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UBC Theses and Dissertations

A study of the relationship between available food and nutritive requirements of blue grouse chicks. Stiven, Alan Ernest 1959

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A STUDY OF THE RELATIONSHIP BETWEEN AVAILABLE FOOD AND NUTRITIVE REQUIREMENTS OF BLUE GROUSE CHICKS by A l a n E. S t i v e n B.Sc. U n i v e r s i t y of New Brunswick A T h e s i s Submitted i n P a r t i a l F u l f i l m e n t of the Requirements f o r the Degree of MASTER OF ARTS i n the Department of ZOOLOGY We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA far9 1959 ABSTRACT A study of the r e l a t i o n s h i p between a v a i l a b l e f o o d , n u t r i t i o n a l requirements, and the abundance of blue grouse (Dendragapus obscurus f u l i g i n o s u s ) c h i c k s was conducted on the seven year o l d B e a v e r t a i l Burn near Campbell R i v e r , Vancouver I s l a n d , B.C. The abundance of i n v e r t e b r a t e s , a v a i l a b l e as food t o the c h i c k s , was determined by sampling. The food requirements of the c h i c k s at v a r i o u s ages was a l s o estimated from the known n u t r i t i o n of other g a l l i f o r m e s . From the l i m i t a t i o n s set by the abundance and n u t r i t i v e q u a l i t y of the i n v e r t e -b r a t e s , the p o t e n t i a l number of c h i c k s on the study areas was found to be much g r e a t e r than the a c t u a l d e n s i t y of c h i c k s . T h i s suggested t h a t under i d e a l weather c o n d i t i o n s , the food supply was not l i m i t i n g the s u r v i v a l of blu e grouse c h i c k s . However, adverse weather was shown to a f f e c t both the abun-dance and composition of the i n v e r t e b r a t e i n the samples. 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 at the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r 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 of t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by t h e Head o f my Department o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department of ZOOLOGtg  The U n i v e r s i t y of B r i t i s h Columbia, Vancouver Canada. Date A p r i l , 195.9 TABLE OF CONTENTS Page INTRODUCTION AND LITERATURE REVIEW 1 ACKNOWLEDGEMENTS 7 FINANCIAL ASSISTANCE 8 MATERIALS AND METHODS The Time and P l a c e of Study 9 Recording of Weather 9 Sampling of I n v e r t e b r a t e s 10 Measurement of P l a n t Food 16 N u t r i e n t A n a l y s i s of the Foods . . . 17 A n a l y s i s of Chick Crops 19 Energy Requirements of the Ch i c k s . . 19 RESULTS THE STUDY AREA 21 The Study P l o t s 22 ANALYSIS OF MACROCLIMATE RECORDS 26 THE CROP CONTENTS OF BLUE GROUSE CHICKS . . . . 28 AVAILABLE INVERTEBRATE FOOD 34 I n v e r t e b r a t e Numbers 37 E f f e c t of Macroclimate on I n v e r t e b r a t e Abundance 40 Weight of I n v e r t e b r a t e s 42 R e l i a b i l i t y o f I n v e r t e b r a t e Sampling Method 48 AVAILABLE PLANT FOOD 52 NUTRIENT ANALYSIS OF CHICK FOODS 54 I n v e r t e b r a t e s 54 P l a n t Foods 56 The A v a i l a b l e Food 59 GROWTH OF BLUE GROUSE CHICKS 6 l Growth of C a p t i v e and W i l d Chicks . . 63 THE ENERGY AND FOOD REQUIREMENTS OF THE CHICKS 70 B a s a l Metabolism 70 M e t a b o l i z a b l e Energy and Q u a n t i t y of Food Required 72 TABLE OF CONTENTS (continued) Page ADEQUACY OF AVAILABLE FOOD 78 Adequacy of Q u a n t i t y 78 Adequacy of Q u a l i t y 84 P r o t e i n Requirements 85 F a t , F i b e r , and M i n e r a l Requirements . 86 DISCUSSION 90 SUMMARY AND CONCLUSIONS 94 REFERENCES 97 ILLUSTRATIONS F a c i n g Page F i g u r e 1. Map of General Study Areas Showing the 1938 and 1951 Burns 22 F i g u r e 2. (a) P l o t A, (b) P l o t B 23 F i g u r e 3. (a) Quinsam Burn i n 1943 (b0! Quinsam Burn i n 1952 (c) B e a v e r t a i l Burn i n 1951 (d) B e a v e r t a i l Burn i n 1958 25 F i g u r e 4. Composition of Morning and Mid-day Samples, May 27 - June 7> 1958 41 F i g u r e 5. D i s t r i b u t i o n of Weights 43 F i g u r e 6. D i s t r i b u t i o n o f I n v e r t e b r a t e Weights ( P a i r e d Sums) 43 F i g u r e 7> Percent Composition of Major P l a n t Foods i n Samples 53 F i g u r e 8. Growth of Blue Grouse Chicks 66 F i g u r e 9. Body Weight and B a s a l Metabolism R e l a t i o n s h i p (from M i t c h e l l et a l . 1927) 72 F i g u r e 10. R e l a t i o n Between Age and Average D a i l y Food Consumption 77 INTRODUCTION AND LITERATURE REVIEW T h i s study r e p r e s e n t s a p o r t i o n o f a l a r g e r i n v e s -t i g a t i o n i n t o the f i e l d ecology of the blue grouse, Dendra-gapus obscurus f u l i g i n o s u s , on Vancouver I s l a n d , B r i t i s h Columbia i n s t i g a t e d by Fowle ( 1 9 4 4 ) and continued by B e n d e l l ( 1 9 5 4 ) . In p a r t i c u l a r I was concerned wi t h the amount and q u a l i t y of the i n v e r t e b r a t e foods a v a i l a b l e t o the c h i c k over the f i r s t f o u r weeks i n r e l a t i o n t o the c h i c k ' s nut-r i t i v e requirements. Most animals undergo f l u c t u a t i o n s i n numbers w i t h i n l i m i t s s e t by environmental c o n d i t i o n s or b i o l o g i c a l i n t e r -a c t i o n . The problem of n a t u r a l c o n t r o l o f animal numbers has r e c e i v e d a c t i v e a t t e n t i o n from '^biologists f o r many y e a r s . P e a r l ' s ( 1 9 3 2 ) e a r l y experiments with D r o s o p h i l a i n d i c a t e d t h a t the p r o d u c t i v i t y of an animal p o p u l a t i o n was d i r e c t l y r e l a t e d ' to i t s d e n s i t y . M o d i f i c a t i o n o f t h i s con-cept by Robertson and Sang ( 1 9 4 4 ) e s t a b l i s h e d the importance o f space and the a v a i l a b i l i t y of food, as w e l l as the d e n s i t y o f animals, i n the r e g u l a t i o n o f the numbers o f organisms. S t u d i e s by Crombie ( 1 9 4 2 , 1 9 4 4 ) on d i f f e r e n t p o p u l a t i o n d e n s i t i e s o f g r a i n b e e t l e s f u l l y analyzed those f a c t o r s con-t r i b u t i n g t o the d e c l i n e o f h i s experimental p o p u l a t i o n s (accumulation of waste p r o d u c t s , d e p l e t i o n o f e s s e n t i a l r e s o u r c e s ) . 1 2 The relation of survival of animals to the supply of available food seems to be well established in experimental laboratory populations of invertebrates (Nicholson 1954, Gause 1934). Its importance, however, in influencing populations of higher animals and invertebrates in the natural state is only slightly understood. Part of the problem lies in comprehending the complexity of an eco-system and i t s many energy relationships; and thus an under-standing of a particular portion of the quantitative energy turnover is very d i f f i c u l t . Coupled with this is the know-ledge that the abundance of a food and i t s quality (as energy) are continually changing under environmental conditions of climate (Chauvin and d fAguilar, 1946) and time (Cowan et a l 1950, Spinner and Bishop 1950). There is good evidence to suggest that food is important in regulating the abundance of some birds. Lack (1954) points out that to understand f u l l y the complex relationships between a bird and i t s food supply, one must measure the abundance and availability of i t s chief foods and the quantity of each consumed. He further summarizes four main reasons why some bird populations appear to be regulated by their food supply: (1) predation and disease often seem unimportant; (2) birds are more numerous where their food supply is more abundant; (3) related species normally eat different types of food; and (4) there is 3 u s u a l l y f i g h t i n g between b i r d s d u r i n g p e r i o d s when food i s s c a r c e . The F i n n i s h worker Palmgren (1932) has shown t h a t the abundance of G o l d c r e s t s (Regulus r . r e g u l u s ) and Bl a c k -capped Chickadees (Parus a n t r i c a p i l l u s ) was c l o s e l y c o r r e l a t e d w i t h the ground v e g e t a t i o n and f o r e s t stand type. Deciduous f o r e s t s by v i r t u e of t h e i r g r e a t e r i n s e c t abundance supported l a r g e r numbers of these b i r d s , w h ile c o n i f e r o u s f o r e s t s , w i t h r e l a t i v e l y s m a l l e r p o p u l a t i o n s of i n s e c t s , supported fewer b i r d s . A d d i t i o n a l s t u d i e s by Tinbergen (1949) i n H o l l a n d and B e t t s (1955) i n England on the Great and Blue T i t m i c e (Parus s p e c i e s ) have shown the i n f l u e n c e of these breeding b i r d s on p o p u l a t i o n s of f o r e s t i n s e c t s . B e t t s determined, by o b s e r v a t i o n from a b l i n d , the number of c a t e r p i l l a r s f e d to the young. In a d d i t i o n she i n d i r e c t l y estimated the number of c a t e r p i l l a r s i n the f o r e s t by c a l c u l a t i n g t h e i r average r a t e s of d e f a e c a t i o n and r e l a t i n g t h i s to the abundance of t h e i r faeces ( c o l l e c t e d i n t r a y s ) . Tinbergen estimated the c a t e r p i l l a r d e n s i t y by c o r r e l a t i n g t h e i r number w i t h the number of pine needles, t h i s i n t u r n being me asured by c a l -c u l a t i n g the pine needle d e n s i t y on the f o r e s t f l o o r . A rec e n t study by Stenger (1958) has compared the food eaten and a v a i l a b l e to the Ovenbird (Seiurus & u r o c a p i l l u s ) i n r e l a t i o n to the b i r d ' s s i z e of t e r r i t o r y . Besides the s t u d i e s of B e t t s , the Edward Grey 4 I n s t i t u t e of F i e l d O r n i t h o l o g y at Oxford, has been a c t i v e i n the assessment of the f e e d i n g ecology of s e v e r a l s p e c i e s o f b i r d s . Gibb (1953» 1957) found t h a t food was p a r t i c u l a r l y s c a r c e d u r i n g the mid-winter p e r i o d r e s u l t i n g i n severe com-p e t i t i o n among Chickadees."'' He a l s o attempted to determine the w i n t e r n u t r i t i v e requirements of the Great, Blue and C o a l T i t s by a r t i f i c i a l f e e d i n g of c a p t i v e b i r d s . H a r t l e y (1948, 1 9 5 3 ) , a l s o working on the Great, Blue, C o a l and Marsh T i t s found that these f o u r s p e c i e s were d i s t i n c t l y separated e c o l o g i c a l l y a c c o r d i n g t o t h e i r r e s p e c t i v e f e e d i n g h a b i t s . Each s p e c i e s was d i s t r i b u t e d w i t h i n p a r t i -c u l a r v e r t i c a l l i m i t s i n the crowns of t r e e s , each had i t s favored f o r a g i n g t r e e s , and i t s own d i s t i n c t food-seeking behaviour. L o c k i e (1955> 1956) has assessed the food supply of Jackdaws and Rooks by attempting to c o r r e l a t e a v a i l a b l e food w i t h breeding and n e s t i n g success. The r o l e of food i n the s u r v i v a l o f g a l l i n a c e o u s b i r d s i s b r i e f l y reviewed by Hickey (1955)* He p l a c e s l i t t l e s i g n i f i c a n c e on i t s importance, due to a g e n e r a l l a c k of s u b s t a n t i a t e d evidence. However Stokes (no date) r e p o r t s t h a t a shortage of food d u r i n g the summer months may be an important f a c t o r i n l i m i t i n g p o p u l a t i o n growth of pheasants on Pelee I s l a n d , O n t a r i o . With r e s p e c t t o r u f f e d grouse, 1 The names Chickadee and T i t are used synonymously. 5 Edminster (1947) s t a t e s t h a t a shortage of i n s e c t s i n June or e a r l y J u l y , a v i t a l p e r i o d f o r the young b i r d s , would be d i s a s t r o u s . At t h i s time of year he i n d i c a t e s that grouse c o v e r t s c o n t a i n from one hundred to f i v e hundred thousand a v a i l a b l e i n v e r t e b r a t e s per a c r e . In b r i e f , these s t u d i e s attempted to develop some understanding of the r e l a t i o n s h i p s between the food supply and the numbers of w i n t e r i n g and breeding b i r d s . I t appears that q u a n t i t a t i v e work on the importance of food to the young b i r d s i s r e l a t i v e l y s c a r c e . Moreover, s t u d i e s s t r e s s i n g the importance of food q u a l i t y i n r e l a t i o n to the n u t r i t i v e requirements of growing b i r d s , a l s o seems to have been g e n e r a l l y n e g l e c t e d . T h i s present study was undertaken not o n l y as p a r t of a search i n t o animal - food r e l a t i o n s h i p s , but a l s o as p a r t of a c o n t i n u i n g study on the b l u e grouse, Dendraganus obscurus f u l i g i n o s u s . Work was conducted i n the v i c i n i t y of the Quinsam Lakes, Vancouver I s l a n d . Fowle (1944) who i n s t i g a t e d the i n v e s t i g a t i o n was concerned c h i e f l y w i t h l i f e h i s t o r y and summer food h a b i t s . Continued study by B e n d e l l (1954, 1955) covered l i f e h i s t o r y and p o p u l a t i o n dynamics du r i n g the p e r i o d 1950 to 1953. At t h a t time B e n d e l l found a r e l a t i v e l y h i g h d e n s i t y of blue grouse (o.40 a d u l t males and y e a r l i n g and O.78 adult/females per a c r e ) . He suggests that t h i s h i g h d e n s i t y can be e x p l a i n e d p r i m a r i l y as the r e s u l t of 6 an abundance of the i n v e r t e b r a t e food supply f o r the c h i c k s , and from the change i n the s t r u c t u r e of the v e g e t a t i o n f o l l o w i n g the f o r e s t f i r e of 1938, M o r t a l i t y o f the c h i c k s on the summer range d u r i n g the p e r i o d 1950 to 1953 was approx-imat e l y 67 per c e n t . I t was much higher (80 to 90 percent) when b r o o d l e s s hens were^ taken i n t o account. Most of t h i s m o r t a l i t y was ex p l a i n e d by a h i g h l e v e l of i n f e c t i o n w i t h the helminths Dispharynx nasuta and Plagiorhynchus formosus. However, B e n d e l l , unable to r u l e out the p o s s i b i l i t y t h a t c h i c k s may have d i e d of s t a r v a t i o n as w e l l as from the e f f e c t s of the p a r a s i t e s , has suggested t h a t a shortage of i n v e r t e -b r a t e foods d u r i n g the f i r s t few weeks of a c h i c k ' s l i f e , combined w i t h the e f f e c t s of extreme weather c o n d i t i o n s , may be p a r t i a l l y r e s p o n s i b l e f o r some of the m o r t a l i t y . S i m i l a r e x p l a n a t i o n s f o r unaccountable m o r t a l i t y i n f u f f e d grouse (Bonasa umbellus) c h i c k s and ring-necked pheasant (Phasianus c o l c h i c u s ) c h i c k s have been advanced by Edminster (1947), Bump et a l (1947), C r i d d l e (1930), and Stokes (no d a t e ) . T h e r e f o r e the purpose of t h i s study was to measure the amount of food a v a i l a b l e to the blue grouse c h i c k s , b o t h i n abundance and q u a l i t y . By r e l a t i n g t h i s t o the q u a l i t y and q u a n t i t y of the food r e q u i r e d by the c h i c k s , the importance of food c o u l d be assessed as a f a c t o r i n f l u e n c i n g the pro-d u c t i v i t y of a blue grouse range w i t h r e s p e c t to the c o n d i t i o n and number of c h i c k s produced. ACKNOWLEDGMENTS S e v e r a l people have c o n t r i b u t e d time, e f f o r t and advice t o t h i s study and I g r a t e f u l l y acknowledge t h e i r a s s i s t a n c e . My s u p e r v i s o r , Dr. J.P. B e n d e l l , o r i g i n a l l y suggested the problem. I n a d d i t i o n h i s h e l p , p a t i e n c e , and c o n s t r u c t -i v e c r i t i c i s m both i n the f i e l d and at the U n i v e r s i t y have been i n v a l u a b l e . S p e c i a l thanks go to Dr. I . MoT. Cowan f o r h i s many su g g e s t i o n s , but e s p e c i a l l y f o r s e c u r i n g f i n a n -c i a l a s s i s t a n c e f o r me throughout the p a s t two y e a r s . I am a l s o g r a t e f u l t o Dr. A . J . Wood, Dr. W.D. K i t t s , and Dr. J.J.R. Campbell of the D i v i s i o n o f Animal S c i e n c e f o r p r o v i d i n g space and equipment, and f o r suggest i n g h e l p f u l techniques f o r the n u t r i e n t a n a l y s i s o f the v a r i o u s foods; and t o Dr. J . B i e l y o f the D i v i s i o n o f P o u l t r y S c i e n c e f o r h i s many s u g g e s t i o n s . To f e l l o w graduate s t u d e n t s , D o r i s and George Gibson, go very s p e c i a l thanks not o n l y f o r p e r m i s s i o n t o use the weights of t h e i r blue grouse c h i c k s i n t h i s t h e s i s , but a l s o f o r t h e i r a s s i s t a n c e and p r o f i t a b l e d i s c u s s i o n s d u r i n g the course o f the f i e l d work. I am a l s o g r a t e f u l to Drs. L. von Haartman, P.A. L a r k i n , and K. Graham o f the Department o f Zoology f o r t h e i r a d v i c e on sampling methods and compila-t i o n o f some of the i n v e r t e b r a t e data. A l s o Messrs. D.J. Robinson and J . Bandy of the B r i t i s h Columbia Game 7 8 Department p r o v i d e d some f i e l d equipment, h i s t o r i c a l data, a d v i c e , and frequent t r a n s p o r t a t i o n . Many thanks a l s o go t o the commendable members of Hut M-19 f o r t h e i r many p r o f i t a b l e d i s c u s s i o n s . And f i n a l l y , I am e s p e c i a l l y g r a t e f u l t o my wif e f o r h e r a s s i s -tance, f o r t i t u d e and understanding i n many aspects o f the problem. FINANCIAL ASSISTANCE During the course o f the two w i n t e r s (1957 t o 1958), my s t u d i e s were supported by two Canadian I n d u s t r i e s . L i m i t e d F e l l o w s h i p s f o r W i l d l i f e C o n s e r v a t i o n . Summer f i e l d work was f i n a n c e d both by a C.I.L. summer grant and by a s s i s t a n c e from the B r i t i s h Columbia Game Department f o r f i e l d equipment. The Department o f Zoology p r o v i d e d Laboratory A s s i s t a n t s h i p s f o r both w i n t e r s . MATERIALS AND METHODS The Time and Pl a c e of Study The i n v e s t i g a t i o n was c a r r i e d out i n the s p r i n g and e a r l y summer of 1958. The g e n e r a l area of study l i e s to the west and south of the town of Campbell R i v e r , Vancouver I s l a n d , B.C. In p a r t i c u l a r I was concerned w i t h areas near the B e a v e r t a i l and Middle Quinsam Lakes. Due to c o n d i t i o n s of drought, p a r t i a l f o r e s t c l o s u r e was i n e f f e c t d u r i n g the l a t t e r p a r t of the study. Complete c l o s u r e f o r c e d a t e r m i n -a t i o n of the f i e l d work i n the f i r s t week of J u l y . During the winter 1958-1959, data were analyzed i n the Department of Zoology, U n i v e r s i t y of B r i t i s h Columbia. Recording of Weather The study of f a c t o r s p o t e n t i a l l y capable of l i m i t i n g animal numbers, n e c e s s i t a t e s the measurement of the v a r i a b i l i t y of as many of the environmental i n f l u e n c e s as p o s s i b l e . T h e r e f o r e the macroclimate about the study areas was recorded f o r two reasons. F i r s t , there i s a s t r o n g p o s s i b i l i t y t h a t adverse weather may i n f l u e n c e the s u r v i v a l of the c h i c k s d i r e c t l y . Second, weather may be an important f a c t o r i n determining the a v a i l a b l e supply of i n v e r t e b r a t e foods and t h e r e f o r e i n d i r e c t l y a f f e c t the p r o d u c t i v i t y of the grouse range. A maximum-minimum thermometer and a F i s h e r standard 9 10 e i g h t i n c h r a i n rauge were l o c a t e d at the s i t e of B e n d e l l ' s 1950-1953 study (on the Quinsam R i v e r , two and one-half m i l e s from Quinsam Lake). The thermometers were i n continuous shade on the n o r t h s i d e of a c a b i n and about s i x f e e t above the ground. D a i l y temperature and r a i n f a l l r e c o r d i n g s were taken, the former averaged on a weekly b a s i s , the l a t t e r expressed as a weekly sum. Sunshine was r e c o r d e d each day on blue photo-graphic p r i n t paper and r e p r e s e n t e d as the average d a i l y percent of p o s s i b l e sunshine f o r a week. The e f f e c t of m i c r o c l i m a t i c a l changes on i n v e r t e b r a t e a c t i v i t y and abundance has been demonstrated by Chauvin and d ' A u i l a r (1946) and Uvarov (193D* T h e r e f o r e an attempt was made to assess i t s d i r e c t i n f l u e n c e upon the i n v e r t e b r a t e s a v a i l a b l e to the blue grouse c h i c k s . Records of m i c r o c l i m a t e w i t h r e s p e c t to temperature one i n c h from the ground, and humidity at approximately the same l e v e l were taken a f t e r each i n v e r t e b r a t e sample ( d e s c r i b e d i n next s e c t i o n ) had been c o l l e c t e d . The r e l a t i v e humidity was r e c o r d e d on a Serdex-type hygrometer. Sampling of I n v e r t e b r a t e s The food h a b i t s of blue grouse c h i c k s i n Washington S t a t e have been d e s c r i b e d by Beer (1943) and i n the r e g i o n c l o s e to the present study area by Fowle (1943). T h e i r f i n d -ings i n d i c a t e t h a t blue grouse c h i c k s f e e d on a d i e t composed of almost e n t i r e l y i n v e r t e b r a t e s d u r i n g t h e i r f i r s t few weeks of l i f e . 