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UBC Theses and Dissertations

Thermal adaptation in North American Sturnidae Johnson, Stephen Robert 1972

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THERMAL ADAPTATION IN NORTH AMERICAN STURNIDAE by » STEPHEN ROBERT JOHNSON B.S., Humboldt State College M.S., Kansas State University A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n the Department of Zoology accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA 1972 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia , I agree that 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 re ference and study . I f u r t h e r agree t h a t pe rmiss ion f o r e x t e n s i v e copying o f 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 granted by the Head of 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 understood that copying o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not be a l lowed wi thout my w r i t t e n p e r m i s s i o n . Department of The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada i t ABSTRACT D i f f e r e n t i a l c o l o n i z a t i o n success by the European s t a r l i n g (Sturnus v u l g a r i s ) and the t r o p i c a l c r e s t e d myna (Sturnus c r i s t a t e l l u s ) , both introduced t o North America i n the l a t e 1890's was examined i n the Lower Mainland of B r i t i s h Columbia. Evidence e x i s t e d which i n d i c a t e d mynas might be l e s s w e l l adapted than.the European s t a r l i n g t o the thermal regime i n the Lower Mainland, thus, the f o l l o w -i n g hypothesis was formulated: "an important reason f o r the observed d i f f e r e n c e i n c o l o n i z a t i o n success i n North America by s t a r l i n g s and c r e s t e d mynas i s the r e l a t i v e d i f f e r e n c e i n thermal adaptation". To t e s t the above hypothesis a two p a r t study was designed. (1) F i e l d measurements i n d i c a t e d n e s t i n g season, c l u t c h s i z e , hatching success, growth, f l e d g i n g success and ontogeny of thermoregulation f o r both s p e c i e s . A l s o , simple f i e l d experiments were designed to measure i n c u b a t i o n temperatures and determine r e s u l t s of between species c r o s s -f o s t e r i n g s t u d i e s . (2) Laboratory i n v e s t i g a t i o n s were con-ducted on w i l d caught, c a p t i v e a d u l t s . Energy i n p u t , outgo and metabolic response t o temperature f l u c t u a t i o n s were measured under both l a b o r a t o r y and o u t s i d e Vancouver c o n d i t i o n s f o r both s p e c i e s . F i n a l l y , plumage q u a l i t y was assessed i n a s e r i e s of c o o l i n g experiments using f e a t h e r e d and unfeathered carcasses of both s p e c i e s . i i The most important f a c t o r s s upporting my hypothesis were the r e l a t i v e l y low nest a t t e n t i v e n e s s and consequent poor i n c u b a t i o n success e x h i b i t e d by c r e s t e d mynas, com-pared w i t h both the European s t a r l i n g l i v i n g i n the same environment and the common myna (Sturnus t r i s t i s ) l i v i n g i n West Bengal ( I n d i a ) . B a s a l r e s t i n g ' metabolism i n both the c r e s t e d myna and the European s t a r l i n g d i d not deviate s i g n i f i c a n t l y from the p r e d i c t e d values f o r b i r d s of s i m i l a r weight, however, at the extremes i n the environmental temperature spectrum, both a d u l t and n e s t l i n g mynas were not as e f f i c i e n t i n conserving energy as the s t a r l i n g s . N e s t l i n g myna growth (weight g a i n and plumage development) was slower than s t a r l i n g growth, however, n e s t l i n g response t o f l u c t u a t i o n s were not d i f f e r e n t i f comparisons are made on the b a s i s of percent t o t a l plumage development. The r e s u l t s of c o o l i n g experiments i n d i c a t e d t h a t a d u l t c r e s t e d myna plumage was an i n f e r i o r i n s u l a t o r a g a i n s t c o l d compared w i t h s t a r l i n g plumage. Re s u l t s of b i o e n e r g e t i c s i n v e s t i g a t i o n s suggested mynas r e q u i r e d more energy at colder temperatures t o maintain a d a i l y caged e x i s t e n c e . Poor c o r r e l a t i o n s were observed between energy i n t a k e , energy metabolizeable and energy excreted by caged b i r d s and environmental temperature f l u c t u a t i o n s i n an outdoor i i i s i t u a t i o n . O n l y i n the c o l d e r t h a n u s u a l e a r l y h a l f o f 1969 was t h e r e s i g n i f i c a n t c o r r e l a t i o n s between m e t a b o l i z e a b l e energy and e n v i r o n m e n t a l t e m p e r a t u r e . F a c t o r s n o t i n v e s t i g a t e d i n t h i s s t u d y were: (1) i n t e r and i n t r a s p e c i f i c c o m p e t i t i o n , (2) d i f f e r -e n t i a l r e s p o n s e to. i n t e r f e r e n c e by humans,, r e s u l t i n g i n m o r t a l i t y , and (3) f o o d l i m i t a t i o n s t h r o u g h o u t t h e y e a r w h i c h c o u l d l i m i t s t u r n i d p o p u l a t i o n s i n t h e Lower M a i n l a n d . i v TABLE OF CONTENTS PAGE ABSTRACT . . i TABLE OF CONTENTS . . i v LIST OF TABLES v i i i LIST OF APPENDIX TABLES i x LIST OF ILLUSTRATIONS x LIST OF APPENDIX ILLUSTRATIONS x i i ACKNOWLEDGMENTS x i i i INTRODUCTION 1 MATERIALS AND METHODS . 