o n v i a f e r m e n t a t i o n , b a s a l m e t a b o l i s m and a c t i v i t y . , H e a t l o s s e s by warming f o o d and w a t e r , r a d i a t i o n , c o n d u c t i o n and c o n v e c t i o n a r e c a l c u l a t e d and c o m p a r e d t o h e a t p r o d u c t i o n o f t h e a n i m a l t o d e t e r m i n e w h e t h e r t h e a n i m a l i s i n i t s t h e r m o n e u t r a l z o n e o r w h e t h e r t h e r m o g e n e s i s i s n e c e s s a r y . The n e t e n e r g y g a i n o r l o s s i s t h e n u s e d t o u p d a t e t h e w e i g h t o f t h e a n i m a l . The model s t r u c t u r e i s d e p i c t e d i n F i g u r e 1. JiS-Eiti V a r i a b l e s The i n p u t v a r i a b l e s and p a r a m e t e r s r e g u i r e d f o r t h e model i n c l u d e : A b i o t i c d a t a - d a t e - w i n d s p e e d a t 60 cm(km/hr) - a i r t e m p e r a t u r e a t 60 cm ( C e n t i g r a d e ) - snow d e p t h t h r o u g h o u t t h e w i n t e r (cm) A n i m a l c o n d i t i o n - w e i g h t (Kg.) - deep body t e m p e r a t u r e ( C e n t i g r a d e ) - c o h o r t ( c a l f , y e a r l i n g , a d u l t ) F o r a g e p a r a m e t e r s - d i g e s t i b i l i t y 17 warming _ food evaporation convection radiation conduction / I V SDE BMR HEAT LOSS —I OIL) shivering thermogene s i s (HL-HP) -VIR | activity HEAT PRODUCTION (HP) ENERGY REQUIREMENT (ER) I NETABOLIZ-ABLE ENERGY < 0 >o ENERGY INTAKE undigested IN-DIGESTIBLE ENERGY efficiency loss WEIGHT LOSS WEIGHT GAIN Figure 1, General relationships considered i n model BIOEN. 18 - e n e r g y c o n t e n t l£ter§ediate V a r i a b l e s The model c o m p u t e s a number o f i n t e r m e d i a t e v a r i a b l e s t h a t i n f l u e n c e t h e c h a r a c t e r o f t h e o u t p u t b u t do n o t a p p e a r i n i t . T h e s e v a r i a b l e s a r e : - d i g e s t i b l e e n e r g y i n t a k e - h e a t o f f e r m e n t a t i o n - b a s a l m e t a b o l i c r a t e e n e r g y c o s t o f t h e v a r i o u s a c t i v i t i e s ( w a l k i n g , l y i n g , s t a n d i n g , g r a z i n g ) - t o t a l h e a t l o a d - s u r f a c e a r e a o f t h e a n i m a l - r a d i a n t s u r f a c e t e m p e r a t u r e o f t h e a n i m a l - s k i n t e m p e r a t u r e - h e a t l o s s by c o n v e c t i o n , r a d i a t i o n , e v a p o r a t i o n , w a r m i n g f o o d - a d d e d e n e r g y c o s t o f t h e r m o g e n e s i s ( i f a p p l i c a b l e ) - n e t e n e r g y f o r w e i g h t c h a n g e V a l i d a t i o n D a t a f o r I n t e r m e d i a t e V a r i a b l e s Many o f t h e i n t e r m e d i a t e v a r i a b l e s c a n be v a l i d a t e d f r o m l i t e r a t u r e e s t i m a t e s f o r lanjiJJI s p e c i f i c a l l y o r f o r r u m i n a n t s i n g e n e r a l . Some o f t h e i n t e r m e d i a t e v a r i a b l e s a r e c a l c u l a t e d f r o m t h e few d a t a f o u n d i n t h e l i t e r a t u r e and t h e r e f o r e v a l i d a t i o n w o u l d be c i r c u l a r . R e a l i s m o f t h e p r o j e c t e d h e a t p r o d u c t i o n c a n be d e t e r m i n e d 19 from data on g e n e r a l i z e d r e l a t i o n s h i p s f o r f r e e g r a z i n g ruminants. Young and C o r b e t t (1972) provided f i e l d e s timates f o r f r e e - r a n g i n g sheep f o r which average d a i l y metabolism was 1.86 -2.56 times f a s t i n g metabolism. McEwan and Whitehead (1970) r e p o r t e d that the break i n the growth curve of c a r i b o u (mid-August to mid-November) " c o i n c i d e d with the p e r i o d of s e x u a l maturation and reduced voluntary food consumption". During t h i s p e r i o d , heat production per u n i t of metabolic body s i z e decreased from 200 to 150 Kcal/Kgo ? s p € r day (2.2 to 1.65 times b a s a l metabolic r a t e ) . For the r e s t of the winter, heat production amounted to 200 Kcal/Kgo 7 5 / d a y (2.2 times BMR) . O v e r a l l heat l o s s can be evaluated by determining the c r i t i c a l environment of the animal i n s t i l l a i r . Hart et a l (1961) showed no i n c r e a s e i n the metabolism of a 9 - month o l d c a r i b o u c a l f at an ambient temperature of as low as -55 degrees Centigrade i n s t i l l a i r . Gutjaut V a r i a b l e s The model output c o n s i s t s of the d a i l y weight of an i n d i v i d u a l throughout the winter. V a l i d a t i o n Data f o r Cutout V a r i a b l e s Weight l o s s of R a n g i f e r over winter has been determined by a few r e s e a r c h e r s . I t scon becomes obvious that weight l o s s over winter depends upon the s e v e r i t y of the winter and upon the q u a l i t y of the winter range. Steen (1968) s t a t e s t h a t mountain r e i n d e e r i n Norway average 100 Kg. f o r males and 80 Kg. f o r females and that "weight decrease i n winter... amounts to 10 Kg or more per a n i m a l " (amounting t o 10 - 1255). McEwan (1970) s t a t e s t h a t s l i d c a l v e s may l o s e up to 17% of t h e i r body weight d u r i n g t h e f i r s t w i n t e r compared w i t h c a p t i v e c a l v e s which m a i n t a i n or even i n c r e a s e t h e i r weight. Jacobsen and S k j e n n e b e r g (1975) r e p o r t t h a t "weight l o s s of a r e i n d e e r t h r o u g h a season may approach 20 per c e n t " i n the Norwegian e x p e r i m e n t a l herd. Dauphine (1970) r e p o r t s weight l e s s o f i n d i v i d u a l s i n t h e K a m i n u r i a k p o p u l a t i o n as 13 - 26% from November t o A p r i l . I n R u s s i a , Davydov (1965) quotes weight l o s s of r e i n d e e r as 20 25% of t h e i r p r e w i n t e r weight "due t o poor d i e t and energy l o s s w h i l e d i g g i n g f o r fo o d under t h e sncw". I t i s t h e r e f o r e p o s s i b l e t o compare p r o j e c t e d weight change i n the model w i t h weight l o s s e s t i m a t e s i n t h e f i e l d . Heather data can be used from t h e w i n t e r i n g a r e a s f o r p o r t i o n s o f t h e K a m i n u r i a k h e r d , and weight changes compared d i r e c t l y w i t h those r e p o r t e d by Dauphine (1S70). DESCRIPTION AND DISCUSSION Of TEE fiODEI Heat Losses B l a x t e r e t a l , (1959) i n d i c a t e f o u r avenues of heat l e s s i n c l o s e l y c l i p p e d sheep. T h e i r g e n e r a l e g u a t i o n f o r the p a r t i t i o n o f heat l o s s e s i s : E = W + V + C + R (1) 21 where: E the t o t a l heat l o s s , W = heat loss due to warming of food and drinking water, V = heat loss by vaporization of water, C = heat loss by convection and conduction, and E = heat loss by radiation ifiss of heat due to warming of food and drinking l a t e r Food and water entering the body require heat to warm them to body temperature. Elaxter et a l (1959) noted that at higher environmental temperatures sheep consumed greater guantities of water, more than was required to eliminate body s o l i d s . This greater volume of water heated up over a smaller temperature gradient resulted in a r e l a t i v e l y constant heat loss over a wide range in temperature. As temperatures drop belos 0 C the s p e c i f i c heat of water decreases (0.502 at -1 C to 0.449 at -30 C). In addition, the heat of fusion (melting) requires 79.1 cal/g of water. Estimation of the energy loss due to warming food and water to body temperature i s : ( i f T < 0) W = (0 - T„) x I w x S w + 79.1 x I w + T a x I w + (T a - T w) x I f x S f (2a) ( i f T > 0) W = (T •a - T w) x ( I f x S f) + ( I w x S w) (2b) 22 w h e r e : '8 = h e a t l o s s o f warming o f f o o d a n d w a t e r , Ta = t h e r e c t a l t e m p e r a t u r e ( C ) , I = t h e i n t a k e o f w a t e r ( k g ) , Sw = t h e s p e c i f i c h e a t o f w a t e r a t Tw ( c a l / g / C ) , I f = t h e i n t a k e o f f o o d ( k g ) , Sf = t h e s p e c i f i c h e a t o f f o o d {0.32 c a l / g / C ) , a nd Tw = t h e a m b i e n t a i r t e m p e r a t u r e ( C ) . Heat o f v a l o r i z a t i o n o f w a t e r v ajaor An a d d i t i o n a l l o s s i s t h a t a s s o c i a t e d w i t h t h e e n e r g y a b s o r b e d as l i g u i d w a t e r i s c h a n g e d t o a g a s e o u s s t a t e . B l a x t e r §Jt a l (1959) d e t e r m i n e d t h a t t h e h e a t o f v a p o r i z a t i o n was i n d e p e n d e n t o f t e m p e r a t u r e below t h e t e m p e r a t u r e where v a s o d i l a t i o n o c c u r s . I n d e e d , a t low t e m p e r a t u r e s l o s s i s n o t d e p e n d e n t on n u t r i t i o n a l l e v e l o r f l e e c e l e n g t h . F o r s h e e p t h e e s t i m a t e o f h e a t l o s s v i a e v a p o r a t i o n was 311 K c a l / m 2 / d a y ( B l a x t e r e t a l ^ 1 9 5 9 ) . F o r c a l v e s ( B l a x t e r and Wainman, 1964) and a d u l t c a t t l e ( G o n z a l e z e t a l , 1962) t h e l o s s o f h e a t by v a p o r i z a t i o n m o i s t u r e a t b e l o w c r i t i c a l t e m p e r a t u r e was 340 K c a l / m 2 / d a y . A s i n g l e e s t i m a t e o f 288 K c a l / m * / d a y h a s b e e n d e t e r m i n e d f o r r e i n d e e r (Hammel, e t a l , 1 9 6 2 ) . , S e n s i b l e h e a t l o s s U n l i k e e v a p o r a t i v e h e a t l o s s , s e n s i b l e l o s s i s c o n t r o l l e d p r i m a r i l y by e n v i r o n m e n t a l c o n d i t i o n s a nd t h e a n i m a l r e g u l a t e s t h e l o s s b e h a v i o u r a l l y . The a n i m a l c a n be d i v i d e d t h e o r e t i c a l l y i n t o t h r e e r e g i o n s , t h e i n n e r t h e r m a l r e g i o n , t h e b o u n d a r y l a y e r and t h e e x t e r n a l t h e r m a l r e g i o n ( E l a x t e r , 1962) . Heat p r o d u c e d i n t h e i n t e r n a l t h e r m a l r e g i o n , by f e r m e n t a t i o n o f f o o d , m u s c u l a r w o r k , t i s s u e m a i n t e n a n c e , e t c . must be d i s s i p a t e d i n o r d e r t o m a i n t a i n a c o n s t a n t deep body t e m p e r a t u r e . T h i s h e a t i s c o n d u c t e d t h r o u g h t h e t i s s u e l a y e r t o t h e e x t e r n a l t h e r m a l r e g i o n a t a r a t e e q u a l t o t h e r e c i p r o c a l o f t h e t i s s u e i n s u l a t i o n , known a s t h e t h e r m a l c o n d u c t i v i t y o f t h e t i s s u e s . B l a x t e r (1962) l i s t s t h e r m a l c o n d u c t a n c e a n d t h e r m a l i n s u l a t i o n o f t i s s u e f o r v a r i o u s a n i m a l s . F o r r u m i n a n t s t h e a v e r a g e a p p e a r s t o be 222 K c a l / m 2 / d a y / C g r a d i e n t i n t e m p e r a t u r e . The l o s s o f n o n - e v a p o r a t i v e h e a t d e p e n d s on t h e t e m p e r a t u r e g r a d i e n t b e t w e e n t h e i n t e r n a l and e x t e r n a l t h e r m a l r e g i o n ( a t m o s p h e r e and s u b s t r a t e ) . I n t h e m o d e l , t h e h e a t t r a n s f e r t o t h e b o u n d a r y l a y e r f r o m t h e i n n e r t h e r m a l l a y e r i s c o n s i d e r e d s u f f i c i e n t t o m a i n t a i n a c o n s t a n t s k i n t e m p e r a t u r e a t a g i v e n a m b i e n t a i r t e m p e r a t u r e . The h e a t l e s s o c c u r s a t t h e b o u n d a r y l a y e r o r h a i r -a i r i n t e r f a c e by c o n v e c t i o n , c o n d u c t i o n and r a d i a t i o n . C o n v e c t i v e h e a t l o s s e s f o r w h i t e - t a i l d e e r were d e t e r m i n e d by S t e v e n s ( 1 9 7 2 ) , She u s e d a 12 i n . d i a m e t e r c y l i n d e r , c o v e r e d w i t h h i d e and d e t e r m i n e d c o n v e c t i v e c o e f f i c i e n t s u n d e r v a r y i n g w i n d and t e m p e r a t u r e r e g i m e s . S t e v e n s c o n c l u d e d t h a t t h e c o e f f i c i e n t u n d e r f o r c e d c o n v e c t i o n , f o r e x a m p l e i n w i n d c r a s t h e a n i m a l moved, was: H = 3.7 x V 0 - 3 3 / D ° - 6 7 (3) 24 where: H = the convective c o e f f i c i e n t . V = the wind velocity (cm/sec), and D = the diameter of the cylinder (cm) . And the heat loss by convection i s therefore: A v x t x H X T (4) where: Av = the convective surface (ra 2), t = the time (hr), T = the temperature gradient between the atmosphere and the skin surface of the animal, and H =• the convective c o e f f i c i e n t fron Egn. 3. The second avenue of heat transfer to the environment from the animal i s by conduction. Conduction losses occur only when a part of the body i s in contact with the ground. Therefore, conduction losses are minimal when standing and become more important while l y i n g when maximum surface i s i n contact with the ground. Heat loss by conduction, Qk, can be estimated from: Q k = K x A c x t x T / d (5) where: K = Ac = t = the thermal conductivity (Kcal/m 2/hr/C cm), the surface area for conduction (m2), time (hr), 25 T = t h e t e m p e r a t u r e g r a d i e n t ( C ) , and d = f u r t h i c k n e s s (cm). The t h i r d means o f d i s s i p a t i n g h e a t a t t h e b o u n d a r y l a y e r i s by r a d i a t i o n . E a d i a n t h e a t l e s s c a n be a p p r o x i m a t e d u s i n g t h e S t e f e n - B o l t z m a n l a w s t a t i n g t h a t t h e r a d i a t i o n f r o m t h e u n i t a r e a o f a p e r f e c t r a d i a t o r i s p r o p o r t i o n a l t o t h e f o u r t h power o f t h e a b s o l u t e t e m p e r a t u r e o f t h e e m i t t i n g body o r : " R = A r x E a x E e x x x ( T w 4 - T r 4 ) ( 6 ) i where: B = t h e h e a t l o s s by l o n g - w a v e r a d i a t i o n ( K c a l / d ) , Ar = t h e a r e a o f t h e r a d i a n t s u r f a c e (m 2) , E = t h e e m i s s i v i t y o f t h e e n v i r o n m e n t (Ee) a n d t h e a n i m a l ( E a ) , T = t h e S t e f e n - E o l t z m a n c o n s t a n t , T r = t h e r a d i a n t s u r f a c e t e m p e r a t u r e o f t h e a n i m a l (C) , and Tw = t h e a m b i e n t a i r t e m p e r a t u r e ( C ) . I n t h e abo v e e g u a t i o n s many v a r i a b l e s must be e s t i m a t e d f r o m s t u d i e s on s p e c i e s r e l a t e d t o t h e genus B a n ^ j i f e r . I n many c a s e s t h e r e g u i r e d m e a s u r e m e n t s were n o t c o n d u c t e d on B a n g i f e r b u t on o t h e r r u m i n a n t s . G e n e r a l i z e d v a l u e s a r e s u b s t i t u t e d . I n Egn. 2 t h e e s t i m a t e o f r e c t a