11 In order to assess the amount of I n v e r t e b r a t e food a v a i l a b l e to the blue grouse c h i c k s , i t was necessary to devise a means of e s t i m a t i n g t h i s amount p e r i o d i c a l l y by sampling the h a b i t a t of the c h i c k s f o r i n v e r t e b r a t e s that l i v e w i t h i n the "zone of a v a i l a b i l i t y " . T h i s zone of a v a i l -able food has been described by Edminster (19^7) f o r the r u f f e d grouse c h i c k as th a t between the loose ground l i t t e r to a height of one foot above the e a r t h . I accepted t h i s zone as a p p l i c a b l e to blue grouse c h i c k s . Disturbance of the l i t t e r l a y e r by s c r a t c h i n g w h i l e i n search of food has never been observed i n f o r a g i n g by blue grouse c h i c k s . Several sampling techniques have been described f o r measuring the abundance of s o i l i n v e r t e b r a t e s by Macfadyen (1955). Walcott (1937) describes a method i n which a p a i l i s i n v e r t e d over a square fo o t of ground surface and a pie c e of cotton soaked i n ether was i n s e r t e d i n t o the p a i l . Two hours were r e q u i r e d to o b t a i n one sample. The use of sweep nets f o r sampling purposes has been described by Carpender and Ford (1936). S i i v o n e n (1939), i n assessing the abundance of food of the Song Thrush (Turdus ericetorum p h i l o m e l o s ) , placed a wooden frame 50 centimeters square over the surface of the ground. W i t h i n a h a l f hour most of the i n v e r t e b r a t e s w i t h i n the square area had appeared and were c o l l e c t e d . There are two reasons why these methods were not adequate f o r t h i s study. F i r s t , most l i t t e r i n h a b i t i n g 12 I n v e r t e b r a t e s have been shown to be d i s t r i b u t e d c o n t a g i o u s l y (Cole 1946, Wadley 1950, Flemming and Baker 1936). To e l i m i n -ate c o n t a g i o n on the study areas using orthodox sampling techniques would r e q u i r e such a l a r g e s i n g l e sample area as to be i m p r a c t i c a l (Flemming and Baker, 1936). Second, v a r i a -t i o n s i n m i c r o c l i m a t e , even over short p e r i o d s of time, cause r a d i c a l changes i n the a c t i v i t y of d i f f e r e n t i n v e r t e b r a t e groups and hence changes i n t h e i r abundance (Uvarov 1931, T a l b o t 1946). T h e r e f o r e i t was necessary to c o l l e c t as many samples as p o s s i b l e w i t h i n a s h o r t p e r i o d of time and s t i l l keep the v a r i a n c e ( s t a t i s t i c a l sense) about the sample mean at a minimum. Sampling was undertaken i n a manner to s t i m u l a t e , i n a g e n e r a l way, the circumstances under which grouse c h i c k s a c q u i r e t h e i r food as they p i c k up exposed i n v e r t e b r a t e s . F o r the convenience of d e t e c t i o n by the human obser v e r , a band one f o o t wide was f o l l o w e d , w i t h o b s e r v a t i o n from a h e i g h t of twenty inches from the ground. With t h i s aspect of the procedure f i x e d , t h e r e remained to be recorded t h r e e i n t e r r e l a t e d v a r i a b l e s ; y i e l d , area covered, and time e l a p s e d . One of these had to be chosen f o r the independent v a r i a b l e as the b a s i s of sampling, w i t h the other two dependent on i t . We b e g i n w i t h the premise t h a t the q u a n t i t y of food o b t a i n a b l e depends f i r s t l y upon the q u a n t i t y present on a g i v e n area. The amount a c t u a l l y obtained t h e r e a f t e r depends upon the area searched or the time spent s e a r c h i n g (an a r b i t r a r y u n i t ) . T h i s narrows the choice of the independent v a r i a b l e t o area or time. Time appears to be the b e t t e r e x p r e s s i o n of a v a i l -a b i l i t y to a c h i c k i f one c o n s i d e r s the need to s a t i s f y the food requirements w i t h i n the hours of d a y l i g h t . Area appears to be the b e t t e r e x p r e s s i o n of a v a i l a b i l i t y i f the a c q u i s i t i o n of the food depends upon the d i s t a n c e t h a t must be t r a v e r s e d to a c q u i r e the necessary q u a n t i t y of food. Since t h e r e are p h y s i o l o g i c a l and environmental causes l i m i t i n g the time a v a i l a b l e to the b i r d , time may become more important. Time was t h e r e f o r e used as the independent v a r i a b l e . Advance along the s t r i p was e s t a b l i s h e d at a r a t e t h a t was w i t h i n the c o n s i s t e n t e f f i c i e n c y of the o b s e r v e r . W i t h i n c e r t a i n l i m i t s change of r a t e of the human observer should have no s i g n i f i c a n c e f o r the a v a i l a b i l i t y of food t o c h i c k s . I f the observer i s s t a t i o n a r y , time i s a l l - i m p o r t a n t because the moving i n d i v i d u a l s of the i n v e r t e b r a t e p o p u l a t i o n w i l l b r i n g an i n c r e a s i n g number i n t o c o n t a c t w i t h the observer the longer the lapse of time. The moment the observer begins to advance the r a t e of advance should not i n f l u e n c e the y i e l d over an area u n t i l a speed of coverage beyond the scope of r a p i d v i s i o n i s exceeded. I f one does not l i n g e r at any p o i n t or r e t r a c e the area covered, the p o p u l a t i o n at any p o i n t r e p r e s e n t s a balance between i n f l u x and outgoing, t h a t i s , the same average as i f the e n t i r e s t r i p i s taken i n s t a n t a n e o u s l y . T h e r e f o r e the sampling technique c o n s i s t e d of s e a r c h -i n g along a s t r i p of ground one f o o t wide f o r f i v e minutes, the time i n t e r v a l being a r b i t r a r i l y chosen. A l l i n v e r t e b r a t e s w i t h i n the zone one f o o t i n w i d t h and one f o o t i n h e i g h t were c o l l e c t e d r a p i d l y i n an a s p i r a t o r , k i l l e d i n a cyanide b o t t l e and preserved by d r y i n g i n s m a l l envelopes. To convert the average abundance of i n v e r t e b r a t e s per 14 f i v e minutes to abundance per u n i t area, t e n preliminary-samples were taken and the d i s t a n c e moved d u r i n g each sample M. was measured. T h i s gave an average d i s t a n c e of 45.2 + 0.98^ f e e t . Thus the area covered i n each sample was 45.2 ± 2 % square f e e t . An attempt was made to maintain a c o n s i s t e n t and com-para b l e d a i l y method of sampling. T h i s was accomplished by choosing d a i l y one corner of the study p l o t and walking t e n to one hundred paces towards the d i a g o n a l l y o p p o s i t e c o r n e r . T h i s gave the s t a r t i n g p o i n t of the f i r s t sample. D i s t a n c e between samples was constant at twenty paces, but the d i r e c t i o n taken from the preceding sample was chosen from the main t h i r t y - s i x compass p o i n t s . A l l the above-mentioned c h o i c e s were made from a t a b l e of random numbers ( A r k i n and C o l t o n , 1950). The r e q u i r e d number of samples to be c o l l e c t e d each day to g i v e a minimum v a r i a t i o n between samples was estimated by t a k i n g a s e r i e s from each of the two P l o t s ( d e s c r i b e d l a t e r ) . Data were a p p l i e d to e q u a t i o n (1) g i v e n by Snedecor (1956, pg. 501) N - 4 s 2 (x) " d2 N = number of samples, s = v a r i a n c e , and d = a l l o w a b l e e r r o r about the mean. The r e s u l t s of t h i s t e s t are g i v e n i n T a b l e s I and I I . I t can be seen from Table I I t h a t from 6 to 10 samples give an e r r o r of 15 percent each s i d e of the mean. T h i s # 95$ confidence i n t e r v a l expressed as a percentage of the mean. 15 T a b l e I R e s u l t s of P r e l i m i n a r y Sampling i n E s t i m a t i n g the Required Number of Samples. . P l o t A P l o t B mean (animals /5 min.) 4.27 6.10 v a r i a n c e 1.07 1.21 standard e r r o r 0.27 0.35 no. of.samples 15 10 T a b l e I I The Estimated Required Number of Samples (N) at V a r i o u s D e v i a t i o n s from the Mean. P l o t A P l o t B % d e v i a t i o n from mean d 2 N d 2 N 5% .0545 78 .0930 52 10% .1823 23 .3721 13 15% .4363 10 .8373 6 20% .7293 6 1.4884 3 25% 2.8477 2 2.3256 2 number of samples was c l o s e l y maintained each day through-out the p e r i o d of study. Beer (1943) s t a t e s that a d u l t b l u e grouse r e a c h t h e i r peak of f e e d i n g between 7AM and 9AM w i t h an e q u a l l y i n t e n s i v e p e r i o d d u r i n g the evening hours. However, he found t h a t c h i c k s tend to feed c o n t i n u o u s l y throughout the day. Due to the p a r t i a l f o r e s t c l o s u r e , sampling was c o n f i n e d to the e a r l y morning hours w i t h o c c a s i o n a l sampling d u r i n g mid-day to assess any d i f f e r e n c e s i n abundance and composition of the 16 i n v e r t e b r a t e s . At the Department of Zoology, a l l i n v e r t e b r a t e s of each sample were c l a s s i f i e d and counted. Each sample was then d r i e d f o r f o r t y - e i g h t hours at 80°C and weighed to the n e a r e s t t e n t h of a m i l l i g r a m . A l l m a t e r i a l was s t o r e d f o r a n a l y s i s of n u t r i e n t s , as d e s c r i b e d l a t e r . Measurement of P l a n t Foods An attempt was made to measure the amount of p l a n t food a v a i l a b l e to blue grouse c h i c k s . Fowle (1944) has l i s t e d many p l a n t s p e c i e s used as food by the c h i c k s and t h a t p o r t i o n which i s most f r e q u e n t l y eaten. Since p l a n t food does not predominate the d i e t of the young c h i c k s u n t i l approximately the t h i r d week, i t was d e c i d e d that one instantaneous sample to estimate the amount of a v a i l a b l e p l a n t food would be s u f f i c i e n t . T h i s was taken i n the l a s t week of June. To sample each study area f o r the a v a i l a b l e q u a n t i t y of p l a n t food, twenty p l o t s were e s t a b l i s h e d i n two l i n e s . P l o t s were f i f t y paces a p a r t . The sample p l o t c o n s i s t e d of an area f i v e f e e t square w i t h i n which a l l p l a n t m a t e r i a l eaten by the c h i c k s from ground l e v e l to one f o o t above ground was c o l l e c t e d . M a t e r i a l from each sample p l o t was p l a c e d i n s e a l e d p l a s t i c bags and immediately weighed to the n e a r e s t t e n t h of a gram. I t was then pressed and d r i e d . At the Department of Zoology, a l l p l a n t m a t e r i a l was thoroughly d r i e d f o r t h r e e days at 80°C and again weighed. I t was t h e n s t o r e d f o r f u t u r e a n a l y s i s of n u t r i e n t s . 17 N u t r i e n t A n a l y s i s of, the Foods In order to determine the amount of food a v a i l a b l e to blue grouse c h i c k s , the q u a l i t y as w e l l as the q u a n t i t y of the food must be understood. T h i s q u a l i t y was then r e l a t e d to the q u a l i t a t i v e requirements of the growing c h i c k s w i t h a view to e s t i m a t i n g the q u a l i t a t i v e adequacy of the food. A l l i n v e r t e b r a t e and p l a n t m a t e r i a l c o l l e c t e d by sampling was analyzed f o r the b a s i c n u t r i e n t s ; p r o t e i n , f a t , and ash. The e s t i m a t i o n of the remaining p o r t i o n , composed of crude f i b e r and n i t r o g e n - f r e e e x t r a c t , i s d e a l t w i t h on page 5.7» The methods used i n determining the n u t r i e n t com-p o s i t i o n of the foods were those of "Methods of A n a l y s i s of the A s s o c i a t i o n of O f f i c i a l A g r i c u l t u r e Chemists" (1950) w i t h the e x c e p t i o n of the f a t content. T h i s was determined by e x t r a c t i n g the f a t from a known weight of m a t e r i a l w i t h three a l i q u o t s of 10 ml. of e t h e r . The ether was then evaporated and the remaining r e s i d u e weighed. A l l analyses were done on moisture f r e e m a t e r i a l . M o isture contents of the p l a n t foods were c a l c u l a t e d by d r y i n g the m a t e r i a l at 80°C f o r t h r e e days and measuring to a constant d r y weight. With the s c a l e a v a i l a b l e i t was not p r a c t i c a l to weigh f r e s h i n s e c t s i n the f i e l d t o the p r e c i s e value r e q u i r e d s i n c e the samples were i n the order of 50 m i l l i -grams. T h e r e f o r e , f o r purposes of c a l c u l a t i n g the f r e s h food requirements of the c h i c k s , i t was necessary to assume a moisture content of approximately 65 p e r c e n t . The water content 18 of :• few i n s e c t s are gi v e n : B e e t l e ( a d u l t ) - 60$; Cockroach ( a d u l t ) - 61$; F l y (blue b o t t l e l a r v a ) - 73$ (Spector, 1956), To c a l c u l a t e the energy of the foods t h a t i s a v a i l a b l e to the c h i c k s f o r metabolism, some idea of the v a r i o u s n u t r i e n t energy c a t e g o r i e s i s necessary. Gross Energy: T h i s i s the heat o f combustion of a food; t h a t i s , the heat g i v e n o f f when a substance i s com-p l e t e l y burned t o i t s u l t i m a t e o x i d a t i o n p r o d u c t s . D i g e s t i b l e Energy; T h i s energy category i s u s u a l l y considered to be t h a t p o r t i o n of the gross energy t h a t remains a f t e r f e c a l energy has been s u b t r a c t e d . In p o l y g a s t r i c animals f e r m e n t a t i o n l o s s e s must a l s o be c o n s i d e r e d . M e t a b o l l z a b l e Energy: T h i s i s co n s i d e r e d to be t h a t p o r t i o n of the t o t a l t h a t i s a c t u a l l y capable of t r a n s f o r -mation w i t h i n an organism. I t i s a l s o d e f i n e d as the gross energy minus the energy l o s t i n the f e c e s and u r i n e (Maynard and L o o s l i , 1956). West and Todd (1956) s t a t e that about 1.3 C a l o r i e s per gram of p r o t e i n are l o s t to the organism and by using an average of 5«6 C a l o r i e s per gram f o r mixed p r o t e i n (gross energy), 4 .3 C a l o r i e s per gram remain as energy a v a i l -able a f t e r o x i d a t i o n . However, n e i t h e r p r o t e i n , f a t , nor carbohydrate are completely absorbed and t h e y c o n s i d e r t h a t l i t t l e e r r o r i s i n t r o d u c e d by rounding o f f to the f o l l o w i n g v a l u e s : p r o t e i n 4, carbohydrate 4, and f a t 9, a l l i n C a l o r i e s per gram i n g e s t e d . T h i s energy category was used i n t h i s study. 19 Net Energy; Net energy i s t h a t p o r t i o n of the food energy that i s completely u s e f u l to the organism. I t i s d e f i n e d by Brody (1945) as the gross energy l e s s the f e c a l and u r i n a r y energy and the S p e c i f i c Dynamic A c t i o n a f f e c t . S p e c i f i c Dynamic A c t i o n (S.D.A.); T h i s energy category appears to r e p r e s e n t the decrease i n the e f f i c i e n c y of energy metabolism of food eaten and compared to t h a t o c c u r r i n g under b a s a l c o n d i t i o n s (Crampton, 1956). A n a l y s i s of the Chick's Crops During the p e r i o d of study as many c h i c k s as p o s s i b l e were c o l l e c t e d and t h e i r crop contents preserved i n 10 percent f o r m a l i n . These crops were analyzed l a t e r and a l l food s p e c i e s v o l u m e t r i c a l l y recorded. No more than two c h i c k s were taken from the same brood at any one time. These data were supple-mented by crop analyses made durin g 1950 to 1953 by Dr. B e n d e l l from adjacent areas i n a s l i g h t l y l a t e r stage of s e r a i p l a n t s u c c e s s i o n . I t was hoped t h a t these analyses would serve b o t h as an i n d i c a t i o n of f e e d i n g trends and act as a check upon the sampling of a v a i l a b l e i n v e r t e b r a t e foods. Energy Requirements of the Chicks The d e t e r m i n a t i o n of the energy and feed requirements of the growing blue grouse c h i c k s was accomplished by a p p l i -c a t i o n of the f a c t o r i a l method d e s c r i b e d by M i t c h e l l et a l (1930, 1931) Brody (1945) and Maynard and L o o s l i (1956) t o weights of c h i c k s grown both i n c a p t i v i t y and under n a t u r a l c o n d i t i o n s . 