10 F i e l d Studies . 10 Captive Studies 13 RESULTS . 18 Nesting . . . . . 18 S t a r l i n g 18 Myna 18 Incubation 21 S t a r l i n g 21 Myna 21 Hatching and Fledging 23 S t a r l i n g Hatching 23 Fledging 24 Nest Parasitism 24 V PAGE Myna Hatching .. 24 Fledging . 24 Growth and Development 28 Starling Growth . . 28 Development of Endothermy and Homeothermy 30 Nestling Food Intake 32 Myna Growth 36 Development of Endothermy and Homeothermy 36 Nestling Food Intake 37 Nest and Egg Manipulation Experiments . . . . . . . . 39 Cross-fostering Between Species 39 Heated Nestboxes 39 The Energy Cycle 41 Starling Gross Energy 41 Excretory Energy 43 Metabolizable Energy 43 Efficiency of Food Conversion 43 Molt 44 Weight Dynamics 44 v i PAGE S t a t i s t i c a l T r e a t ment o f E n e r g e t i c s Data 46 Myna Gros s Energy 47 E x c r e t o r y Energy 48 M e t a b o l i z a b l e Energy 48 E f f i c i e n c y o f Food C o n v e r s i o n 49 M o l t 49 Weight Dynamics . 49 S t a t i s t i c a l T r e a t ment o f E n e r g e t i c s Data 51 Thermal Response t o t h e E x t e r n a l E n v i r o n m e n t 5 3 S t a r l i n g E f f e c t s o f Ambient Temperature on Energy U t i l i z a t i o n 53 Myna E f f e c t s o f Ambient Temperature on Energy U t i l i z a t i o n 53 L a b o r a t o r y S t u d i e s o f Thermal Response 54 S t a r l i n g Oxygen Consumption . 54 L e t h a l Temperature 56 S e a s o n a l E f f e c t s on M e t a b o l i s m 56 R.Q. and S h i v e r i n g 58 Myna Oxygen Consumption 58 v i i PAGE L e t h a l Temperature „ 58 S e a s o n a l E f f e c t s on M e t a b o l i s m . . . 58 R.Q. and S h i v e r i n g 59 I n s u l a t i o n and Thermal Conductance . . . 59 C o o l i n g E x p e r i m e n t s - 59 S u r f a c e A r e a 61 DISCUSSION . 64 N e s t i n g 65 I n c u b a t i o n 67 H a t c h i n g and F l e d g i n g 68 Growth 70 N e s t l i n g E n ergy I n t a k e 72 Development o f Plumage and Endothermy . 76 N e s t and Egg M a n i p u l a t i o n E x p e r i m e n t s 78 Energy C y c l e i n t h e A v i a r y 81 M e t a b o l i s m Under L a b o r a t o r y C o n d i t i o n s . 88 Plumage Q u a l i t y and Thermal Conductance 95 SUMMARY AND CONCLUSIONS 1 0 0 LITERATURE CITED 1 0 7 APPENDIX , H 7 v i i i LIST OF TABLES TABLE PAGE 1 . Change i n body temperature (t^) and body weight during metabolism experiments . . . . . . . 57 2. Conductance values obtained from cooling curves of sturnids 60 3. Comparative reproductive data for s t a r l i n g s and mynas . 69 4. Comparison of sturnid r e s t i n g metabolic rates . . . 93 i x LIST OF APPENDIX TABLES TABLE PAGE 1. Meteorological data for lower mainland area, B r i t i s h Columbia, 1969 121 2. Results of an analysis of variance on energy balance data 122 3. Results of a regression analysis of temperature against G.E., E.E. and M.E. for' s t a r l i n g s . . . 124 4. Results of a regression analysis of temperature against G.E., E.E. and M.E. for mynas 125 X LIST OF ILLUSTRATIONS FIGURE PAGE 1. Extent of s t a r l i n g and myna c o l o n i z a t i o n since t h e i r respective introduction i n 1 8 9 0 and 1 8 9 7 . 3 2. Relative growth of myna and s t a r l i n g popula-tions since t h e i r introductions i n 1 8 9 7 and 1 8 9 0 at Vancouver and New York, re s p e c t i v e l y . . . . . . . . . 5 3. Climograph showing mean temperature and photoperiod i n native myna habitat (Hong Kong) and introduced myna habitat (Vancouver) . 8 4. Dates of f i r s t eggs i n f i r s t and second clutches for Vancouver Sturnidae 19 5. Nest attentiveness and mean d a i l y maximum and minimum temperature i n the egg c l u s t e r of Vancouver Sturnidae for the complete incubation period (o = s t a r l i n g ; © = crested myna) 22 6. Growth and plumage development of n e s t l i n g Vancouver Sturnidae . 25 7. Growth of n e s t l i n g Vancouver Sturnidae, presented i n the manner described by Ric k l e f s 29 8. Development of i n t e r n a l heat production (endothermy) i n n e s t l i n g Vancouver Sturnidae; oxygen consumption at varying ambient temperatures by birds i n d i f f e r e n t weight classes ( 0 , 0 , £ t , & , • ( H represent b i r d s weighing.between 1 0 - 2 0 , 2 0 - 3 0 , 3 0 - 4 0 , 4 0 - 5 0 and 6 0 - 7 0 grms, res p e c t i v e l y 31 9. Development of homeothermy i n n e s t l i n g Vancouver Sturnidae.expressed as the change i n body temperature (during 30 minute t r i a l s at - 5 C) of nestlings at varying stages of development (o = s t a r l i n g ; e = crested myna) . 