l t e m p e r a t u r e i s t a k e n f r o m Hammel e t a l (1962) a s 38.5 C. The t o t a l s u r f a c e a r e a o f t h e a n i m a l i s c a l c u l a t e d by t h e e g u a t i o n f o r w h i t e t a i l e d d e e r p r e s e n t e d i n Hoen (1968) r e l a t i n g s u r f a c e a r e a t o body w e i g h t o f 26 t h e a n i m a l . C o n v e c t i v e , c o n d u c t i v e and r a d i a n t s u r f a c e a r e a s h ave n o t been d e t e r m i n e d f o r R a j n g i f e r . T h e r e f o r e , v a l u e s u s e d i n BIOEN a r e t a k e n f r o m t h e l i t e r a t u r e f o r o t h e r r u m i n a n t s . The c o n v e c t i v e s u r f a c e a r e a f o r R a n g i f e r w h i l e s t a n d i n g i s c o n s i d e r e d t h e t o t a l s u r f a c e a r e a o f t h e a n i m a l . T h i s f a c t o r i s r e d u c e d t o 0.6 t i m e s t o t a l s u r f a c e a r e a when l y i n g (Moen, 1 S 6 8 ) . B l a x t e r e t a l (195 9) f o u n d t h e c o n d u c t i v e s u r f a c e a r e a t o be i n s i g n i f i c a n t w h i l e t h e a n i m a l was s t a n d i n g a n d 0.4 o f t h e t o t a l a r e a when l y i n g . B l a x t e r e t a l (1959) d e c i d e d on 0.7 o f t o t a l s u r f a c e a r e a a s t h e r a d i a n t s u r f a c e f o r s h e e p . A n o t h e r v a r i a b l e u s e d i n t h e c a l c u l a t i o n o f t h e c o n d u c t i v e h e a t l o s s i s t h e t h e r m a l c o n d u c t i v i t y o f R a n g i f e r h i d e . Hammel (1955) d e t e r m i n e d t h e i n s u l a t i o n o f R a n g i f e r w i n t e r c o a t a s 4.4 c l o o r .033 d e g r e e s C / k c a l / m 2 / d a y w h i c h i s e q u i v a l e n t t o a t h e r m a l c o n d u c t i v i t y o f 30.3 K c a l / m 2 / d a y / C . Moote (1955) d e t e r m i n e d t h e c o n d u c t i v i t y o f w i n t e r i n g c a r i b o u w i t h a f u r t h i c k n e s s o f 3.28 cm a s 3.81 K c a l / m 2 / h r / d € g r e e C o r 27.9 K c a l / m 2 / d a y / C / c m . The p r e s e n t model u s e s t h e e s t i m a t e o f M o o t e ( 1 9 5 5 ) . An i m p o r a t a n t v a r i a b l e w h i c h must be i n c l u d e d i n some o f t h e a b o v e e q u a t i o n s i s t h e r a d i a n t s u r f a c e t e m p e r a t u r e o f t h e a n i m a l . S t e v e n s (1972) d e t e r m i n e d r a d i a n t s u r f a c e t e m p e r a t u r e f o r w h i t e - t a i l d e e r a s a f f e c t e d by a i r t e m p e r a t u r e and w i n d s p e e d . I n t h e m o d e l , w i n d v e l o c i t y i s c o n v e r t e d t o m i / h r t o i n c o r p o r a t e i n t o S t e v e n ' s e g u a t i o n : 27 where T r = t h e r a d i a n t s u r f a c e t e m p e r a t u r e ( C ) , V •= t h e wind v e l o c i t y (mph), Tw - t h e a i r t e m p e r a t u r e ( C ) . To d e t e r m i n e t h e c o n v e c t i v e h e a t l o s s f r o m t h e a n i m a l t h e s k i n s u r f a c e t e m p e r a t u r e must be c a l c u l a t e d . J o y c e and B l a x t e r (1964) measured s k i n s u r f a c e t e m p e r a t u r e u n d e r v a r y i n g wind and t e m p e r a t u r e v a l u e s f o r sheep. F i g u r e s 2 and 3 a r e an a d a p t a t i o n o f t h e i r d a t a . I n summary, h e a t l o s s by B a n j j i f e r c o n s i s t s o f h e a t l o s s by c o n d u c t i o n , c o n v e c t i o n , e v a p o r a t i o n and t h e warming o f f o o d and d r i n k i n g w a t e r . T a b l e I summarizes p a r a m e t e r v a l u e s u s e d i n E gns. 2 t h r o u g h 7. J s s i a i S i s ^ j i s i i o s s i S s a a i f s r E a s a l m e t a b o l i c r a t e No r e l a t i o n s h i p between m e t a b o l i c r a t e and body w e i g h t i s a v a i l a b l e f o r c a r i b o u o r r e i n d e e r . However, v a l u e s a r e a v a i l a b l e f o r t h e f a s t i n g m e t a b o l i c r a t e o f c a r i b o u c a l v e s w e i g h i n g 5.3 5.9 Kg ( H a r t e t a l , 1961) and f o r two c a r i b o u w e i g h i n g 80 and 90 Kg (McEwan, 1970). Due t o t h e l a c k o f a p p r o p r i a t e d a t a on B a n g i f e r i t i s assumed t h a t between 5 and 35 Kg body w e i g h t , t h e f a s t i n g m e t a b o l i c r a t e , FHB, o f c a r i b o u f o l l o w s a p a t t e r n s i m i l a r t o t h a t f o r d o m e s t i c s h e e p . From d a t a o f B i t z m a n n , r e c a l c u l a t e d by B l a x t e r (1962), i t can be shown t h a t FMB (Kcal/Kg° 7 5 / d a y ) i n c r e a s e s l i n e a r l y w i t h body w e i g h t v i z : 28 38 o> a) u •P (0 M •H tn -16 A i r temp. (°C) Figure 2. Simulated e f f e c t of a i r temperature on skin temperature i n s t i l l a i r (adapted from data by Joyce and Blaxter, 1964). 1.00 Wind speed (km/hr) Figure 3. Simulated modification of skin surface temperature due to wind speed (adapted from data by Joyce and Blaxter, 1964). Table I. Summary of parameter values and l i t e r a t u r e sources used i n equations 2 - 7 . Parameter B r i e f d e s c r i p t i o n Value Source Tc r e c t a l temperature 38.5oc Hammel et a l (1962) D diameter of animal 30.48 cm Moen (1973) A t o t a l surface area variable Moen (1968) Av convective surface area same as A Moen (1968) Ts sk i n surface temperature see Figs. 2 and 3 Joyce and Blaxter (1964) K thermal conductivity 28.3 Kcal/m 2/day/°C Moote (1955) d f u r thickness 3.28 cm /cm Moote (1955) Ar radiant surface area v 0.7 * A Blaxter (1962) Ea e m i s s i v i t y of environment 1.0 Moen (1973) Ee em i s s i v i t y of animal 1.0 Blaxter (1962) Tr radiant surface temperature see .Eqn." 7 Stevens (1972) Ac conductive surface area 0 - standing Blaxter (1972) 0.4 * A - l y i n g to ID \ \ 30/ IMS = 9.77 + 1.62BW (8> where: - BW i s t h e body w e i g h t i n Kg<35.0. F o r a n i m a l s g r e a t e r t h a n 35 Kg, McEwan's e s t i m a t e s f o r w i n t e r PM.H o f 91 Kcal/Kg° 7 5 a r e u s e d (McEwan, 1 9 7 0 ) . S p e c i f i c d y n a m i c e f f e c t H e a t p r o d u c t i o n doe t o d i g e s t i o n and m e t a b o l i s m o f f o o d i s t e r m e d t h e s p e c i f i c d y n a m i c e f f e c t ( S DE). The m a g n i t u d e o f t h e SDE i s a f f e c t e d by t h e g u a n t i t y and q u a l i t y o f f o o d c o n s t i t u e n t s ( K l e i b e r , 1 9 6 1 ; B l a x t e r , 1 9 6 2 ) . B l a x t e r (1962) r e p o r t e d t h a t t h e e f f i c i e n c y o f u t i l i z a t i o n o f m e t a b o l i z a b l e e n e r g y f o r m a i n t e n a n c e i s a b o u t 8 3%. T h e r e f o r e , model BIOEN c a l c u l a t e s SDE a s 100 - 83 o r 17$ o f t h e t o t a l m e t a b o l i z a b l e e n e r g y . M o d e l ACTIVE p r e s e n t s a more d y n a m i c method f o r c a l c u l a t i n g SDE b a s e d on t i m e s i n c e t h e a n i m a l l a s t f e d . T h i s method i s n o t p r a c t i c a l f o r t h e l o w e r r e s o l u t i o n BIOEN m o d e l . c o s t f o r a c t i v i t y A c t i v i t y p a t t e r n s As m e n t i o n e d p r e v i o u s l y , l i t t l e r e s e a r c h h a s been c o n d u c t e d on a c t i v i t y b u d g e t s o f b a r r e n - g r o u n d c a r i b o u i n w i n t e r . I t i s n e c e s s a r y , t h e r e f o r e , t o u t i l i z e d a t a on r e i n d e e r f r o m S c a n d i n a v i a n c o u n t r i e s . D a t a f r o m N o r w e g i a n s o u r c e s (Thomson, 1970; S k o g l a n d , 1974) show a c t i v i t y b u d g e t s f o r w i n t e r i n g 31 r e i n d e e r . T a b l e I I s u m m a r i z e s d a t a f r o m Thomson (1971) on a c t i v i t y o f r e i n d e e r d u r i n g t h e w i n t e r months. The e n e r g y e x p e n d e d i n p u r s u i t o f t h e s e v a r i o u s a c t i v i t i e s c a n be e s t i m a t e d f r o m v a r i o u s s o u r c e s . i ) E n e r g y c o s t o f s t a j i d i n q i s b a s e d on e s t i m a t e s o f 2.1 -2.82 K c a l / K g / d a y f o r c a t t l e and s h e e p ( B l a x t e r , 1 9 6 2 ) . BIOEN c a l c u l a t e s t h e e n e r g y c o s t o f s t a n d i n g , SEN, a s : SEN = 0.117 K c a l / K g / h r (9) i i ) ISgray c o s t s o f w a l k i n c | h a s been m e a s u r e d f o r s h e e p ( B l a x t e r , 1962) w a l k i n g on a h o r i z o n t a l p l a n e . E l a x t e r d e t e r m i n e d t h a t s h e e p e x p e n d e d 0.6 c a l / k g / m a t a v e l o c i t y c f 24 m/min and 0.69 c a l a t 48 m/min. W h i t e ( p e r s . comm.) d e t e r m i n e d s l i g h t l y l o w e r e s t i m a t e s f o r r e i n d e e r w a l k i n g on t h e t u n d r a , h o w e v e r , t h e s e e s t i m a t e s a r e n o t p r e s e n t l y a v a i l a b l e . T h e r e a p p e a r s t o be e v i d e n c e t h a t c a r i b o u e x p e n d a p p r e c i a b l y more e n e r g y w a l k i n g on wet t u n d r a t h a n on d r y r o a d s u r f a c e s ( W h i t e , p e r s . comm.). G a a r e e t a l (1970) r e p o r t t h a t r e i n d e e r d u r i n g t h e g r a z i n g p e r i o d a r e more s t a t i o n a r y i n w i n t e r t h a n i n summer. W i t h i n t h e model i t i s assumed t h e a n i m a l s g r a z e w h i l e w a l k i n g a t 0.5 Km/hr w h i c h i s h a l f t h e s p e e d d e t e r m i n e d by Thomson (1973) i n summer. C a l c u l a t i o n o f t h e e n e r g y c o s t o f w a l k i n g (EWALK, K c a l ) u n d e r snow f r e e c o n d i t i o n s i s : 32 Table I I . Mean percentage of time the reindeer spend on d i f f e r e n t a c t i v i t i e s each month. (Thomson, 1971) Month November January February-March A p r i l Grazing 41 46 44 48 Lying 38 30 36 40 Standing Walking 11 11 9 2 9 12 10 9 T r o t t i n g and Running >1 >1 :>i Other V i ' •>1 >1 Table I I I . Estimates of intake during the winter <;g./Kg-75/d), Description Summer estimate * Winter estimate year l i n g s 114 92.3 l a c t a t i n g females 118 non-lactating females . . - y 102 .88.3 b u l l s 96 . 7 3 . 5 * Data from White et a l . , 1975 33 EWALK = 0.53 + 0.0033 v e l o c i t y (m/min) (10) M a k a r c v a and S e g a l (1958) u s i n g t h e mask t e c h n i g u e , d e t e r m i n e d t h a t t h e e n e r g y p r o d u c e d by w a l k i n g t h r o u g h snow o f a v e r a g e d e n s i t y 70 - 80 cm deep i s 177% o f r e s t i n g l e v e l s . W a l k i n g i n t h e a b s e n c e c f snow i n c r e a s e d o x y g e n c o n s u m p t i o n by o n l y 3 5 % . I f we assume a l i n e a r r e l a t i o n s h i p w i t h snow d e p t h . F i g u r e 4 r e p r e s e n t s t h e m o d i f i c a t i o n o f w a l k i n g e n e r g y due t o c h a n g i n g snow d e p t h . The c a l c u l a t i o n o f e n e r g y c o s t s o f w a l k i n g ( i n c l u d e s t r o t t i n g , r u n n i n g , e t c . ) wo u l d be t h e sum o f e n e r g y e x p e n d e d s t a n d i n g p l u s e n e r g y c o s t o f w a l k i n g , m o d i f i e d by snow when p r e s e n t . i i i ) E n e r g y c o s t o f e a t i n g i s t a k e n f r o m t h e e n e r g y c o s t o f e a t i n g r c u g h a g e e s t i m a t e d f o r s h e e p (1.5 K c a l / K g d r y m a t t e r e a t e n / K g body w e i g h t ) f r c m Young ( 1 9 6 6 ) . i v ) IHSiay c o s t o f d i e t i n g o r c r a t e r i n g h a s n o t b e e n m e a s u r e d i n N o r t h A m e r i c a . B a s k i n (1970) r e p o r t s t h a t " c a l c u l a t i o n s o f e n e r g y e x p e n d i t u r e c f t h e r e i n d e e r o r g a n i s m f o r l o c o m o t i o n , d i g g i n g f o r l i c h e n s u n d e r t h e snow and h e a t e x c h a n g e h a v e been made", b u t h i s d a t a a r e n o t a v a i l a b l e . I t i s t h e r e f o r e n e c e s s a r y t o make some a s s u m p t i o n s r e g a r d i n g t h e e n e r g y e x p e n d i t u r e d u r i n g c r a t e r i n g . M o d e l BIOEN assumes t h a t t h e e n e r g y c o s t o f d i g g i n g o v e r a s p e c i f i c t i m e i n t e r v a l i s e q u i v a l e n t t o t h e e n e r g y c o s t o f w a l k i n g f o r an e q u a l t i m e 34 i n t e r v a l ( a s s u m i n g w a l k i n g s p e e d i s t h e same as i n n o r m a l s e a r c h i n g a c t i v i t y ) . The c a l c u l a t i o n o f t h e amount o f t i m e s p e n t d i g g i n g i s i m p o r t a n t t o t h e d e t e r m i n a t i o n o f a s s o c i a t e d e n e r g y c o s t s . Davydov (1965) r e c o r d e d s t e p s and d i g g i n g movements t h r o u g h o u t t h e w i n t e r i n m o u n t a i n o u s t u n d r a and f o r e s t . U t i l i z i n g t h e s e d a t a and snow d e p t h v a l u e s w h i c h Davydov (1965) p r e s e n t s , an a p p r o x i m a t e r e l a t i o n s h i p b e t w e e n snow d e p t h and d a i l y d i g g i n g movements has be e n p o s t u l a t e d ( F i g . 5 ) . S k o g l a n d (1974) r e l a t e d snow d e p t h , DEPTH (cm) , t o t h e number o f d i g g i n g m ovements/min., DIG, a s : DIG = 2.598 + 16 x DEPTH (11) From F i g u r e 5 and I g n . 11 i t i s p o s s i b l e t o d e t e r m i n e a d a i l y d i g g i n g b u d g e t w i t h v a r i o u s snow d e p t h s . F o r e x a m p l e , i n snow d e p t h s o f 50 cm r e i n d e e r d i g a t a r a t e o f 30 paws p e r m i n u t e ( f r o m E g n . 11) f o r a t o t a l o f 6000 paws p e r 24 h r . day ( F i g u r e 5) '. The t i m e t a k e n t o d i g , t h e r e f o r e , i s 6000/30 = 200 min . o r 13.5% o f t h e d a y . I f we e x a m i n e a wi d e r a n g e o f snow d e p t h s , h o w e v e r , d i s c r e p a n c i e s i n t h e d a t a become o b v i o u s . S i n c e Egn. 11 i s l i n e a r no p r o v i s i o n i s made f o r t h e a n i m a l t i r i n g a t d e e p e r snow d e p t h s , flt v e r y h i g h snow d e p t h s t h e p e r c e n t o f t h e day s p e n t d i g g i n g a c t u a l l y d e c r e a s e s due t o t h e u n r e a l i s i c a l l y h i g h p a w i n g r a t e s c o m b i n e d w i t h t h e d e c r e a s i n g r a t e i n t h e number o f d i g g i n g movements/day ( F i g . 5 ) . S i n c e t h e d a t a a b o v e 35 3 ~> c TJ O TJ +> CJ TJ ft C X o O U a n H CJ <W C I 0) 5 o H C O (0 u c CJ *H r4 H Cn 04 G H t-i M A! H rH 3 rJ 5 S 1 J Snow depth (cm.) F i g u r e 4. simulated e f f e c t of snow depth-on energy expenditure while walking (adapted from data of Makarova and Segal, 1958 8000 J 0 20 40 60-Snow depth (cm.) Fi g u r e 5. Simulated e f f e c t of snow depth on d i g g i n movements per day (adapted from data of Davydov, 1965). 