20 Weight of s i x c h i c k s captured on the study areas and s u c c e s s f u l l y r a i s e d by Mr. and Mrs. George Gibson, Department of Zoology, were used as a b a s i s i n c a l c u l a t i n g the energy and feed requirements. The f a c t o r i a l method c o n s i s t s e s s e n t i a l l y i n e s t i m a t i n g the m e t a b o l i z a b l e energy requirements f o r a b i r d of given weight. The m e t a b o l i z a b l e energy i s considered to be the sum of the energy r e q u i r e d f o r b a s a l metabolism, p l u s the S.D.A. energy, and plus the sum of the energy r e q u i r e d f o r a c t i v i t y and growth. T h i s r e s u l t a n t f i g u r e d i v i d e d by the m e t a b o l i z a b l e C a l o r i f i c v a l u e of the f e e d eaten, g i v e s a value r e p r e s e n t i n g the minimum d a i l y feed i n t a k e of the b i r d . A check of t h i s c a l c u l a t i o n was made by comparing the a c t u a l feed i n t a k e of pen - r a i s e d pheasant c h i c k s (Skoglund, 1940) of s i m i l a r weight and ages. These values were then r e l a t e d t o the amount of a v a i l a b l e food estimated from the study ar e a s , thus i n d i c a t i n g the p o t e n t i a l h o l d i n g c a p a c i t y of the grouse range i n terms of the number of c h i c k s . T h i s i s d i s c u s s e d more f u l l y i n the s e c t i o n on food requirements, page 73* RESULTS THE STUDY AREA The g e n e r a l area of study i s s i t u a t e d on the east coast of Vancouver I s l a n d approximately twelve miles south-west by west from the town of Campbell R i v e r . Before l o g g i n g and f i r e s , t h i s r e g i o n , c o n s i d e r e d by H a l l i d a y (1937) as l y i n g i n the Southern Coast S e c t i o n of the C o a s t a l F o r e s t Region, was composed of v a r i o u s t r e e a s s o c i a t i o n s , n o t a b l y those of Douglas f i r (Pseudotsuga m e n z i e s i i ) . western hemlock (Tsuga h e t e r o p h y l l a ) and western red cedar (Thuja, p l i c a t a ) . In p a r t i c u l a r the non burned areas c o n t a i n the Douglas f i r -s a l a l ( G a u l t h e r i a s h a l l o n ) a s s o c i a t i o n i n t e r s p e r s e d w i t h bracken ( P t e r i d i u m aqullin&um). The s o i l i s a p o d z o l type. In 1938 f o l l o w i n g extensive l o g g i n g of mature Douglas f i r , western hemlock and western red cedar, and subsequent s l a s h b u r n i n g s , a severe f o r e s t f i r e swept from Menzies Bay i n the n o r t h to Courtenay i n the south along a f r o n t two m i l e s wide. T h i s f i r e burned an area of approximately 75,000 a c r e s . The c o n d i t i o n of the area i n 1943 i s d e s c r i b e d by Fowle (1944) and again i n 1950 to 1953 by B e n d e l l (1954). During the p e r i o d 1942 to 1943, Fowle c o n s i d e r e d the range optimum h a b i t a t f o r the p r o d u c t i o n of b l u e grouse. Together these s t u d i e s have documented one of the g r e a t e s t blooms i n the numbers of b l u e grouse i n B r i t i s h Columbia from the time of the o r i g i n a l 21 L. SCALE OF CULES Figure 1. Map of general study area shewing the 1938 and 1951 bur-no. HUH <i 1938 burn perimeter (western edge) 1951 burn perimeter burn t o the subsequent s t a b i l i t y o f the grouse p o p u l a t i o n which was reached around 1951* In 1951 a second severe f i r e swept from j u s t south of Campbell R i v e r (west o f Campbell Lake) south tottie I r o n R i v e r and west to the Upper Quinsam and Upper Campbell Lakes. The f r o n t of the f i r e extended a c r o s s a width of f i v e m i l e s and denuded an area o f 30,000 a c r e s . I t o r i g i n a t e d i n June and at f i r s t was c o n f i n e d t o an area about R e g i n a l d and B e a v e r t a i l Lakes. Here the f i r e was extremely severe, the la n d b e ing bared t o the m i n e r a l s o i l and to patches of rocky o u t c r o p s . The f i r e passed r e l a t i v e l y q u i c k l y through the Middle Quinsam Lake a r e a and was e v e n t u a l l y e x t i n g u i s h e d i n October. F i g u r e 1 shows the g e n e r a l area o f study and the p e r i m e t e r s o f the 1938 and 1951 burns, h e r e a f t e r r e f e r r e d t o as the Quinsam and B e a v e r t a i l Burns r e s p e c t i v e l y . The Study P l o t s Two study p l o t s of 40 a c r e s each were e s t a b l i s h e d on the B e a v e r t a i l Burn; P l o t A on the n o r t h shore of B e a v e r t a i l Lake at an a l t i t u d e of 1000 f e e t , and P l o t B on the south s l o p e o f Middle Quinsam Lake at an a l t i t u d e o f 1200 f e e t above sea l e v e l . These P l o t s were c o n s i d e r e d to be r e p r e s -e n t a t i v e of the r e l a t i v e l y homogeneous B e a v e r t a i l Burn. T h e i r p o s i t i o n and s u p e r f i c i a l c h a r a c t e r i s t i c s are i n d i c a t e d i n F i g u r e 2. Ptg^ 2 (b) PLOT B 23 An attempt was made to determine the s u r f a c e cover of the two study p l o t s , and the occurrence of the "cover c a t e g o r i e s " ( d e s c r i b e d below). T h i s was done to (1) a p p r e c i a t e the v e g e t a t i o n a l cover of the ground s u r f a c e , and (2^ to i n d i c a t e s i m i l a r i t i e s or d i f f e r e n c e s between the two p l o t s i n r e l a t i o n to the g e n e r a l observed homogeneity of the burn. A s e r i e s of c i r c u l a r p l o t s , each ten f e e t i n diameter (78.6 square f e e t ) were run i n s t r a i g h t l i n e s , twenty yards a p a r t , across the contours of the study P l o t s . E s t i m a t i o n of the surface cover w i t h i n each p l o t was d e s c r i b e d a c c o r d i n g to the f o l l o w i n g c a t e g o r i e s . Averages of percent composition were c a l c u l a t e d f o r each study P l o t . (1) Stumps - Logs: the ground s u r f a c e covered by charred stumps and l o g s , and wood i n a l l stages of decomposition. (2) Bare E a r t h ; areas of bare s o i l , devoid of v e g e t a t i o n , but e x c l u d i n g r o c k s . (3) V e g e t a t i o n It areas covered by a l l v e g e t a t i o n under 6 inches i n h e i g h t . (4) V e g e t a t i o n l i t areas covered by a l l v e g e t a t i o n between 6 inches and 2 f e e t . (5) V e g e t a t i o n I I I ; areas covered by v e g e t a t i o n over 2 f e e t i n h e i g h t . (6) Bare Rock Sampling of the s u r f a c e cover on P l o t s A and B y i e l d e d the r e s u l t s presented i n T a b l e I I I . From these r e m i t s i t i s evident that a l a r g e p o r t i o n of the ground s u r f a c e supports no v e g e t a t i o n at a l l ; stumps, l o g s , bare e a r t h and rocks composing approximately 50 percent T a b l e I I I A Comparison of the Surface Cover Between the Study P l o t s A and B. i f r e q . of i " % Cover occurrence Cov erase Coverage A B A B aver. A & B Stumps-logs 90 100 21 17 19 Bare E a r t h 88 100 31 31 31 Veg. I 100 100 26 30 28 Veg. I I 83 69 9 7 8 Veg. I l l 53 100 4 12 8 Rock 65 23 9 3 6 Sample p l o t s i n A = 40 Sample p l o t s i n B = 26 of the s u r f a c e cover. The remaining s u r f a c e i s covered p r i n -c i p a l l y by v e g e t a t i o n l e s s than 6 inches i n h e i g h t (about 28 percent over the e n t i r e study a r e a ) . Buckland (1941) i n d i c a t e s t h a t f l o r a l r e g e n e r a t i o n covers about 70 percent of the ground s u r f a c e f o u r years a f t e r a non severe f o r e s t f i r e . However the presence of such p l a n t s as E p i l o b l u m , Rubus macropetalus, G a u l t h e r i a , Mahonia and P t e r i d i u m on the P l o t s seem to i n d i c a t e , a c c o r d i n g to Buckland, the s e v e r i t y of the B e a v e r t a i l Burn, thus g i v i n g reason f o r the apparent subsequent slow r e g e n e r a t i o n . In 1943 Fowle (1944) found about 50$ of the ground s u r f a c e barren of p l a n t growth (5 years a f t e r the 1938 Quinsam F i r e ) . By o b s e r v a t i o n , i t appears t h a t most of the g u l l i e s support some growth of a l d e r and w i l l o w . The h i g h e r and more s e v e r e l y burned areas support (besides those mentioned) F i g . 3 (a) Quinsam Burn i n I94.3 ( a f t e r Fowle, 1944) P i g . 3 (b) Quinsam Burn i n 1952 ( a f t e r B e n d e l l , 1954) P i g . 3 (c) B e a T e r t a i l Burn i n 1951 F o l l o w i n g l i r e . P i g . 3 (&) B e a v e r t a i l Burn i n 1958. 25 sparse patches of mosses, and i n many p l a c e s abundant Hypochaeris r a d i c a t a . A census i n the t h i r d week of May r e v e a l e d an ad u l t male (hooting) d e n s i t y of 0.12 and 0.10 per acre:on P l o t s A and B r e s p e c t i v e l y . Another, two estimates of 0.22 and 0.15 h o o t i n g males per acre were made by Miss J u d i t h Strenger, who was a l s o conducting an o r n i t h o l o g i c a l i n v e s -t i g a t i o n on the B e a v e r t a i l Burn. T h i s g i v e s an average of 0.15 a d u l t males per ac r e . Fowle (1944) r e p o r t s a com-parable d e n s i t y of 0.15 i n 1942 and 1943. I t t h e r e f o r e appears t h a t the B e a v e r t a i l Burn i n 1958, both" i n terms of f l o r a l r e g e n e r a t i o n , and d e n s i t y o f hooting a d u l t male blue grouse i s very s i m i l a r to t h a t of the Quinsam Burn as d e s c r i b e d by Fowle i n 1943. F i g u r e 3 ( a , b, c, d) i l l u s t r a t e s a comparison o f the B e a v e r t a i l Burn i n 1951 and 1958 w i t h the Quinsam Burn i n 1943 and 1953. ANALYSIS OF MACROCLIMATE RECORDS The r e s u l t s o f the macroclimate r e c o r d s are g i v e n i n Table IV. Table IV Climate During the Spr i n g and Summer of 1958.  May 25-31 1-7 8-14 June 15-21 22-28 J u l y 29-2 Aver. Max. Temp. 77°F 80° 76° 91° 76° 78° Aver. Min. Temp. 52° 54° 51° 60° 56° 52° T o t a l R a i n f a l l 1.43" 0.06" 0.99" 0.41" Days of Rain 2 1 2 1 D a i l y % of Sun P o s s i b l e 52 73 60 98 43 41 Days of Sunshine 4 6 6 7 4 3 The c l i m a t e g e n e r a l l y tended towards long p e r i o d s of drought coupled w i t h h i g h temperatures. T h i s r e s u l t e d i n a p a r t i a l f o r e s t c l o s u r e d u r i n g the l a s t h a l f of June imposed by the B.C. F o r e s t S e r v i c e , and e v e n t u a l l y a complete c l o s u r e i n the l a s t week of the f i e l d study. R a i n f e l l a t o t a l of s i x days from May 25 to J u l y 2 and amounted to 2.89 inches. There were t h i r t y days of sunshine out of a p o s s i b l e t o t a l of t h i r t y - n i n e . 27 An attempt was made to r e l a t e changes i n the s i z e s of blue grouse broods w i t h changes i n weather. However, no c o r r e l a t i o n was e v i d e n t . In f a c t , d u r i n g the p e r i o d of June 8 to June 21 (time of hatch and e a r l y growth of c h i c k s ) , there were t h i r t e e n days of sunshine, no r a i n , r e l a t i v e l y h i g h daytime temperatures and w i t h no extremes d u r i n g the n i g h t ; suggesting i d e a l weather c o n d i t i o n s f o r fee d i n g and subsequent s u r v i v a l o f the c h i c k s . An a n a l y s i s of the r e l a t i o n s h i p between m i c r o c l i m a t e and i n v e r t e b r a t e abundance i s g i v e n i n a l a t e r s e c t i o n . THE CROP CONTENTS OF BLUE GROUSE CHICKS An a n a l y s i s of the crop contents of b l u e grouse c h i c k s i s u s e f u l i n two ways. F i r s t , i t p r o v i d e s a com-p a r i s o n of the r e l a t i v e p r o p o r t i o n s of i n v e r t e b r a t e and p l a n t foods consumed d u r i n g the f i r s t f o u r weeks of l i f e , and second, i t a c t s as a check on the b a s i c assumptions u n d e r l y i n g the method f o r sampling i n v e r t e b r a t e s . During the p e r i o d of study e l e v e n c h i c k crops were c o l l e c t e d on and immediately around the study areas. No more than two c h i c k s were taken from any one brood at one time. T h i s s m a l l sample s i z e appears to be a r e f l e c t i o n of one or two t h i n g s ; (1) the r e l a t i v e s c a r c i t y of broods, (2) the i n a b i l i t y of the searcher to l o c a t e e a r l y hatched broods due to t h e i r h a b i t of remaining s t i l l u n t i l the observer i s w i t h i n a few f e e t . However, these crop data are supplemented by twenty-three a d d i t i o n a l crops ( o n l y e i g h t a d d i t i o n a l f o r June) taken by B e n d e l l (1954) on the Quinsam Burn area d u r i n g June and J u l y , 1952. Crops were preserved i n 10% f o r m a l i n and t h e i r contents measured v o l u m e t r i c a l l y . pooled and Data were^summarized by percentages. The data are presented i n two p a r t s ; the f i r s t , a g e n e r a l breakdown of the 1958 c r o p s , and second, a more c o n c i s e combined a n a l y s i s of the 1952 and 1958 data. Table V g i v e s a g e n e r a l d e s c r i p t i o n of the crop contents f o r 1958. For a more s p e c i f i c breakdown of the food types eaten, Table VI presents the r e s u l t s of a n a l y s i s on the combined 28 29 1952 and 1958 crops. In a d d i t i o n Table V I I g i v e s a g e n e r a l i z e d summary of T a b l e VI. Table V General Food Types of Blue Grouse Chicks (1958) Food Types June 15-21 June 22-5 (3 c h i c k s ) (8 c h i c k s ) I n s e c t Larvae Adult I n s e c t s Isopoda Arachnida Gastropoda 13 2 56 16 20 7 1 3 T o t a l Animal 90 28 F r u i t s Leaves Flowers Seeds 8 52 1 10 1 6 4 T o t a l P l a n t s 10 72 From these t a b u l a r r e s u l t s , b l u e grouse c h i c k s are d e p i c t e d as s u b s i s t i n g on a predominantly i n v e r t e b r a t e d i e t f o r the f i r s t two to t h r e e weeks of l i f e . In g e n e r a l a l a r g e percentage of t h i s d i e t c o n s i s t s of m i s c e l l a n e o u s l a r v a e , members of the order Homoptera and the f a m i l y F o r m i c i d a e , and P o r c e l l i o scaber (Isopoda) where i t o c c u r s . The youngest c h i c k c o l l e c t e d s t i l l r e t a i n e d evidence of incomplete c l o s u r e of the y o l k sac and was estimated to be one or two days o l d . I t s crop contents were e n t i r e l y animal m a t e r i a l , of which Formicidae and Homoptera composed an equal volume. Table VI:> S p e c i f i c Food Types of Blue Grouse Chicks ( F i g u r e s r e p r e s e n t v o l u m e t r i c percentages) Food Types June b-14 (2 c h i c k ) June 15-21 (3 c h i c k ) June 22-30 -(9 c h i c k ) J u l y 1-7 (7 c h i c k ) J u l y b-14 (6 c h i c k ) . J u l y 15-21 (4 c h i c k ) J u l y 22-31 (3 c h i c k ) ANIMAL FOOD Insect Larvae T e n t h r e d i n i d a e Ossuridae 37 17 1 4 1 6 1 A d u l t I n s e c t s Homoptera Cercopidae Aphididae Membracidae 3 1 9 9 + 1 1 1 + Hymenoptera Formicidae 9 19 7 8 5 3 1 C o l e o p t e r a Carabidae C u r c u l i o n i d a e 13 4 1 1 Orthoptera L o c u s t i d a e 7 Isopoda 34 6 2 5 5 Arachnida 1 D i p t e r a + + O T a b l e VI (continued) Food Types June 8- June 15-14 21 June 22-30 J u l y 1-7 J u l y 0-14 J u l y 15-21 J u l y 22-31 Diplopoda 3^ + Gastropoda 1 T o t a l Animal 85 88 36 20 12 14 10 PLANT FOOD Rubus ( f r t ) 3 7- 24 12 22 16 36 F r a g a r i a ( f r t ) 4 Vaccinium ( f r t ) 9 20 2 P t e r i d i u m (fronds) 1 3 2 2 16 T r i f o l i u m ( l v s ) 11 2 10 2 U n i d e n t i f i e d l v s . 6 5 G a u l t h e r i a ( f l s ) 2 1 9 17 28 30 Hypochaeris ( f l s ) 23 33 14 31 8 Campanula ( f l s ) 2 4 10 Seeds 2 1 3 2 T o t a l P l a n t 15 12 64 80 88 86- 90 M Table VII General Food Types o f Blue Grouse C h i c k s , 1952 and 1958 ( F i g u r e s r e p r e s e n t v o l u m e t r i c percentages) Food Types June 8-14 June 15-21 June 22-30 J u l y 1-7 J u l y 8-14 J u l y 15-21 J u l y 22-31 ANIMAL FOOD Ins e c t Larvae 37 38 18 4 1 6 1 A d u l t I n s e c t s 13 50 8 6 3 9 M i s c . Animal 35 9 2 5 5 Gastropoda 1 TOTAL ANIMAL 85 88 36 20 12 14 10 PLANT FOOD F l e s h y F r u i t s 3 7 28 21 42 18 36 Green Leaves 12 3 8 12 2 7 16 Flowers 2 26 46 41 59 38 Seeds 2 1 3 2 TOTAL PLANT 15 12 64 80 88 86 90 O J l\9 33 As the change over to v e g e t a t i o n a l food o c c u r s , f r u i t s , l e a v e s and flowers tend to compose the l a r g e s t p a r t of the d i e t w i t h Rubus b e r r i e s and Hypochaeris flowers predominating. T h e r e f o r e , by the f i r s t week of J u l y , the c h i c k s , which are now two to f o u r weeks of age are e a t i n g v o l u m e t r i c a l l y about 80 percent p l a n t food. I t appears t h e r e f o r e that the d i e t of the blue grouse c h i c k s during t h e i r f i r s t two t o three weeks i s p r e -dominantly composed of i n v e r t e b r a t e s . A t r a n s i t i o n to a d i e t c h i e f l y made up of v e g e t a t i o n a l m a t e r i a l f o l l o w s . I t now remains to determine the amount of animal and p l a n t food a v a i l a b l e as energy to the blue grouse c h i c k s . AVAILABLE INVERTEBRATE FOOD During the f i r s t month of the b l u e grouse c h i c k ' s l i f e , i n v e r t e b r a t e food makes up a v e r y important p o r t i o n of i t s d i e t . A f t e r the f i r s t week of J u l y , t h i s type of food i s g r a d u a l l y r e p l a c e d by p l a n t foody t h i s becoming the t o t a l d i e t of the b i r d by l a t e f a l l and winter. I t i s necessary now t o determine the amount of i n v e r t e b r a t e food a v a i l a b l e to the b l u e grouse c h i c k s on the study a r e a s . Sampling f o r a v a i l a b l e i n v e r t e b r a t e food began on May 25 and continued i n t o the f i r s t week of J u l y . Most of the sampling was c o n f i n e d t o the e a r l y morning hours (between 6:00 - 10:00 A.M.) w i t h a few samples c o l l e c t e d d u r i n g mid-day to assess the e f f e c t of temperature r i s e s and humidity drops t h a t normally accompany the temporal passage of a day. A s e r i e s of e i g h t samples were taken i n the evening of May 23 (8 P.M.) and compared to a s e r i e s of f i f t e e n taken i n the morning of the same day (7 :30 A.M.). No s i g n i f i c a n t d i f f e r e n c e e x i s t e d between the numbers of i n v e r t e b r a t e s ( t = 1.95, df = 21, P = 0.10) suggesting t h a t the numbers of i n v e r t e -b r a t e s are r e l a t i v e l y constant d u r i n g these times. On May 28 a s e r i e s of samples were taken d u r i n g a heavy d o w n f a l l of r a i n . Not only was the number of i n v e r t e b r a t e s n e g l i g i b l e , but the a b i l i t y of the observer was v e r y l i m i t e d , so much so, t h a t sampling d u r i n g such p e r i o d s was d i s c o n t i n u e d . Edminster (1947) s t a t e s that d u r i n g s h o r t p e r i o d s of such weather, r u f f e d grouse c h i c k s tend to remain under the hen and do not f e e d . 34 35 Throughout the p e r i o d of sampling, members of the order Orthoptera were c o l l e c t e d along w i t h other i n v e r t e -b r a t e s . However, on examination of the crop contents of c h i c k s up to f o u r weeks of age, both from 1958 and 1952, t h i s group was found to be absent i n a l l cases. Fowle (1944) however, does r e c o r d t h e i r presence i n e i g h t j u v e n i l e s from J u l y and August of 194-3 i n which they made up 1.2 percent of the summer d i e t . He makes no mention of t h e i r presence i n crops c o l l e c t e d i n June. T h e r e f o r e i n the a n a l y s i s of the weights of i n v e r t e b r a t e samples, a l l c o n t r i b u t i n g O r t h o p t e r a have been excluded. However i n the a n a l y s i s of the numbers of i n v e r t e b r a t e s from- the samples, which i s t r e a t e d s e p a r a t e l y , they are i n c l u d e d . The f o l l o w i n g c l a s s e s and o r d e r s are r e p r e s e n t e d i n the samples. C l a s s CRUSTACEA Order Isopoda: T h i s order i s r e p r e s e n t e d e n t i r e l y by the s p e c i e s P o r c e l l i o scaber (sow bug). T h i s s p e c i e s i s completely absent from P l o t B, but made up an a p p r e c i a b l e percentage of the samples from P l o t A. The reason f o r t h i s i s unknown. C l a s s INSECTA Order Orthoptera: T h i s order i s represented by the f a m i l i e s L o c u s t i d a e and T e t t i g i d a e . L o c u s t i d a e makes up the g r e a t e s t percentage of the samples although a p p a r e n t l y i s not eaten by the very young c h i c k s . A p o s s i b l e reason may be the lack of movement in a stationary grasshopper which would not attract the chick's attention. In addition a grasshopper can leap several feet, thereby possibly placing i t s e l f beyond the range of site of a feeding chick. Lorenz (1943) states that a young raven is incapable of seeing a grasshopper until i t moves, suggesting that the above argument has some validity. However these findings are not consistent with those of Beer (1943) who found that Orthoptera made up 13 percent of the crop volume in June in Washington State blue grouse chicks. Order Homoptera; The families Membracidae,. Cie'adell-idae, and Aphididae made up the largest portion of this order. Order Hemiptera: Very few members of this group were collected in the samples. Order Coleoptera: (the beetles) Order Hymenoptera; The black and reddish-brown car-pender ant, members of the family Formicidae were the sole representatives of this order. The reddish-brown phase composed a large percentage of the samples from Plot B, and the black phase a large percentage on Plot A. Order Diptera: No attempt was made to classify the individuals belonging to this order. Order Lepidoptera: Here again the moths and butter-f l i e s made up a very small portion of the samples. Class AHACHNJ-DAt This class is abundantly represented on both Plots by the orders Araneae and Pseudoscorpionida. C l a s s MYRIAPODA: T h i s i s rep r e s e n t e d by the two s u b c l a s s e s Chilopoda ( c e n t i p e d e s ) and Diplopoda ( m i l l i p e d e s ) . LARVAE: A l l l a r v a e are lumped i n t o t h i s group. I t i s com-posed p r i m a r i l y of the l a r v a e from the i n s e c t orders Hymen-opt e r a , p a r t i c u l a r l y the f a m i l y T e n t h r e d i n i d a e , and L e p i d o p t e r a . Numbers of I n v e r t e b r a t e s In the f o l l o w i n g a n a l y s i s of i