3 3 x i FIGURE PAGE 10. A d u l t a c t i v i t y a t 2 s t a r l i n g (1 i n 1969 and 1 i n 1970) n e s t b o x e s 34 11. A d u l t a c t i v i t y a t 2 myna (1 i n 1969 and 1 i n 1970) n e s t b o x e s 38 12. R e s u l t s o f egg s w i t c h i n g e x p e r i m e n t s and subsequent a d u l t i n c u b a t i o n by Vancouver S t u r n i d a e 40 13. R e s u l t s o f h e a t e d n e s t b o x e x p e r i m e n t s . . . . 42 14. D e p i c t i o n o f s t u r n i d g r o s s e n e r g y • i n t a k e . (G.E.), e x c r e t o r y o u t p u t (E.E.) and m e t a b o l i z a b l e energy (M.E.) ( a l l i n k c a l / b i r d - d a y ) w i t h m o l t , w e i g h t and ambient t e m p e r a t u r e changes 45 15. Energy c o n t e n t o f e x c r e t a and d i g e s t i o n e f f i c i e n c y d u r i n g t h e 1 y e a r e x p e r i m e n t a l p e r i o d 50 16. S t u r n i d t h e r m a l r e s p o n s e c u r v e s i l l u s t -r a t i n g t h e o r e t i c a l LCT and e x p e r i m e n t a l l y o b s e r v e d LCT, and l e a s t s q u a r e s r e g r e s s i o n l i n e s e x t r a p o l a t e d t o o b s e r v e d body t e m p e r a t u r e s . 55 17. Comparison o f e x p e r i m e n t a l l y o b t a i n e d (o) and t h e o r e t i c a l (Meeh 189 7: 10.4 V?2/3) s u r f a c e a r e a v a l u e s f o r 9 b i r d s r a n g i n g i n s i z e from a j u v e n a l b a r n s w a l l o w t o an a d u l t r o c k dove 62 x i i L I S T OF A P P E N D I X I L L U S T R A T I O N S F I G U R E P A G E 1. C o m p u t e r p l o t o f m e a n c a g e a r e a a m b i e n t t e m p e r a t u r e (°C maximum a n d m i n i m u m ) a n d s t u r n i d G . E . i n t a k e f o r t h e p e r i o d 1 J a n u a r y 1 9 6 9 t o 1 J a n u a r y 1 9 7 0 1 1 8 2 . P l o t o f h e a t l o s s f r o m f e a t h e r e d ( f ) a n d u n f e a t h e r e d ( u f ) s t a r l i n g c a r c a s s e s c o o l e d a t 0 ° C 1 1 9 3 . P l o t o f h e a t l o s s f r o m f e a t h e r e d ( f ) a n d u n f e a t h e r e d ( u f ) m y n a c a r c a s s e s c o o l e d a t 0 ° C . 1 2 0 4. S t u r n i d t h e r m a l r e s p o n s e ( c a l / g m - h r ) c a l c u l a t e d o n t h e b a s i s o f wt (gms) 2 2 8 x i i i ACKNOWLEDGMENTS I am t h a n k f u l to Dr. Ian McTaggart Cowan, who provided funds and guidance throughout t h i s study, and f o r h i s patience and help d u r i n g the p r e p a r a t i o n of t h i s t h e s i s . Dr. Rudolf Drent gave i n v a l u a b l e advice and spent much time d i s c u s s i n g v a r i o u s aspects of t h i s r e s e a r c h . Dr. Harold Nordan g r a c i o u s l y provided V i v a r i u m space and equipment, sometimes a t the expense of h i s own res e a r c h . Dr. E o i n McEwan of the Canadian W i l d l i f e S e r v i c e provided both l a b o r a t o r y space and equipment. A l s o acknowledged i s the help and c o n s i d e r a t i o n given by many students both i n the Department of Zoology and I n s t i t u t e of Animal Resource Ecology. I would e s p e c i a l l y l i k e to thank Lance Steigenberger, Wayne Weber, Wayne Campbell, John Ward, Tony K o e l i n k , Ian Robertson, B r i a n Kemper and others who p a r t i c i p a t e d i n the many s t a r l i n g r o o s t counts and banding and" capture a c t i v i t i e s . Drs. Peter Larkim, James B e n d e l l and J . Mary T a y l o r provided guidance through t h e i r e f f o r t s on my t h e s i s committee. I am indebted t o Ronald M o d a f f e r i f o r c r i t i c a l l y reading the manuscript. 1 INTRODUCTION The s t u r n i d s o r s t a r l i n g s and s t a r l i n g - l i k e b i r d s a r e n a t i v e t o Europe, A f r i c a and A s i a (Wetmore 1964). The f a m i l y i n c l u d e s 100 s p e c i e s (Amadon 1946), two of w h i c h were i n t r o d u c e d t o N o r t h A m e r i c a i n the l a t e n i n e t e e n t h c e n t u r y . F i r s t a t t e m p t s t o i n t r o d u c e s t a r l i n g s ( S t u r n u s v u l g a r i s  v u l g a r i s L.) i n P e n n s y l v a n i a i n 1850 and i n Ohio i n the w i n t e r of 1872-73 f a i l e d ( P h i l l i p s 1928). L a t e r i n 1889, 20 p a i r s were r e l e a s e d i n P o r t l a n d , Oregon, and a l t h o u g h t h e p o p u l a t i o n i n i t i a l l y i n c r e a s e d , the c o l o n y presumably d i e d o u t around 1901 or 1902 (Lord 1902). F i n a l l y , 40 p a i r s of s t a r l i n g s were s u c c e s s f u l l y i n t r o d u c e d i n 1890 and 1891 a t C e n t r a l P a r k , New York C i t y (Forbush 1915). W i t h i n t h e l a s t c e n t u r y , s t