36 .16 .14 Snow depth (cm) F i g u r e 6. Postulated r e l a t i o n s h i p between snow depth and p r o p o r t i o n o f day spent d i g g i n g . 37 a p p e a r u n r e a l i s t i c , t h e p e r c e n t o f day s p e n t d i g g i n g i s assumed t o f o l l o w t h e r e l a t i o n s h i p i n F i g u r e 6. A l t h o u g h u n d o u b t e d l y i m p o r t a n t , l a c k o f any d a t a p r e v e n t e d t h e i n c l u s i o n o f t h e e f f e c t s o f snow d e n s i t y and h a r d n e s s . M o d e l BIOEN assumes t h a t t h e d i g g i n g t i m e a l t e r s t h e g r a z i n g p e r i o d r a t h e r t h a n a l t e r i n g n o n - g r a z i n g a c t i v i t i e s . I t i s assumed t h a t t h e p e r c e n t o f t h e day s p e n t d i g g i n g a f f e c t s t h e amount o f t i m e s p e n t e a t i n g by a l t e r i n g g r a z i n g i n t e n s i t y ( p r o p o r t i o n o f t i m e s p e n t e a t i n g i n a g r a z i n g p e r i o d ) . The e x a m p l e b e l o w d e s c r i b e s t h e c a l c u l a t i o n o f t h e p r o p o r t i o n o f t i m e s p e n t s e a r c h i n g , d i g g i n g and e a t i n g i n a g r a z i n g p e r i o d . Assume 4 5 % o f t h e day i s s p e n t g r a z i n g o f w h i c h 12% i s s p e n t d i g g i n g and a maximum ( s n o w - f r e e c o n d i t i o n s ) g r a z i n g i n t e n s i t y o f 0,8. S e a r c h t i m e i s c a l c u l a t e d a s .45x (1-0.8) = 0.09 (91 o f t h e d a y ) . T h e r e f o r e , d i g g i n g and e a t i n g t i m e amounts t o .45 - .09 = .36 (36$ o f t h e d a y ) . M o d e l BIOEN assumes t h a t 5 0 % o f t h e t i m e t h a t t h e a n i m a l d i g s i t a l s o e a t s and t h a t d u r i n g t h e o t h e r 50$ o f t h e t i m e , d i g g i n g i s t h e o n l y a c t i v i t y p u r s u e d . T h e r e f o r e , e a t i n g t i m e e g u a l s .36 - (.12x0.5) o r 3 0 % o f t h e day ( e f f e c t i v e g r a z i n g i n t e n s i t y i s .30/.45 o r . 6 7 ) . I n summary, t h e e n e r g y e x p e n d e d d u r i n g a g r a z i n g p e r i o d c o n s i s t s o f BMB, SDE, t h e e n e r g y c o s t o f s t a n d i n g , t h e e n e r g y c o s t o f w a l k i n g ( s e a r c h i n g ) , t h e e n e r g y c o s t o f d i g g i n g t h r o u g h snow ( i f a p p l i c a b l e ) and t h e e n e r g y c o s t o f e a t i n g . I f l e r g y i n t a k e I n o r d e r t o e x p l o r e t h e e f f e c t on t o t a l e n e r g y b a l a n c e o f v a r i o u s n u t r i t i o n a l l e v e l s , as d e t e r m i n e d by m e t a b o l i z a b l e 38 e n e r g y i n t a k e , a c a l c u l a t i o n o f d i g e s t i b l e e n e r g y i n t a k e must be made. B l a x t e r e t a l 11961) e x p l o r e d t h e r e l a t i o n b e t w e e n v o l u n t a r y f o o d i n t a k e (VFI) and f o o d g u a l i t y f o r s h e e p . They d e t e r m i n e d t h a t a l i n e a r r e l a t i o n s h i p e x i s t e d b e t w e e n V F I and f o o d g u a l i t y , a s m e a s u r e d by t h e a p p a r e n t d i g e s t i b l e e n e r g y . F o r f o r a g e s o f l o w t o medium g u a l i t y ( d i g e s t i b l e e n e r g y b e l o w 2.24 K c a l / g DM) i n t a k e i s c o n t r o l l e d by t h e p h y s i c a l d i s t e n s i o n o f t h e rumen w h e r e a s i n h i g h g u a l i t y f o o d s i n t a k e i s c o n t r o l l e d c h e m i c a l l y by t h e VFA ( v o l a t i l e f a t t y a c i d ) p r o d u c t i o n i n t h e rumen ( F i g . 7 ) . The s p e c i f i c p a r a m e t e r s i n F i g u r e 7 h a v e n o t been d e t e r m i n e d f o r B a n j g i j e r . F o r t h i s r e a s o n t h e method d e s c r i b e d b e l o w was used i n t h e m o d e l t o c a l c u l a t e e n e r g y i n t a k e . W h i t e e t a l (1975) e s t i m a t e d i n t a k e f o r c a r i b o u g r a z i n g 5 1 % o f t h e d a y w i t h a g r a z i n g i n t e n s i t y o f 85% ( T a b l e I I I ) . Thomson (1971) d e t e r m i n e d t h a t r e i n d e e r g r a z e d a p p r o x i m a t e l y 4 5 % o f t h e day i n w i n t e r and S k o g l a n d (1974) e s t i m a t e d a g r a z i n g i n t e n s i t y o f 65% o f t h e g r a z i n g p e r i o d i n w i n t e r . U s i n g t h e d a t a f r o m W h i t e e t a l m o d i f i e d by t h e f i n d i n g s o f S k o g l a n d and Thomson, t h e amount o f t i m e s p e n t e a t i n g i n summer i s 4 3 % o f t h e day w h i l e i n w i n t e r i t i s 2 9 % . W h i t e e t a l (1975) r e l a t e d r y m a t t e r i n t a k e p e r m i n u t e s p e n t e a t i n g t o l i v e p l a n t b i o m a s s . I f we assume an a v e r a g e p l a n t b i o m a s s i n summer o f 40 - 60 g/m 2 ( i h i t e e t a l , 1975) and 100 g/m 2 on s i n t e r r a n g e s , t h e e s t i m a t e o f d r y m a t t e r i n t a k e p e r m i n u t e i n w i n t e r i s 1.2 t i m e s g r e a t e r t h a n i n summer. By c o m b i n i n g t h e p e r c e n t o f day s p e n t e a t i n g and i n t a k e p e r m i n u t e , we c a n compare r e l a t i v e d a i l y i n t a k e b e t w e e n summer and w i n t e r . T a b l e I I I r e p r e s e n t s d a i l y i n t a k e / K g 0 7 5 f o r v a r i o u s 2 . 2 4 DE K c a l DE/gra Figure 7. Assumed relationship between voluntary food intake and.digestible energy of the food (adapted from data of Blaxter et a l , 1961). c o h o r t s i n summer ( f r o m W h i t e e t a l , 1975) and an e s t i m a t e f o r w i n t e r , m o d i f i e d f r o m t h e a b o v e d a t a , U t i l i z i n g t h e s e f i g u r e s a 100 Kg male c a r i b o u w o u l d h a v e a d a i l y f o o d i n t a k e o f 2316 g o r a b o u t 4585 t o 5419 K c a l m e t a b o l i z a b l e e n e r g y ( i f we assume a c a l o r i c c o n t e n t o f 4,5 K c a l / g m and a d i g e s t i b i l i t y o f 55 t o 6 5 1 ) . T h i s v a l u e (4585 t o 5419 K c a l ) c o r r e s p o n d s t o 1,59 t o 1.88 X BUB* L i t e r a t u r e e s t i m a t e s o f e n e r g y e x p e n d i t u r e f o r f r e e r a n g i n g a n i m a l s v a r y b e t w e e n 1.86 - 2.56 t i m e s BHR (Young a n d C o r b e t t , 1 9 7 2 ) . S i n c e a v a i l a b l e d a t a i n d i c a t e a v a r i a b i l i t y i n t h e s p e c i f i c c o m p o n e n t s o f e n e r g y i n t a k e , t h e c a l c u l a t i o n o f i n t a k e i n t h e mo d e l i s p e r f o r m e d i n a d y n a m i c f a s h i o n w i t h t h e a b i l i t y t o t e s t t h e r e l a t i v e s e n s i t i v i t y o f t h e v a r i o u s c o m p o n e n t s . I n t h e model BIOEN f o o d i n t a k e , INTAKE, i s c a l c u l a t e d a s : INTAKE = E I X GBAZE X FIRPH (12) where: E I •= t h e p r o p o r t i o n o f t h e t i m e s p e n t e a t i n g i n a g r a z i n g p e r i o d , GBAZE = p r o p o r t i o n o f t h e day s p e n t g r a z i n g , and FIRPM = f o o d i n t a k e r a t e / m i n The f o o d i n t a k e p e r m i n u t e o f e a t i n g (FIBPJ!!) h a s b e e n s u g g e s t e d ( W h i t e , e t a l , 1975) t o f o l l o w t h e f o r m : FIRPM = 6.2 x (1 - e-0-0433 x (b-10)>• (13) 41 where: b= a v a i l a b l e b i o m a s s ( g / m 2 ) A b i o t i c v a r i a b l e s A b i o t i c v a r i a b l e s ( t e m p e r a t u r e , w i n d s p e e d , snow d e p t h ) a r e p r o j e c t e d on a d a i l y b a s i s . The w e a t h e r d a t a were o b t a i n e d f o r s e l e c t e d y e a r s c n s p e c i f i c a r e a s f r o m t h e C a n a d i a n D e p a r t m e n t o f t h e E n v i r o n m e n t w e a t h e r s u m m a r i e s . I t i s r e a l i z e d t h a t t h e a b i o t i c d a t a o f a p a r t i c u l a r l o c a l i t y may v a r y b e t w e e n f e d e r a l w e a t h e r s t a t i o n s and c a r i b o u w i n t e r i n g a r e a s , however no c o r r e c t i o n f a c t o r s were c o n s i d e r e d . A r e a s c o n s i d e r e d i n c l u d e F t . S i m p s o n ( b o r e a l ) and C o n t w a y t o l a k e ( t u n d r a ) i n t h e N o r t h w e s t T e r r i t o r i e s (Rowe, 1 9 5 9 ) . T h e s e a r e a s a r e known t o be w i n t e r i n g a r e a s f o r b a r r e n - g r o u n d c a r i b o u ( K e l s a l l , 1 9 6 8 ) . D a t a i n c l u d e snow d e p t h s a t t h e end o f e a c h month i n t e r p o l a t e d b e t w e e n months on a d a i l y b a s i s . A v e r a g e t e m p e r a t u r e s f o r t h e months were a l s o i n t e r p o l a t e d b e t w e e n months. The d a t a a v a i l a b l e on w i n d s p e e d i n c l u d e t h e number o f d a y s i n e a c h month a v e r a g i n g 0, 1 - 12, 13 - 3 8 , and 38+ mph- ( c o n v e r t e d t o km/hr i n t h e m o d e l ) . The d a y s c f t h e month were r a n d o m l y a s s i g n e d t o one o f t h e s e c a t e g o r i e s s u c h t h a t , f c r e x a m p l e , 5 r a n d o m l y s e l e c t e d d a y s o f t h e month had 0 w i n d , 20 had 1 - 12 mph w i n d ( a c t u a l w i n d s p e e d s a r e r a n d o m l y a s s i g n e d b e t w e e n 1 - 12 mph on any i n d i v i d u a l d a y ) , e t c . D1SC0SSIGN OF MCDEI O01F0T C r i t i c a l e n v i r o n m e n t The c r i t i c a l e n v i r o n m e n t o f an a n i m a l i s d e f i n e d a s t h e 42 c o m b i n a t i o n o f w i n d and t e m p e r a t u r e a t w h i c h t h e a n i m a l h a s t o i n c r e a s e i t s h e a t p r o d u c t i o n t o p r e v e n t i t s deep body t e m p e r a t u r e f r o m f a l l i n g . The c r i t i c a l e n v i r o n m e n t c a n be i n f l u e n c e d by n u t r i t i o n a l l e v e l , body w e i g h t , and h e a t p r o d u c t i o n . U s i n g t h e model BIOEN, t h e s i m u l a t e d c r i t i c a l e n v i r o n m e n t o f R a n g i f e r was d e t e r m i n e d u n d e r d i f f e r e n t w i n d a n d t e m p e r a t u r e r e g i m e s . F i g u r e 8 i l l u s t r a t e s t h e c r i t i c a l e n v i r o n m e n t f o r a 100 Kg a n i m a l w i t h d i g e s i b i l i t y c o e f f i c i e n t s o f 0.5 and 0.55 r e p r e s e n t i n g d i f f e r e n t n u t r i t i o n a l p l a n e s . I f we assume t h a t a i r t u r b u l e n c e a r o u n d t h e a n i m a l c n a w i n d l e s s day c o r r e s p o n d s t o a w i n d s p e e d o f 0.5 Km/hr, t h e n t h e c r i t i c a l t e m p e r a t u r e i n t h e two r u n s a r e -56 C. and -41 C. f o r d i g e s t i b i l i t y c o e f f i c i e n t s o f 0.55 and 0.5 r e s p e c t i v e l y . T h e r e f o r e a d r o p o f 5% i n d i g e s t i b i l i t y r e s u l t s i n an i n c r e a s e o f 15 C. i n c r i t i c a l t e m p e r a t u r e , i l l u s t r a t i n g t h e i m p o r t a n c e o f n u t r i t i o n a t l o w e n v i r o n m e n t a l t e m p e r a t u r e s . F i g u r e 8 a l s o r e v e a l s t h a t i n c r e a s i n g w i n d s p e e d h a s l i t t l e e f f e c t on h e a t l o s s a t t e m p e r a t u r e s a r o u n d -20 C . The r e l a t i o n s h i p b e t w e e n wind s p e e d v e r s u s t o t a l h e a t l o s s , r a d i a t i o n l o s s and c o n v e c t i o n l o s s a t -20 C. i s shown i n F i g u r e 9. I t a p p e a r s t h a t t h e a d d i t i o n a l l o s s o f h e a t t h r o u g h c o n v e c t i o n i s more t h a n c o m p e n s a t e d f o r by t h e r e s u l t a n t i n c r e a s e i n h e a t r e t e n t i o n o f r a d i a t i o n . T h i s c o m p e n s a t i o n i s due t o t h e d e c r e a s e d d i f f e r e n c e between t h e r a d i a n t s u r f a c e t e m p e r a t u r e o f t h e a n i m a l and t h e a m b i e n t t e m p e r a t u r e o f t h e e n v i r o n m e n t . - D i g e s t i b i l i t y =0.5 « _ D i g e s t i b i l i t y « 0.55 Wind speed fkia/hr) Fig-ore 8. Simulated c r i t i c a l environment. I T 5 -0 H L O S M f l X = 6 0 0 0 . fi M R X = 6 0 0 0 . •' C M f l X = 6 0 0 0 . ' TOTAL CONVECTION •— — . — , ^ RADIATION i t i • i 1 i « . . . . . 1 . • . - 1 5 W:ND SPEED (MPH) Figure 9 . Cccwnents .o£ heat loss total (* - -3 due. to radiation (- - due to convection C 3 "versus wind speed, at 20 cc 45 The e f f e c t o f snow der-th The e f f e c t o f snow d e p t h on t o t a l h e a t p r o d u c t i o n and m e t a b o l i z a b l e e n e r g y i n t a k e was e x a m i n e d f o r a 100 Kg a n i m a l i n a t b e r m e n e u t r a l e n v i r o n m e n t and a f o r a g e d i g e s t i b i l i t y o f 5536 ( T a b l e I V ) . The s i m u l a t e d t o t a l m e t a b o l i s m v a r i e d b e t w e e n 4845 -5538 K c a l / d a y w h i c h c o r r e s p o n d s t o 1.64 - 1.92 t i m e s BMS r e s p e c t i v e l y . T h e s e v a l u e s a r e l e s s t h a n f i e l d e s t i m a t e s f o r f r e e r a n g i n g s h e e p f o r whose a v e r a g e d a i l y m e t a b o l i s m was 1.86 -2.56 t i m e s BHB (Young and C o r b e t t , 1 9 7 2 ) . T o t a l m e t a b o l i z a b l e e n e r g y i n t a k e r a n g e d b etween 5130 6084 K c a l / d a y o r 1.78 - 2.11 t i m e s BM8 r e s p e c t i v e l y . McEwan a n d W h i t e h e a d (1970) d e t e r m i n e d a t o t a l m e t a b o l i z a b l e e n e r g y i n t a k e i n w i n t e r o f 217.3 K c a l / K g 0 7 S / d a y w h i c h i s e g u i v a l e n t t o 6518 K c a l / d a y f o r a 100 Kg aEimal. I t i s d i f f i c u l t t c c o m p a r e t h e s e d a t a w i t h s i m u l a t e d r e s u l t s s i n c e t h e r e i n d e e r i n t h e a b o v e s t u d y were penned and f e d ad l i b i t u m . £gffl£§^A§2S o f t u n d r a and b o r e a l w i n t e r i n g a r e a s The model was u s e d t o p r o j e c t w e i g h t c h a n g e o f i n d i v i d u a l s s u b j e c t e d t c w i n t e r c l i m a t i c c o n d i t i o n s e x p e r i e n c e d on t h e t u n d r a and i n t h e b o r e a l r e g i o n s . K e l s a l l (1968) o b s e r v e d w i n t e r i n g a r e a s f o r c a r i b o u between 1951 - 1962. A r e a s c h o s e n f o r s i m u l a t i o n were known w i n t e r i n g a r e a s n e a r F t . S i m p s o n i n t h e b o r e a l r e g i o n s and C c n t w a y t o L a k e c n t h e t u n d r a . F i g u r e 10 c o m p a r e s t h e r e s u l t a n t e n e r g y r e l a t i o n s b e t w e e n t h e two a r e a s d u r i n g t h e w i n t e r s o f 1961 - 62 and 1966 - 6 7 . The g e n e r a l t r e n d i n h e a t l o s s t h r o u g h t h e w i n t e r c a n be a t t r i b u t e d l a r g e l y t c t h e t r e n d i n t e m p e r a t u r e . The e r r a t i c f l u c t u a t i o n s 46 Table IV. Simulated e f f e c t of snow depth on heat production and t o t a l metabolizable energy i n t a k e . Snow Depth Heat Load M e t a b o l i z a b l e Energy (cm) ( m u l t i p l e of BMR) ( m u l t i p l e o f BMR) 0 1-64 .. ' 2.11 1 0 1-75 •. 