n v e r t e b r a t e numbers w i t h i n the samples, a l l samples have been grouped by P l o t s i n t o weekly averages. T a b l e V I I I i n d i c a t e s the weekly t r e n d i n numbers. Confidence l i m i t s of 95 percent are p l a c e d on the means (Snedecor, 1956). T a b l e V I I I Weekly Trend i n Average D a i l y Number of I n v e r t e b r a t e s per 45.2 square f e e t . PLOT A PLOT B Week' Aver. No. I n v e r t e b r a t e s No. of Samples Aver. No. I n v e r t e b r a t e s No. of Samples May 25-3.1 5.4 ± 1.0 31 9.0 ± 1.6 19 June 1-7 7.3 i 1.1 12 13.8 ± 1.5 23 June 8-14 8.7 ± 2.0 21 21.3 ± 3.2 20 June 15-21 7.8 + 1.6 24 18.9 ± 1.7 24 June 22-28 16.9 + 5.2 7 June 29-5 10.0 * 4.1 5 These r e s u l t s i n d i c a t e two p o i n t s . F i r s t , the abundance of i n v e r t e b r a t e s was c o n s i s t e n t l y g r e a t e r on P l o t B 38 than on P l o t A. T h i s d i f f e r e n c e i s v e r y r e a l as shown by c a l c u l a t i n g f o r the week June 8-14, a t of 3«5» The r e a son f o r t h i s d i f f e r e n c e i s not known. However, i t i s I n t e r e s t i n g to s p e c u l a t e on the causes by i n d i c a t i n g f i r s t t h a t P l o t B has a v e g e t a t i o n a l ground s u r f a c e cover (Veg.l) of 30 per-cent compared to 26 percent f o r P l o t A ( d i f f e r e n c e i s not s i g n i f i c a n t ) . T h i s v e g e t a t i o n i s i n most eases the food supply of many of the i n v e r t e b r a t e s , p a r t i c u l a r l y the members of O r t h o p t e r a . In a d d i t i o n , due to the s e v e r i t y of the B e a v e r t a i l F i r e on P l o t A, the organic matter i n the s o i l has been g r e a t l y reduced compared to t h a t of the s o i l on P l o t B which r e c e i v e d o n l y a s l i g h t b u r n i n g . T h i s o r g a n i c matter i s not o n l y b e n e f i c i a l to p l a n t growth but i s a l s o an important source of food f o r such i n v e r t e b r a t e s as P o r c e l l i o scaber and members of the f a m i l y F o r m i c i d a e . The second p o i n t i n d i c a t e d by T a b l e V I l i i s t h a t of a g e n e r a l b u i l d up i n the numbers of i n v e r t e b r a t e s over the p e r i o d of study; i n the case of P l o t A, from 5*4 to 10.0 per 45.2 square f e e t , and on P l o t B, from 9.0 to 21 .3 (June 8-14) and hence down to 16-9 by the t h i r d week of June. T h i s seems to i n d i c a t e a g r e a t e r p o t e n t i a l of i n v e r t e b r a t e p r o d u c t i v i t y on P l o t B, probably due i n p a r t to the same reasons c i t e d f o r the f i r s t p o i n t . To give a more comprehensive p i c t u r e to t h i s t r e n d i n numbers and to the d i f f e r e n c e i n o v e r a l l averages between 39 P l o t A and B, the weekly samples are broken down to show the percentage composition of the v a r i o u s r e p r e s e n t a t i v e groups. T h i s i s presented i n Table IX. Tabl e IX Average Weekly Percent Composition o f Samples to Show Trends of the D i f f e r e n t Groups over the P e r i o d of Study I n v e r t e b r a t e P l o t May June June June June 25-31 1-7 8-14 15-21 22-5 ORTHOPTERA A 53.0 41 .6 50.7 21.6 8.0 B 85.7 79.4 56.8 43.4 22.9 ISOPODA A 24 .9 7.6 6.7 8.2 6.0 FORMICIDAE A 4.2 5.0 3.1 20.1 18.0 B 1.1 4.7 7.1 23.7 ARACHNIDA A 6.5 29.4 22.7 17.1 62.0 B 5.6 4.3 15.5 6.8 30.5 DIPTERA A 1.0 6.1 3.8 5.6 B 1.7 1.1 2.3 MYRIAPODA A 0.6 0.6 2.0 B 2.7 0.5 0.2 LARVAE A 7.5 6.9 2.2 1.3 B 2.1 1.1 0.5 COLEOPTERA A 1.4 1.8 B 1.1 0.2 HEMIPTERA A 1.1 2.6 B 0.6 LEPIDOPTERA A 2.8 1.4 0.4 0.9 0.8 B 0.6 0.4 0.2 0.5 HOMOPTERA A 0.9 7.6 24 .0 4.0 B 0.6 11.5 8.8 40 .9 20.3 Members of the order Orthoptera make up the l a r g e s t 40 p o r t i o n of the samples throughout the e n t i r e sampling p e r i o d except d u r i n g the l a s t week o f June. By t h i s time grasshoppers have approached the a d u l t form, become l a r g e and more a c t i v e and hence l e s s prone to be caught. T h i s r e d u c t i o n i n sample composition f o r O r t h o p t e r a i s t h e r e f o r e a product of the sample and not n e c e s s a r i l y o f the range. Up u n t i l June, members of Homoptera, n o t a b l y the Cer-copidae, are s t i l l i n the " s p i t t l e mass" stage. T h e i r sub-sequent emergence i s shown by t h e i r i n c r e a s i n g composition i n the samples towards the end o f June. I t i s not u n t i l the l a s t weeks o f June t h a t the Formi-cideae group begin t o occupy an a p p r e c i a b l e percentage o f the samples. T a l b o t (1946) has shown t h a t the a c t i v i t y o f t h i s group i s l a r g e l y a f u n c t i o n o f temperature. I t t h e r e -f o r e appears t h a t the g e n e r a l r i s e i n e a r l y morning tempera-t u r e s over June ( P l o t A.: from 52°F on May 29 to 77°F on June 30) r e f l e c t s the i n c r e a s e i n the percentage o f t h i s group. E f f e c t o f M i c r o c l i m a t e on I n v e r t e b r a t e Abundance As p r e v i o u s l y mentioned, some mid-day samples were c o l l e c t e d t o assess not o n l y the i n f l u e n c e o f d a i l y v a r i a -t i o n s o f m i c r o c l i m a t e on o v e r a l l abundance, but a l s o i t s e f f e c t on the composition of the samples. F i g u r e 4 shows the l a t t e r r e l a t i o n s h i p between morning and mid-day samples on the t h r e e groups, Ort h o p t e r a , Formicidae, and A r a c h n i d a . Samples were taken between May 27 and June 7 and the z O 8 0 6 0 co O 4 0 o_ 2 O u I— 2 0 z u a. Q. ° LU O S 2 0 5 4 0 P L O T B M O R N I N G 1- ' . ' / . ' I M I D - D A Y A R A C H N I D A F O R M I C I D A E P L O T A O R T H O P T E R A F I G . 4 C O M P O S I T I O N O F M O R N I N G A N D M I D -DAY S A M P L E S , M A Y 2 7 - J U N E 1, 1958 41 percentages r e p r e s e n t the averages d u r i n g t h a t p e r i o d . From F i g u r e 4, i t i s evi d e n t t h a t o f the thr e e groups temperature changes appear t o have the g r e a t e s t i n f l u e n c e on the members o f the f a m i l y Formicidae, and the l e a s t i n f l u e n c e on members of the c l a s s A r a c h n i d a . C l a r k (1949) found t h a t the l o c u s t , C h o r t o i c e t e s t e r m l n i f e r a , was i n a s t a t e o f d i s -a b i l i t y due t o c o l d a t a temperature o f 36°F. Between 36°F and 68°F, the l o c u s t g r a d u a l l y became more a c t i v e u n t i l even-t u a l l y a "preferendum" was reached around 107°F. The r e s u l t s o f c o r r e l a t i n g o v e r a l l changes i n i n v e r t e -b r a t e abundance w i t h changes i n temperature and humidity taken at the time the samples were c o l l e c t e d are pres e n t e d i n Table X ., Ta b l e X The R e l a t i o n s h i p between Changes i n Cl i m a t e and Average D a i l y Number of I n v e r t e b r a t e s between S u c c e s s i v e Days Expressed as a Percentage of the T o t a l o f the Three P o s s i b l e E f f e c t s ; P o s i t i v e E f f e c t , Inverse E f f e c t and No E f f e c t . Type o f E f f e c t Temp. Humidity Average P o s i t i v e 41 % 50 % 46 £ Inverse 34 42 38 No E f f e c t 25 8 16 There appears t o be some d i r e c t i n f l u e n c e o f temper-atur e and humidity on the abundance of i n v e r t e b r a t e s . The i n v e r s e e f f e c t o f c l i m a t e (an i n c r e a s e i n temperature o r humid i t y p r o d u c i n g a decrease i n the average abundance o f 42-i n v e r t e b r a t e s , or the converse) i s s l i g h t l y l e s s than the p o s i t i v e e f f e c t of c l i m a t e (an i n c r e a s e i n temperature o r h umidity producing an i n c r e a s e i n the abundance o f i n v e r t e -b r a t e s ) . However, the t o t a l d i r e c t i n f l u e n c e s of changes i n temperature and humidity p r o d u c i n g changes i n the numbers of I n v e r t e b r a t e s between s u c c e s s i v e days was e f f e c t i v e 84 p e r -cent of the time. The remaining 16 p e r c e n t of the cases showed no e f f e c t whatsoever. I t appears t h e r e f o r e , t h a t c l i m a t e not o n l y produced changes i n the composition of the i n v e r t e b r a t e samples, but a l s o some s l i g h t e f f e c t s on the o v e r a l l abundance of the i n v e r t e b r a t e s as i n d i c a t e d by the samples. However, i t was a l s o shown t h a t no s t a t i s t i c a l d i f f e r e n c e e x i s t s i n the a v a i l a b l e i n v e r t e b r a t e food supply (expressed as numbers only) between the morning and evening sampling p e r i o d s . Weight o f I n v e r t e b r a t e s As p r e v i o u s l y mentioned, the c o n t r i b u t i n g weight of members of the O rder O r t h o p t e r a have been excluded i n c a l c u l -a t i n g the f i n a l f i g u r e r e p r e s e n t i n g the a v a i l a b l e i n v e r t e b r a t e food, s i n c e i t s i n d i v i d u a l s were found to be completely absent i n the crops of the c h i c k s up to f o u r weeks o f age. Weight data are grouped on a weekly b a s i s by P l o t s , t h e r e f o r e g i v i n g a more s i g n i f i c a n t sample (as w e l l as a r e d u c t i o n of the standard e r r o r o f the mean) on which the 43 subsequent c a l c u l a t i o n s are based. T h i s grouping of the d a i l y samples i n t o a week p e r i o d was co n s i d e r e d v a l i d s i n c e any major v a r i a b i l i t y i n weight between the samples should not be e x c e s s i v e l y masked. An a d d i t i o n a l reason i s f o r the sake of convenience i n c a l c u l a t i n g the amount of a v a i l a b l e food. Frequency d i s t r i b u t i o n s of the samples w i t h i n the v a r i o u s weeks are shown i n F i g u r e 5« I t i s immediately evident t h a t the weights f a l l i n t o extremely skewed d i s t r i b u t i o n s . Rather than d e a l w i t h the data as sue, which would i n v o l v e t r a n s f o r m a t i o n s and long complex c a l c u l a t i o n s , the i n d i v i d u a l d a i l y samples were a r b i t r a r i l y grouped i n t o p a i r e d sums. Any ex t r a v alue was d i s c a r d e d . T h i s i s a common s t a t i s t i c a l method i n e l i m i n a t i n g c o ntagion, though not always s u c c e s s f u l . T h i s r e s u l t s i n a mean value r e p r e s e n t i n g weight of i n v e r t e -b r a t e s per 10 minutes r a t h e r than the o r i g i n a l 5 minute i n t e r v a l . P l o t t i n g the r e s u l t i n g frequency d i s t r i b u t i o n i n F i g u r e 6 r e v e a l s r e l a t i v e l y improved symmetrical curves. I t i s f e l t t h a t t h i s symmetry, w h i l e not f i t t i n g the "normal curve" p r e c i s e l y i n i t s e n t i r e l y , i s s a t i s f a c t o r y f o r the a p p l i c a t i o n o f "normal" s t a t i s t i c s . The succeeding c a l c u -l a t i o n s , t h e r e f o r e , are based on the frequency d i s t r i b u t i o n s p l o t t e d i n F i g u r e 6. T a b l e XI shows the d a i l y average weights of i n v e r t e b r a t e s by weeks from May 25 to the f i r s t week i n J u l y on P l o t s A and B. MAY 25-31 P L O T A J U N E 1—7 J U N E 8 - 1 4 J U N E 15-21 _ i i i i _ 15 30 45 60 75 <T0 W E I G H T C L A S S E S ( M I L L I G R A M S ) P L O T B i— z LU u a. LU a _ i i I u J I I L FIG. 5 D I S T R I B U T I O N O F W E I G H T S M A Y 2 5 - 3 1 U z UJ o UJ cr u. IX> 4 0 4 0 W 100 H O P L O T A J U N E I — 7 J U N E 8 - 1 4 J U N E 1 5 - 2 1 .J i_ WEIGHT C L A S S E S ( M I L L I G R A M S ) P L O T B _ l I I I L F I G . 6 D I S T R I B U T I O N O F I N V E R T E B R A T E W E I G H T S . ( P A I R E D S U M S ) 44 T a b l e XI D a i l y Mean Weight o f I n v e r t e b r a t e s ( m i l l i g r a m s p e r 10 minutes) Week P l o t A P l o t B Mean Weight Samples Mean Weight Samples May 25-31 June 1-7 June 8 -14 June 15-21 June 22-28 June 29-5 52.9 + 10.9* 15 48.1 + 16.5 6 64.5 ± 22.9 10 47.6 + 15.7 12 33.0 + 13.6 2 47.6 + 18.9 9 55.4 + 17.4 11 88.2 + 22.6 10 77.2 + 16.7 12 84.7 ± 6.6 3 Average 53.2 + 8.0 45 67.I + 11.3 45 These r e s u l t s i n d i c a t e a wide v a r i a n c e on p r a c t i c a l l y a l l the mean weights. In the case o f the l a s t week i n both P l o t s , o n l y two and th r e e samples were a v a i l a b l e , y e t the mean d a i l y weight was r e l a t i v e l y low. To t e s t whether the v a r i a t i o n expressed f o r the mean d a i l y weights f o r each week i s r e a l o r simply due t o sampling e r r o r , an a n a l y s i s o f v a r -i a n c e was c a l c u l a t e d f o r the f i r s t f o u r weeks. These r e s u l t s are p resented i n T a b l e s XI!" and XHIfor P l o t s A and B r e s p e c t -i v e l y . From these a n a l y s e s o f v a r i a n c e , i t i s c l e a r l y i n d i c a t e d t h a t the expressed v a r i a t i o n between the mean weights f o r each week i s not r e a l and t h e r e f o r e due p r i m a r i l y t o sampling e r r o r . S ince no s i g n i f i c a n t v a r i a t i o n e x i s t s between the weeks o f each P l o t , i t i s p e r m i s s i b l e t o group 95 $ c o n f i d e n c e l i m i t s about the mean. 45 a l l weekly means to g i v e a mean estimate of i n v e r t e b r a t e weight t h a t would apply to any p e r i o d d u r i n g the f i r s t f o u r weeks. T h i s mean weight i s gi v e n f o r both p l o t s i n Tab l e X I I I . T a b l e XII A n a l y s i s of Variance f o r P l o t A Source of E r r o r Sum Squares df Mean Square Between Weeks Between Samples T o t a l 16.81.16 25941.98 27623.59 3 39 42 560.64 665.17 F = 0.84 (0.01 l e v e l of confidence) T a b l e X I I I A n a l y s i s of Va r i a n c e f o r P l o t B Source of E r r o r Sum Squares df Mean Square Between Weeks Between Samples T o t a l 11105.62 48777.31 59882.93 3 38 41 3701.87 1283.61 F = 2.88 (0.01 l e v e l of confidence) In a d d i t i o n , t o determine whether t h e r e i s any s i g -n i f i c a n c e i n the d i f f e r e n c e s between corresponding weekly means of each P l o t , t t e s t s of s i g n i f i c a n c e are a p p l i e d . The r e s u l t s of the t e s t s are g i v e n i n Table XIV. Here aga i n at the 0.01 l e v e l of co n f i d e n c e , there are no r e a l d i f f e r e n c e s . However at the 0.05 l e v e l , there i s a s l i g h t s i g n i f i c a n t d i f f e r e n c e d u r i n g the week June 15-21. The use of the 0.01 l e v e l of confidence i s c o n s i s t e n t w i t h the h i g h degree of 46 Table XIV Test of D i f f e r e n c e ( t ) Between Average I n v e r t e b r a t e Weights on P l o t s A and B ( 0 . 0 1 l e v e l of c o n f i d e n c e ) . Week t df May 25-31 0 . 5 1 22 not s i g n i f . June 1-7 0 . 5 3 15 it June 8-14 0 . 8 5 18 it June 15-21 2.58 22 tt v a r i a t i o n about the means. From these r e s u l t s , i t i s evi d e n t t h a t the a v a i l a b l e i n v e r t e b r a t e abundance i n terms of weight i s f a i r l y c o n s i s -t e n t throughout the p e r i o d of t h e i r g r e a t e s t importance to the blue grouse c h i c k s . In both P l o t s , peak abundance appears to e x i s t d u r i n g the second week of June. However s t a t i s t i c a l a n a l y s i s has shown t h a t t h i s d i f f e r e n c e i s due p r i m a r i l y to sampling e r r o r , and should not be construed to be a product of the range. In a d d i t i o n d u r i n g the same week, P l o t B appears to e x h i b i t a g r e a t e r abundance of a v a i l a b l e i n v e r t e -b r a t e s than i s evident on P l o t A. T h i s d i f f e r e n c e w h i l e t e s t i n g s i g n i f i c a n t at the 0 . 0 5 l e v e l of c o n f i d e n c e i s below s i g n i f i c a n c e at the 0 . 0 1 l e v e l . There are two apparent reasons why the weekly means gives an appearance of approaching a maximum as the sampling p e r i o d p r o g r e s s e s . F i r s t , the i n v e r t e b r a t e s themselves i n c r e a s e i n s i z e and weight f o l l o w i n g s u c c e s s i v e moultings (as w e l l as a s l i g h t i n c r e a s e i n numbers, TablevirO. A c t u a l c o l l e c t e d data d e s c r i b i n g t h i s are scanty. However, on e x t r a c t i n g members of the order Orthoptera from the t o t a l v/eight of samples, average weights were c a l c u l a t e d f o r L o c u s t i d a e . During the l a s t week of May the average weight of one i n d i v i d u a l was 2.7 m i l l i g r a m s compared to 4.0 i n the f i r s t two weeks of June. T h i s r e p r e s e n t s approximately a 33 percent i n c r e a s e . The second reason may be a t t r i b u t e d to an i n c r e a s i n g sampling e f f i c i e n c y . One of the assumptions u n d e r l y i n g the past c a l c u l a t i o n s i s t h a t sampling e f f i c i e n c y of the observer would remain constant throughout the p e r i o d of sampling. However t h i s i s u n l i k e l y . I t i s q u i t e probable t h a t the observer's e f f i c i e n c y i n c r e a s e d to a s u s t a i n e d l e v e l d u r i n g the f i r s t week of sampling and then remained constant f o r the r e s t of the p e r i o d . Hoglund (1955) has shown t h a t C a p e r c a i l l z i e c h i c k s are f i r s t i n f l u e n c e d i n the i n s t i n c t i v e hunt f o r food by movement and c o l o r , green being the most a t t r a c t i v e and b l a c k the most repugnant. However t h e i r e f f i c i e n c y i n pecking was g r e a t l y reduced d u r i n g the f i r s t few days due to the weakness of t h e i r beaks. As mentioned on pages 13 and 14, an attempt was made to convert the i n v e r t e b r a t e s per 5 minutes to an area d e n s i t y f a c t o r . The mean area covered i n t e n measured f i v e minute search samples was 45.2 square f e e t w i t h a standard e r r o r of 0.49 and a 95 percent confidence i n t e r v a l o f 1 square f o o t . C o n v e r t i n g to 10 minute samples gives an estimate of 90.4 48 square f e e t w i t h a conf i d e n c e i n t e r v a l of 2 square f e e t or approximately 2 percent of the mean. R e l i a b i l i t y of I n v e r t e b r a t e Sampling Method At t h i s p o i n t i t i s necessary to c o n s i d e r the r e l i a b i l i t y of the i n v e r t e b r a t e sampling method as a technique f o r e s t i m a t i n g the amount of animal foods a v a i l a b l e t o the blue grouse c h i c k s . T h i s must be done i n order to j u s t i f y any c o n c l u s i o n s which would be based on the a n a l y s i s o f these samples. E s s e n t i a l l y , t h e r e are two ques t i o n s t h a t must be answered. F i r s t , i s the sampling method measuring, e i t h e r c l o s e l y or approximately, the types of i n v e r t e b r a t e s eaten by the blu e grouse c h i c k s , that i s , i s the use of the words " a v a i l a b l e f o o d s " a p p l i c a b l e t o t h i s technique of measure-ment? Second, does the accuracy of the sampling method j u s t i f y a s t a t e d r e l i a b l e estimate of the weight of i n v e r t e -b r a t e s per u n i t area? With r e s p e c t to the f i r s t q u e s t i o n , a comparison between the " c a t c h " of the samples over the p e r i o d of study, and the contents of the crops of the c h i c k s during the same p e r i o d , would i n d i c a t e the f i r s t p o i n t . T h i s i s done by com-p a r i n g the frequency of occurrence of the r e s p e c t i v e i n v e r t e -b r a t e groups i n the crops of the c h i c k s w i t h the occurrence i n the samples. The f r e q u e n c i e s are expressed as percentages 49 f o r comparative purposes. The r e s u l t s of t h i s assessment are shown i n T a b l e XV. T a b l e XV The R e l a t i o n s h i p of Percent Frequency of Occurrence Between the Chick Crops and I n v e r t e b r a t e Samples, P l o t s A and B Combined. (June 1 - J u l y 5) % Frea uency of Occurrence Animal Crops D a i l y Sample One H a l f Sample Isopoda 40 38 32 Homoptera 50 100 68 Hemiptera 5 8 3 C o l e o p t e r a 25 31 18 F o r m i c i d a e 90 94 80 D i p t e r a 20 69 38 L e p i d o p t e r a 5 31 26 Arachnida 10 100 94 Myriapoda 5 13 3 Larvae 60 31 24 The D a i l y Sample column expresses the frequency of occurrence out of each t o t a l d a i l y sample (sum of a l l the 45.2 square f o o t samples i n one day). The One H a l f Sample column i n d i c a t e s t h a t the t o t a l d a i l y sample has been d i v i d e d i n t o two groups of equal number, g i v i n g twice the number of samples over the p e r i o d of study from which to c a l c u l a t e the occurrence of i n v e r t e b r a t e s . 