a r l i n g s have been s u c c e s s -f u l l y i n t r o d u c e d t o and s u b s e q u e n t l y s p r e a d i n a l l c o n t i n e n t s e x c e p t South A m e r i c a . S t u r n u s v u l g a r i s o r i g i n a t e s from a temperate environment and most p o p u l a t i o n s w h i c h b r e e d i n h i g h l a t i t u d e s m i g r a t e t o warmer a r e a s d u r i n g c o l d months. Banding r e t u r n s s u g g e s t t h a t t h e m a j o r i t y o f s t a r l i n g s b r e e d i n g i n t h e s o u t h c o a s t a l a r e a o f B r i t i s h C o l u m b i a a r e no t m i g r a t o r y , w h i l e most b i r d s b r e e d i n g f u r t h e r n o r t h do m i g r a t e t o and t h r o u g h t h e s o u t h c o a s t of t h e p r o v i n c e i n the f a l l and s p r i n g . A s i m i l a r s i t u a t i o n e x i s t s i n B r i t a i n (Thompson 1926). Barnes (1951) however, mentions t h a t i n t r o d u c e d s t a r l i n g s d i d n o t show m i g r a t o r y t e n d e n c i e s d u r i n g 2 t h e i r f i r s t y e a r s i n N o r t h A m e r i c a , b u t may have a c q u i r e d the t r a i t t h r o u g h a s s o c i a t i o n w i t h b l a c k b i r d s and o t h e r m i g r a t o r y s p e c i e s . The c r e s t e d myna (Stu r n u s c r i s t a t e l l u s c r i s t a t e l l u s ( D e i g n a n ) ) , i s a s u b t r o p i c a l member o f the S t u r n i d a e , and was i n t r o d u c e d t o Vancouver, B r i t i s h C o l u m b i a , i n 1897. A p p a r e n t l y o n l y 1 o r 2 p a i r s e i t h e r escaped o r were r e l e a s e d t o found the e n t i r e c o l o n y (Cummings 1925). The taxonomy o f the c r e s t e d myna i s u n s e t t l e d . Deignan f a v o u r s the genus S t u r n u s o v e r A c r i d o t h e r e s ( M c C l u r e , p e r s o n a l communication, 1969), w h i l e o t h e r s cannot agree. Taxonomy f o l l o w i n g Deignan has been a c c e p t e d i n t h i s s t u d y . E a r l i e r , t h e c r e s t e d myna was s u c c e s s f u l l y i n t r o d u c e d t o the P h i l l i p i n e s i n 1850, however, egg c o l l e c t i n g and s h o o t i n g k e p t t h e p o p u l a t i o n reduced (McGregor 1920). They have a l s o been i m p o r t e d i n t o Japan and Germany and s o l d as d o m e s t i c p e t s f o r many y e a r s (Wood 1934:132). The c r e s t e d myna i s n a t i v e t o t h e s u b t r o p i c s o f S o u t h e a s t A s i a i n c l u d i n g S o u t h e r n C h i n a , E a s t e r n I n d i a , Taiwan and t h e I n d o c h i n e s e r e g i o n ( D e l a c o u r and Mayr 1946; A l i 1949; Smythies 1953; W h i s t l e r 1949; W i l d a s h 1968). F i g u r e 1 i l l u s t r a t e s t h e g e n e r a l p a t t e r n s o f c o l o n i z a t i o n o f b o t h s p e c i e s s i n c e t h e i r r e s p e c t i v e i n t r o d u c t i o n s t o N o r t h A m e r i c a i n 1890 and 1897. A l t h o u g h t h e c r e s t e d myna has n o t been as s u c c e s s f u l a 3 F i g u r e 1. I s o p l e t h s d e s i g n a t e e x t e n t o f s t a r l i n g c o l o n i z a t i o n s i n c e i n t r o d u c t i o n a t New York i n 1890. No i n c r e a s e i n myna d i s t r i b u t i o n has o c c u r r e d . 4 c o l o n i z e r as t h e European s t a r l i n g , many e a r l y s o u r c e s e x p r e s s e d a l a r m a t t h e r a t e i n which t h e myna p o p u l a t i o n i n c r e a s e d i n the Vancouver a r e a between 1897 and 1927 (Kermode 1921; Munro 1922; Racey 1924; Cummings 1932; K e l l e y 1927: See F i g u r e 2 ) . E a r l y r e p o r t s n o t e d mynas seen near B l a i n e , Washington, (Cummings 1925) and as f a r s o u t h as P o r t l a n d , Oregon, ( G a b r i e l s o n and J e w e t t 19 40) and S e a t t l e , Washington, ( J e w e t t e t a l 1953). Saunders (1930) r e p o r t e d c r e s t e d mynas common a t A l e r t Bay, B r i t i s h C o l u m b i a , however, Munro (1930) q u e s t i o n e d t h i s r e p o r t . C r e s t e d mynas e s t a b l i s h e d t h e m s e l v e s i n Nanaimo, B r i t i s h C o l u m b i a , (Vancouver I s l a n d ) i n t h e e a r l y 1950's ( S c h e f f e r 19 5 5 ) , however, a b r e e d i n g p a i r was s h o t i n V i c t o r i a , B r i t i s h C olumbia (Vancouver I s l a n d ) as e a r l y as 19 46. The myna p o p u l a t i o n r e a c h e d a peak i n t h e l a t e 1920's w i t h numbers i n B r i t i s h C olumbia e s t i m a t e d a t near 20,000 ( K e l l e y 1927). S c h e f f e r (1931) n o t e d t h a t myna numbers had been s t a b l e f o r the 3-4 y e a r p e r i o d p r i o r t o 1931. Cummings (1932) r e p o r t e d mynas n a t u r a l l y d e c r e a s i n g d u r i n g t h e e a r l y 1930's. Cowan e s t i m a t e d t h e p o p u l a t i o n t o be 4,000 b i r d s i n 1955 ( S c h e f f e r 1955). More r e c e n t l y , MacKay and Hughes (1963) e s t i m a t e d the myna p o p u l a t i o n t o be about 2000-3000 b i r d s . The p r e s e n t p o p u l a t i o n i s p r o b a b l y near 5000-6000 b i r d s ( F i g u r e 2 ) . 