1.96 2 0 1.79 ' 1.88 3 0 1-83 ' • . 1.85 4 0 1.86 1.82. 5 0 1-88 1.80 6 0 1.92 1.78 10000 <3 o u V c 0) o 5000 10000 5000 : TUNDRA 1961-62 180 1966-67 I 1 I 180 .TAIGA 1961-62 I J V J I I i v v \ \ \ 180 1966-67 180 D a y 3 from Oct.l Days from Oct.l Figure 10. Energy relations of Rangifer In t w o n«.i«~«. A ' , winter range (-, Kr^HSta* £ SrS,*"" *..*»*« «nd tai*> 48 a r e t h e r e s u l t o f v a r y i n g d a i l y w i n d s p e e d s . I n c r e a s e o r d e c r e a s e i n h e a t p r o d u c t i o n r e f l e c t s t h e c h a n g i n g snow c o n d i t i o n s . The p l o t s r e v e a l some i n t e r e s t i n g g e n e r a l i z a t i o n s r e g a r d i n g t u n d r a and b o r e a l w i n t e r r a n g e s . I t c a n be s e e n f r o m t h e o u t p u t t h a t t h e t u n d r a c l i m a t e i s more s e v e r e i n t e r m s o f w i n d and t e m p e r a t u r e ( h e a t l o s s c u r v e s i n F i g u r e 1 0 ) . However, g r e a t e r snow d e p t h s i n t h e b o r e a l r e g i o n s r e s u l t i n h i g h e r a v e r a g e e n e r g y e x p e n d i t u r e d u r i n g c r a t e r i n g and w a l k i n g t h a n on ^ t h e t u n d r a . T a b l e V r e p r e s e n t s w e i g h t c h a n g e o f a 100 Kg c a r i b o u f r o m O c t o b e r 1 t o M a r c h 31 f o r t h e two y e a r s i n t h e two a r e a s . A b i o t i c d a t a f o r t h e s e r u n s a l s o a r e p r e s e n t e d i n T a b l e v. I t c a n be s e e n f r o m T a b l e V t h a t t h e b o r e a l r e g i o n s o f f e r s a more f a v o u r a b l e w i n t e r e n v i r o n m e n t f o r c a r i b o u i n t e r m s o f m i n i m i z i n g w e i g h t l o s s . A l t h o u g h K e l s a l l (1968) o b s e r v e d a n i m a l s w i n t e r i n g i n b o t h a r e a s i n numerous y e a r s , t h e v a s t m a j o r i t y o f t h e c a r i b o u u t i l i z e d b o r e a l w i n t e r r a n g e s . I t i s m i s l e a d i n g t o compare w e i g h t l o s s v a l u e s i n T a b l e V w i t h l i t e r a t u r e v a l u e s b e c a u s e o f t h e s e n s i t i v i t y o f s p e c i f i c c o m p o n e n t s i n t h e model f o r w h i c h l i t t l e d a t a e x i s t . T a b l e VI p r e s e n t s t h e r e s u l t s o f s e n s i t i v i t y a n a l y s e s p e r f o r m e d on s e l e c t e d c o m p o n e n t s o f t h e m o d el f o r b o r e a l and t u n d r a r a n g e s . A l t e r i n g g r a z i n g i n t e n s i t y p l u s o r minus 10$ , c a n r e s u l t i n a 30% d i f f e r e n c e i n p r o j e c t e d w e i g h t c h a n g e o v e r w i n t e r . F o r a g e d i g e s t i b i i t y a l s o a p p e a r s t o be a v e r y s e n s i t i v e f a c t o r i n t h e p r o d u c t i v i t y o f an i n d i v i d u a l ( T a b l e V I ) . I t c a n be shown t h a t t h e s e n s i t i v i t y o f f o r a g e d i g e s t i b i l i t y and g r o s s e n e r g y c o n t e n t 49 Table V. Simulated weight l o s s (percent) a t F t . Simpson and Contwayto Lake. Area Year Weight Loss (percent) A b i o t i c Data min. avg. temp, (O Q ) max. snow depth (cm) fldays wind greater 12 F t . Simpson 1961-62 1966-67 5 9 -31.7 -26.3 53 71 18 17 Contwayto Lk. 1961-62 1966-67 21 14 -36.4 -34.3 58 38 67 79 Table VI. Results of component s e n s i t i v i t y a n a l y s i s on f i n a l weight ( i n i t i a l weight = 100 kg) on tundra and t a i g a ( a b i o t i c data from 1966-67). Area Component grazing i n t e n s i t y * x 0.9 x 1.0 x 1.1 D i g e s t i b i l i t y ** x 0.9 x 1.0 x 1.1 F t . Simpson Contwayto Lk. 77 70 91 86 107 101 •82 71 91 86 100 100 * base (x 1.0) = 0.8 ** base (x 1.0) = 0.55 i s e q u i v a l e n t t o t h e s e n s i t i v i t y o f d i g e s t i b i l i t y . I n t h e model v a l u e s f o r t h e s e c o m p o n e n t s a r e t o some e x t e n t i n a c c u r a t e s i n c e a i d e v a r i a b i l i t y i n t h e d a t a e x i s t . An i n a p p r o p r i a t e e s t i m a t e o f o n l y one o f t h e s e c o m p o n e n t s c a n s i g n i f i c a n t l y a l t e r p r o j e c t e d Height d u r i n g w i n t e r . 5 1 ACTIVE z 1 HODEI OF SUMKEJ ACTIVITY AND ENERGY EXPENDITURE IHSfiPJGf ION S t u d i e s o f s e c o n d a r y p r o d u c t i o n w i t h i n e c o s y s t e m s a r e n o t o n l y i n t e g r a l t o t h e s t u d y o f e c o s y s t e m s t r u c t u r e and f u n c t i o n , b u t f u n d a m e n t a l t o a l l c o n s i d e r a t i o n s o f h a r v e s t a n d y i e l d . B a t e s o f s e c o n d a r y p r o d u c t i o n a r e c l e a r l y i n f l u e n c e d by a n i m a l s 1 a c t i v i t y p a t t e r n s and e n e r g y e x p e n d i t u r e s a s s o c i a t e d w i t h t h e s e a c t i v i t i e s . T h i s c h a p t e r d e s c r i b e s t h e use o f c o m p u t e r s i m u l a t i o n t e c h n i q u e s t c p r o j e c t c a r i b o u a c t i v i t y p a t t e r n s and e n e r g y e x p e n d i t u r e u t i l i z i n g d a t a g a t h e r e d p r i m a r i l y a t t h e U. S. I B P s i t e a t P r u d h o e E a y , A l a s k a , S P E C I F I C OBJECTIVES The model h a s f o u r b a s i c o b j e c t i v e s : 1. To p r o j e c t r e a l i s t i c a l l y t h e amount o f t i m e a male o r n o n -l a c t a t i n g f e m a l e s p e n d s l y i n g , s t a n d i n g , i n l o c o m o t i o n ( w a l k i n g , t r o t t i n g , r u n n i n g ) and g r a z i n g . The g r a z i n g a c t i v i t y i s f u r t h e r s u b d i v i d e d i n t o w a l k i n g and e a t i n g p e r i o d s . 2. To p r o v i d e a r e a l i s t i c s e t o f r u l e s f o r c h a n g e w h i c h d e t e r m i n e t h e manner i n w h i c h t h e d i f f e r e n t a c t i v i t i e s i n f l u e n c e e a c h o t h e r and a r e f u r t h e r i n f l u e n c e d by i n s e c t h a r a s s m e n t . 52 3. To p r o j e c t t h e e n e r g y e x p e n d e d by a n i m a l s u n d e r v a r y i n g c o n d i t i o n s o f w i n d s p e e d , a i r t e m p e r a t u r e and i n s e c t h a r a s s m e n t . 3. To i n t e g r a t e t h e r e s u l t s o f t h e s i m u l a t i o n f o r t h e i n c o r p o r a t i o n i n t o a model o f l o w e r r e s o l u t i o n , f o r e x a m p l e , a model t o g u i d e management, SUMMARY Of THE JIGJDEL B a s i s rood e l s t r u c t u r e The c u r r e n t v e r s i o n o f t h e model i s s t a t e - o r i e n t e d a n d p r o j e c t s t h e a c t i v i t i e s o v e r d i s c r e t e t i m e - s t e p s . A t t h e b e g i n n i n g o f e a c h t i m e - s t e p an a c t i v i t y i s s e l e c t e d on t h e b a s i s o f t h e c u r r e n t s y s t e m s t a t e and t h e r u l e s f o r c h a n g e b e t w e e n s t a t e s . The s e l e c t e d a c t i v i t y i s p u r s u e d u n t i l t h e n e x t t i m e -s t e p , when t h e s y s t e m s t a t e i s a g a i n r e v i e w e d , u p d a t e d and t h e n e x t a c t i v i t y s e l e c t e d . A t i m e - s t e p o f o n e - h a l f h o u r i s p r e s e n t l y e m p l o y e d , and e n e r g y e x p e n d i t u r e i s s i m u l a t e d o v e r a s i n g l e summer. The d i s a d v a n t a g e s o f u s i n g d i s c r e t e t i m e - s t e p s and d e t e r m i n i s t i c p r o j e c t i o n s a r e a p p a r e n t . The d e v e l o p m e n t o f an e v e n t - o r i e n t e d m o d e l , w h i l e more r e a l i s t i c , w o u l d r e g u i r e a d i f f e r e n t d a t a b a s e . C o m p u t a t i o n s p e r f o r m e d by t h e m o d e l f o r any g i v e n d ay a r e s t r a i g h t f o r w a r d . At t h e b e g i n n i n g o f e a c h h a l f - h o u r p e r i o d o r 53 t i m e - s t e p t h e m o d e l c o m p u t e s t h e a n i m a l ' s b a s a l m e t a b o l i c r a t e , t h e s p e c i f i c d y n a m i c e f f e c t o f f o o d d i g e s t i o n a n d t h e l e v e l o f i n s e c t h a r a s s m e n t , a n d u p d a t e s t h e a c c o u n t o f t h e t i m e s p e n t i n d i f f e r e n t a c t i v i t i e s . T h e m o d e l t h e n s e l e c t s o n e o f t h e f o u r a c t i v i t y s u b r o u t i n e s - L I E , W A L K , S T A N D o r G B A Z E a n d t r a n s f e r s c o n t r o l t o t h a t r o u t i n e . T h e p r o c e d u r e i s r e p e a t e d f o r e a c h t i m e - s t e p d u r i n g t h e d a y a n d t h e t i m e a n d e n e r g y e x p e n d e d i n p u r s u i t o f e a c h a c t i v i t y i s a c c u m u l a t e d f o r t h e d a y . D u r i n g a n y s p e c i f i c d a y t h e a n i m a l ' s d i r e c t i o n a n d s p e e d o f m o v e m e n t i s m o n i t o r e d t c d e t e r m i n e h o w f a r i t i s f r o m t h e c o a s t a l s a n d d u n e s , f i g u r e 1 1 i l l u s t r a t e s t h e g e n e r a l s t r u c t u r e a n d s u b r o u t i n e t r a n s f e r s f o u n d i n t h e m o d e l . L U R y t v a r i a b l e s T h e i n p u t v a r i a b l e s a n d d a t a r e q u i r e d t o r u n t h e m o d e l i n c l u d e : A n i m a l c o n d i t i o n - w e i g h t ( K g ) , - i f m a l e - i n r u t c o n d i t i o n o r n o t , - i f c a l f - w e a n e d o r n o t a n d a g e ( w k ) I n i t i a l c o n d i t i o n s r e s u l t i n g f r o m p a s t a c t i v i t y p a t t e r n - l e n g t h o f l a s t g r a z i n g p e r i o d ( h r ) , - l e n g t h o f l a s t e a t i n g p e r i o d ( h r ) , - c u r r e n t s t a t e : l y i n g a n d f o r h o w l o n g ( h r ) , - d i s t a n c e i n f r o m c o a s t 54 A b i o t i c d a t a (cn a h a l f h o u r l y o r t i m e - s t e p b a s i s ) - d a t e - w i n d s p e e d a t 60 cm (km/hr) - a i r t e m p e r a t u r e a t 60 cm ( C) I&teindiate v a r i a b l e s D u r i n g c o m p u t a t i o n t h e model c o m p u t e s a number o f i n t e r m e d i a t e v a r i a b l e s w h i c h i n f l u e n c e t h e c h a r a c t e r o f t h e o u t p u t , b u t do n o t a p p e a r i n t h e o u t p u t . T h e s e v a r i a b l e s i n c l u d e : - s t a n d a r d f a s t i n g m e t a b o l i c r a t e (FMH) f o r e a c h t i m e p e r i o d and t o t a l f o r t h e day ( K c a l ) s p e c i f i c d y n a m i c e f f e c t f o r e a c h t i m e p e r i o d and t o t a l f o r t h e day ( K c a l ) d a i l y e n e r g y c o s t s o f a c t i v i t i e s ( s t a n d i n g , w a l k i n g , e a t i n g ) ( K c a l ) i n s e c t h a r a s s m e n t d u r i n g e a c h t i m e p e r i o d ( i n d e x 0 . 0 - 1 . 0 ) - d i r e c t i o n o f movement (away f r o m o r t o w a r d s c o a s t ) and d i s t a n c e f r o m c o a s t (km) a v e r a g e s p e e d o f w a l k i n g i n e a c h a p p l i c a b l e p e r i o d and a v e r a g e d a i l y w a l k i n g s p e e d (km/hr) T h e s e i n t e r m e d i a t e v a r i a b l e s a r e c u r r e n t l y c o m p u t e d on t h e b a s i s o f o b s e r v a t i o n s r e p o r t e d f o r d o m e s t i c s t o c k ( c a t t l e , s h e e p , b u r r o s ) and mule d e e r . To some e x t e n t t h e y c a n be e v a l u a t e d a g a i n s t e x i s t i n g i n f o r m a t i o n w h i c h h a s been e m i t t e d Figure 1 1 . Basic relationships and sequence of rales for chana sucessive time-periods i n a day " • 9 e i n s imu la t ing DAYS A T T A C K D R O P S T O O . 3 3 / T I M E sn M I L D A T T A C K A T T A C K D R O P S K - s - 3 D L A S T G R A Z -I N G , W I N D s V R E A C H E S C O A S T W T U N D E R S E V E R S A A T T A C K A. N  S E V E - R S A T T A C K L > K I N S E C T S D R O P S ^ S E V E R E AT^r - t_ / T I M S STwrr • L A S T G R A Z E K O D J D V n T ^ m * " G R A • z E B Y D I S T A N C E W A L K E D A C T I V I T Y U P D A T E D I S T A N C E P U R S U E D F R O M C O A S T T O T A L E N E R G Y E X P E N D I T U R E D I S T A N C E F R O M C O A S T / " function of T I M E S P E N T I N E A C H A C T I V I T Y E N E R G Y S P E N T I N E A C H A C T I V I -T Y 5 6 f r o m t h e p r o c e s s o f model c o n s t r u c t i o n t o a v o i d c i r c u l a r r e a s o n i n g ; t o some e x t e n t t h e y c a n be e v a l u a t e d f r o m d a t a c o l l e c t e d i n 1973 ( Y o u s e f and H h i t e , 1 9 7 4 ) . I n a few i n s t a n c e s v a l i d a t i o n i s v e r y n e a r l y i m p o s s i b l e o r c a n p r o c e e d o n l y i n d i r e c t l y . l a l i d a t i o n d a t a f o r i n t e r m e d i a t e v a r i a b l e s Computed f a s t i n g m e t a b o l i c r a t e s i s c o m p a r e d w i t h d a t a c f HcEwan (1970) w h i c h i n d i c a t e t h a t d a i l y FHE f o r c a r i b o u w e i g h i n g more t h a n 35 Kg v a r i e s b e t ween 90 t o 100 Kcal/Kg° 7 S . The s p e c i f i c d y n a m i c e f f e c t i s i m p o s s i b l e t o measure d i r e c t l y and i s e s t i m a t e d f r o m t h e d i f f e r e n c e b e t ween m e a s u r e s o f h e a t p r o d u c t i o n and b a s a l m e t a b o l i c r a t e . The i n s e c t h a r a s s m e n t i n d e x was e s t a b l i s h e d e m p i r i c a l l y . The computed d i r e c t i o n and d u r a t i o n o f movement w i l l be co m p a r e d w i t h t h e e s t i m a t e o f C h i l d (1973) and Thomson ( 1 9 7 3 ) . I n t e r m e d i a t e v a r i a b l e s a l s o a r e e x a m i n e d t o d e t e r m i n e w h e t h e r t o t a l d a i l y e n e r g y e x p e n d i t u r e i n an i n s e c t - f r e e day i s w i t h i n t h e l i m i t s o f 1.86 - 2.52 t i m e s FHR. T h i s r a n g e i s t a k e n f r o m e s t i m a t e s f o r t h e m e t a b o l i c r a t e o f g r a z i n g s h e e p a t m a i n t e n a n c e (Young and C o r b e t t , 1 9 7 2 ) . M o d e l c u t j u t v a r i a b l e s The m o d el o u t p u t c o n s i s t s o f t h e d a i l y b u d g e t o f t i m e ( h r ) and t h e f r a c t i o n o f e a c h day s p e n t i n p u r s u i t o f v a r i o u s a c t i v i t i e s u n d e r d i f f e r e n t c o n d i t i o n s o f w i n d s p e e d , a i r 57 t e m p e r a t u r e and i n s e c t h a r a s s m e n t . T o t a l d a i l y e n e r g y e x p e n d