50 T h i s comparison i n d i c a t e s t h a t the i n v e r t e b r a t e sampling technique has been a r e l i a b l e method f o r e s t i m a t i n g the abundance of the major animal foods of the blue grouse c h i c k . However, one major group, the m i s c e l l a n e o u s l a r v a e , d i d not occur as f r e q u e n t l y i n the samples as they d i d i n the c h i c k c r o p s . In f a c t c h i c k s were f i n d i n g l a r v a e twice as f r e q u e n t l y as the sampling observer. T h i s suggests t h a t the sampling method i s l e s s e f f i c i e n t as f a r as the l a r v a e are concerned. However t h i s f a c t can be r e c o n c i l e d by i n d i c a t i n g t h a t l a r v a e , d u r i n g June 15 - 21, 1958, composed only an average of 13 percent of the volume of the crop contents. Other groups, such as Arachnida and L e p i d o p t e r a , o c c u r r i n g more f r e q u e n t l y i n the samples than i n the crops suggested e i t h e r t hat the e f f i c i e n c y of the sampling observer w i t h r e s p e c t to these groups, was probably s l i g h t l y b e t t e r than t h a t of the c h i c k or t h a t i t was l e s s d i s c r i m i n a t i n g . In a d d i t i o n , the zone of a v a i l a b i l i t y was c o n s i d e r e d to be a c u b i c measurement. Yet the q u a n t i t y of i n v e r t e b r a t e s has been expressed as so much per u n i t a r e a . T h i s i s con-s i d e r e d v a l i d s i n c e most of the i n v e r t e b r a t e s were c o l l e c t e d from the ground s u r f a c e , o n l y a few being found on the v e g e t a t i o n . The second q u e s t i o n can be answered by examining the v a r i a b i l i t y about the mean estimates of the weight of a v a i l a b l e i n v e r t e b r a t e s . I t was o r i g i n a l l y estimated t h a t from 6 to 10 d a i l y samples would give a mean value f o r the number of i n v e r t e b r a t e s per u n i t area that would l i e w i t h i n 15 percent of the mean (page 14<K From T a b l e X I I I , the mean weight of i n v e r t e b r a t e s per 90.4 square f e e t has, at any time over the study p e r i o d , 9 5; ;P ercent c o n f i d e n c e l i m i t s of 15*4 percent f o r P l o t A and 16.8 percent f o r P l o t B. T h i s suggests t h a t the number of d a i l y samples was q u i t e s a t i s f a c t o r y f o r the c a l c u l a t e d estimates of the average weights of i n v e r t e -b r a t e s . T h e r e f o r e , i t can be concluded t h a t the sampling method employed i n e s t i m a t i n g the weight of i n v e r t e b r a t e s on the study area appears to be f a i r l y r e l i a b l e as a technique f o r d etermining the abundance of i n v e r t e b r a t e s a v a i l a b l e t o t h e v b l u e grouse c h i c k s . AVAILABLE PLANT FOOD One instantaneous s e r i e s of samples was taken on both P l o t s i n the l a s t week of June i n order to assess the p l a n t food a v a i l a b l e to blue grouse c h i c k s . T h i s c o n s i s t e d of twenty 25 f o o t square samples, taken s y s t e m a t i c a l l y on both P l o t s . From each sample p l o t a l l e d i b l e p l a n t m a t e r i a l was c o l l e c t e d from ground l e v e l to one f o o t above the ground. I t has been suggested by v a r i o u s authors t h a t a shortage of p l a n t food i n the s p r i n g i s an extremely r a r e occurrence w i t h r e s p e c t to g a l l i n a c e o u s b i r d s (Edminster 1947, Bump et a l 1947» Stokes no d a t e ) . I t was f e l t t h a t an estimate at t h i s time (when the d i e t of the c h i c k s i s changing from predominantly animal to predominantly p l a n t m a t e r i a l ) would give an i n s i g h t i n t o whether t h i s s u g g e s t i o n was v a l i d i n the case of blue grouse. As a r e s u l t of an a n a l y s i s of the c o l l e c t e d p l a n t m a t e r i a l , t h e r e appears to be an adequate supply of p l a n t foods a v a i l a b l e during t h i s p a r t i c u l a r p e r i o d . In a d d i t i o n , t h i s estimate can be presumed to be very c l o s e to the minimum amount a v a i l a b l e , s i n c e f u r t h e r r i p e n i n g of b e r r i e s and seeds had yet to take p l a c e . T a b l e XVI i n d i c a t e s the average dry weight of p l a n t foods per 25 square f e e t on each P l o t . The average t o t a l d ry weight of p l a n t food ( w i t h 95 percent confidence l i m i t s ) are as f o l l o w s : (grams/25 s q . f t . ) P l o t A P l o t B 6.64 ± 1.05 7.58 £ 1?79 52 S O £ 40 O LU < 30 L L O z LU U cr LU Q. 20 £51 P L O T A I | P L O T B S A L I X H Y P O C H A E R I S L V S . F L S . S A L A L M A H O N IA B R A C K E N R U B U S F I G . 7. P E R C E N T C O M P O S I T I O N O F M A J O R P L A N T F O O D S IN S A M P L E S . 53 T a b l e XVI Average Dry Weight of P l a n t Foods During Last Week of June. (Grams per 25 s q . f t . ) Occurrence i n 20 p l o t s Average Dry Weight A B A B S a l i x app. ( I v s ) 8 11 0.86 3.04 Hypochaeris r a d i c a t a ( l e a v e s ) ( f l o w e r s ) 17 17 20 18 0.80 0.47 1.43 1.33 G a u l t h e r i a s h a l l o n ( f l o w e r s & f r u i t ) 12 13 0.52 0.48 Rubus spp. ( f r t . ) 5 4 0.23 0.16 Mahonia nervosa ( f r t . ) 3 7 0.14 0.51 Senecio spp. ( I v s . ) 3 6 0.03 0.11 P t e r i d i u m a q u i l i n u m ( f r o n d s ) 17 5 3.57 0.52 Rosa spp. ( f r t . ) 1 0.03 No s i g n i f i c a n t d i f f e r e n c e e x i s t s between the two P l o t s w i t h r e s p e c t to the average dry weights of a v a i l a b l e p l a n t foods ( t = 0.91, d f = 38, 0.05 l e v e l of c o n f i d e n c e . ) T h i s means t h a t both P l o t s c o n t a i n on the average the same a v a i l a b l e weight of p l a n t f o od. To give a more comprehensive p i c t u r e of the r e l a t i v e abundance of the v a r i o u s s p e c i e s of p l a n t foods on the two P l o t s , the percent composition by weight of the major p l a n t s i s given i n F i g u r e 7. Bracken fronds by f a r make up the g r e a t e s t percentage of the weight i n P l o t A, and s i m i l a r l y S a l i x spp. leaves i n P l o t B. However, between the two P l o t s most of the d i f f e r e n c e s are s l i g h t , w i t h the average o v e r a l l weight of the p l a n t foods being r e l a t i v e l y the same. 54 NUTRIENT ANALYSIS OF THE CHICK FOODS  In v e r t e b r a t e s As d i s c u s s e d on page 16, the proximate m i c r o a n a l y s i s of the i n v e r t e b r a t e foods was done a c c o r d i n g to "Methods of A n a l y s i s of the A s s o c i a t i o n of O f f i c i a l A g r i c u l t u r e Chemists", 1950* T o t a l carbohydrate was determined by t a k i n g the d i f f e r -ence between 100 and the sum of p r o t e i n , f a t , and ash. How-ever f o r purposes of e s t i m a t i n g the d i g e s t i b i l i t y of the i n v e r t e b r a t e foods, i t was necessary to have an estimate of the two p o r t i o n s of the carbohydrate f r a c t i o n , crude f i b e r and n i t r o g e n - f r e e e x t r a c t . T h i s was estimated by examining the r a t i o of these two carbohydrate components as r e p o r t e d by s e v e r a l authors who have done proximate analyses on the same groups of i n v e r t e b r a t e s ( B i r g e 1922, P h i l l i p s and Brockway 1954, Embody and Gordon 1924, Beck and Beck 1955). A d i s c u s s i o n of the "proximate a n a l y s i s " i s given i n Crampton (1956). The d e t e r m i n a t i o n of the m e t a b o l i z a b l e energy v a l u e of the i n v e r t e b r a t e s ( f o r purposes of e s t i m a t i n g the amount of f r e s h food e a t e n by the c h i c k , n e c e s s i t a t e s knowledge of the d i g e s t i b l e p o r t i o n of the p r o t e i n , f a t , and carbohydrate c o n s t i t u e n t of the foods. As i n d i c a t e d on page 18, the d i g e s t i b l e p o r t i o n of each n u t r i e n t i s then m u l t i p l i e d r e s p e c t i v e l y by 4, 9, and 4 ( p r o t e i n , f a t , carbohydrate) t o g i v e the t o t a l m e t a b o l i z a b l e energy of the food (Ewing, 195D* T i t u s (1949) gives a l i s t of foods of animal o r i g i n and the d i g e s t i b i l i t y i n the c h i c k e n of t h e i r component n u t r i e n t s . These were averaged to give the approximate r e l a t i v e d i g e s t i b i l i t y of animal p r o t e i n , f a t , and carbohydrate. However arthropods possess a c u t i c l e composed of p r o t e i n s and c h i t i n , a nitrogenous p o l y s a c c h a r i d e , i n d i g e s t i b l e i n the v e r t e b r a t e s ( P r o s s e r et a l , 1950). Tsao and Richards (1952) have found the percentage of c h i t i n i n v a r i o u s r e p r e -s e n t a t i v e i n s e c t s , both l a r v a l and a d u l t forms. A d u l t s on the average contained approximately 6 percent c h i t i n (per t o t a l dry weight) and l a r v a e contained o n l y 4 percent. T h e r e f o r e i t was necessary t o s u b t r a c t t h i s i n d i g e s t i b l e p o r t i o n from the t o t a l d i g e s t i b l e n i t r o g e n - f r e e e x t r a c t p o r t i o n of the carbohydrates r e p o r t e d by T i t u s . In Tab l e XVII the average d i g e s t i b i l i t y i s given f o r foods of animal o r i g i n ( i n c l u d i n g the removal of the i n d i g e s t i b l e c h i t i n ) and f o r s e v e r a l green p l a n t foods. The l a t t e r w i l l be used i n determining the m e t a b o l i z a b l e energy of the p l a n t foods. T a b l e XVII Average D i g e s t i b i l i t y ( p e r c e n t ) i n the Chicken of Products of Animal O r i g i n and of Green Feeds (from T i t u s , 1949). N u t r i e n t Category Animal Foods P l a n t Foods P r o t e i n 85 65 F a t 84 55 Nitrogen-Free E x t r a c t 66 68 ( A d u l t s ) (Larvae) 65 Crude F i b e r 20 (Crampton, 1956) 32 56 The r e s u l t s of the proximate a n a l y s i s , and the estimate of the d i g e s t i b l e p o r t i o n of each n u t r i e n t category are g i v e n f o r each i n v e r t e b r a t e group i n Tab l e XVIII. Table XVIII Proximate A n a l y s i s of I n v e r t e b r a t e s from P l o t s A and B i n Percent Dry Weight. Nitrogen-Free E x t r a c t and F i b e r E s t i m a t e d . N u t r i e n t Compos sit i o n # D i g e s t i b l e P o r t i o n Animal P F a t NFE F Ash P F a t NFE F Isopoda 62.8 2.9 19.1 9.2 6.0 5.3.4 2.4 12.6 1.8 Orthoptera 73.8 2.2 10.0 10.0 4 . 0 62.7 1.9 6.6 2.C Homoptera 73.3 3.8 9.8 9.8 3.3 62.2 3.2 6.5 2.0 C o l e o p t e r a 70.6 4 .6 17.6 4.1 3.1 60.0 3.9 11.6 0.8 Formicidae 66.8 2.9 23.7 4 . 0 2.6 56.8 2.4 15.6 0.8 D i p t e r a 60.9 3.4 23.8 5.9 6.0 51.7 2.9 ' 15.7 1.2 Arachnida 73.9 2.9 16.8 3.0 2.4 62.8 2.4 11.1 0.6 Larvae 76.5 6.4 6.0 6.0 5.1 65.0 5.4 4 .1 1.2 # P - P r o t e i n , NFE • Nitrogen-Free E x t r a c t , F = Crude F i b e r . The average m e t a b o l i z a b l e energy of the i n v e r t e b r a t e foods on a moisture f r e e b a s i s i s 3.11 ± 0.10 C a l o r i e s per gram. C o n v e r t i n g to a value e x p r e s s i v e of the i n v e r t e b r a t e s i n a f r e s h s t a t e y i e l d s 0.91 - 0.03 C a l o r i e s per gram. T h i s i s much lower than that of the a r t i f i c i a l c h i c k s t a r t e r s which are around 2.2 C a l o r i e s per gram and c o n t a i n about 10 percent moisture. M i s c e l l a n e o u s l a r v a e y i e l d not o n l y the h i g h e s t p r o t e i n content but a l s o the h i g h e s t m e t a b o l i z a b l e energy v a l u e . T h i s i s due to the higher p r o t e i n content and to the r e l a t i v e l a c k 57 of c h i t i n i n the c u t i c l e compared to t h a t i n the a d u l t i n s e c t s . P l a n t Foods The n u t r i t i v e a n a l y s i s of the v a r i o u s p l a n t foods was performed by the same methods used f o r the i n v e r t e b r a t e s . Here again f o r purposes of c a l c u l a t i n g d i g e s t i b i l i t y and m e t a b o l i z a b l e energy o f the foods i t was necessary to c o n s u l t the l i t e r a t u r e f o r estimates o f the two carbohydrate f r a c t i o n s , crude f i b e r and n i t r o g e n - f r e e e x t r a c t . In the case of bracken, these v a l u e s were obtained from Moon and P a l (1949). F o r the remaining p l a n t s i t was necessary to p l o t the percentage of p r o t e i n a g a i n s t the percentage of crude f i b e r f o r a l a r g e number of p l a n t s i n c l u d i n g a l l of those eaten by the blue grouse c h i c k s . For the g i v e n percentage of p r o t e i n the corresponding per-centage of crude f i b e r c o u l d then be determined. Chemical composition of the s e v e r a l p l a n t s p e c i e s were obtained from the f o l l o w i n g sources: M i l l e r (1958), R u s s e l (1947), Schneider (1947), Spinner and Bishop (1950), Beck and Beck (1950). The average d i g e s t i b i l i t y of the p l a n t s was a p p r o x i -mated from T i t u s (1949) and presented i n T a b l e XVII. The r e s u l t s of the n u t r i t i o n a l a n a l y s i s of the p l a n t foods i s give n i n T a b l e XIX. These r e s u l t s show that i n the p l a n t foods, the p r o t e i n content i s much l e s s than i n the i n v e r t e b r a t e s , but the carbohydrate percentage i s i n c r e a s e d a c c o r d i n g l y . The average m e t a b o l i z a b l e energy v a l u e f o r the p l a n t s (dry weight) i s 2.18 + 0.02 C a l o r i e s per gram and as f r e s h m a t e r i a l 0.57 ^ 0.006 C a l o r i e s per gram. 58 In a d d i t i o n to the r e d u c t i o n i n p r o t e i n composition of the p l a n t s p e c i e s t h e r e i s a corresponding r e d u c t i o n i n the m e t a b o l i z a b l e energy on an average f r e s h b a s i s due to the r e l a t i v e l y h i g h moisture content of the p l a n t s . T a b l e XIX N u t r i e n t Composition and Estimated D i g e s t i b i l i t y of P l a n t Foods from P l o t s A and B. Crude F i b e r and N i t r o g e n F r e e E x t r a c t are Estimated. (Percent Dry Weight) N u t r i e n t Composition D i g e s t i b l e P o r t i o n P l a n t P F a t F NFE Ash P F a t F NFE S a l i x ( l v s ) 8.8 2.6 21.0 60.2 7.4 5.7 1.4 6.7 39.1 Hvpochaeris ( l v s ) 10.9 4.4 18.0 50.8 15.9 7.1 2.4 5.8 33.0 ( F l s ) 14 .4 5.4 14 .0 53.5 12.7 9.4 3.0 4.5 34.8 G a u l t h e r i a ( f l s & f r t ! 9.2 2.0 20.0 63.8 5.0 6.0 1.1 6.4 41 .5 Mohonia(frt: 12.5 1.7 16.0 62.4 7.4 8.1 0.9 5.1 40 .5 R u b u s ( f r t ) 13.4 1.4 15.0 64.3 5.9 8.7 0.8 4.8 41 . 8 P t e r i d i u m ( f r o n d s ) 12.9 2.4 27.0 49 .2 8.5 8.4 1.3 8.6 32.0 Senecio ( l v s ) 10.9 6.1 18.0 51.1 13-9 7.1 3.4 5.8 33.2 I t should be p o i n t e d out t h a t changes i n n u t r i t i v e values i n v e g e t a t i o n occur over r e l a t i v e l y s h o r t p e r i o d s of time, the g r e a t e s t d i f f e r e n c e s o c c u r r i n g between seasons, but w i t h some changes even between months (Cowan et a l , 1950; Hellmers, 1940). Another f a c t o r a f f e c t i n g n u t r i t i v e changes i s t h a t of the moisture content of the l i v i n g p l a n t . T h i s would depend on the c l i m a t e , time of day sampling o c c u r r e d , and 59 how q u i c k l y wet weights were measured. Consequently, the use of the m e t a b o l i z a b l e energy values of the v e g e t a t i o n i n c a l c u l a t i n g the a v a i l a b l e range energy f o r c h i c k p r o d u c t i o n i s a p p l i c a b l e o n l y w i t h i n a short time p e r i o d , p r e f e r a b l y not more than a month. The A v a i l a b l e Food From the preceding r e s u l t s of sampling, i t i s p o s s i b l e to estimate the amount of both i n v e r t e b r a t e and p l a n t foods on a l a r g e area s i m i l a r to the study P l o t s . T h i s i s done both i n terms of the m e t a b o l i z a b l e energy and as f r e s h a v a i l a b l e grams of food. These estimates are g i v e n i n Tables XX and XXI. Table XX A v a i l a b l e Energy and Grams of Food S u p p l i e d by In v e r t e b r a t e s During June, 1958. Week P l o t A P l o t B Gm./acre C a l . / a c r e dry dry f r e s h Gm./acre C a l . / a c r e dry d r y f r e s h May 25-31 June 1-7 June 8-14 June 15-21 June 22-28 June 29-5 22.5 + 20$ 70.0 30.5 23.2 ± 34$ 72.1 21.1 31.1 ± 35$ 96.6 28.3 22.9 ± 33$ 71.2 20.8 15.9 ± 41$ 49.4 14 .5 22.9 ± 40$ 71.3 20.8 26.7 t 31$ 83.0 24 .3 42.4 + 26$ 131.8 38.6 37.2 ± 22$ 115.5 33.8 40 .8 ± 8$ 124.2 37.1 Average 25.6 + 15$ 71.9 21.0 32.2 i 17$ 105.2 30.9 T a b l e XXI Average A v a i l a b l e Energy and Weight S u p p l i e d by P l a n t s P l o t A P l o t B Average Grams/acre (dry) 11570 + 16$ 13210 + 24$ 12390 + 14$ ( f r e s h ) 32900 " 37600 35250 " S a l . / a c r e (dry) 25220 28790 27000 ( f r e s h ) 6590 7540 7060 60 Confidence i n t e r v a l s of 95 percent are p l a c e d on the estimates of a v a i l a b l e grams per acre of food. An e r r o r of 2 percent i s present on the estimate of acreage due to the c o n v e r s i o n of grams per t e n minutes to grams per acre. However i n view of the l a r g e r sampling e r r o r s , t h i s 2 percent i s n e g l i g i b l e and can be i g n o r e d . S i m i l a r l y i n e s t i m a t i n g the a v a i l a b l e m e t a b o l i z a b l e energy per acre, a comparable e r r o r of 3 percent occurs on the energy val u e s of the i n v e r t e b r a t e foods. I t a l s o can be n e g l e c t e d . GROWTH OF BLUE GROUSE CHICKS The growth of an organism i s an extremely c o m p l i c a t e d process i n v o l v i n g an i n c r e a s e i n s i z e , i n mass, and a complete and c o o r d i n a t e d development of a l l i t s p a r t s . The p h y s i o l o g y of growth and the i n t e r r e l a t i o n s h i p s concerned are o n l y s l i g h t l y understood today. D e s c r i p t i o n s of growth and attempts to e x p l a i n i t , both q u a n t i t a t i v e l y and q u a l i t a t i v e l y , have f i l l e d the l i t e r -a ture s i n c e the e a r l y p a r t of the century. P e a r l and Reed (1920) were i n s t r u m e n t a l i n a p p l y i n g mathematical f o r m u l a t i o n to both i n d i v i d u a l and p o p u l a t i o n growth. They proclaimed the l o g i s t i c r e p r e s e n t a t i o n the "law of growth". However, the b a s i c assumptions of t h i s mathematical curve have ye t to achieve v a l i d i t y w i t h i n b i o l o g i c a l r e a l i t y ( F e l l e r 1940, Sang 1950). The d e s c r i p t i o n of i n d i v i d u a l growth g i v e n by Brody (1927 and 1945) and m o d i f i e d by von B e r t a l a n f f y (1938) by a simple a l g e b r a i c t r a n s f o r m a t i o n , i s worthy of c o n s i d e r a t i o n . Brody c o n s i d e r s a sigmoid shaped curve w i t h two p r i n c i p a l growth segments: (1) the s e l f - a c c e l e r a t i n g phase w i t h i n c r e a s i n g s l o p e , and (2) the s e l f - i n h i b i t i n g phase w i t h d e c r e a s i n g s l o p e , both phases under the combined i n f l u e n c e of what he c a l l s the g r o w t h - a c c e l e r a t i n g f o r c e and the growth-retarding f o r c e . E v e n t u a l l y growth w i l l come under the complete 41 62 i n f l u e n c e of t h i s l a t t e r f o r c e and w i l l f i n a l l y s t a b i l i z e . In a d d i t i o n he c o n s i d e r s the i n f l e c t i o n p o i n t (the change i