5 F i g u r e 2. R e l a t i v e growth o f myna and s t a r l i n g p o p u l a t i o n s s i n c e t h e i r i n t r o d u c t i o n s i n 1897 and 1890 a t Vancouver and New Y o r k , r e s p e c t i v e l y (o = s t a r l i n g ; ® = c r e s t e d myna). 6 A f t e r a review of the r e l a t i v e colonizing success of these two sturnids, the obvious question arises as to the causes of such a difference. The myna i s a non-migratory subtropical sturnid whose recent evolution has been i n an environment quite d i f f e r e n t from the temperate regions of Europe and Western Asia, from which the European s t a r l i n g o riginates. Being non-migratory, only two other major avenues of colonization were open; d i s p e r s a l from an over-populated environment and/or wanderlust s i m i l a r to that described for the European s t a r l i n g by Cooke (1928:3). Except for the e a r l i e r scattered sightings i n Oregon and Washington, no accounts of crested myna sightings have been made outside the present r e s t r i c t e d North American range of the species. Thus, the question i s posed, why has the myna population not increased to the point where d i s p e r s a l to other areas has become e f f e c t i v e . The hypothesis upon which this research was based i s the following: an important reason for the observed d i f f e r -ence i n success of colonization by North American Sturnidae has been the r e l a t i v e difference i n thermal a d a p t a b i l i t y . A p r i o r i evidence exists for the formulation of such an hypothesis. I n i t i a t i o n of egg laying by mynas i n North America and Asia begins at the same time; about 15 A p r i l (MacKay and Hughes 1963; Vaughn and Jones 1913). However, 7 the mean 10-day d a i l y t e m p e r a t u r e p r i o r t o egg l a y i n g f o r mynas i s a p p r o x i m a t e l y 11°C lower i n Vancouver (10°C) th a n i n t h e Hong Kong and Macao a r e a o f South C h i n a (21°C) from w h i c h the b i r d s were s u p p o s e d l y i m p o r t e d , and w h i c h i s near the n o r t h e r n l i m i t of t h e s p e c i e s ' d i s t r i b u t i o n . F i g u r e 3 p r e s e n t s c l i m o g r a p h i c i l l u s t r a t i o n o f t h e t e m p e r a t u r e and p h o t o p e r i o d regimes i n Vancouver and Hong Kong. S t a r l i n g s , on t h e o t h e r hand, i n i t i a t e egg l a y i n g a t many d i f f e r e n t t e m p e r a t u r e and p h o t o p e r i o d c o m b i n a t i o n s t h r o u g h o u t Europe, N o r t h A m e r i c a , B r i t a i n and Western A s i a ( K e s s e l 1957; R o y a l l 1966; Anderson 1961; Dunnet 1955; H a v l i n and F o l k 1961). F u r t h e r , t h e r e i s e v i d e n c e t h a t mynas s u f f e r d u r i n g c o l d w e a t h e r . I n Vancouver, o b s e r v e r s have n o t i c e d mynas h u d d l e d on chimneys near h e a t e f f l u e n t on c o l d w i n t e r days (Cummings 1925; Weber p e r s o n a l communication; and my own r e c o r d s ) . P h i l i p s (1928) a l s o mentioned t h a t mynas s u f f e r from c o l d and would p r o b a b l y be c o n f i n e d t o t h e immediate c o a s t . There i s no such e v i d e n c e t h a t s t a r l i n g s s i m i l a r l y s u f f e r i n c o l d c l i m a t e s , presumably because most p o p u l a t i o n s m i g r a t e t o warmer areas d u r i n g w i n t e r . I n g e n e r a l , the a b i l i t y o f a s p e c i e s t o w i t h s t a n d a b r o a d range o f t h e t h e r m a l spectrum i s dependent upon i t s s u c c e s s i n c o n s e r v i n g energy. K i n g and F a r n e r (1960) have 8 Figure 3. Cliraograph showing mean temperature and photo-period i n native myna habitat (Hong Kong) and introduced myna habitat (Vancouver). Data contributed by Canada Dept. of Transport, 1969, and the Royal Observatory, Hong Kong, 1969. 9 g i v e n a comprehensive r e v i e w o f e n e r g e t i c s t h e o r y p e r t a i n i n g t o b i r d s . T o l e r a n c e t o a p a r t i c u l a r e n v i r o n m e n t a l temper-a t u r e range i s t h e r e s u l t o f e v o l u t i o n and a d a p t a t i o n t h a t has t a k e n p l a c e i n a p a r t i c u l a r t y p e o f e n v i r o n m e n t a l system. S c h o l a n d e r (1955 and 1956) has g i v e n a good d i s c u s s i o n of t e m p e r a t u r e a d a p t a t i o n by b o t h a r c t i c and t r o p i c a l s p e c i e s , and d i s c u s s e s the b a s i c t h e o r y b e h i n d c l i m a t i c a d a p t a t i o n i n homeotherms. A f t e r e x a m i n i n g t h e above e v i d e n c e , a t w o - p a r t s t u d y was i n i