e d ( K c a l / K g 0 7 S ) and e n e r g y u s e d i n e a c h a c t i v i t y ( K c a l / d a y and % o f t o t a l e n e r g y e x p e n d e d ) i s c o m p u t e d . The d a i l y d i s t a n c e w a l k e d and t h e l o c a t i o n w i t h r e s p e c t t o t h e c o a s t a t t h e end c f e a c h day i s r e c o r d e d . A r e c o r d i s k e p t o f t h e f r a c t i o n o f t h e d i s t a n c e t r a v e l l e d by w a l k i n g (<4.0 K m / h r ) , t r o t t i n g (4.0 - 9.6 Km/hr) and r u n n i n g (>9.6 K m / h r ) . The d a i l y a v e r a g e g r a z i n g i n t e n s i t y ( f r a c t i o n o f t i m e s p e n t e a t i n g i n a g r a z i n g p e r i o d ) i s a l s o c o m p u t e d . V a l i d a t i o n d a t a f o r o u t p u t F i e l d d a t a on d a i l y a c t i v i t y b u d g e t s a r e a v a i l a b l e f o r c a r i b o u a t P r u d h o e Bay (Thomson, 1973) f o r c o m p a r i s o n w i t h t h e d a i l y t i m e b u d g e t s g e n e r a t e d by t h e m o d e l . C o m p a r i s o n c f p r e d i c t e d c h a n g e s i n g r a z i n g i n t e n s i t i e s ( f r a c t i o n o f t i m e s p e n t e a t i n g i n a g r a z i n g p e r i o d ) w i t h i n c r e a s i n g l e v e l s o f i n s e c t h a r a s s m e n t c a n be c o m p a r e d w i t h o b s e r v a t i o n s f o r c a r i b o u a t P r u d h o e Bay ( S k o g l a n d , 1973; R u s s e l l , u n p u b l i s h e d d a t a ) . P r e l i m i n a r y e s t i m a t e s o f h e a t p r o d u c t i o n o f c a p t i v e r e i n d e e r u n d e r i n s e c t - f r e e c o n d i t i o n s and u n d e r m o d e r a t e i n s e c t h a r a s s m e n t and a t two r a t e s o f l o c o m o t i o n a r e a v a i l a b l e {White and l u i c k , 1971) f o r c o m p a r i s o n w i t h t h e model o u t p u t . DESCRIPTION AND DISCOSSICN OF MODFI 58 B i t i n g and s u c k i n g i n s e c t s a r e known t c h a r a s s r e i n d e e r and c a r i b o u c a u s i n g them t c s e e k r e l i e f e i t h e r by movement t o a r e a s o f r e l a t i v e l y l o w i n s e c t numbers ( e . g . , c o a s t a l s a n d d u n e s , i c e and snow f i e l d s , l a r g e l a k e s a nd r i v e r and g r a v e l b e d s ) o r by c r o w d i n g t o g e t h e r , t h u s p r o t e c t i n g t h e more s e n s i t i v e p a r t s o f t h e body s u c h a s t h e h e a d , l e g s and h i n d g u a r t e r s f r o m a t t a c k . Thomson (1971) h a s r e p o r t e d i n d e t a i l on movement and b e h a v i o r r e s p o n s e s o f w i l d r e i n d e e r t o i n s e c t h a r a s s m e n t on t h e H a r d a n g e r v i d d a s t u d y a r e a i n Norway. I n 1972 he e x t e n d e d t h e s e s t u d i e s t o P r u d h c e Bay ( w h i t e e t a l , 1 9 7 5 ) . The r e l a t i o n s h i p s b e t w e e n c a r i b o u and i n s e c t s e x a m i n e d by t h e model a r e b a s e d l a r g e l y on Thomson's s t u d i e s . I n s e c t h a r a s s m e n t i s c a l c u l a t e d as an i n d e x b a s e d on t h e f o l l o w i n g d e f i n i t i o n s w h i c h were m o d i f i e d f r o m Thomson ( 1 9 7 1 , 1 9 7 3 ) . 1. " m o d e r a t e h a r a s s m e n t " i f i n d i v i d u a l s o r g r o u p s were n o t e d t c p e r f o r m one o r more o f t h e f o l l o w i n g r e a c t i o n s : v i g o u r o u s w a g g i n g and f l i c k i n g o f t a i l s ; s h a k i n g o f h e a d s o r w h o l e b o d y ; t u r n i n g head g u i c k l y t o b i t e a t some p a r t o f t h e bo d y ; i n v o l u n t a r y t w i t c h i n g o r s t a m p i n g o f f r o n t o r b a c k l e g . 2. " m o d e r a t e t o s e v e r e h a r a s s m e n t " i f a n i m a l s s t a m p e d t h e i r f e e t c o n t i n u o u s l y i n t e r s p e r s e d w i t h c o n s t a n t s t o p p i n g o r r u n n i n g f o r w a r d , c o n t i n u a l t r o t t i n g , o r a t e n d e n c y t o m i l l t o g e t h e r . 3. " s e v e r e h a r a s s m e n t " i f a n i m a l s b r o k e i n t o i n t e r m i t t e n t o r c o n t i n u a l g a l l o p i n g f r o m a t r o t t i n g 59 g a i t , o r f o r m e d h e r d s w h i c h a g g r e g a t e d i n a r e a s o f h i g h e r e l e v a t i o n ( e . g . , r o a d s y s t e m s o r c o a s t a l s a n d dunes) o r l a k e s . Thomson ( 1 9 7 1 , 1973) was a b l e t o d e m o n s t r a t e t h a t t h e l e v e l o f h a r a s s m e n t was an i n d i r e c t f u n c t i o n o f «ind s p e e d and a m b i e n t t e m p e r a t u r e b o t h o f w h i c h g o v e r n i n s e c t m o b i l i t y . T h e s e d a t a were e m p l o y e d t o c o n s t r u c t a c o n t i n u o u s i n d e x o f i n s e c t h a r a s s m e n t f r o m a m b i e n t w i n d s p e e d and a i r t e m p e r a t . ( F i g u r e 12) . The i n d e x h a s been made c o n t i n u o u s t o f a c i l i t a t e i t s use i n o t h e r f u n c t i o n a l r e l a t i o n s h i p s . The t r a n s f o r m a t i o n b e t w e e n t h e c a l c u l a t e d i n d e x ( I s ) and Thomson's i n d e x o f i n s e c t h a r a s s m e n t was n o t e d p r e v i o u s l y and i s : 0<Is<0.33•= no h a r a s s m e n t , and 0.33<Is<0.66 = m o d e r a t e h a r a s s m e n t 0.66<Is<1.0 = s e v e r e h a r a s s m e n t The m o d e l a s s u m e s t h a t m o d e r a t e i n s e c t h a r a s s m e n t c a u s e s a d e c r e a s e i n g r a z i n g i n t e n s i t y and an i n c r e a s e i n w a l k i n g s p e e d w i t h i n a g r a z i n g p e r i o d . At t h e u p p e r end c f m o d e r a t e h a r a s s m e n t , c a r i b o u a r e a l l o w e d r e l i e f by s t a n d i n g on r i v e r b a n k s , r o a d s y s t e m s o r g r a v e l b e d s . U n d er s e v e r e a t t a c k a n i m a l s t r o t a n d / c r g a l l o p t o t h e c o a s t a l s a n d d u n e s . Once i n t h e s a n d d u nes t h e i n s e c t a t t a c k l e v e l i s s c a l e d down t o a l l o w r e l a t i v e r e l i e f and i n t e r m i t t e n t g r a z i n g ( F i g . 1 3 ) . C a r i b o u r e m a i n i n t h e s e a r e a s o f r e l a t i v e r e l i e f u n t i l t h e i n s e c t h a r a s s m e n t l e v e l i n t h e d u n e s d e c l i n e s b e l o w a s p e c i f i c t h r e s h o l d ( I s = 0.33) a f t e r w h i c h t h e y resume g r a z i n g i n a d i r e c t i o n away f r o m t h e Air temp. - Shade, at 20cm obove g,roi-nd Wind speed-mph range, at 100cm obove ground Harassment | Severe §x :£: :^ Moderate | None 5 10 15 Ambient temperature 65 °c Figure 12. R e l a t i o n s h i p of i n t e n s i t y of i n s e c t harassment on c a r i b o u w i t h ambient temperature and wind speed (from White e t a l , 197S) c o a s t . C u r r e n t l y t h e model e m p l o y s w e a t h e r d a t a f r o m t h e P r u d h o e Bay a i r p o r t i n t h e n o r t h w e s t p o r t i o n o f t h e s t u d y a r e a . The s i m u l a t e d r e l a t i o n s h i p shown i n F i g u r e 13 i s b a s e d on u n p u b l i s h e d m e t e o r o l o g i c a l o b s e r v a t i o n s o f P a r r i s h and H h i t e . The r a t i o n a l e f o r r e d u c i n g t h e i n s e c t h a r a s s m e n t n e a r t h e c o a s t i s b a s e d on t h e l o w e r t e m p e r a t u r e s and h i g h e r w i n d s p e e d s o b s e r v e d i n t h e c o a s t a l a r e a . D i s t a n c e w a l k e d and d i s t a n c e f r o m c o a s t Hhen a n i m a l s w a l k e i t h e r i m m e d i a t e l y b e f o r e e n t e r i n g a g r a z i n g p e r i o d o r d u r i n g a g r a z i n g p e r i o d t h e y a r e assumed t o w a l k away f r o m t h e c o a s t . S i n c e t h i s w a l k i n g a c t i v i t y i s o f t e n o f a m e a n d e r i n g n a t u r e t h e a c t u a l d i s t a n c e moved away f r o m t h e c o a s t i s c a l c u l a t e d t o t e 0,5 t i m e s t h e d i s t a n c e / w a l k e d . The movement o f c a r i b o u t o w a r d s t h e c o a s t i s more d i r e c t t h a n movement i n l a n d (Thomson, 1 9 7 3 ) . D u r i n g m o d e r a t e t o s e v e r e i n s e c t a t t a c k t h e a n i a m l s a r e assumed t o w a l k t o w a r d s t h e c o a s t ( s u b r o u t i n e 8ALK) and t h e d i s t a n c e f r o m t h e c o a s t i s d e c r e a s e d by 0.8 t i m e s t h e d i s t a n c e w a l k e d . The e s t i m a t e d 20% i n c r e a s e i n d i s t a n c e n e c e s s a r y t o a t t a i n t h e c o a s t r e s u l t s b e c a u s e t h e a n i m a l s must w a l k a r o u n d o b s t a c l e s ( e . g . , l a k e s and man-made b a r r i e r s ) . JLQJLESI c o s t s a s s o c i a t e d w i t h a c t i v i t y , p a t t e r n s 6 2 • F i g u r e 13. S i n u l a t e d r e l a t i o n s h i p between t h e computed i n d e x o f i n s e c t harassment ( I s ) and d i s t a n c e from c o a s t . F a s t i n g m e t a b o l i c r a t e S t a n d a r d f a s t i n g m e t a b o l i c r a t e ( F f l f i , K c a l / h r ) i s c a l c u l a t e d by a s s u m i n g t h a t h e a t p r o d u c t i o n i n c r e a s e s l i n e a r l y w i t h b o d y w e i g h t (Egn. 8 ) . W i t h i n t h e t h e r m c n e u t r a l r a n g e t h e e q u a t i o n p r e d i c t s t h a t a c a r i b o u c a l f w e i g h i n g 5 - 6 Kg w o u l d p r o d u c e h e a t a t a r a t e o f 17.8 - 19.5 K c a l / h r o r 5.2 K c a l / K g 0 7 5 p e r h o u r . T h e s e v a l u e s a r e i n good a g r e e m e n t w i t h t h e o b s e r v e d v a l u e s o f 4.9 K c a l / K g 0 7 S / h r f o r c a r i b o u c a l v e s h e l d i n s t i l l a i r a t 19-22 C ( H a r t e t a l , 1 9 6 1 ) . F o r a n i m a l s w e i g h i n g 32 K g , t h e p r e d i c t e d h e a t p r o d u c t i o n i s 6 1.2 K c a l . h r o r 4.6 K c a l / K g 0 7 V h r . T h i s v a l u e i s l o w e r t h a n e s t i m a t e s o f a p p r o x i m a t e l y 5.5 K c a l / K g 0 7 S p e r h o u r f o r a 9-month o l d c a r i b o u c a l f w e i g h i n g 31.7 Kg ( H a r t e t a l , 1961) . W i t h i n t h e model i t i s assumed t h a t t h e f a s t i n g m e t a b o l i c r a t e i s c o n s t a n t w i t h i n t h e t h e r m c n e u t r a l z o n e o f t h e a n i m a l . S p e c i f i c d y n a m i c e f f e c t W i t h i n t h e a c t i v i t y m o d e l t h e s p e c i f i c d y n a m i c e f f e c t a t any t i m e i s computed a s a f u n c t i o n o f t h e t i m e s i n c e t h e i n i t i a t i o n o f t h e g r a z i n g p e r i o d and e x p o s u r e o f f o r a g e t o d i g e s t i o n . O v e r t h e f i r s t f i v e h o u r s o f t h e g r a z i n g p e r i o d t h e SDE ( K c a l / K g / m i n ) i s assumed t o i n c r e a s e l i n e a r l y , b e y o n d t h i s p o i n t i t d e c l i n e s e x p o n e n t i a l l y w i t h t i m e . The b a s i c r e s p o n s e p a t t e r n i s i l l u s t r a t e d i n F i g u r e 14. The i n i t i a l l i n e a r p o r t i o n o f t h e c u r v e i s b a s e d cn m e a s u r e s o f VFA p r o d u c t i o n by W h i t e and Gau (1975) w h i c h p e a k e d a t 4.8 h o u r s (0.2 d a y s ) a f t e r t h e 64 i n i t i a t i o n o f f e e d i n g . The e x p o n e n t i a l r a t e o f d e c l i n e o f h e a t p r o d u c t i o n i s b a s e d on t h e r e l a t i o n s h i p d e s c r i b e d by M a r s t o n (1948) f o x s h e e p g i v e n a h i g h l e v e l o f f e e d i n g ( s ee B l a x t e r , 1 9 6 2 ) . T h i s r e l a t i o n s h i p i s : SDE = 0.0087 x e " ° - 0 2 8 9 t (14) where SDE = t h e s p e c i f i c d y n a m i c e f f e c t o f r u m i n a t i o n , K c a l / K g Q 7 5 / h r , and t = t h e t i m e ( h r ) . SDE i s f u r t h e r m o d i f i e d m u l t i p l i c a t i v e l y by t h e d u r a t i o n o f t h e l a s t f e e d i n g p e r i o d ( F i g . 15) . The h e a t p r o d u c t i o n v a l u e s d e s c r i b e d by M a r s t o n (1948) a r e b a s e d on a n i m a l s w i t h s u s t a i n e d i n t a k e . The r a t e m o d i f i e r i l l u s t r a t e d i n F i g u r e 15 a l l o w s h e a t p r o d u c t i o n t o d e c l i n e a s t h e l e v e l o f f o o d i n t a k e d e c l i n e s . E n e r g y c o s t s o f a c t i v i t y Movement f r o m a s t a n d i n g t c l y i n g p o s i t i o n o r f r o m l y i n g t o s t a n d i n g p o s i t i o n i s e s t i m a t e d t o be 25 c a l / K g p e r c o m p l e t e d o r r e t u r n movement ( H a l l and E r o d y , 1933; B l a x t e r , 1 9 6 2 ) . The a c c o u n t i n g s y s t e m o f t h e model a s s i g n s t h i s e n e r g y c o s t a t t h e i n i t i a t i o n o f t h e l y i n g p e r i o d . Hhen t h e a n i m a l s t a n d s , e n e r g y c o s t s a r e a s s i g n e d t o t h e s t a n d i n g , g r a z i n g o r w a l k i n g p e r i o d . E n e r g y c o s t s o f s t a n d i n g a r e d e s c r i b e d i n Egn. 9. E n e r g y c o s t s o f w a l k i n g a r e d i s c u s s e d i n c o n n e c t i o n w i t h t h e b i c e n e r g e t i c s model (see Egn. 10) as w e l l a s w i t h t h e e s t i m a t i o n o f e n e r g y e x p e n d e d d u r i n g e a t i n g . T h e s e c a l c u l a t i o n s .008 Time (t) s i n c e s t a r t i n g t o e a t (hr) 14. S i m u l a t e d t r a n s i e n t o f the s p e c i f i c dynamic e f f e c t o f food d i g e s t i o n f o l l o w i n g the o n s e t o f an e a t i n g p e r i o d i n r e i n d e e r . 66 a l s o a p p l y i n t h e p r e s e n t m o d e l , fic t i v i t_y s u b r o u t i n e s I n t h e model ACTIVE t h e d u r a t i o n s o f t h e a c t i v i t i e s ( l y i n g , s t a n d i n g , g r a z i n g and w a l k i n g ) a r e s i m u l a t e d i n s e p a r a t e s u b r o u t i n e s ( F i g . 1 1 ) . The d e c i s i o n t h a t d e t e r m i n e s w h i c h a c t i v i t y w i l l o c c u r i n t i m e p e r i o d , t , i s p r e s e n t l y e s t a b l i s h e d i n t h e s u b r o u t i n e a c t i v a t e d d u r i n g t h e t i m e p e r i o d , t-1,. S u b r o u t i n e L I E P r o v i d e d t h a t t h e i n s e c t h a r a s s m e n t i n d e x i s l e s s t h a n 0.33, t h e a n i m a l e n t e r s s u b r o u t i n e L I E a t t h e t e r m i n a t i o n o f a g r a z i n g p e r i o d . The amount o f t i m e s p e n t l y i n g i s b a s e d on t h e d u r a t i o n o f t h e p r e v i o u s e a t i n g p e r i o d ( F i g . 