n time r a t e of growth) o f the curve t o have p h y s i o l o g i c a l r e a l -i t y . In the case of mammals i t i s puberty, with many f l o w e r s i t i s the time of f l o w e r i n g . In c h i c k e n s , a c c o r d i n g t o Ewing (1951)* growth i n c r e a s e s r a p i d l y from h a t c h i n g time t o t h r e e t o f o u r weeks of age, a f t e r which i t decreases at a s i m i l a r r a t e t o t e n weeks o f age and then cont i n u e s t o decrease more sl o w l y u n t i l m a t u r i t y . He c o n s i d e r s the change i n growth r a t e i s due to some unknown h e r i t a b l e growth d e p r e s s i n g f a c t o r . Maynard and L o o s l i (1956) suggest t h a t t r u e growth i n v o l v i n g i n c r e a s e s i n s t r u c t u r a l t i s s u e s , muscles, bones, and organs should be d i s t i n g u i s h e d from i n c r e a s e s t h a t r e s u l t from d e p o s i t i o n of f a t throughout v a r i o u s p o r t i o n s o f the animal body. However f o r p r a c t i c a l purposes i n measuring growth i n the same i n d i v i d u a l , these f a t r e s e r v e s cannot be measured i n order to exclude them from the t o t a l weight. S e v e r a l methods f o r measuring growth r a t e s have been developed, a l l dependent upon one parameter o f growth, namely weight. Both the average a b s o l u t e growth r a t e and the r e l -a t i v e growth r a t e are c o n v e n t i o n a l methods f o r measuring growth and were developed by Minot (1908). These methods were c r i t -i c i z e d by Brody (1927 and 19^5) on the grounds t h a t Minot f a i l e d t o r e c o g n i z e t h a t the p h y s i o l o g i c s i g n i f i c a n c e o f a p h y s i c a l u n i t of time changes r a p i d l y with age. T h e r e f o r e Brody has suggested the use of the instantaneous r a t e o f growth which e l i m i n a t e d d i s c r e p a n c y between p h y s i o l o g i c and s i d e r a l time. In a d d i t i o n R i c k e r (1958) p o i n t s out t h a t use of the instantaneous growth r a t e i s best s u i t e d f o r compar-i s o n with m o r t a l i t y e s t i m a t e s , a l s o expressed i n i n s t a n t a n -eous terms. E s s e n t i a l l y , the the o r y u n d e r l y i n g t h i s method i n v o l v e s the summation or i n t e g r a t i o n o f an i n f i n i t e number of i n f i n i t e s i m a l s m a l l instantaneous r a t e s over a p e r i o d of time. Thus on i n t e g r a t i o n , W = A e k t (1) where A , the n a t u r a l l o g a r i t h m o f W (weight) when time ( t ) equals 0. For purposes o f computing the instantaneous r a t e (k) over a g i v e n p e r i o d o f time, equation ( l ) i s w r i t t e n , k = l n W 2 - 1* w l a ( 2 ) where k i s the instantaneous r e l a t i v e r a t e o f growth between time t-^ t o t 2 (Brody, 19^5). E s s e n t i a l l y t h i s expresses the i n c r e a s e i n weight p e r u n i t of time i n r e l a t i o n t o the t o t a l body weight. Growth of C a p t i v e and Wild Chicks S e v e r a l c h i c k s were captured on and about the study areas and s u c c e s s f u l l y r a i s e d by Mr. and Mrs. George Gibson o f the Department of Zoology. D a i l y weights were taken by them u n t i l approximately the f i r s t week i n September, a t 64 which time r e c o r d i n g s were made every week. Use of these weights, both as a d e s c r i p t i o n of growth and i n forming a b a s i s f o r the c a l c u l a t i o n of energy requirements i s g r a t e f u l l y acknowledged. A d d i t i o n a l weights of the f i e l d - s h o t b l u e grouse c h i c k s c o l l e c t e d both i n 1958 and i n 1950 to 1952 by myself and B e n d e l l (1954) r e s p e c t i v e l y , are used f o r purposes of com-par i n g growth r a t e s and f a l l weights between the pen-r a i s e d and w i l d c h i c k s . Of the s e v e r a l c h i c k s r a i s e d , o n l y s i x (3 <5cf and 3 are used i n t h i s study. These were not prone to d i s e a s e s and i n j u r i o u s e f f e c t s of c a p t i v i t y and g e n e r a l l y e x h i b i t e d r e l a t i v e l y u n i n t e r r u p t e d growth. F i g u r e 8 shows the growth of the combined s i x c h i c k s i n comparison w i t h the average lumped weights of c h i c k s , c o l l e c t e d i n the f i e l d , up t o nine weeks of age from 1950-52 and 1958, a l l graphed on an a r i t h - l o g p l o t . A f r e e hand curve has been drawn through the p o i n t s r e p r e s e n t i n g the average growth of the p e n - r a i s e d c h i c k s . For purposes of comparison w i t h f i e l d weights, males and females of the p e n - r a i s e d c h i c k s have been combined and i t i s f e l t t h a t p o i n t s are s u f f i c i e n t . However, the f i e l d weights showed a much g r e a t e r v a r i a t i o n about a g i v e n age and consequently, l i n e s r e p r e s e n t -i n g 95 percent confidence l i m i t s have been drawn through the mean p o i n t s . I t must be s t r e s s e d that these weights have been averaged to d e p i c t a comparison, not to i n d i c a t e the growth of an average i n d i v i d u a l f o r each of the groups. 65 Table XXII pres e n t s the r e s u l t s of the instantaneous growth r a t e s of the s i x p e n - r a i s e d blue grouse c h i c k s . T a b l e XXII Growth Rates of S i x Pen-Raised Blue Grouse C h i c k s , Captured From the Study Area. Males Females B i r d # k # # k 2 B i r d # *L k 2 29 .094 .029 30 .080 .016 26 .086 .028 31 .083 .016 41 .091 .027 40 .085 .021 Aver. .090 .028 Aver. .082 .018 # k]_ = instantaneous r a t e d u r i n g f i r s t 4 weeks. 1&2 = instantaneous r a t e d u r i n g next 10 weeks. Here again, i t should not be construed t h a t by averaging growth r a t e s , any r e p r e s e n t a t i o n of an i n d i v i d u a l i s i n d i c a t e d . I t has been done merely f o r comparative purposes. Blue grouse c h i c k s appear to grow at a very h i g h r a t e du r i n g t h e i r f i r s t f o u r weeks. The instantaneous r a t e f o r both male and females d u r i n g t h i s time i s around 0.086 or 8.6 percent per day; or 8.6 x 7 s 60.2 percent per week. In comparison the domestic c h i c k grows d u r i n g the same p e r i o d a t a r a t e of from 5 percent per day or 35 percent per week to 100 percent per week."'' An a d d i t i o n a l comparison w i t h pheasant growth r a t e s (pen-raised) f o r the f i r s t f o u r weeks ( c a l c u l a t e d •'•Personal communication w i t h D r . J . B i e l y , Dept. of P o u l t r y S c i e n c e , U.B.C. 66 from Skoglund, 1940) y i e l d s an instantaneous r a t e o f approx-i m a t e l y 0.077, s l i g h t l y lower than t h a t of the blue grouse. D e f i n i t e d i f f e r e n c e s between growth r a t e s f o r males and females are a l s o evident from Table X X I I I . During the f i r s t f o u r weeks th e r e i s a numerical d i f f e r e n c e o f 0.8 per-cent p e r day i n favour o f the males, w h i l e over a f o u r t e e n week p e r i o d males s t i l l m a i n t a i n a f a s t e r growing r a t e than the females by about 18 p e r c e n t . Both B e n d e l l (1955) and Wing, Beer and Tidyman (1944) have a l s o found o v e r a l l d i f f e r -ences between the growth r a t e o f males and female blue grouse; i n the case of the former t h e r e was a d i f f e r e n c e of t e n grams per week i n favour o f the males, with the l a t t e r , o n l y a 5 percent d i f f e r e n c e f o r the males. Of course these growth r a t e s are p r i m a r i l y dependent upon the q u a l i t y of the food consumed and d i f f e r e n c e s between the g a l l i f o r m e s may not be r e a l , i f a l l the i n d i c a t e d were f e d on the same r a t i o n . I t i s a l s o p o s s i b l e t h a t d a i l y weighing of the p e n - r a i s e d blue grouse c h i c k s may have a f f e c t e d t h e i r growth r a t e p o t e n t i a l , suggesting t h a t i t may even have been g r e a t e r . From the comparison of the f i e l d weights and the pen-r a i s e d c h i c k weights i n F i g u r e 8, t h e r e appears t o be l i t t l e d i f f e r e n c e d u r i n g the f i r s t f o u r weeks. The p e n - r a i s e d grouse however, c o n s i s t e n t l y tend to show g r e a t e r average weekly weights. While these averages are i n c l u d e d w i t h i n the 95 per-cent confidence l i m i t s d u r i n g the e a r l y stage of growth, some degree of d i s c r e p a n c y i s shown from the f i f t h t o the e i g h t h week. T h i s r e l a t i v e d i f f e r e n c e i s b e t t e r e x e m p l i f i e d by com-p a r i n g the mean f a l l weights of the p e n - r a i s e d t o the f a l l -shot j u v e n i l e grouse from the Campbell R i v e r Checking S t a t i o n ( B r i t i s h Columbia Game Department) i n T a b l e XXIII. Ta b l e XXIII Comparison of F a l l (second week September) Weights Between the Pen-Raised and H u n t e r - K i l l e d Grouse. Sex Pen-Raised No. B i r d s F a l l Check No. B i r d s Males Females 968 + 7 8 4 751 ± 3 5 5 718 ± 56 12 660 ± 44 17 Average 847 ± 8 4 9 686 ± 28 29 The two d i f f e r e n t l y r a i s e d groups t e s t s i g n i f i c a n t l y d i f f e r e n t between both males and females and between the averages of males and females ( i n the l a t t e r case t = 4 . 2 , df « 36). T h i s may i n d i c a t e t hat blue grouse produced i n the Campbell River, area are not growing under the best c o n d i t i o n s s i n c e they o b v i o u s l y are not reaching the p o t e n t i a l f a l l weights suggested by the p e n - r a i s e d b i r d s . . There are a number of v a l i d reasons why t h i s d i f f e r -ence i s such. F i r s t , the a c t u a l t i s s u e composition of the growing b i r d s i s not known, t h a t i s , t h i s e x t r a weight of the 68 c a p t i v e c h i c k s may be simply f a t accumulation due to ample food and a comparative sedentary e x i s t e n c e . A more l i k e l y reason may be t h a t the food supply of the c h i c k s i n the f i e l d i s not n u t r i t i o n a l l y adequate f o r the c h i c k ' s i n h e r e n t growth p o t e n t i a l . Coupled with t h i s i s the completely d i f f e r e n t types of environments i n h a b i t e d by the two groups; the w i l d b i r d s p o s s i b l y l i v i n g under a r e l a t i v e l y h i g h e r nervous s t r a i n due to the "normal" p r e d a t i o n and c l i m a t i c v a r i a t i o n s , and the p e n - r a i s e d b i r d s l i v i n g an e x i s t e n c e f r e e of t h i s type of t e n s i o n . T h i s type of weight d i f f e r e n c e i s a l s o e v i d e n t when comparing growth of p e n - r a i s e d pheasants (Skoglund, 1940) with the growth of pheasants on Pelee I s l a n d , O n t a r i o (Stokes, no d a t e ) . I t must be remembered a l s o t h a t weights taken at f a l l road checks are much l e s s a c c u r a t e due t o the weighing method ( o f t e n s p r i n g s c a l e s ) , and t o the e f f e c t o f l o s s of b l o o d . Dehydration may a l s o i n f l u e n c e the road check weight, but probably t o a l e s s e r degree than l o s s o f b l o o d . Because of the reasons c i t e d f o r t h i s apparent d i f f e r e n c e , care must be e x e r c i s e d i n drawing c o n c l u s i o n s from these data. In c o n c l u s i o n , blue grouse tend t o f o l l o w the gener-a l l y accepted growth p a t t e r n o f g a l l i n a c e o u s b i r d s ; n o t a b l y an i n i t i a l r a p i d r a t e of growth d u r i n g the f i r s t f o u r weeks f o l l o w e d by a d e c r e a s i n g r a t e b e f o r e r e a c h i n g m a t u r i t y . In a d d i t i o n , i t i s p o s s i b l e t h a t a d i f f e r e n c e e x i s t s i n the growth r a t e s and f a l l weights between s i x p e n - r a i s e d c h i c k s 69 and the j u v e n i l e s taken d u r i n g the Campbell R i v e r f a l l road check. T h i s d i f f e r e n c e may i n p a r t be due t o the r e l a t i v e a v a i l a b l e food, both q u a n t i t y and q u a l i t y , and to the o v e r a l l d i f f e r e n c e i n environments. D i f f e r e n c e s i n growth r a t e s and f a l l weights are s i g n i f i c a n t between the sexes, the males p o s s e s s i n g a g r e a t e r growth p o t e n t i a l a f t e r h a t c h i n g . Females possess a g r e a t e r growth p o t e n t i a l w h i l e s t i l l i n the egg and on h a t c h i n g are p h y s i o l o g i c a l l y o l d e r than the males (Brody, 19^5). THE ENERGY AND FOOD REQUIREMENTS OF THE CHICKS A l l animals r e q u i r e food t o p r o v i d e energy necessary f o r t h e i r maintenance, and growth metabolism needs. T h i s food w i l l vary g r e a t l y i n q u a n t i t y and composition with spec-i e s and age of the animal (Brody, 1945). To date much of the experimental work r e l a t i n g to metabolism, d i g e s t i b i l i t y , and n u t r i t i v e v a l u e s o f feeds has been dome p r i m a r i l y with mammals. The s t u d i e s t h a t have been done on b i r d s have been concerned almost e x c l u s i v e l y with domestic chickens and turkeys--and then on the b a s i s o f improv-i n g p o u l t r y p r o d u c t i o n by the development of b e t t e r f e e d s . Such s t u d i e s by N e s t l e r (1946), and N e s t l e r et a l (1948) on V i t a m i n A and m i n e r a l requirements o f q u a i l ; N o r r i s (1934) and N o r r i s et a l (1936) on the p r o t e i n requirements o f pheasant c h i c k s ; S c o t t and Reynolds (1949) on n u t r i t i o n i n pheasants, h i g h l i g h t some of the n u t r i t i o n a l i n v e s t i g a t i o n s on g a l l i n a c e o u s game b i r d s . The f o l l o w i n g d e t e r m i n a t i o n o f the minimum energy requirements o f blue grouse c h i c k s w i l l be based on t h e i r t h e o r e t i c a l l y c a l c u l a t e d b a s a l metabolism and the n u t r i t i o n a l v alues o f the types o f foods eaten i n the f i e l d . B a s a l Metabolism The minimum amount of energy r e q u i r e d when an animal i s a t complete r e s t i n a thermoneutral environment and i n a 70, post a b s o r p t i v e c o n d i t i o n i s the energy r e q u i r e d f o r b a s a l metabolism (Brody, 1945). I t i s u s u a l l y measured by the amount of heat produced under such a c o n d i t i o n . Much of the work on b a s a l metabolism has been concerned w i t h i t s r e l a t i o n to body weight and s u r f a c e area. However s i n c e measurements of s u r f a c e area are extremely hard to make and tend to be v a r i a b l e , b a s a l metabolism i s u s u a l l y c o n s i d e r e d as a f u n c t i o n of body weight. Since no s t u d i e s on the b a s a l metabolism of growing blue grouse are recorded i n the l i t e r a t u r e , i t was decided that estimates would have to be made from p r e v i o u s l y recorded s t u d i e s on the domestic c h i c k e n . The work of M i t c h e l l , Card, and Hairies (1927) i n which the b a s a l metabolism of a great number of domestic c h i c k s of d i f f e r e n t weights was determined, was t e s t e d f o r i t s u s e f u l n e s s i n t h i s problem. A s t r a i g h t l i n e was f i t t e d to these data r e s u l t i n g i n a constant r e l a t i o n -ship between b a s a l metabolism and body weight ( F i g u r e 9) f o r the f i r s t f o u r week p e r i o d . The equation of t h i s s t r a i g h t l i n e i s as f o l l o w s : Y = 0.167 X 1 * 0 1 (3) where Y « b a s a l metabolism i n C a l o r i e s per day, and X = weight i n grams. K i b l e r and Brody (1944) measured the r e s t i n g metabolism ( t h e r m o n e u t r a l i t y ) of growing chickens and found t h i s r e l a t i o n s h i p between body weight and metabolism: Y = 0.22 X 0 , 9 8 (males) . . . . (4) Y = 0.21 X 1 , 0 0 (females) . . . (5) 72 M i t c h e l l et a l and K i b l e r and Brody's data are compared i n the f o l l o w i n g Table XXIV. Table XXIV Comparison Between B a s a l Metabolism and R e s t i n g Metabolism i n Chickens. (Metabolism as..: C a l o r i e s per day) (grams) Weight R e s t i n g Metabolism Males Females Average B a s a l Metabol. Percent D i f f e r e n c e 25. 5.2 5.3 5.3 4 .3 19 50 10.2 10 .5 10.4 8.7 17 100 20.1 21.0 20.5 17.5 15 200 39.6 42.0 40 .8 35.2 14 There appears to be l i t t l e d i f f e r e n c e i n r e s t i n g metabolism between males and females of the same weight. The d i f f e r e n c e between r e s t i n g and b a s a l metabolism i s due to the f a c t t h at the former i n c l u d e s b a s a l metabolism, and the S p e c i f i c Dynamic Energy (energy used i n food u t i l i z a t i o n ) (Brody, 1945). Because of t h i s r e s t i n g metabolism appears to be a more con-venient s t a r t i n g p o i n t i n the subsequent c a l c u l a t i o n of the energy requirements of the b l u e grouse c h i c k s . A c c o r d i n g l y , the equations of K i b l e r and Brody on r e s t i n g metabolism of chickens d u r i n g t h e i r f i r s t f o u r weeks of age are assumed to rep r e s e n t approximately the r e s t i n g metabolism of blue grouse c h i c k s . M e t a b o l i z a b l e Energy and Q u a n t i t y of Food Required The e s t i m a t i o n of the b a s a l and r e s t i n g metabolism of known aged c h i c k s forms a b a s i s f o r e v a l u a t i n g t h e i r minimum 73 m e t a b o l i z a b l e energy requirements. The procedure f o l l o w e d i s w i d e l y used f o r e s t i m a t i n g the feed requirements of farm animals and i s c a l l e d the f a c t o r i a l method (Maynard and L o o s l i , 1956). E s s e n t i a l l y the f a c t o r i a l method c o n s i s t s of e s t i m a t i n g f o r a growing animal the m e t a b o l i z a b l e energy requirements-by c o n s i d e r i n g them to be the sum of the energy r e q u i r e d f o r r e s t i n g metabolism ( i n c l u d e s S.D.A.), f o r a c t i v i t y , and f o r a d d i t i o n a l t i s s u e growth. Energy r e q u i r e d f o r b a s a l metabolism and f o r a c t i v i t y i s g e n e r a l l y r e f e r r e d to as the maintenance requirements. M i t c h e l l et a l (1930, 193D i n a s s e s s i n g the energy requirements f o r domestic chickens found t h a t the energy expended f o r muscular a c t i v i t y ranged Between 43 and 52 percent of the expenditures f o r b a s a l metabolism. Crampton (1956) supports t h i s f i g u r e . A c c o r d i n g l y , the C a l o r i e s r e q u i r e d f o r a c t i v i t y i n the blue grouse c h i c k have been taken to be 50 per-cent of b a s a l . U n t i l s t u d i e s on the e n e r g e t i c s of w i l d g a l l -inaceous b i r d s are a v a i l a b l e , f i g u r e s of the above nature that p e r t a i n to domestic fowl must be assumed f o r w i l d g a l l i f o r m e s . D e t ermination of the energy requirements f o r a d d i t i o n a l t i s s u e growth has been accomplished from an a p p r e c i a t i o n of the d a i l y r a t e of growth (average of 8.6$ per day f o r blue grouse c h i c k s ) , and from an approximation of the chemical c o m p o s i t i o n of the weight g a i n . The l a t t e r was obtained from M i t c h e l l et a l (1931). For i n s t a n c e , a c h i c k weighing 32.7 grams gains 2.8 grams per day, of which approximately 21 percent i s dry matter, 15 percent i s p r o t e i n , and 4 percent f a t . Knowing t h a t 5»65 and 9.4 C a l o r i e s r e s p e c t i v e l y are r e q u i r e d to put on one gram 74 of p r o t e i n and f a t (Brody, 1945), the t o t a l C a l o r i e s r e q u i r e d f o r t h i s g a i n can be computed (3.2 C a l o r i e s ) . However t h i s r e p r e s e n t s the net requirements f o r growth which are ro u g h l y 70 percent of the m e t a b o l i z a b l e requirements (Brody, 1945). T h e r e f o r e 4.6 C a l o r i e s are necessary f o r the growth f r a c t i o n . The t o t a l m e t a