t i a t e d t o i n v e s t i g a t e s t u r n i d s i n t h e l o w e r m a i n l a n d of B r i t i s h C o lumbia. F i e l d d a t a were c o l l e c t e d t o o b t a i n b a s i c n a t u r a l h i s t o r y i n f o r m a t i o n on b r e e d i n g b i o l o g y , growth and development o f young. S i m p l e f i e l d e x p e r i m e n t s were d e s i g n e d t o d e t e r m i n e the r a t e , q u a n t i t y and q u a l i t y o f energy i n t a k e by growing young and t o d e t e r m i n e t h e i n c u b a t i o n s u c c e s s o f a d u l t s t u r n i d s . L a b o r a t o r y i n v e s t i -g a t i o n s were made o f the m e t a b o l i c r e s p o n s e s by a d u l t s t u r n i d s t o v a r y i n g t e m p e r a t u r e s and t o d e t e r m i n e t h e r e l a t i v e i n s u l a t i o n v a l u e s o f t h e plumage o f b o t h s p e c i e s . A d u l t s o f b o t h s p e c i e s were c a p t u r e d and k e p t i n o u t d o o r a v i a r i e s under Vancouver c l i m a t i c c o n d i t i o n s where t h e i r b i o e n e r g e t i c s were i n v e s t i g a t e d . 10 MATERIALS AND METHODS F i e l d S t u d i e s One hundred c e d a r n e s t b o x e s were c o n s t r u c t e d from t h e d e s i g n d e s c r i b e d by K e s s e l (1957) . These boxes were p l a c e d t h r o u g h o u t the Vancouver a r e a , w i t h emphasis on l o c a t i o n s n e a r the U n i v e r s i t y o f B r i t i s h C o l u m b i a , and upon t h e i s l a n d s o f the F r a s e r R i v e r d e l t a , w h i c h r e p r e s e n t the major a g r i c u l t u r a l d i s t r i c t s i n t h a t p o r t i o n of the Puget Sounds Lowlands (See Cowan 1965:19-20) l y i n g w i t h i n B r i t i s h C o l u m b i a . Nestboxes were checked s e v e r a l t i m e s each week d u r i n g n e s t b u i l d i n g , egg l a y i n g , i n c u b a t i o n and growth. D u r i n g t h i s s t u d y 4 a c t i v e s t a r l i n g and 4 a c t i v e myna n e s t b o x e s were e q u i p p e d w i t h Y e l l o w S p r i n g s I n s t r u m e n t Co. (YSI) t h e r m i s t o r probes (#504) f o r m o n i t o r i n g n e s t t e m p e r a t u r e i n t h e v i c i n i t y o f the egg c l u s t e r . A YSI t e l e t h e r m o m e t e r was the n used t o check i n c u b a t i o n temper-a t u r e s d u r i n g v i s i t s t o t h e n e s t b o x e s . A l s o , 2 myna and 2 s t a r l i n g n e s t b o x e s were c o n s t a n t l y m o n i t o r e d d u r i n g i n c u b a t i o n u s i n g R u s t r a k model 2 88, 2 c h a n n e l t e m p e r a t u r e r e c o r d e r s . I n a d d i t i o n t o ambient and n e s t b o x t e m p e r a t u r e s , c o r e t e m p e r a t u r e s ( p r o v e n t r i c u l a r ) were r e c o r d e d u s i n g an i n s t a n t r e a d i n g S c h u l t e s R e p t i l e thermometer (-10°C t o +50°C) . Most a d u l t and a l l n o n - e x p e r i m e n t a l n e s t l i n g s were banded w i t h U.S. F i s h and W i l d l i f e S e r v i c e aluminum l e g 11 bands. D u r i n g growth, n e s t l i n g s were marked w i t h a d h e s i v e p o l y v i n y l c h l o r i d e t a p e (See Johnson 1971) f o r i n d i v i d u a l i d e n t i f i c a t i o n . Oxygen consumption and change i n c o r e t e m p e r a t u r e were r e c o r d e d f o r a s e r i e s o f d e v e l o p i n g s t a r l i n g s and mynas exposed t o v a r y i n g ambient t e m p e r a t u r e s i n a B e l l c r a f t c o n t r o l l e d environment c a b i n e t ( t e m p e r a t u r e f l u c t u a t e d ± 1.0°C). A Beckman F-3 p a r a m a g n e t i c a n a l y z e r was used t o measure 0^ consumption from a c l o s e d system. N e s t l i n g s a n a l y z e d were n o t n e c e s s a r i l y p o s t a b s o r p t i v e and R.Q. ( r e s p i r a t o r y q u o t i e n t s ) d e t e r m i n a t i o n s were n o t made. Body t e m p e r a t u r e s were r e c o r d e d a t t h e n e s t and a g a i n a f t e r they had been t r a n s p o r t e d t o the l a b o r a t o r y . Many s t a r l i n g nests- were found w i t h i n 200 y a r d s of t h e l a b o r a t o r y and t r a n s p o r t o f t h e s e b i r d s was eas y , however, t h e c l o s e s t myna n e s t s (5 n e s t s ) were l o c a t e d 1 m i l e from t h e l a b o r a t o r y and h e a t e d i n s u l a t e d boxes were employed t o i n s u r e a g a i n s t h e a t l o s s by t h e s e n e s t l i n g s . Growth was a s s e s s e d by measurement o f the l o n g e s t p r i m a r y as w e l l as by w e i g h t g a i n . The l a t t e r was measured t o the n e a r e s t 0.1 gm u s i n g P e s o l a #491 and 498 s p r i n g b a l a n c e s . F e e d i n g and a c t i v i t y r a t e s of a d u l t s t u r n i d s were a s c e r t a i n e d by use o f o b s e r v e r s w a t c h i n g n e s t b o x e s t h r o u