1 6 ) . The l y i n g p e r i o d c a n be i n t e r r u p t e d p r e m a t u r e l y by an i n c r e a s e d l e v e l o f i n s e c t h a r a s s m e n t c a u s i n g t h e a n i m a l t o e n t e r s u b r o u t i n e STAND o r s u r o u t i n e 8ALK, d e p e n d i n g on t h e s e v e r i t y o f t h e a t t a c k . D u r i n g p e r i o d s o f m o d e r a t e i n s e c t h a r a s s m e n t ( I s = 0.33 0,66) a n i m a l s may a l s o e n t e r s u b r o u t i n e L I E f r o m s u b r o u t i n e 8ALK o n c e t h e y r e a c h a l o c a t i o n c f r e l a t i v e l y l o w i n s e c t a b u n d a n c e ( e . g . , r e a d s y s t e m s o r g r a v e l p a d ) . The e n e r g y e x p e n d e d d u r i n g t h i s s u r o u t i n e i n c l u d e s FHE, SDE and t h e e n e r g y c o s t c f m o v i n g f r o m s t a n d i n g t o l y i n g . S u b r o u t i n e GRAZE The g r a z i n g p e r i o d may be i n t e r r u p t e d p r e m a t u r e l y by i n c r e a s i n g l e v e l s o f i n s e c t h a r a s s m e n t ; t h e a n i m a l t h e n i s 1 . 0 1 2 3 •• D u r a t i o n o f p r e v i o u s e a t i n g p e r i o d (hr) F i g u r e i s Simulated i n f l u e n c e o f the d u r a t i o n o f the e a t i n g p e r i o d s p e c i f i c dynamic e f f e c t o f d i g e s t i o n . 3 Tiine spent l y i n g , w a l k i n g o r s t a n d i n g 2_ b e f o r e e n t e r i n g t h e n e x t g r a z i n g p e r i o d (hr) 1 2 3 Duration of previous grazing period (hr) Figure iQ . Simulated r e l a t i o n s h i p botwrcrn duration of the inter-grazing period v..It and thu duration of eating. 68 d i r e c t e d t o s u b r o u t i n e WALK. N o r m a l l y t h e g r a z i n g p e r i o d i s t e r m i n a t e d when t h e c u m u l a t i v e e a t i n g t i m e r e a c h e s 2 h o u r s o r t h e c u m u l a t i v e g r a z i n g t i m e r e a c h e s 3 h o u r s . Upon n o r m a l c e s s a t i o n o f a g r a z i n g p e r i o d t h e a n i m a l i s d i r e c t e d t o s u b r o u t i n e L I E . W i t h i n s u b r o u t i n e GKAZE, t h e a l l o c a t i o n o f t i m e s p e n t e a t i n g and w a l k i n g i s b a s e d on e m p i r i c a l o b s e r v a t i o n s c f g r a z i n g i n t e n s i t y f o r c a r i b o u a t P r u d h o e Bay (Thomson, 1973; S k o g l a n d , 1973) and r e i n d e e r a t B a r d a n g e r v i d d a ( G a a r e , S k o g l a n d , Thomson, 1970; G a a r e and S k o g l a n d , 1 9 7 1 ) . To a c c o u n t f o r d i s r u p t i o n o f e a t i n g , t h a t i s , a d e c r e a s e i n g r a z i n g i n t e n s i t y d u r i n g m o d e r a t e i n s e c t h a r a s s m e n t , t h e f r a c t i o n o f t i m e s p e n t e a t i n g i s d e c r e a s e d d u r i n g i n s e c t a t t a c k as shown i n F i g u r e 17. E g n s . 15 and 16 compute t h e a l l o c a t i o n o f t i m e s p e n t e a t i n g and w a l k i n g i n a g r a z i n g p e r i o d . TEAT = TIME x F-^  x M]_ (15) BWALK = TIME - TEAT (16) Where TEAT r e p r e s e n t s t h e t i m e s p e n t e a t i n g , BWALK r e p r e s e n t s t h e t i m e s p e n t w a l k i n g and TIME r e p r e s e n t s t h e t i m e s p e n t g r a z i n g . F1 r e p r e s e n t s t h e f r a c t i o n o f t i m e s p e n t e a t i n g i n a g r a z i n g p e r i o d ( g r a z i n g i n t e n s i t y ) when t h e l e v e l o f i n s e c t h a r a s s m e n t i s z e r o , and M1 i s t h e m o d i f i e r o f g r a z i n g i n t e n s i t y (F1) due t o i n s e c t h a r a s s m e n t ( f r o m F i g . 1 7 ) . I n c r e a s i n g i n t e n s i t y o f i n s e c t a t t a c k n o t o n l y r e d u c e s t h e t i m e s p e n t e a t i n g , b u t i n c r e a s e s t h e s p e e d o f w a l k i n g i n b o t h g r a z i n g and w a l k i n g p e r i o d s (Thomson, 1 9 7 3 ) . The r e l a t i o n s h i p 69 i ? •H W c •p •H Cn C •rt ti u tn U4 o n 0) •ri «W •H •8 1.0 . 5 .33 «66 Index o f i n s e c t harassment u o w tn •H F i g u r e j .7- Simulated e f f e c t of i n s e c t harassment on .„ - grazing i n t e n s i t y . 18. 15 12 9 6 .33 I .66 - I 1.0 Index of insect harassment Figure i s . Effect of .harassment on walking speed. 70 between t h e l e v e l o f i n s e c t h a r a s s m e n t a nd t h e s p e e d c f w a l k i n g i s e m p i r i c a l and i s shown i n F i g u r e 18. The i n f l u e n c e o f i n s e c t h a r a s s m e n t on e n e r g y e x p e n d i t u r e i n a g r a z i n g p e r i o d i s t h e r e f o r e m e d i a t e d t h r o u g h b o t h g r a z i n g i n t e n s i t y and s p e e d and d u r a t i o n c f w a l k i n g . E n e r g y e x p e n d e d by e a t i n g d u r i n g a g r a z i n g p e r i o d , ENBG, i s computed by: ENBG = EEAT X TEAT + FME x TEAT /ATIME + SEN x HI X TEAT + SDE X 60. X WT X TEAT /ATIHE ( 1 7 ) where EEAT = e n e r g y c o s t o f e a t i n g , K c a l ( Young, 1 9 6 6 ) , TEAT = t i m e s p e n t e a t i n g ( h r ) d u r i n g a s p e c i f i c a c t i v i t y i n t e r v a l , FME = f a s t i n g m e t a b o l i c r a t e ( K c a l / h r ) , ATIME = a c t i v i t y t i m e i n t e r v a l ( h a l f - h o u r ) , SEN = e n e r g y c o s t o f s t a n d i n g (0.117 K c a l / K g / h r ) , WT = body w e i g h t o f t h e a n i m a l ( K g ) , and SDE = s p e c i f i c d y n a m i c e f f e c t o f f o o d m e t a b c l i s m d u r i n g ATIME ( K c a l / K g / h r ) . E n e r g y c o s t s o f w a l k i n g , ENG, dep e n d on t h e d i s t a n c e w a l k e d and t h e s p e e d o f w a l k i n g . 71 ENG = (0.53 + 0.0033 x WRATE2) x WT x DWALK ( 1 8 ) I n Egn. 18, HRATE2 i s t h e s p e e d c f w a l k i n g w h i l e DBAIK i s t h e d i s t a n c e w a l k e d . The t o t a l e n e r g y e x p e n d e d ( K c a l ) i n w a l k i n g d u r i n g a g r a z i n g p e r i o d , WNRG, i s t h u s c o mputed by t h e e g u a t i o n : HNRG = ENG + (SEN x RT) + FBR + (SDE X 6G. X WT) X BWALK The sum o f ENEG and WNRG r e p r e s e n t s t h e t o t a l e x p e n d i t u r e o f e n e r g y d u r i n g t h e g r a z i n g p e r i o d . S u b r o u t i n e WALK S u b r o u t i n e WALK i s i n i t i a t e d o n l y u n d e r c o n d i t i o n s o f s e v e r e i n s e c t a t t a c k . W a l k i n g d u r i n g a g r a z i n g p e r i o d i s a c c o u n t e d f o r i n s u b r o u t i n e GRAZE. Under s e v e r e i n s e c t a t t a c k a n i m a l s c o n s i s t e n t l y move t o w a r d s t h e c o a s t a t s p e e d s d e p e n d e n t upon t h e d e g r e e o f i n s e c t h a r a s s m e n t ( F i g . 1 8 ) . Movements away f r o m t h e c o a s t a r e more o f a m e a n d e r i n g n a t u r e d u r i n g g r a z i n g . I d e a l l y t h e p a t t e r n o f movement w o u l d be s i m u l a t e d by a s p a t i a l d y n a m i c s m o d e l , h o w e v e r , c o n s t r u c t i o n o f s u c h a model was n o t a t t e m p t e d . S u b r o u t i n e WALK i s t e r m i n a t e d o n c e t h e a n i m a l r e a c h e s t h e c o a s t . A t t h e c o a s t t h e l e v e l o f i n s e c t h a r a s s m e n t i s l o w e r and t h e aniaal»s a c t i v i t y i s s i m u l a t e d by s u b r o u t i n e L I E , STAND o r GRAZE. The s e c o n d way o f t e r m i n a t i n g t h e w a l k i n g r o u t i n e i s by a r e d u c t i o n o f i n s e c t h a r a s s m e n t b e l o w I s = 0.5 w h i l e t h e a n i m a l i s en r o u t e t o t h e c o a s t . A g a i n , s u b r o u t i n e L I E , STAND o r GRAZE a r e c a l l e d . The r u l e s g o v e r n i n g e n t r y i n t o l y i n g , s t a n d i n g o r g r a z i n g p e r i o d s a r e d e t e r m i n e d by t h e r e g u i r e m e n t t c e a t . The e a t i n g 72 r e q u i r e m e n t i s p r e s e n t l y a f u n c t i o n o f t h e p r e v i o u s g r a z i n g p e r i o d ( F i g . 16) m o d i f i e d by t h e d i s t a n c e and s p e e d o f w a l k i n g i n t h e i m m e d i a t e l y p r e c e e d i n g w a l k i n g p e r i o d . F i g u r e 19 i l l u s t r a t e s t h e i n f l u e n c e o f d i s t a n c e and s p e e d o f w a l k i n g upon t i m e b e t w e e n g r a z i n g p e r i o d s , fit w a l k i n g s p e e d s b e l o w 12 km/hr t h e t i m e b e tween g r a z i n g i n t e r v a l s d e c l i n e s l i n e a r l y w i t h d i s t a n c e t r a v e l l e d . A t more r a p i d r a t e s o f w a l k i n g {> 12 km/hr) i t i s assumed t h a t t h e a n i m a l t i r e s a f t e r a d i s t a n c e o f 10 km has been c o v e r e d . T h u s , a t t h e end o f t h e w a l k i n g p e r i o d t h e a n i m a l may be r e g u i r e d t o r e s t , i n a l y i n g o r s t a n d i n g p o s i t i o n , w h i l e rumen f e r m e n t a t i o n i s resu m e d and a p p e t i t e d r i v e r e n e w e d . The c o m p u t e d t i m e b e t w e e n g r a z i n g p e r i o d s i s o b t a i n e d by a p p l y i n g t h e m o d i f i e r , M2, i l l u s t r a t e d i n F i g u r e 19, t c t h e i n t e r v a l p r e d i c t e d by t h e r e l a t i o n s h i p shown i n F i g u r e 16. When t h e l e v e l o f i n s e c t h a r a s s m e n t i s l e s s t h a n 0.5 b u t g r e a t e r t h a n 0.33, t h e a n i m a l ' s a c t i v i t y i s s i m u l a t e d by s u b r o u t i n e STAND. I f t h e i n d e x o f i n s e c t h a r a s s m e n t i s 0.33, t h e a n i m a l ' s a c t i v i t y i s s i m u l a t e d by s u b r o u t i n e L I E . E n e r g y e x p e n d i t u r e d u r i n g t h e w a l k i n g p e r i o d i s c a l c u l a t e d by E g n s , 17 and 18. S u b r o u t i n e STAND E n t r y i n t o a s t a n d i n g p e r i o d may o c c u r by two means. F i r s t , STAND i s c a l l e d f r o m s u b r o u t i n e L I E , f o l l o w i n g an i n c r e a s e i n t h e l e v e l o f i n s e c t h a r a s s m e n t f r o m l e s s t h a n 0.33 t o between 0.33 and 0.5. STAND c a n be c a l l e d f r o m s u b r o u t i n e WALK i f i n s e c t h a r a s s m e n t d r o p s b e t w e e n 0.33 - 0.5 o r i f t h e a n i m a l r e a c h e s t h e c o a s t . The s t a n d i n g p e r i o d i s t e r m i n a t e d by a r e g u i r e m e n t t o f e e d 73 r * 1.0 M-2> EiocUfier °f t i m e between grazing periods . Walking velocity . > 12 km/hr Walking velocity < 12 km/hr 0 2 4 .6 8 30 12 14 16 18 20 22 24 Distance walked (km) Figure 19:. Simulated influence of walking velocity and distance on time . between grazing periods, see Fig. 17. 74 (as d e s c r i b e d f o r s u b r o u t i n e s GBAZE and WALK) o r by a d e c l i n e I n i n s e c t h a r a s s m e n t t o l e s s t h a n 0.33 a c c o m p a n i e d by a w i n d s p e e d o f l e s s t h a n 24 Km/hr. I f t h e wind s p e e d i s g r e a t e r t h a n 24 Km/hr., e v e n t h o u g h t h e i n d e x o f i n s e c t h a r a s s m e n t i s l e s s t h a n 0.33, t h e a n i m a l w i l l r e m a i n s t a n d i n g u n t i l r e g u i r e d t c g r a z e . T o t a l e n e r g y e x p e n d e d ( K c a l ) d u r i n g a s t a n d i n g p e r i o d i s com p u t e d a s : ESTA KB = (SEN x WT + FME + SEE x 60. X WT) x ASTAND (20) ,where SEN, WT, FME and SDE a r e as b e f o r e , and ASTAND i s t h e t i m e ( h r ) s p e n t s t a n d i n g . When a p p r o p r i a t e t h e e n e r g y e x p e n d e d i n c h a n g i n g f r o m a l y i n g t o a s t a n d i n g p o s i t i o n i s i n c l u d e d i n t h e t o t a l e n e r g y e x p e n d i t u r e . DISCUSSION OF MODEL OUTPUT To d e v e l o p o u t p u t f o r c o m p a r i s o n w i t h f i e l d d a t a a s i m u l a t i o n r u n was made e m p l o y i n g P r u d h o e Bay t e m p e r a t u r e s and w i n d s p e e d s f o r J u l y and A u g u s t , 1971. By u s i n g m e a s u r e d a b i o t i c d a t a t o g e n e r a t e a c t i v i t y b u d g e t s and a v e r a g e d a i l y m e t a b o l i s m , i t was c o n s i d e r e d t h a t any l i m i t a t i o n i n t h e g e n e r a l model s t r u c t u r e w o u l d become a p p a r e n t d u r i n g c o m p a r i s o n w i t h a p p r o p r i a t e f i e l d d a t a . F o r i n s e c t f r e e p e r i o d s t h e t i m e b u d g e t s i m u l a t e d by t h e 75 m o d e l i s shown i n T a b l e V I I . The p r e s e n t model p r e d i c t i o n o f a c t i v i t y b u d g e t a p p e a r s t o a g r e e w i t h f i e l d o b s e r v a t i o n s f o r i n s e c t f r e e d a y s . The s i m u l a t e d g r a z i n g i n t e n s i t y ( t i m e s p e n t e a t i n g / t i m e s p e n t g r a z i n g ) i s a b o u t 8 5 % w h i c h i s h i g h e r t h a n e s t i m a t e s o f 67 -19% ( S k o g l a n d , 1 9 7 3 ) . H o w e v e r , t h e s i m u l a t e d v a l u e i s a t h e o r e t i c a l p o t e n t i a l and t h e v a l u e i s d e c r e a s e d i n t h e m o d e l d u r i n g t h e g r a z i n g p e r i o d by t h e amount o f t i m e s p e n t s e a r c h i n g f o r f o o d ( s e e GRAZE) and by i n s e c t h a r a s s m e n t . The s i m u l a t e d t i m e s p e n t s t a n d i n g i s z e r o m i n u t e s o u t o f a 24 h r . p e r i o d . Thomson's d a t a s u g g e s t t h a t a n i m a l s do s p e n d o n l y a v e r y s m a l l p o r t i o n o f t h e i r t i m e s t a n d i n g (0 - 2%). The s m a l l c o n t r i b u t i o n t h i s a c t i v i t y w o u l d make t o t h e t o t a l e n e r g y b u d g e t i s i n c l u d e d i n t h e g r a z i n g a c t i v i t y . The e s t i m a t e o f t h e a v e r a g e d a i l y m e t a b o l i c r a t e i s shown i n T a b l e V I I I . A v e r a g e m e t a b o l i s m was c a l c u l a t e d a s 156 K c a l / K g 0 7 5 w h i c h was 1.72 t i m e s f a s t i n g m e t a b o l i s m . T h i s i s l o w e r t h a n f i e l d e s t i m a t e s f o r f r e e - g r a z i n g s h e e p f o r w h i c h a v e r a g e d a i l y m e t a b o l i s m f o r m a i n t e n a n c e was 106 - 148 K c a l / K g 0 7 5 / o r 1.86 - 2.56 t i m e s f a s t i n g m e t a b o l i s m (Young and C o r b e t t , 1972) . The s i m u l a t e d e s t i m a t e o f a v e r a g e d a i l y m e t a b o l i c r a t e (156 K c a l / K g 0 7 S / d a y ) i s 1.5 t i m e s r e s t i n g h e a t p r o d u c t i c n c f r e i n d e e r (1.7 K c a l / K g / h r o r 128 K c a l / K g 0 7 5 / d a y ) (Hammel e t a l , 1 9 6 2 ) . I n c o m p a r i s o n , f i e l d e s t i m a t e s o f a v e r a g e d a i l y m e t a b o l i s m o f f r e e - g r a z i n g s h e e p a r e a p p r o x i m a t e l y 1.7 t i m e s g r e a t e r t h a n h o u s e d c o u n t e r p a r t s o f s i m i l a r body w e i g h t (Young and C o r b e t t , 1 9 7 2 ) . The e s t i m a t e f r o m t h e s i m u l a t e d o u t p u t i s s l i g h t l y l o w e r t h a n t h e s e e s t i m a t e s and may be a r e f l e c t i o n o f t h e u n d e r e s t i m a t e o f t h e t i m e s p e n t w a l k i n g ( T a b l e 76 Table VII. Comparison of simulated a c t i v i t y budgets (% of 24 hr period) f o r i n s e c t free days with f i e l d observations. Source of data Eating Caribou A c t i v i t i e s Lying Standing Walking* White et a l (1975) 53 33 13 Computer Simulation 52 (49-54) 36 (34-41) 12 (9-15) * includes walking, t r o t t i n g and running, (?) range of simulated values during the month 7 7 Table VIII. Simulated estimates of energy expenditure f o r adult non-lactating caribou weighing 100kg. Degree of Insect Harassment Average Dailv^ Metabolism (kcal/kg °-7-) ( x FMR) S p e c i f i c Dynamic E f f e c t (kcal/kg ' 7 5 ) (%) in s e c t free I s=0 0.33 V Is <0.66 4 hr. 156 (143-198) 176 (135-199) 1.72 1.94 33.3 3 3 . 