b o l i z a b l e energy requirements of the blue grouse c h i c k s f o r the f i r s t f our weeks are giv e n i n T a b l e XXV. At the same time estimates of d a i l y food i n t a k e are gi v e n as the average d a i l y f e e d consumption over a p e r i o d of a week. These estimates are given f o r both f r e s h " n a t u r a l f o o d " and f o r the turkey s t a r t e r which was a c t u a l l y f e d to the pen - r a i s e d c h i c k s during t h e i r e a r l y p e r i o d of growth. Estimated food i n t a k e i s c a l c u l a t e d i n the f o l l o w i n g manner ( a f t e r Brody, 1945): T o t a l M e t a b o l i z a b l e Energy R e q u i r . (Cal./day) _ Grams food M e t a b o l i z a b l e Energy Value of Food (Cal./gm) per day T h i s c a l c u l a t e d amount of food i s t h e o r e t i c a l l y s u f f i c i e n t t o s a t i s f y the g i v e n m e t a b o l i z a b l e energy requirements of the animal. The m e t a b o l i z a b l e energy value of the turk e y s t a r t e r g i v e n by the manufacturer (B and K Feeds, Vancouver) i s approximately 2.2 C a l o r i e s per gram. However when c a l c u l a t i n g consumption of f r e s h food n o r m a l l y eaten i n the f i e l d , some changes occur i n i t s m e t a b o l i z a b l e energy v a l u e as the c h i c k ' s food h a b i t s d i g r e s s from i n v e r t e b r a t e to p l a n t consumption. T a b l e XXV C a l c u l a t e d M e t a b o l i z a b l e Energy and Food Requirements of One Chick Based on the Average Growth of S i x Pen-Raised Blue Grouse C h i c k s . Energy Requirements (Cal./d&y) Food Requirement ^ m/day) Age (days) Weight (grams) B a s a l R e s t i n g A c t i v . Net Growth T o t a l Growth T o t a l Metabol. S t a r t e r T o t a l F r e s h Inverteb. H' - 7 32.7 5.4 6.8 2.7 3.2 4.6 14.1 6.4 15.5 15.5 8 - 1 4 63.6 10.5 13.1 5.3 6.4 9.1 27.5 12.5 32.4 27.5 15 - 21 116.8 20.0 23.9 10.0 13.4 19.2 53.1 24.1 61.1 53.7 22 - 28 195.3 36.6 39.8 18.3 23.1 33.0 91.1 41.4 130.0 46.8 These changes are giv e n i n T a b l e XXVI and are based on the a n a l y s i s of crop contents p r e v i o u s l y g i v e n i n Tabl e V I I . The evident r e s u l t s of the changes i n the C a l o r i f i c v a lue of the foods i s an i n c r e a s e i n food i n t a k e as the me t a b o l i z a b l e energy v a l u e of the food decreases. T a b l e XXVI C a l c u l a t e d M e t a b o l i z a b l e Energy Values of F r e s h Foods Eaten by the Blue Grouse C h i c k s During June. Age Chick of (Weeks) % Crop Composition Animal P l a n t Metabol. Energy"1" of Food (Cal./gm) H - 1 100 0 0.91 1 - 2 85 15 0.85 2 - 3 88 12 0.87 3 - 4 36 64 0.70 4 - 5 25 80 0.69 1 Average I n v e r t e b r a t e Metab. Energy = 0.91 i 0.03 Average P l a n t M e t a b o l i z a b l e Energy = 0.57 - 0.006 In order to t e s t the v a l i d i t y of the t h e o r e t i c a l c a l c u l a t i o n s of food i n t a k e i n blue grouse, a comparison i s made w i t h the a c t u a l food i n t a k e of growing pheasant c h i c k s . Average d a i l y feed consumption over a week p e r i o d i s compared between the two s p e c i e s . Pheasant data were c a l c u l a t e d from. Skoglund (1940). The r e s u l t s of t h i s comparison are presented i n histogram form i n F i g u r e 10. T h i s comparison i n d i c a t e s a f a i r l y c l o s e agreement between feed consumption i n pheasant and blue grouse c h i c k s 7 0 -6 0 -2 < S O a. z 4 0 g 2 3 0 to z o 5 2 20-10 P H E A S A N T S O N S T A R T E R f S K O G L U N D 1 9 4 0 ) 1 I B L U E G R O U S E O N S T A R T E R I 3 0 - 0 B L U E G R O U S E O N N A T U R A L F O O D F I G . IO R E L A T I O N B E T W E E N A G E A N D D A I L Y F O O D C O N S U M P T I O N V. WAS 1 ^ A . H — I 1 — 2 2 — 3 A G E IN W E E K S 3 — 4 77 of s i m i l a r ages. The average weight of a pheasant c h i c k between i t s f i r s t and second week i s r o u g h l y 70 grams compared to 64 grams f o r the blue grouse c h i c k . T h i s may account f o r the s l i g h t d i f f e r e n c e i n food i n t a k e between the two s p e c i e s at t h i s time. Skoglund (1940) makes no r e f e r e n c e to the m e t a b o l i z a b l e energy value of the feed used i n h i s i n v e s t i -g a t i o n , but t h i s was r o u g h l y estimated from the i n g r e d i e n t s of the feed to be about 2.2 C a l o r i e s per gram, supporting the r e l a t i v e l y c l o s e agreement between the two groups. In a d d i t i o n the estimate of 6.5 grams of feed per day f o r blue grouse c h i c k s d u r i n g t h e i r f i r s t week agrees w i t h the feed i n t a k e of domestic c h i c k s grown on a s i m i l a r r a t i o n . T h i s amounts to 45 grams per c h i c k per week or 7 grams per day.''" Of p a r t i c u l a r concern to t h i s study i s the amount of f r e s h food eaten by a s i n g l e c h i c k during i t s f i r s t f o u r weeks i n r e l a t i o n to the amount of food a v a i l a b l e . Of equal importance i s the adequacy of the v a r i o u s foods i n s u p p l y i n g the r e q u i r e d n u t r i t i o n a l elements ( p r o t e i n , f a t , m i n e r a l s , and carbohydrates) during t h i s c r i t i c a l p e r i o d . The next p o r t i o n of the t h e s i s concerns an e v a l u a t i o n of these p o i n t s . 1 P e r s o n a l communication w i t h Mrs. B.E. March, Department of P o u l t r y S c i e n c e , U.B.C. 78 ADEQUACY OF AVAILABLE FOOD Adequacy of Q u a n t i t y From an estimate, approximating the minimum of a v a i l -a ble food on the study areas and the minimum r e q u i r e d by a growing blue grouse c h i c k , i t i s now p o s s i b l e to evaluate the adequacy of the B e a v e r t a i l Burn w i t h r e s p e c t to the p r o d u c t i o n of c h i c k s . T h i s i s the t e s t of the o r i g i n a l h y p o t h e s i s , t h a t the numbers of c h i c k s may be l i m i t e d i n p a r t by an inadequate supply of food. From Tables XXV and XXVI c a l c u l a t i o n of the r e q u i r e d amount of i n v e r t e b r a t e s f o r the f i r s t f o u r weeks i s p o s s i b l e . S i m i l a r l y w i t h r e f e r e n c e to Table XX, an e s t i m a t i o n of the f r e s h a v a i l a b l e i n v e r t e b r a t e foods i s a l s o p o s s i b l e . There-f o r e i n T a b l e XXVII a comparison between these two f r a c t i o n s i s d e p i c t e d . T a b l e XXVII Adequacy of A v a i l a b l e I n v e r t e b r a t e Q u a n t i t y and the Estimated T h e o r e t i c a l Number of P o t e n t i a l Chicks on the Study P l o t s . Age of Chick (days) Aver. Inverteb. (Grams/acre) P l o t A P l o t B Inverteb. Requr/day (Gm/Chick) P o t e n t i a l No. of C h i c k s / a c r e P l o t A P l o t B 1-7 73 .4 ± 11 92.1 + 1 6 15.5 4.7 6.0 8 - 1 4 tt !! 27.5 2.7 3 . 4 15-21 !? tl 53.7 1.4 1.7 22-28 1! tt 46.8 1.6 2.0 The l a s t column of t h i s t a b l e g i v e s an estimate of the average p o t e n t i a l h o l d i n g c a p a c i t y of the study areas w i t h r e s p e c t to the l i m i t a t i o n s of the supply of i n v e r t e b r a t e s (expressed as the 95 percent confidence l i m i t s about the mean estimate at any time d u r i n g the given week). An examination of the meaning and i m p l i c a t i o n of Table XXVII i s neceessary at t h i s p o i n t . The average amount of i n v e r t e b r a t e s on P l o t A i s 73*4 + 11 grams per acre. T h i s estimate, v a r y i n g w i t h i n the 11 gram l i m i t , i s present, a c c o r d i n g to the r e s u l t s of sampling, at any p o i n t of time ( e s s e n t i a l l y ) d u r i n g the f i r s t week. During t h i s f i r s t week a c h i c k r e q u i r e s an average of 15«5 grams per day. Assuming t h a t the c a l c u l a t i o n s are r e a s o n a b l y c o r r e c t , and assuming that the c h i c k can a c q u i r e the r e q u i r e d amount of i n v e r t e b r a t e s each day, a c h i c k w i l l consume a t o t a l of 109 grams by the end of i t s f i r s t week, a t o t a l of 193 grams by the end of the second week, and so on. S i n c e s e v e r a l c h i c k s do i n h a b i t each of the study P l o t s , i t must be r e a l i z e d t h a t a c e r t a i n q u a n t i t y of i n v e r t e b r a t e s i s being taken from the P l o t s each day which would not be accounted f o r i n the samples. The amount taken of course depends upon the s i z e of the p o p u l a t i o n of c h i c k s . However, s i n c e the q u a n t i t y of i n v e r t e b r a t e s appears to be the same at the b e g i n n i n g , as w e l l as at the end of the week, i t must be concluded t h a t the d a i l y or weekly consumption of i n v e r t e b r a t e s by c h i c k s i s approximately equal to the d a i l y or weekly p r o d u c t i o n of i n v e r t e b r a t e s upon each of the P l o t s . I f the d e n s i t y of c h i c k s i s r o u g h l y 0.5 per a c r e , ( t h i s i s estimated on page 82) t h i s means a p r o d u c t i o n and consumption of 8 grams 80 per day f o r the f i r s t week. I f these areas were b a r r e n of ch i c k s i t would be reasonable to conclude t h a t the q u a n t i t y of i n v e r t e b r a t e s would be g r e a t e r at the end than at the beginning of the week. S i m i l a r l y , i f the p o p u l a t i o n of c h i c k s was g r e a t e r than i t a c t u a l l y appears to be, one would expect t h a t the q u a n t i t y of i n v e r t e b r a t e s would have been reduced by the end of the week. Th e r e f o r e the estimate of i n v e r t e b r a t e food given i n T a b l e XXVII i s e s s e n t i a l l y the " c a p i t a l s t o c k " below t h a t which i s being u t i l i z e d by the e x i s t i n g p o p u l a t i o n of c h i c k s . T h i s reasoning can a l s o be a p p l i e d to each of the remaining weeks. During the second week a c h i c k r e q u i r e s r o u g h l y 28 grams per day. T h i s means t h a t the p r o d u c t i o n and consumption i s 14 grams per day (assuming 0.5 c h i c k s per a c r e ) . For the t h i r d week p r o d u c t i o n reached approximately 27 grams per day, f o r the f o u r t h , 23 grams per day. During t h i s p e r i o d the " c a p i t a l growing stock " remained r e l a t i v e l y constant. R e t u r n i n g to Table XXVII i t i s now seen t h a t the l a s t column r e p r e s e n t s the p o t e n t i a l number of c h i c k s above the number a l r e a d y present on the study P l o t s . These numbers p o r t r a y a c o n d i t i o n which i n d i c a t e s a t h e o r e t i c a l l y complete u t i l i z a t i o n of a l l i n v e r t e b r a t e s d u r i n g each week. From these r e s u l t s i t appears t h a t i f i n v e r t e b r a t e s are to l i m i t the abundance of blue grouse c h i c k s , the prob-a b i l i t y of t h i s o c c u r r i n g i s g r e a t e s t d u r i n g the t h i r d week of the c h i c k ' s l i f e . I t i s d u r i n g t h i s p e r i o d that the 81 minimum h o l d i n g c a p a c i t y o c c u r s ' o n both. Study P l o t s . Any a d v e r s e e n v i r o n m e n t a l e f f e c t a c t i n g o v e r t h i s f o u r week p e r i o d would be i n c l i n e d t o exert, i t s g r e a t e s t i n f l u e n c e a t t h i s c r i t i c a l , t i m e . U n f o r t u n a t e l y no< data a r e a v a i l a b l e on t h e u t i l i z a t i o n o f t h e i n v e r t e b r a t e p r o d u c t i o n by s m a l l b i r d s and mammals, i n d i c a t i n g t h a t t h i s a s p e c t r e q u i r e s f u r t h e r s tudy. I n a s i m i l a r f a s h i o n t h e abundance o f a v a i l a b l e p l a n t foods can be a n a l y z e d i n l i g h t o f t h e v e g e t a t i o n a l requUxements o f t h e c h i c k s . As mentioned b e f o r e , c h i c k s make a. t r a n s i t i o n i n t h e i r d i e t from i n v e r t e b r a t e s t o p l a n t f o o d s d u r i n g t h e t h i r d and f o u r t h week o f l i f e . Peak h a t c h on t h e s t u d y a r e a s o c c u r r e d a p p r o x i m a t e l y w i t h i n t h e f i r s t two< weeks o f June. I n p r e v i o u s y e a r s (1950 t=o 1952) B e n d e l l (1954) c a l c u l a t e d from f r e q u e n c y o f o b s e r v i n g week-old c h i c k s t h a t peak h a t c h o c c u r r e d i n t h e f i r s t week o f June. T h e r e f o r e t h e p e r i o d d u r i n g which th e p l a n t f o o d was sampled ( l a s t week o f June) ca n be r egarded as a s u i t a b l e t i me t o compare? t h e adequacy o f t h e v e g e t a t i o n a l f o o d abundance s i n c e i t has been shown t h a t c h i c k s , by t h i s t i m e , a r e e a t i n g a d i e t o f almost 90 p e r c e n t v e g e t a t i o n . . T h i s e s t i m a t e was a l s o c o n s i d e r e d t o be minimum. Prom T a b l e XXI t h e average e s t i m a t e o f a v a i l a b l e p l a n t f o o d on b o t h s t u d y a r e a s was 55250 grams p e r a c r e . D u r i n g t h e t h i r d and f o u r t h week o f l i f e , a c h i c k e a t s appmxr-i m a t e l y 36 percent p l a n t food; c o n s e q u e n t l y r e q u i r i n g about 82 15 grams per day. T h i s g i v e s a very h i g h f i g u r e f o r h o l d i n g c a p a c i t y of the grouse range i n terms of c h i c k abundance, t h e r e f o r e suggesting t h a t the q u a n t i t y of p l a n t food i s f a r i n excess of t h a t r e q u i r e d . Before determining the r e l a t i v e h o l d i n g c a p a c i t i e s of the study areas i t i s necessary to know the approximate number of c h i c k s produced. The abundance of c h i c k s on the areas was estimated by o b s e r v a t i o n and i n t i m a t e f a m i l i a r i t y w i t h both P l o t s . These P l o t s were v i s i t e d r e g u l a r l y once every other day and o f t e n every day. Three to f i v e hours were spent d a i l y t r a v e r s i n g the P l o t s . I t i s of i n t e r e s t to note t h a t broods were o f t e n found i n the same r e l a t i v e areas i n which they were p r e v i o u s l y seen, thus suggesting o n l y s l i g h t d i s p e r s i n g . The presence of broods d i d not appear to be c o r r e l a t e d w i t h any p a r t i c u l a r v e g e t a t i o n a l c h a r a c t e r i s t i c or time of day, c h i c k s being found both on open b a r r e n dry areas and i n moist bracken-f i l l e d g u l l i e s . On June 15 three broods and accompanying hens were observed w i t h i n an area of approximately t h i r t y square f e e t , presumably f e e d i n g on the pods of C y t i s u s  s c o p a r i u s which were very abundant at t h i s p a r t i c u l a r spot. B e n d e l l (1954) a l s o found t h a t broods of very young c h i c k s moved r e l a t i v e l y short d i s t a n c e s , with a tendency towards g r e a t e r d i s p e r s i n g as the j u v e n i l e s matured, ending i n e v e n t u a l m i g r a t o r y movements i n the f a l l . 8 5 The average brood s i z e i n June f o r P l o t s A and B was r e s p e c t i v e l y 4*1 and 3«6 c h i c k s p e r brood ( B e n d e l l found an average brood s i z e between 3 and 4 i n t h e l a s t week of. J u n e ) . No s i g n i f i c a n t d i f f e r e n c e e x i s t s between th e two P l o t s . Brood abundance was e s t i m a t e d t o be r e s p e c t i v e l y 5 and 4 broods on P l o t s A and B1-. T h i s r e s u l t s i n t h e f o l l o w i n g v a l u e s : P l o t A - 0.5 C h i c k s p e r A c r e P l o t B'- 0.4 C h i c k s per. A c r e An attempt was made t o determine t h e abundance o f c h i c k s by t h e s t r i p census method. (Hayne, 1949)• However, t h e b e h a v i o u r o f t h e hen w i t h h e r brood i s such t h a t c e n s u s i n g by t h i s means was not s a t i s f a c t o r y * Hens and broods o f t e n r e f u s e d t o f l u s h even when the o b s e r v e r was w i t h i n a few f e e t . I n a d d i t i o n any attempt t o determine a c c u r a t e l y c h i c k m o r t a l i t y i s s i m i l a r l y i m p r a c t i c a l due' t o t h e s m a l l number o f o b s e r v a b l e broods o v e r t h e p e r i o d o f s tudy. From t h e s e ^ r e s u l t s , and assuming t h a t t h e c h i c k s can o b t a i n t h e r e q u i r e d amount o f f o o d , i n v e r t e b r a t e and p l a n t f o o d appears t.o> be f a r i n excess o f t h a t r e q u i r e d by t h e a c t u a l number o f c h i c k s on t h e study a r e a s . T h i s i s par-t i c u l a r l y e v i d e n t i n t h e case o f p l a n t f o o d , and though l e s s so f o r t h e most i m p o r t a n t i n v e r t e b r a t e foods, i t i s s t i l l s t r i k i n g l y g r e a t e r t h a n t h e amount r e q u i r e d . 84 Adequacy of Q u a l i t y I t i s v e r y e s s e n t i a l t h a t q u a n t i t a t i v e measurements of b i o l o g i c a l systems be q u a l i f i e d , e s p e c i a l l y when d e a l i n g w i t h p o t e n t i a l l i m i t i n g f a c t o r s . C o n v e r s e l y , the use o f q u a l i t a t i v e d e s c r i p t i o n i n b i o l o g i c a l assay i s o f t e n of no value u n l e s s the q u a l i t y v a r i a t i o n i s measurable and a s s e s s -a b l e . T h e r e f o r e i n an a n a l y s i s o f the r e l a t i o n s h i p between the b l u e grouse c h i c k and i t s food, the importance o f the e s s e n t i a l n u t r i e n t composition o f the foods i s j u s t as impor-t a n t as t h e i r abundance. T h i s i s p a r t i c u l a r l y e x e m p l i f i e d by the study o f N e s t l e r ( 1 9 4 6 ) i n which the l a c k of the n u t r i e n t V i t a m i n A was found t o be f a t a l w i t h i n t h r e e weeks to a q u a i l c h i c k r e g a r d l e s s o f the V i t a m i n A l e v e l i n the p a r e n t . Evidence s u p p o r t i n g N e s t l e r both f o r q u a i l and pheasants has been presented by Thompson and Baumann (1950). In o r d e r t o assess the r e l a t i v e s t a t u s o f the v a r i o u s foods eaten by the blue grouse c h i c k , i t i s necessary t o know or c l o s e l y approximate the n u t r i e n t elements r e q u i r e d f o r an adequate d i e t . U n f o r t u n a t e l y data of t h i s nature are not a v a i l a b l e f o r the blue grouse f o r the f o l l o w i n g reasons. A supply of c h i c k s f o r any experimental n u t r i e n t i n v e s t i g a t i o n must be o b t a i n e d from the f i e l d s h o r t l y a f t e r h a t c h i n g s i n c e b l u e grouse have never been known to breed i n c a p t i v i t y . From experience i n c o l l e c t i n g c h i c k s , i t i s f e l t t h a t the l a r g e number r e q u i r e d (from 100 t o 500; N e s t l e r 1946, Skoglund 1940) 85 c o u l d never be c o l l e c t e d i n t h i s manner. In a d d i t i o n only seven nests were found i n the course of the 1950 - 1954 and 1958 i n v e s t i g a t i o n s , thus p l a c i n g t h i s p o t e n t i a l supply beyond reach. Consequently f o r the time b e i n g , an estimate of the minimum n u t r i t i v e elements r e q u i r e d f o r s a t i s f a c t o r y growth must be gleaned from t h a t known f o r other g a l l i n a c e o u s b i r d s . I t i s probable t h a t the b a s i c n u t r i t i o n of c h i c k s w i t h i n the G a l l i f o r m order i s more s i m i l a r than that of the a d u l t s . T h i s s u g g e s t i o n may be v a l i d a t e d by i n d i c a t i n g t h a t the foods of c h i c k s are much the same d u r i n g the f i r s t few weeks, w h i l e t h a t of the ad u l t may vary w i d e l y ( F e s t l e r 1939? Bump et a l 1947, Edminster 1954). In a d d i t i o n , the blue grouse c h i c k s ( p e n - r a i s e d ) appeared to grow w e l l on the s y n t h e t i c t u r k e y s t a r t e r . P r o t e i n Requirements Much of the experimental work i n determining the com-p a r a t i v e value of the v a r i o u s l e v e l s of p r o t e i n on growth i n w i l d g a l l i f o r m e s has been done on the ring-necked pheasant. N o r r i s , Elmore, Ringrose and Bump (1936) conducted a study i n which c h i c k s were s t a r t e d on v a r y i n g p r o t e i n content d i e t s . Using t h r e e r e p l i c a t i o n s they concluded t h a t a d i e t c o n t a i n -i n g 28 percent p r o t e i n was necessary f o r e a r l y r a p i d growth. T h i s i s four percent more than t h a t r e q u i r e d f o r the domestic c h i c k e n . C o n f i r m a t i o n o f the p r o t e i n content has s i n c e been made by S c o t t , Holm, and Reynolds (1954), who i n a d d i t i o n , found t h a t t h i s l e v e l c ould be reduced to 24 percent f o r the three to f i v e week growth p e r i o d . A s i m i l a r l e v e l i s accepted 86 by Beck and Beck (1955) i n comparing adequacy of w i l d foods eaten by the turk e y p o u l t . T h e i r e s t i m a t e s are based on those g i v e n f o r the domestic t u r k e y by Marsden and M a r t i n (1946). F a t , F i b e r and M i n e r a l Requirements N o r r i s (1934) has suggested a s t a r t e r d i e t c o n t a i n i n g 5.3 to 6.0 p e r c e n t f a t , 4.1 t o 4.3 p e r c e n t crude f i b e r , 1.6 t o 1.7 p e r c e n t c a l c i u m , and 0.80 and O.85 percent phosphorus f o r pheasant c h i c k s . In comparison, N e s t l e r and B a i l e y (1941) g i v e the f o l l o w i n g d i e t f o r bobwhite q u a i l chicks.: 27 p e r -cent p r o t e i n , 5.3 p e r c e n t crude f a t , 4.3 percent crude f i b e r , 1.0 and 0.7 p e r c e n t f o r c a l c i u m and phosphorus r e s p e c t i v e l y . The d i e t used by Beck and Beck ( l o c . c i t . ) c o n s i s t e d o f the following.: 4 .0 p e r c e n t ash o f which 1.6 was ca l c i u m and 0.5 was phosphorus, 4 p e r c e n t f a t , 6 p e r c e n t crude f i b e r , and 54 p e r c e n t n i t r o g e n - f r e e e x t r a c t . A l l the above d i e t s c o ntained from 8 to 10 p e r c e n t m o i s t u r e . From t h i s comparison o f such d i v e r s e g a l l i n a c e o u s forms as the pheasant, turkey, and the q u a i l , i t i s obvious t h a t t h e i r n u t r i t i v e element requirements d i f f e r very l i t t l e . I t i s t h e r e f o r e probable t o assume t h a t the n u t r i e n t r e q u i r e -ments of the blue grouse w i l l be o f the same ord e r . These are requirements t h e r e f o r e estimated as follows.: p r o t e i n -28 p e r c e n t , f a t - 5 p e r c e n t , ash - 4 p e r c e n t , carbohydrate -54 p e r c e n t , and moisture - 9 p e r c e n t . 