g h 30X s p o t t i n g s c o p e s . C o n t i n u o u s m o n i t o r i n g o f the i n c u b a t i o n 12 regimen and o f the r a t e w h i c h a d u l t s t u r n i d s f e e d t h e i r n e s t l i n g s was u n d e r t a k e n by e m p l o y i n g L i c o n model 10-722 m i c r o s w i t c h e s a t t a c h e d t o t h e top o f n e s t b o x h o l e s , i n c o n j u n c t i o n w i t h E s t e r l i n e - A n g u s 20 c h a n n e l e v e n t r e c o r d e r s . Food i t e m s were c o l l e c t e d from n e s t l i n g s t a r l i n g s and mynas u s i n g t h e " c l o s e f i t t i n g c o l l a r " t e c h n i q u e d e s c r i b e d by K l u i j v e r (1933). Food i t e m s were t h e n d r i e d and sub-s e q u e n t l y a n a l y z e d f o r energy c o n t e n t u s i n g a P h i l l i p s o n Micro-bomb c a l o r i m e t e r . Energy and w e i g h t v a l u e s were p o o l e d f o r c a l c u l a t i n g a d a i l y mean energy i n t a k e o f n e s t -l i n g s t u r n i d s . I n o r d e r t o t e s t d i f f e r e n c e s i n egg q u a l i t y and i n the e f f e c t i v e n e s s o f i n c u b a t i o n on t h e p a r t o f the two s p e c i e s , a s e r i e s o f i n t e r s p e c i e s c r o s s f o s t e r i n g e x p e r i m e n t s were conducted i n 1969 and 1970. I n t h e s e e x p e r i m e n t s 5 myna and 5 s t a r l i n g c l u t c h e s (5 eggs each) w h i c h were s y n c h r o n i z e d (± 1 day) i n t h e i r i n c u b a t i o n c y c l e s were s w i t c h e d a t day 2 from t h e n e s t of one s p e c i e s t o the o t h e r and f o l l o w e d t h r o u g h i n c u b a t i o n t o h a t c h i n g and f l e d g i n g . To i n v e s t i g a t e t h e r o l e o f n e s t t e m p e r a t u r e , 5 n e s t -boxes were m o d i f i e d u s i n g E l e c t r o - t h e r m a l h e a t i n g t a p e and Fenwal #17300-23 t h e r m a l s w i t c h e s t o keep n e s t b o x temper-a t u r e s from d r o p p i n g below +28°C. C a p t i v e a d u l t s t a r l i n g s and mynas were o b t a i n e d from w i l d p o p u l a t i o n s i n t h e Vancouver a r e a i n 1968-69. S t a r l i n g s 13 were c a p t u r e d on t h e campus o f the U n i v e r s i t y o f B r i t i s h C o lumbia u s i n g b a i t e d f u n n e l t r a p s . C r e s t e d mynas were c a p t u r e d w i t h m i s t n e t s a t n i g h t i n a communal r o o s t . Sex o f s t a r l i n g s can be d e t e r m i n e d e x t e r n a l l y ( K e s s e l 1951) , and an even number of males and f e m a l e s were s e l e c t e d . C r e s t e d mynas, however, show no e x t e r n a l s e x u a l c h a r a c t e r -i s t i c s , t h e r e f o r e b i r d s c o u l d n o t be c o l l e c t e d on the b a s i s o f sex. No e x p e r i m e n t a t i o n o r d a t a c o l l e c t i o n was i n i t i a t e d u n t i l t h e w e i g h t and b e h a v i o u r o f the b i r d s i n d i c a t e d they had become a d j u s t e d t o c o n f i n e m e n t (1-3 months). C a p t i v e S t u d i e s I n i t i a l l y , twenty b i r d s o f each s p e c i e s were c a p t u r e d and c o n f i n e d two p e r cage. S i n c e c o m p e t i t i o n f o r f o o d and space w i t h i n i n d i v i d u a l cages was e v i d e n t , sample s i z e s were h a l v e d t o one b i r d p e r cage. E x p e r i m e n t a l b i r d s were housed i n 0.5 x 1 x 1 meter cages o u t d o o r s a t t h e V i v a r i u m , U n i v e r s i t y o f B r i t i s h C o l u m b i a , where t h e y were exposed t o Vancouver t e m p e r a t u r e and l i g h t c o n d i t i o n s . However, a r o o f o v e r and opaque p o l y e t h y l e n e s h e e t i n g around t h e cage a r e a gave s h e l t e r from p r e c i p i t a t i o n and w i n d . The moder-a t i n g i n f l u e n c e o f t h i s s h e l t e r on a i r t e m p e r a t u r e i s shown i n Appendix T a b l e 1. 14 Food and w a t e r were a v a i l a b l e on an ad l i b i t u m b a s i s from s p e c i a l l y c o n s t r u c t e d c o n t a i n e r s d e s i g n e d t o reduce s p i l l a g e . A l l e x p e r i m e n t a l b i r d s were f e d B u c k e r f i e l d 1 s C h i c k S t a r t e r w i t h Amprolium crumbles ( a n t i c o c c i d i o s u s a g e n t ) . B u c k e r f i e l d ' s g u a r a n t e e s t h e f o l l o w i n g a n a l y s i s of t h e i r C h i c k S t a r t e r : (Min.) (Max.) (Max.) ( M i n . / l b ) P r o t e i n F a t ( F i b e r N a C l P V i t . A Amprolium 20% 3.5% 5.5% 0.45% 0.7% 1500 I.U. 0.0125% Energy u t i l i z a t i o n e x p e r i m e n t s were c o n d u c t e d f o r the y e a r p e r i o d 1 J a n u a r y 1969 t o 1 J a n u a r y 1970. Feed cans were weighed b e f o r e and a f t e r each t r i a l and f i l l e d w i t h f r e s h f e e d e v e r y two days. Water was a l s o changed e v e r y two days e