5 21 19 7 hr. 281 (184-357) 3.09 3 1 . 6 11 0.50 <I S < 1.0 f o r 3 hr. plus 455 I s>,0.66 f o r 10 hr. (379-563) 5.0 30.9 Table IX. Simulated estimates of energy expenditure f o r adult non-lactating caribou weighing 100 kg. with modified walking speeds. Degree of Insect Harassment Average Da i l y Metabolism (kcal/kg " (x FMR) S p e c i f i c Dynamic E f f e c t ( k c a l A g - 7 5) (%) ins e c t free I s = 0 0.33 < < 0.66 4 hr.' 7 hr. 0. 50 "<• I s^< 1.0 for 3 hr. plus I s »> 0.66 f o r 10 hr. 145 (134-165) 160 (153-185) 233 (170-282) 283 (243-366) 1.59 1.76 2.57 3.11 33.3 33.5 31.7 30.7 23 21 14 11 78 V I I ) . S i m u l a t i o n e s t i m a t e s o f d a i l y h e a t p r o d u c t i o n u n d e r m o d e r a t e i n s e c t h a r a s s m e n t (176-281 Kcal/Kg° 7 S / d a y ) a g r e e w i t h f i e l d e s t i m a t e s o f 293 measured i n r e i n d e e r g r a z i n g u n d e r m o d e r a t e h a r a s s m e n t ( w h i t e and L u i c k , 1 9 7 1 ) . The e f f i c i e n c y o f u t i l i z a t i o n o f m e t a b o l i z a b l e e n e r g y f o r m a i n t e n a n c e i s a p p r o x i m a t e l y 83% ( B l a x t e r , 1 9 6 2 ) . T h u s , t h e s p e c i f i c d y n a m i c e f f e c t s h o u l d be 100 - 83 o r 17% o f m e t a b o l i z a b l e e n e r g y . W i t h i n t h e s i m u l a t e d p r o j e c t i o n s a v e r a g e d a i l y h e a t p r o d u c t i o n s h o u l d a p p r o x i m a t e m e t a b o l i z a b l e e n e r g y i n t a k e , p r o v i d e d t h e a n i m a l s a r e c o n s i d e r e d t o be a t m a i n t e n a n c e . D u r i n g i n s e c t f r e e p e r i o d s t h e s p e c i f i c d y n a m i c e f f e c t was e s t i m a t e d a t 2 1 * o f a v e r a g e d a i l y m e t a b o l i s m ( T a b l e V I I I ) , w h i c h i s c l o s e t o t h e p o s t u l a t e d v a l u e . The e f f e c t s o f i n s e c t h a r a s s m e n t on d a i l y a c t i v i t y p a t t e r n s a r e shown i n F i g u r e 20. The t r e n d s o r p a t t e r n s o f t i m e s p e n t e a t i n g , l y i n g and s t a n d i n g a r e i n good a g r e e m e n t w i t h t h e f i e l d d a t a o f Thomson ( 1 9 7 3 ) . T a b l e V I I I r e v e a l s t h a t i n s e c t h a r a s s m e n t i n c r e a s e d a v e r a g e d a i l y m e t a b o l i s m t o 281 K c a l / K g 0 7 S f o r p r o l o n g e d m o d e r a t e a t t a c k and t o as h i g h as 455 f o r 1 - 3 h o u r s o f s e v e r e a t t a c k c o u p l e d w i t h m o d e r a t e h a r a s s m e n t l a s t i n g a b o u t 10 h o u r s . G r a z i n g i n t e n s i t y d e c l i n e d f r o m a t h e o r e t i c a l maximum o f 85% d u r i n g an i n s e c t - f r e e p e r i o d t o 66 - 75?? u n d e r p r o l o n g e d m o d e r a t e i n s e c t h a r a s s m e n t w h i c h i s g r e a t e r t h a n u n p u b l i s h e d e s t i m a t e s (57%) o f Thomson. One o f t h e most i m p o r t a n t f u n c t i o n s i n t h e model ( F i g . 17) r e l a t e s s p e e d o f movement t o l e v e l s o f i n s e c t h a r a s s m e n t . T h i s f i g u r e was d e r i v e d f r o m a m o d i f i c a t i o n o f Thomson's u n p u b l i s h e d Prudhoe Bay Simulation MILD SEVERE NONE MILD SEVERE Comparison of simulated projections with f i e l d results to i l l u s t r a t e the effects of insect harassment on daily a c t i v i t y patterns. Data for Prudhoe bay taken fron Thomson (1973). 80 d a t a . The o r i g i n a l d a t a a v e r a g e d w a l k i n g s p e e d o v e r t h e a c t i v e p e r i o d u n d e r v a r i o u s h a r a s s m e n t l e v e l s . I n s t a n t a n e o u s r a t e s were n o t a v a i l a b l e and were t h e r e f o r e d e r i v e d f r o m t h e a v e r a g e v a l u e s . T a b l e I X , w h i c h o u t l i n e s t h e r e s u l t s o f a r u n u s i n g t h e s e a v e r a g e v a l u e s , i l l u s t r a t e s t h e s e n s i t i v i t y o f t h i s r e l a t i o n s h i p . I n J u l y and a u g u s t , 1971 c a r i b o u a t P r u d h o e Bay e x p e r i e n c e d 1096.5 i n s e c t f r e e h o u r s , 312.0 h o u r s o f m o d e r a t e h a r a s s m e n t and 31,5 h o u r s c f s e v e r e h a r a s s m e n t . I f we assume t h a t any added e n e r g y c o s t p e r d a y , a b o v e t h e v a l u e f o r an i n s e c t f r e e d a y , i s due t o i n s e c t h a r a s s m e n t t h e t o t a l e n e r g y c o s t o f i n s e c t h a r a s s m e n t i n 1971 was 3106 K c a l / K g 0 7 5 i n J u l y and A u g u s t o r 51.8 K c a l / K g 0 7 s / d a y . An i m p o r t a n t c o n s i d e r a t i o n i n t h e o r i g i n a l • c o n s t r u c t i o n o f t h e model was t h a t i t w o u l d e v e n t u a l l y be g e n e r a l i z e d and r e l a t i o n s h i p s e x t r a c t e d and i n c o r p o r a t e d i n t o a f r a m e w o r k o f l o w e r r e s o l u t i o n ' t o e x a m i n e w e i g h t c h a n g e s o v e r a number o f y e a r s . A t t h e p r e s e n t r e s o l u t i o n ( h a l f - h o u r t i m e - s t e p ) s i m u l a t i o n c o s t s w o u l d be t o o h i g h f o r p r o j e c t i o n s o f o v e r a y e a r . F o r t h i s r e a s o n , r e g r e s s i o n a n a l y s e s were p e r f o r m e d r e l a t i n g l e v e l o f i n s e c t h a r a s s m e n t ( d e t e r m i n e d f r o m w i n d and t e m p e r a t u r e d a t a ) and t o t a l d a i l y m e t a b o l i c e n e r g y . T a b l e X o u t l i n e s t h e r e s u l t s o f m u l t i p l e r e g r e s s i o n u s i n g t h e number o f h o u r s p e r day i n t h e t h r e e i n s e c t h a r a s s m e n t c a t e g o r i e s a s i n d e p e n d e n t v a r i a b l e s . T h e r e a p p e a r t o be s i g n i f i c a n t r e l a t i o n s h i p s u s i n g most o f t h e c o m b i n a t i o n s o f i n s e c t h a r a s s m e n t ( n o n e , m o d e r a t e and s e v e r e ) . A t y p i c a l e g u a t i o n a c c o u n t i n g f o r 96% o f t h e v a r i a t i o n i n TUB ( t o t a l m e t a b o l i c Table X. Regression summary for simulated energy production using parameters i n Figure 2.2; Independent S.E. Multiple correlation " R Variables of estimate coefficient squared (hrs. per day) None 44.8 .87 .75 Mild 58.5 .76 .59 Severe 51.3 .83 .68 None, Mild 18.2 .98 • .96 None, Severe 18.2 .98 .96 Mild, Severe 18.2 .98 -.96 rate, Kcal/kg/day) i s : TMB = 1107 - 39.9 x NONE - 32.2 x MODERATE (21) Egn. 21 can be incorporated within a lower resolution model to predict energy expenditure of adult males and non-lactating females during the summer months. SUJMABY Simulation models are used to examine the energetics of barren-ground caribou in winter and summer. The conceptual framework of each model incorporates data on Rangifer from North America, Scandinavia and the Soviet Union. Where necessary, data on other ruminants are u t i l i z e d . The models integrate these data, examine the generality of the data from various countries and determine the s e n s i t i v i t y of weight loss and t o t a l metabolic rate to some of the model components. Simulated projections of model BIOEN determined the c r i t i c a l environment for a 100 Kg caribou on two n u t r i t i o n a l planes. Snow depths are related to t o t a l heat production and metabolizable energy intake, weight changes of a 100 Kg animal are examined for selected years on tundra and boreal winter ranges. I t i s documented that with data used i n the simulation, boreal ranges are more favourable in terms of energy balance than tundra ranges during winter. Results suggest that wintering animals must compromise the high heat loss experienced in the tundra with greater energy expenditure associated with deeper snow in the boreal region. It i s conceivable that i n a mild winter tundra pastures could be more favourable i n terms of energy balance and resultant weight changes than boreal ranges. Moreover, s e n s i t i v i t y analyses indicate that small errors in the measurement of d i g e s t i b l i t y , gross energy content of forage, food intake rate or grazing i n t e n s i t y have a s i g n i f i c a n t effect on weight projections during the winter. In i t s present form, model BIOEN has l i m i t a t i o n s . More research must be conducted on food intake in winter to estimate d i g e s t i b l e e n e r g y i n t a k e on a m e t a b o l i c body w e i g h t b a s i s . The i m p a c t o f fiangifer on t h e l i c h e n r e s o u r c e s s h o u l d a l s o be c o n s i d e r e d as more d a t a become a v i a l a b l e . M o d e l ACTIVE e x a m i n e s t h e r o l e o f i n s e c t s i n t h e summer e n e r g e t i c s o f b a r r e n - g r c u n d c a r i b o u . Much o f t h e d a t a u t i l i z e d i n t h e m o d el were c o l l e c t e d a t P r u d h c e B a y , A l a s k a . The a c t i v i t y b u d g e t and a s s o c i a t e d e n e r g y e x p e n d i t u r e o f c a r i b o u u n d e r n o , m i l d and s e v e r e i n s e c t h a r a s s m e n t a r e d e t e r m i n e d . E n e r g y e x p e n d i t u r e s o f a 100 Kg male o r n o n - l a c t a t i n g f e m a l e a r e p r o j e c t e d f o r J u l y and A u g u s t w i t h a b i o t i c d a t a f r o m P r u d h o e Eay i n 1971. R e s u l t s i n d i c a t e d t h a t i n s e c t s c a u s e d a s i g n i f i c a n t i n c r e a s e i n h e a t p r o d u c t i o n { a v e r a g e 51.8 K c a l / K g 0 7 s / d a y ) . M u l t i p l e r e g r e s s i o n a n a l y s e s e x a m i n i n g t h e o u t p u t y i e l d a p r e d i c t i v e e g u a t i o n r e l a t i n g t o t a l h e a t p r o d u c t i o n ( K c a l / K g 0 7 S / d a y ) t o t h e number o f h o u r s p e r d a y o f m i l d and no i n s e c t h a r a s s m e n t f o r an a d u l t male c r n o n - l a c t i n g f e m a l e . P r e s e n t l y , model ACTIVE e x a m i n e s e n e r g y e x p e n d i t u r e o f c a r i b o u i n summer. An e s t i m a t e o f d i g e s t i b l e e n e r g y i n t a k e i s n e c e s s a r y t o p r o j e c t w e i g h t c h a n g e s d u r i n g t h e i n s e c t s e a s o n . To e x a m i n e t h e r o l e o f i n s e c t s on w e i g h t c h a n g e , d i g e s t i b l e e n e r g y i n t a k e must be c o n s i d e r e d a t t h e same r e s o l u t i o n a s e n e r g y e x p e n d i t u r e . B o r e r e s e a r c h i s n e e d e d on t h e e f f e c t o f h a r a s s m e n t on d i g e s t i o n , a p p e t i t e d r i v e and f o o d i n t a k e r a t e . A f u r t h e r l i m i t a t i o n o f ACTIVE i s t h a t t h e model e x a m i n e s o n l y a d u l t b u l l s and n o n - l a c t a t i n g f e m a l e s . A c t i v i t y p a t t e r n s u n i g u e t o f e m a l e s w i t h c a l v e s and t o t h e c a l v e s t h e m s e l v e s , have n e t been d o c u m e n t e d . I n summary, t h e a g r e e m e n t o f t h e m o d e l s t o a v a i l a b l e 85 e v a l u a t i o n data s u g g e s t s the complex h y p o t h e s i s r e p r e s e n t e d by the two models are n o t g r o s s l y i n c o r r e c t . The major o b j e c t i v e s o f the t h e s i s , t h a t o f e x a m i n i n g , i n t e g r a t i n g and t e s t i n g t h e a v a i l a b l e d a t a on R a n g i f e r e n e r g e t i c s , has been l a r g e l y a t t a i n e d . The models can be employed t o h e l p guide f u r t h e r r e s e a r c h and e v a l u a t e r e s e a r c h p r i o r i t i e s i n the f i e l d of R a n g i f e r p r o d u c t i v i t y . BIJIIGGfiJlHY B a n f i e l d , A. W. F. 1954. P r e l i m i n a r y i n v e s t i g a t i o n o f t h e b a r r e n - g r o u n d c a r i b o u . C.W.S. B i l d l . a g i s t . B u l l . S e r . 1, Nos. 10A S 10E. B a s k i n , 1. M. 1970. R e i n d e e r e c o l o g y and b e h a v i o r . T r a n s l . Dept. I n d i a n A f f a i r s € N o r t h e r n D e v e l o p . No. 0538. B l a x t e r , K. I . 1962. E n e r g y m e t a b o l i s m o f r u m i n a n t s . H u t c h i n s o n , L o n d o n , 332 p. B l a x t e r , K. L., N. McC. Graham, F. Wainman S D. G. A r m s t r o n g . 1959. The p a r t i t i o n o f h e a t l o s s e s i n c l o s e l y c l i p p e d s h e e p . J . A g r i c . S c i . 52:25-40. B l a x t e r , K. I . , N. McC. Graham S F. W. Wainman. 1963a. E n v i r o n m e n t a l t e m p e r a t u r e , e n e r g y m e t a b o l i s m and h e a t r e g u l a t i o n i n s h e e p . I I . The p a r t i t i o n o f h e a t l o s s e s i n c l o s e l y c l i p p e d s h e e p . J . A g r i . S c i . 5 2 ( 1 ) : 2 5 - 4 0 . B l a x t e r , K. L., N. KcC. Graham S F. B. Wainman. 1963b. E n v i r o n m e n t a l t e m p e r a t u r e , e n e r g y m e t a b o l i s m and h e a t r e g u l a t i o n i n s h e e p . I I I . The m e t a b o l i s m and t h e r m a l e x c h a n g e s o f s h e e p w i t h f l e e c e s . J , A g r i c . S c i . 5 2 ( 1 ) :4 1-49. B l a x t e r , K. L. S F. W. Rainman. 1960. E n v i r o n m e n t a l t e m p e r a t u r e and e n e r g y m e t a b o l i s m and h e a t e m i s s i o n o f s t e e r s . J. A g r i c . S c i . 5 6 : 8 1 - 9 0 . B l a x t e r , K. L. S F. 8. Wainman. 1964. The e f f e c t o f i n c r e a s e d a i r movement cn t h e h e a t p r o d u c t i o n and e m i s s i o n o f s t e e r s . J . A g r i c . S c i . 