87 D e t e r m i n a t i o n of the percentage of each n u t r i e n t met by a food i s done i n the f o l l o w i n g manner. For example, Hypochaeris r a d i c a t a f l o w e r s c o n t a i n 1 4 . 4 percent p r o t e i n which meets 5 1 . 4 p e r c e n t o f the requirements of a growing c h i c k . F o r purposes o f t h i s study crude f i b e r i s i n c l u d e d i n the carbohydrate percentage. E x t r a amounts of the n u t r i t i o n a l elements above t h a t r e q u i r e d need not be d i s c a r d e d s i n c e e x t r a p r o t e i n can be used f o r energy, and e x t r a f a t and c a r -bohydrates can be s t o r e d as f a t (Maynard and L o o s l i , 1 9 5 6 ) . T a b l e XXVJII p r e s e n t s some of the major foods of the blue grouse c h i c k compared wi t h the c h i c k ' s estimated n u t r i t i v e r e q u i r e -ments. I t i s e v i d e n t t h a t most o f the major c h i c k foods are n u t r i t i o n a l l y d e f i c i e n t . A l l i n v e r t e b r a t e foods while con-t a i n i n g adequate p r o t e i n l a c k the necessary carbohydrates. On the other hand w h i l e most of the p l a n t foods possess the r e q u i r e d carbohydrates, they are d e f i c i e n t i n p r o t e i n . Any d e f i c i e n c y i n f a t can be made up from the carbohydrate per-centage at the r a t i o of 1 f a t t o 2 . 2 5 carbohydrate. I t i s obvious then t h a t blue grouse c h i c k s would not r e c e i v e the e s s e n t i a l amount of n u t r i e n t s from any one s i n g l e food u n l e s s the food were t o be eaten i n g r e a t q u a n t i t i e s . From the crop a n a l y s e s , the foods were found to have been eaten i n v a r i o u s combinationsj thus w h i l e one food i n the crop may be d e f i c -i e n t i n a c e r t a i n n u t r i e n t another may compensate f o r the 88 T a b l e XX7I I I Major Poods o f the Blue Grouse Compared with E s t i m a t e d N u t r i t i o n a l Requirements (Dry B a s i s ) . Percent of D i e t Met by Poods P r o t e i n Pat Ash Carbohyd. Formicidae 215 52 58 46 Isopoda 200 52 133 48 Arachnida 228 52 54 35 Homoptera 236 70 72 33 Larvae 247 116 113 20 Hypochaeris ( f l s ) 51 100 257 117 G a u l t h e r i a 30 36 112 142 Mahonia 40 31 164 134 Rubus 46 25 130 134 P t e r i d i u m 40 45 188 129 d e f i c i e n c y . As growth reaches i t s maximum, the p r o t e i n requirements decrease, u n t i l the b i r d can s u b s i s t on a complete or n e a r l y complete vegetable d i e t . Maintenance p r o t e i n requirements f o r the bobwhite q u a i l and the t u r k e y are r e s p e c t i v e l y 12 and 13 p e r c e n t , and assuming a s i m i l a r f i g u r e f o r the b l u e grouse, t h i s i n d i c a t e s the adequacy of the p l a n t foods at t h i s time. The adequacy of foods both from the p o i n t of view of q u a n t i t y and q u a l i t y have been compared t o the estimated n u t r i t i o n a l requirements of the blue grouse c h i c k s . I t has been shown t h a t the q u a n t i t y of a v a i l a b l e i n -v e r t e b r a t e foods i s f a r i n excess of t h a t r e q u i r e d by the 89 a c t u a l number of c h i c k s p r e s e n t on the study P l o t s . T h i s a l s o a p p l i e s t o the p l a n t foods but i n a more s t r i k i n g manner. Sin c e the a d u l t b l u e grouse are e a t i n g an e n t i r e v e g e t a t i o n a l d i e t , t h e i r requirements must a l s o be i n c l u d e d with those of the c h i c k s when determining the adequacy of the p l a n t foods. The q u a n t i t a t i v e requirements o f the a d u l t s can be estimated i n the f o l l o w i n g way. There are approximately 0.1 a d u l t males p e r a c r e and 0.2 a d u l t females per acre ( B e n d e l l , 1954, found a 2:1 r a t i o of females t o males) g i v i n g a t o t a l of 0.3 a d u l t breeding b i r d s per a c r e . With an average a d u l t weight of 1000 grams, one b i r d w i l l r e q u i r e 70.5 C a l o r i e s f o r b a s a l metabolism or l 4 l C a l o r i e s f o r maintenance p e r day (based on 0 7 "3 Brody's (194-5) formula.: C a l o r i e s ( b a s a l ) = 70.5 Kilograms ). One b i r d t h e r e f o r e w i l l r e q u i r e l 4 l C a l o r i e s per day o r 25'0 grams of food per day (average m e t a b o l i z a b l e energy of p l a n t food = 0.57 Cal./gm). T h i s means t h a t 0.3 a d u l t b i r d s p e r a c r e w i l l r e q u i r e r o u g h l y 83. grams per day. T h i s a d d i t i o n a l amount added to the c h i c k requirements i s s t i l l f a r l e s s than t h a t a v a i l a b l e at t h a t p a r t i c u l a r time. When the q u a n l i t y of the foods was compared t o the n u t r i t i o n a l requirements of the c h i c k s , a marked inadequacy was r e v e a l e d i n some of the foods. However when the v a r y i n g d i e t of the c h i c k s was taken i n t o account, the d e f i c i e n c i e s were overcome and the foods became adequate. DISCUSSION I t has been suggested by B e n d e l l (1955) t h a t a s h o r t -age o f a c c e p t a b l e i n v e r t e b r a t e foods might e x i s t d u r i n g the f i r s t two weeks o f the l i f e o f a b l u e grouse c h i c k and t h a t t h i s , a s s o c i a t e d w i t h inclement weather, might be p a r t i a l l y r e s p o n s i b l e f o r the removal o f week-old c h i c k s from the e a r l y c h i c k p r o d u c t i o n and thus account f o r a p o r t i o n of the heavy c h i c k m o r t a l i t y which B e n d e l l f e l t c o u l d not be e x p l a i n e d by p a r a s i t i s m . I n a d d i t i o n , t h e r e i s a l s o a p o s s i b i l i t y t h a t the g r e a t i n c r e a s e s i n numbers of blue grouse f o l l o w i n g e x t e n s i v e f o r e s t f i r e s on Vancouver I s l a n d , may be the r e s u l t of an i n c r e a s e i n the abundance of i n v e r t e b r a t e s a v a i l a b l e as food t o the b l u e grouse c h i c k s . T h i s study t h e r e f o r e was undertaken i n the s p r i n g of 1958 i n an attempt t o t e s t the v a l i d i t y of these hypotheses. The i n v e s t i g a t i o n was conducted on the seven year o l d B e a v e r t a i l Burn approximately twelve m i l e s southwest of the town o f Campbell R i v e r , Vancouver I s l a n d , B.C. Vegetat-i o n a l cover a n a l y s i s has shown t h a t f l o r a l r e g e n e r a t i o n i s i n a s e r a i stage s i m i l a r to t h a t i n d i c a t e d f o r the Quinsam Burn i n 1943 by Fowle (1944). S i m i l a r a d u l t male d e n s i t i e s on the B e a v e r t a i l Burn i n 1958 and on the Quinsam Burn i n 1943 a l s o add weight t o the p r o b a b i l i t y o f another subseq-uent bloom i n b l u e grouse numbers comparable to t h a t 90 9 1 experienced on the Quinsam Burn i n the l a t e 19^ 0's and e a r l y 1950's. T h i s study undertook t o determine two f a c t o r s i n the r e l a t i o n s h i p between the c h i c k and i t s food supply; ( l ) the amount of a c c e p t a b l e a v a i l a b l e i n v e r t e b r a t e s as e x h i b i t e d by the weight of the animal m a t e r i a l p r e s e n t over the c r i t i -c a l p e r i o d o f the f i r s t f o u r weeks of the c h i c k ' s l i f e , by the chemical n u t r i e n t composition o f these foods, and by an a n a l y s i s o f the foods eaten by the c h i c k s , and (2) the meta-b o l i z a b l e energy and n u t r i t i o n a l element requirements of growing blue grouse c h i c k s . In a d d i t i o n the q u a n t i t y and q u a l i t y o f the p l a n t foods eaten by the c h i c k s was assessed i n the l a s t week o f June t o t e s t the p r o b a b i l i t y of i n s u f f i -c i e n c y d u r i n g t h i s p e r i o d when c h i c k f e e d i n g h a b i t s t u r n from i n v e r t e b r a t e s t o f r e s h s u c c u l e n t v e g e t a t i o n . I n v e r t e b r a t e s were found t o be e q u a l l y abundant over the p e r i o d o f study, but w i t h a s l i g h t n o n - s t a t i s t i c a l l y s i g n i f i c a n t peak e x h i b i t e d d u r i n g the week o f peak h a t c h . The sampling method was t e s t e d and found t o be a r e l i a b l e technique f o r e s t i m a t i n g the amount o f i n v e r t e b r a t e s a v a i l -a b l e t o the c h i c k s . The n u t r i t i o n a l composition o f the i n v e r t e b r a t e foods was r e l a t i v e l y s i m i l a r , but t h e i r meta-b o l i z a b l e energy v a l u e s were even more remarkably so w i t h o n l y a 95 per c e n t c o n f i d e n c e i n t e r v a l o f 3 percent about the mean of 0.-91 C a l o r i e s p e r gram. C a l o r i f i c v a r i a t i o n between 92 t h e p l a n t s p e c i e s was a l s o s m a l l . No s i g n i f i c a n t d i f f e r e n c e s i n i n v e r t e b r a t e o r p l a n t abundance was apparent between th e two s t u d y P l o t s . The e s t i m a t e d q u a n t i t y o f food r e q u i r e d by t h e grow-i n g b l u e grouse c h i c k compared f a v o u r a b l y w i t h t h a t a c t u a l l y e a t e n by s i m i l a r aged pheasant c h i c k s . I n d e p i c t i n g t h e r e l a t i o n s h i p between a v a i l a b l e food, n u t r i t i o n a l r equirements o f t h e c h i c k s , and t h e a c t u a l prod-u c t i v i t y o f t h e study P l o t s i n terms o f t h e numbers o f c h i c k s p r e s e n t , s e v e r a l e v i d e n t p o i n t s have been i n d i c a t e d . F i r s t , w i t h t h e assumption t h a t c h i c k s can h a r v e s t the amount o f i n v e r t e b r a t e s r e q u i r e d , t h e q u a n t i t y o f a v a i l a b l e and. a c c e p t -a b l e i n v e r t e b r a t e s was c o n s i s t e n t l y f a r i n excess o f t h a t r e q u i r e d , by t h e number o f c h i c k s p r e s e n t on t h e P l o t s . Second, c l i m a t e i n terms o f temperature and h u m i d i t y appeared t o i n f l u e n c e d i r e c t l y t h e abundance and c o m p o s i t i o n o f t h e i n -v e r t e b r a t e samples, presumably by d i f f e r e n t i a l l y a f f e c t i n g t h e a c t i v i t y o f t h e i n d i v i d u a l groups. T h i r d , d u r i n g t h e t h i r d week o f June, t h e p o t e n t i a l c h i c k d e n s i t y , as determined from, the-minimum i n v e r t e b r a t e abundance, was at i t s l o w e s t . This, would suggest a g r e a t e r p r o b a b i l i t y o f an environment adverse-l y a f f e c t i n g c h i c k s u r v i v a l e i t h e r immediately o r l a t e r , as t h e r e s u l t o f m a l n u t r i t i o n d u r i n g t h a t t i m e . F o u r t h , t h e abundance o f p l a n t foods was f a r i n excess o f t h a t r e q u i r e d by.the c h i c k s a t t h e time when t h e y were emerging from a d i e t o f i n v e r t e b r a t e s t o a predominant d i e t o f v e g e t a t i o n . F i f t h , 93 w h i l e a l l . major foods p o s s e s s e d n u t r i t i o n a l d e f i c i e n c i e s i f e v e r e a t e n a l o n e , t h e i r adequacy has been demonstrated when t h e y a r e e a t e n i n c o m b i n a t i o n ( u s u a l l y some combin a t i o n o f ,animal and v e g e t a t i o n as t h e y n o r m a l l y a r e consumed). Thus at t h i s p o i n t i t i s p o s s i b l e t o t ake e x c e p t i o n t o t h e o r i g i n a l h y p o t h e s i s ; t h a t a l a c k o f i n v e r t e b r a t e food (under i d e a l weather conditions:) might be r e s p o n s i b l e p a r t i a l l y f o r e l i m i n a t i n g week-old c h i c k s . T h e r e f o r e , i n v e r t e b r a t e and p l a n t foods appear t o be more t h a n s u f f i c i e n t t o m a i n t a i n a d e q u a t e l y t h e p r e s e n t p r o d u c t i o n o f b l u e grouse c h i c k s on t h e B e a v e r t a i l Burn, t h u s s u g g e s t i n g some a f f i r m a t i o n o:f t h e second hypothesis;. I t must be p o i n t e d out, however, t h a t e vidence i n d i c a t e s t h a t the e f f e c t o f adverse weather ( i . e . , low temperatures and e x c e s s i v e r a i n s ) would p r o b a b l y i n f l u e n c e c h i c k s u r v i v a l i n d i r e c t l y by d e c r e a s i n g t h e a v a i l a b l e s u p p l y o f i n v e r t e b r a t e f o o d s . T h i s t h e s i s has uncovered s e v e r a l p o i n t s which sh o u l d m e r i t f u r t h e r s t u d y . F i r s t , w h i l e a " c a p i t a l s t o c k " t o g e t h e r w i t h t h e consumption o f i n v e r t e b r a t e s by c h i c k s (assuming c h i c k s o b t a i n t h e amount r e q u i r e d ) has been e s t i m a t e d , t h e p o t e n t i a l amount ( i n v e r t e b r a t e s i n t h e l i t t e r and not c o l l e c t e d i n t h e samples) i s not known. I n a d d i t i o n , l i t t l e i s known about the e f f e c t o f small, b i r d s and mammals on t h e y i e l d o f i n v e r t e b r a t e s . Second, t h e v a r i o u s assumptions made when r - e l a t i n g t h e n u t r i t i o n , d i g e s t i b i l i t y , and energy r e q u i r e -ments o f domestic g a l l i f o r m e s t o t h e b l u e grouse c h i c k s , and t h e e f f i c i e n c y o f f e e d i n g o f c h i c k s r e q u i r e t e s t i n g . SUMMARY AND CONCLUSIONS (1) The r e l a t i o n s h i p between e a r l y foods and blue grouse (Dendragapus obscurus f u l i g i n o s u s ) c h i c k n u t r i e n t r e q u i r e -ments has been s t u d i e d on a seven y e a r o l d burn, south-west o f Campbell R i v e r , Vancouver I s l a n d , B.C. (2) The ecology of the B e a v e r t a i l Burn both i n terms o f f l o r a l r e g e n e r a t i o n and d e n s i t y of a d u l t male blu e grouse was found to be very s i m i l a r t o t h a t of the e a r l i e r Quinsam Burn as s t u d i e d by Fowle (1944). (3) Based on the f i n d i n g s o f t h i s study i t was suggested t h a t t h e r e i s a s t r o n g p o s s i b i l i t y of an i n c r e a s e i n grouse numbers from the B e a v e r t a i l Burn, comparable, but on a l e s s e r s c a l e due t o the s m a l l s i z e o f t h i s burn, t o t h a t r e c o r d e d from the Quinsam Burn i n the l a t e 1940"s by B e n d e l l (1954). (4) An attempt was made t o determine the abundance o f accept-a b l e i n v e r t e b r a t e s d u r i n g the f i r s t few weeks of the blue grouse c h i c k ' s l i f e . The r e s u l t s d e p i c t e d a f a i r l y con-s i s t e n t a v a i l a b l e weight d u r i n g t h a t p e r i o d . I n a d d i t i o n the sampling method was shown to g i v e a reasonably r e l i a b l e estimate o f the i n v e r t e b r a t e s a v a i l a b l e to the b l u e grouse c h i c k s . (5) Changes i n c l i m a t e w i t h r e s p e c t to temperature, humidity, and r a i n f a l l a f f e c t e d the abundance and composition o f the i n v e r t e b r a t e samples. T h i s suggests t h a t adverse weather w i l l d i r e c t l y i n f l u e n c e the a v a i l a b l e supply of i n v e r t e b r a t e foods to the c h i c k . (6) One s e r i e s of p l a n t samples was taken i n the l a s t week of June to d e p i c t a v a i l a b l e v e g e t a t i o n a l food to the c h i c k s . (7) N u t r i e n t a n a l y s i s of the foods r e v e a l e d a s i m i l a r s e r i e s of m e t a b o l i z a b l e energy v a l u e s between the groups of i n v e r t e b r a t e s , and between the p l a n t s p e c i e s . (8) A n a l y s i s of eleven c h i c k crops taken d u r i n g t h i s study supplemented by an a d d i t i o n a l twenty-three taken by B e n d e l l (1954) i n d i c a t e d an almost complete i n v e r t e b r a t e d i e t f o r the f i r s t two weeks f o l l o w e d by a t r a n s i t i o n to p l a n t foods to the t h i r d and f o u r t h week of l i f e . (9) D e t e r m i n a t i o n of comparable growth p a t t e r n s between s i x p e n - r a i s e d and s e v e r a l w i l d c h i c k s r e v e a l e d s i m i l a r growth r a t e s f o r the f i r s t f o u r weeks (about 8 .6 percent per day) f o l l o w e d by a g r a d u a l divergence which r e s u l t e d i n a s i g n i f i c a n t d i f f e r e n c e i n the average f a l l weights. (10) The m e t a b o l i z a b l e energy, feed q u a n t i t y and q u a l i t y requirements of the blue grouse c h i c k were determined by the f a c t o r i a l method and from the known n u t r i t i o n of other w i l d g a l l i f o r m e s . (11) The abundance of a v a i l a b l e i n v e r t e b r a t e and p l a n t foods was found to be c o n s i s t e n t l y f a r i n excess of the requirements o f t h e a c t u a l number o f c h i c k s p r e s e n t on t h e study P l o t s . (12) The q u a l i t y o f a c c e p t a b l e c h i c k f o o d s was found t o be adequate when eaten i n co m b i n a t i o n (animal and p l a n t ) but u s u a l l y d e f i c i e n t i n one n u t r i e n t i f eate n a l o n e . (13) The h y p o t h e s i s , t h a t a shortage o f i n v e r t e b r a t e f o o d s i s p a r t i a l l y r e s p o n s i b l e f o r m o r t a l i t y o f young c h i c k s under i d e a l , weather c o n d i t i o n s was not c o n s i d e r e d v a l i d . I n f a c t , assuming t h a t t h e c h i c k s can o b t a i n t h e amount o f i n v e r t e b r a t e s r e q u i r e d , i t appeared t h a t t h e s u p p l y o f i n v e r t e b r a t e s was q u i t e s u f f i c i e n t t o m a i n t a i n t h e pr e s e n t B e a v e r t a i l B u m c h i c k p o p u l a t i o n . 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