6 2 : 2 0 7 - 2 1 4 . B l a x t e r , K. L. € F. 8. Wainman. 1966. The f a s t i n g m e t a b o l i s m o f c a t t l e . B r i t . J . N u t r . 20: 103. B l a x t e r , K. L., R. S. w i l s c n 8 F. •«. Wainman. 1 9 6 1 . The r e g u l a t i o n c f f o o d i n t a k e by s h e e p . A n i m a l P r o d . 3:51-61. B u n n e l l , F. L. 1974. Com p u t e r s i m u l a t i o n o f f o r e s t w i l d l i f e r e l a t i o n s , pp 3 9 - 5 0 . I n B l a c k , H . C . ( E d . ) . W i l d l i f e a n d f o r e s t management i n t h e P a c i f i c N o r t h w e s t . C h i l d , K. N. 1973. The r e a c t i o n s o f b a r r e n - g r o u n d c a r i b o u J R a n c | i f e r t a r a n d u s g r a n t i ) . t o s i m u l a t e d p i p e l i n e a n d p i p e l i n e c r o s s i n g s t r u c t u r e s a t P r u d h o e B a y , A l a s k a . A c o m p l e t i o n r e p o r t o f t h e A l a s k a C o - o p e r a t i v e W i l d l i f e R e s e a r c h U n i t . U n i v e r s i t y o f A l a s k a , F a i r b a n k s . J u n e 3 0, 51 pp. C l a r k e , C. H. D. 1940. A b i o l o g i c a l i n v e s t i g a t i o n o f t h e T h e l o n Game S a n c t u a r y . N a t . Mus. Canada E u l l . 96: 135. D a u p h i n e , T. C. J r . 1970. The b i o l o g y o f t h e K a m i n u r i a k p o p u l a t i o n o f b a r r e n - g r o u n d c a r i b o u . P a r t 3. R e p r o d u c t i o n , g r o w t h and n u t r i t i o n . U n p u b l . B e p t . C.W.S. D a v y d o v , A. F. 1965. The movement o f t h e r e i n d e e r d e p e n d i n g on t h e p a s t u r i n g c o n d i t i o n s . T r a n s l . TB-BUS-30, f i l e s C.W.S., Edmonton, No. 7 7 3 7 , 26 p. de W i t t , C. T. S J . G o u d r i a a n . 1974. S i m u l a t i o n o f e c o l o g i c a l p r o c e s s e s . W a geningen C e n t r e f o r A g r i c u l t u r a l P u b l i s h i n g 6 D o c u m e n t a t i o n , 158 p. F o r m a z o v , A. N. 1946. Snow c o v e r a s an i n t e g r a l f a c t o r o f t h e e n v i r o n m e n t and i t s i m p o r t a n c e i n t h e e c o l o g y o f mammals and b i r d s . T r a n s l . TB-RUS-8, f i l e s C.W.S., Edmonton, 152 p. G a a r e , E. S T. S k o g l a n d . 1971. P r o g r e s s r e p o r t . R e p o r t f r o m t h e g r a z i n g p r o j e c t o f t h e N o r w e g i a n I E P c o m m i t t e e . G a a r e , E., T, S k o g l a n d £ E. fi. Thomson. 1970. W i l d r e i n d e e r f o o d h a b i t s and b e h a v i o u r . B e p o r t f r o m t h e g r a z i n g p r o j e c t o f t h e N o r w e g i a n I B P c o m m i t t e e 97p. G o n z a l e z - J i m i n e z , E. 6 K. I . B l a x t e r . 1962. The m e t a b o l i s m and t h e r m a l r e g u l a t i o n o f c a l v e s i n t h e f i r s t month o f l i f e . B r i t . J . N u t r . 16. p199. Graham, 8. M c C , F. W. wainman, K. I . B l a x t e r & B. G. A r m s t r o n g . 1963. E n v i r o n m e n t a l t e m p e r a t u r e , e n e r g y m e t a b o l i s m and h e a t r e g u l a t i o n i n s h e e p . I . E n e r g y m e t a b o l i s m i n c l o s e l y c l i p p e d s h e e p . J . A g r i c . S c i . 52 ( 1 ) ; 1 - 2 4 . H a l l , W. C. 8 S. B r o d y . 1933. The e n e r g y movement o f s t a n d i n g o v e r l y i n g and t h e e n e r g y c o s t o f g e t t i n g up and l y i n g down. O n i v . Mo. A g r i c . Exp. S t a . B e s . B u l l . No. 180. Hammel, H. T. 1955. T h e r m a l p r o p e r t i e s o f f u r . Amer. J . P h y s i o l . 182,369. Hammel, T. H., T. B. H o u p t , K. I . A n d e r s e n S S. S k j e n n e b e r g . 1962. T h e r m a l and m e t a b o l i c measurements on a r e i n d e e r a t r e s t and e x e r c i s e . A r c t i c A e r o m e d i c a l l a b . . T e c h n i c a l D o c u m e n t a r y S e p t . AAI-TDB-61-54, 34 p. H a r t , J . S., 0. H e r o u x , «. H. C o t t l e S C. A. M i l l s . 1 9 6 1 . The i n f l u e n c e o f c l i m a t e on m e t a b o l i c and t h e r m a l r e s p o n s e s o f i n f a n t c a r i b o u . Can. J . Z o o l . 3 9 : 8 4 5 - 8 5 6 . J a c o b i , A. 1931. The r e i n d e e r - a z o o l o g i c a l monograph on t h e g e n us I a n e | i f e r . T r a n s l . o f p a s s a g e s f r o m "Das B e n t i e r . " T r a n s l . TE-GEB-13, f i l e s C.w.S. J a c o b s e n , E. 6 S. S k j e n n e b e r g . 1975. Seme r e s u l t s f r o m f e e d i n g e x p e r i m e n t s w i t h r e i n d e e r . I n : P r o c . F i r s t I n t n t l . B e i n d e e r 8 C a r i b o u Symp., A u g u s t 9-11, 1972, F a i r b a n k s , A l a s k a , pp 95-107. J e f f e r s . J . N. fi. (Ed.) 1971. M a t h e m a t i c a l m o d e l s i n e c o l o g y , 1 2 t h Symp. E r . E c o l . S e c , , B l a c k b a l l S c i e n t i f i c P u b l i c a t i o n s . J o y c e , J . P. & K. L. B l a x t e r . 1964. The e f f e c t o f a i r movement, a i r t e m p e r a t u r e and i n f r a r e d r a d i a t i o n on t h e e n e r g y r e q u i r e m e n t s o f s h e e p . B r i t . J . N u t r . 18 ( 1 ) : 5 - 1 7 . K e l s a l l , J , P. 1963. E a r r e n - g r o u n d c a r i b o u and t h e i r management. Can. Audubon Mag., Nov. - D e c , 1963 pp 2-8. K e l s a l l , J . P. 1968. The m i g r a t o r y b a r r e n - g r o u n d c a r i b o u i n C a n a d a , Queen's P r i n t e r S C o n t r o l l e r o f S t a t i o n e r y , O t t a w a , C a n a d a . 340 pp, K l e i b e r , ft. 1961. The f i r e o f l i f e , w i l e y , N.Y., 453 p. K l e i n , D. B. 1970. N u t r i t i v e g u a l i t y o f A l a s k a n r a n g e f o r a g e and a s s o c i a t e d g r o w t h and w e l f a r e o f r e i n d e e r and c a r i b o u . C o m p l e t i o n S e p t . t c E u r . Land Mgmt., U.S. D e p t . I n t e r i o r , 30 p. M a k a r o v a , A. B. £ A. N. S e g a l . 1958. P h y s i o l o g i c a l c h a r a c t e r i s t i c s o f t h e w i n t e r g r a z i n g o f t h e r e i n d e e r . T r a n s l . TB-BOS-30, f i l e s C.«.S. M a r s t o n , H. E. 1948. The i n f l u e n c e o f f o d d e r i n t a k e on w o o l p r o d u c t i o n . A u s t . J . S c i . B e s , (B) 1,362. McEwan, E. 1970. E n e r g y m e t a b o l i s m o f b a r r e n g r o u n d c a r i b o u iMsaiigl t a r a n d u s i . Can. J . Z c o l . 4 8 : 3 9 1 - 3 9 2 . McEwan, E. 6 P. E. W h i t e h e a d . 1970. S e a s o n a l c h a n g e s i n t h e e n e r g y and n i t r o g e n i n t a k e i n r e i n d e e r and c a r i b o u . Can. J . Z o o l . 4 8 : 9 0 5 - 9 1 3 . M i l l e r , D. 1970. E i o l c g y o f t h e K a m i n u r i a k p o p u l a t i o n o f b a r r e n -g r o u n d c a r i b o u . P a r t 4. U n p u b l . B e p o r t . , C.W.S. M i l l e r , P. C , E. D. C o l l i e r S F, L, B u n n e l l . I n p r e s s . D e v e l o p m e n t o f e c o s y s t e m m o d e l i n g i n t h e U.S. I B P T u n d r a B i o m e . Moen, A. N. 1968. E n e r g y e x c h a n g e o f w h i t e - t a i l e d d e e r . W e s t e r n M i n n e s o t a E c c l . 4 9 ( 4 ) . Moen, A. N. 1973. W i l d l i f e e c o l o g y - an a n a l y t i c a l a p p r o a c h . ». H. Freeman S Co., San F r a n c i s c o , 458 p. Mo o t e , I . 1955. I n s u l a t i o n o f h a i r . T e x t i l e B e s . J . 2 5 : 8 3 2 - 8 3 7 . N a s i m o v i c h , A. A. 1955. The r o l e o f snow c o v e r c o n d i t i o n s i n t h e l i f e o f u n g u l a t e s i n t h e USSB. T r a n s l . TB-BUS-115, f i l e s 0 • W • S • P a l m e r , I . 1934. B a i s i n g r e i n d e e r i n A l a s k a . U.S. D e p t . A g r i c . M i s c . P u b l . 207. P a r k e r , G. B. 1971, T r e n d s i n t h e p o p u l a t i o n o f b a r r e n - g r o u n d c a r i b o u o f m a i n l a n d Canada o v e r t h e l a s t two d e c a d e s : a r e -e v a l u a t i o n o f t h e e v i d e n c e , O c c a s , P a p e r #10, Can. W i l d . S e r v . , I n f o r . C a n . C a t , # r 6 7 - 1 / 1 0 , 9p, P a t t e n , E. C. ( E d , ) , 1S71. S y s t e m s a n a l y s i s and s i m u l a t i o n i n e c o l o g y . A c a d e m i c P r e s s , N.Y. P r u i t t , W, 0. J r . 1959. Show a s a f a c t o r i n t h e w i n t e r e c o l o g y o f t h e b a r r e n - g r o u n d c a r i b o u J B a n g i f e r a r c t i c u s l . A r c t i c 12 ( 3 ) : 1 5 9 - 1 7 9 , Eowe, J * S. 1959, F o r e s t r e g i o n s o f C a n a d a , C a n a d a D e p t . N o r t h e r n A f f a i r s and N a t i o n a l B e s o u r c e s . B u l l . 1 2 3 . S a b l i n a , T. B. 1962, The f e e d i n g h a b i t s and e c o l o g i c o -m o r p h c l o g i c c h a r a c t e r i s t i c s o f t h e d i g e s t i v e s y s t e m o f t h e r e i n d e e r o f K a r e l i a , A c a d , S c i . , USSB, Moscow. C.W.S. T r a n s l . 1.20-p. S c h o l a n d e r , P. P., B. flock, 7. W a l t e r s & L. I r v i n g . 1950. A d a p t a t i o n t o c o l d a r c t i c and t r o p i c a l mammals and b i r d s i n r e l a t i o n t o body t e m p e r a t u r e , i n s u l a t i o n and b a s a l m e t a b o l i c r a t e . B i o l . B u l l . 9 9 : 2 5 9 . S c o t t e r , G. W. 1964. C h e m i c a l c o m p o s i t i o n o f f o r a g e l i c h e n s f r o m n o r t h e r n S a s k a t c h e w a n a s r e l a t e d t o use by b a r r e n - g r o u n d c a r i b o u . Can. J . P l a n t S c i . 4 5 : 2 4 6 - 2 5 0 . S e g a l , A. N. 1962. The p e r i o d i c i t y o f p a s t u r e and p h y s i o l o g i c a l f u n c t i o n s c f r e i n d e e r . p. 130-150, I n : B e i n d e e r i n t h e K a r e l i a n , USSB a k a d . Nauk, P e t r o z a v o d s k . T r a n s l . D e p t . S e c r e t a r y o f S t a t e , E u r . f o r T r a n s l . , C a nada. S i l v e r , H . , N. F. C c l v o s , J . B. H c l t e r & H. H. H a y e s . 1969. F a s t i n g m e t a b o l i s m o f i s h i t e - t a i l e d d e e r . J . W i l d l . Mgmt. 3 3 : 4 9 0 - 4 9 8 . S k o g l a n d , T. 1973. F o r a g e s e l e c t i o n and i n t a k e o f c a r i b o u and r e i n d e e r a t P r u d h o e B a y . , I n : A s p e c t s o f f e e d i n t a k e and h e a t p r o d u c t i o n c f B a n c j i f e r i n t h e a r c t i c t u n d r a (by B. G. W h i t e 6 3. B. L u i c k ) . P r o g r e s s B e p o r t U.S. T u n d r a Eiome P r o g r a m . S k o g l a n d , T. 1974. B e p o r t f r o m t h e g r a z i n g p r o j e c t o f t h e N o r w e g i a n IBP c o m m i t t e e . T r o n d h e i m , 1974. 133 pp. S t e e n , E. 1968. Some a s p e c t s o f t h e n u t r i t i o n o f s e m i - d o m e s t i c r e i n d e e r . Symp. Z c c l . S o c . L ondon 21:117-128. S t e v e n s , D. S. 1972. T h e r m a l e n e r g y e x c h a n g e and t h e m a i n t e n a n c e o f hcmeothermy i n w h i t e - t a i l e d d e e r . Ph.D. D i s s e r t a t i o n , C o r n e l l U n i v . , 231 p. S t i b i t z , G. B. 1966. M a t h e m a t i c s i n m e d i c i n e and t h e l i f e s c i e n c e s . Y e a r Book Med. P u b l . I n c . C h i c a g o , 391 p., Thomson, B. R. 1971. W i l d r e i n d e e r a c t i v i t y , fiept. f o r G r a z i n g p r o j . N o r w e g i a n I E F Comm., T r o n d h e i m . 76 pp. Thomson, B. B. 1973. E e h a v i c u r and a c t i v i t y o f c a r i b o u a t P r u d h o e Bay. I n : A s p e c t s o f f e e d i n t a k e and h e a t p r o d u c t i o n o f - J a n g i f e r i n t h e a r c t i c t u n d r a (by R. G. W h i t e S J . B. L u i c k ) . P r o g r e s s S e p t . U.S. T u n d r a Biome P r o g r a m . H a l t e r s , C. J . S F. X. E u n n e l l . 1971. A c o m p u t e r management game o f l a n d u s e i n B r i t i s h C o l u m b i a . J . W i l d l . Mgmt. 3 5 ( 4 ) :644-6 5 1 . W e b s t e r , A. J . F. 1971. P r o d u c t i o n o f h e a t l o s s e s f r o m c a t t l e e x p o s e d t c c o l d o u t d o o r e n v i r o n m e n t s . J . App. P h y s . 30 ( 5 ) : 6 8 4 - 6 9 0 . W h i t e , R. G. 1974. Some a s p e c t s o f n u t r i t i o n a l a d a p t a t i o n s o f a r c t i c h e r b i v o r e s . I n : V e r n b e r g , F. J . ( E d . ) . P h y s i o l o g i c a l a d a p t a t i o n t c t h e e n v i r o n m e n t . I n t e x t E d u c . P u b l . , N.Y, W h i t e , B. G. S A. M. Gau. 1975. V o l a t i l e f a t t y a c i d (VFA) p r o d u c t i o n i n t h e rumen and cecum o f r e i n d e e r . P r o c . F i r s t I n t ' l . R e i n d e e r and C a r i b o u Symp. ( E d . by J . L u i c k , P. L e n t , B. K l e i n and B. W h i t e ) , U n i v . o f A l a s k a , F a i r b a n k s . W h i t e , B. G. & J . B. L u i c k . 1973. A s p e c t s o f f e e d i n t a k e and h e a t p r o d u c t i o n o f R a n g i f e r i n t h e a r c t i c t u n d r a . P r o j . Bep. U.S. T u n d r a Eiome P r o g r a m . W h i t e , B. G,, J . R. L u i c k , D. E. B u s s e l l , F. L. B u n n e l l . 1974. A c o m p a r i s o n of f o u r methods f o r e s t i m a t i n g f o o d i n t a k e o f r e i n d e e r and c a r i b o u . A b s t . 4 t h I n t l . Symp. On B u m i n a n t P h y s i o . 1 p. S h i t e , • R . G,, B. , R. Thomson, T. S k o g l a n d , S, J . P e r s o n , D. , E. R u s s e l l , D. F. H o l l e m a n S J . B. L u i c k . 1975. E c o l o g y o f c a r i b o u and a t P r u d h o e B a y , A l a s k a . I n , E c o l o g i c a l i n v e s t i g a t i o n s o f t h e T u n d r a Biome i n t h e P r u d h o e Bay r e g i o n , A l a s k a . B i o l . P a p . o f t h e U. o f A l a s k a S p e c . Rep. No. 2. pp 1 5 1 - 2 0 1 . Young, B. A. 1966. E n e r g y e x p e n d i t u r e and r e s p i r a t i o n , a c t i v i t y o f s h e e p d u r i n g f e e d i n g . A u s t . J . A g r i c . R e s . 17:355. Young, B. A. 8 J . C. C o r b e t t . 1972. M a i n t e n a n c e e n e r g y r e g u i r e m e n t s o f g r a z i n g s h e e p i n r e l a t i o n t o h e r b a g e a v a i l a b i l i t y . I . C a l o r i m e t r i c e s t i m a t e s . A u s t . J . A g r i c . R e s . 2 3 : 5 7 - 7 6 . Y o u s e f , M. K. 8 E. G. w h i t e . 1974. B i o e n e r g e t i c s o f r e i n d e e r , EaS2llJI ta£§J3iI]J§. XXVI Int»l. Cong. Of P h y s i o l . , New E e l h i ( A b s t r . ) . Z h i g u n o v , P. S. ( E d . ) . 1961. R e i n d e e r h u s b a n d r y . 2nd e d i t . T r a n s l . f r o m R u s s i a n by M. F l e i s h m a n n , S i r e a l P r o g r a m f o r S c i . T r a n s l . , J e r u s a l e m . 

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