x c e p t i n w i n t e r when f r e e z i n g t e m p e r a t u r e s n e c e s s -i t a t e d c h a n g i n g w a t e r e v e r y day. Each 100 pound l o t o f f e e d p u r c h a s e d was subsampled and" a n a l y z e d f o r energy c o n t e n t . Four energy d e t e r m i n a t i o n s were performed f o r each f e e d subsample on a Gallenkamp a d i a b a t i c oxygen bomb c a l o r i m e t e r . The mean energy c o n t e n t of f o o d was 4.53 ± .01 kcal/gm f o r e i g h t 100 pound l o t s . Two p e r c h e s were p l a c e d i n each cage from w h i c h b i r d s e x c r e t e d o n t o non-absorbent paper u n r o l l e d beneath each row of cages. The paper was p u l l e d from the ends o f cage rows 15 and the e x c r e t a were c o l l e c t e d f o r each cage on s e c t i o n s c u t from t h e r o l l . E x c r e t a c o l l e c t i o n s were made o v e r 2-8 day p e r i o d s t h r o u g h o u t t h e y e a r . Twenty-three c o l l e c t i o n s were made d u r i n g t h i s s t u d y , r e p r e s e n t i n g 102 days o f s a m p l i n g . E x c r e t a were d r i e d a t 32°C i n a steam-heated d r y i n g room f o r a t l e a s t 7 days, a f t e r w h i c h the d r i e d samples were s c r a p e d from t h e paper and p l a c e d i n p l a s t i c bags. E x c r e t a c o l l e c t i o n s were l a t e r weighed, subsampled and a n a l y z e d t w i c e f o r energy c o n t e n t . A f t e r d r y i n g was c o m p l e t e , f e a t h e r s and s p i l l e d f o o d were s e p a r a t e d from e x c r e t a . Weight o f t h e e x p e r i m e n t a l b i r d s was measured t w i c e p e r month and cage a r e a ambient t e m p e r a t u r e s were measured e v e r y two days on maximum-minimum thermometers. B i o e n e r g e t i c s d a t a f o r c a p t i v e s t u r n i d s were p r o c e s s e d on an IBM 1130 computing system. P l o t t e d graphs o f some raw d a t a a re p r e s e n t e d i n Appendix F i g u r e 1. F o r ease i n s t a t i s -t i c a l t r e a t m e n t , d a t a were p o o l e d i n t o monthly means and an a n a l y s i s of v a r i a n c e was r u n on an IBM 360 computing system. A v a l u e of a^O.10 was chosen f o r a l l t e s t s o f s i g n i f i c a n c e . Energy m e t a b o l i s m e x p e r i m e n t s were c o n d u c t e d on p o s t -a b s o r p t i v e a d u l t b i r d s a t n i g h t i n a B e l l c r a f t c o n t r o l l e d e nvironment c a b i n e t ( t e m p e r a t u r e f l u c t u a t i o n s = ± 1.0°C). A c l o s e d system t e c h n i q u e was used i n w h i c h b i r d s were p l a c e d 3 on a p e r c h i n a 0.8 meter p l e x i g l a s box w i t h i n t h e dar k e n e d 16 environment c a b i n e t . R e l a t i v e h u m i d i t y i n t h e r e s p i r a t i o n chamber was k e p t n e a r 20% d u r i n g e x p e r i m e n t s . A i r temper-a t u r e s were m o n i t o r e d u s i n g a YSI t e l e t h e r m o m e t e r w i t h YSI # 401 p r o b e s . Oxygen u t i l i z a t i o n was measured w i t h a Beckman F-3 P a r a m a g n e t i c Oxygen a n a l y z e r ( f l o w rate=250 c c / m i n ) ; a s c a r i t e tubes were employed t o a n a l y z e CO2 from a i r samples w i t h d r a w n from t h e c l o s e d system. B i r d s were weighed and c o r e ( p r o v e n t r i c u l a r ) t e m p e r a t u r e s were t a k e n o r a l l y b e f o r e and a f t e r m e t a b o l i s m e x p e r i m e n t s . T r i a l s were performed on b i r d s o f b o t h s p e c i e s a t ambient t e m p e r a t u r e s o f -20°C t h r o u g h +40°C. T r i a l s were c o n d u c t e d f o r 3 hours e x c e p t a t +20°C where t r i a l s l a s t e d from 6-9 h o u r s . P o s t a b s o r p t i v e s t a t e was assumed f r o m d e t e r m i n a t i o n s of r a t e o f passage. T h i s r a t e was d e t e r m i n e d by t h e use of f o o d marked w i t h carmine dye. E x p e r i m e n t s t o d e t e r m i n e i n s u l a t i v e v a l u e s f o r a d u l t plumage o f b o t h s p e c i e s were conducted on f r e s h specimens i n t h e e n v i r o n m e n t a l c a b i n e t . F i v e s t a r l i n g s and f o u r mynas were k i l l e d and i m m e d i a t e l y suspended by t h e beak i n the c a b i n e t and a l l o w e d t o c o o l . The r a t e o f n a t u r a l body h e a t l o s s was r e c o r d e d w i t h a YSI model 524 n e e d l e probe i n s e r t e d i n t o t h e c a r c a s s c o r e d u r i n g c o o l i n g e x p e r i m e n t s . S e v e r a l b i r d s were a r t i f i c i a l l y 17 r e h e a t e d t o n a t u r a l c o r e t e m p e r a t u r e s and c o o l e d a g a i n t o t e s t f o r p o s s i b l e d i f f e r e n c e s between the l o s s o f a r t i f i -c i a l l y i n d u c e d and n a t u r a l h e a t . F i n a l l y , the f e a t h e r e d c a r c a s s was a g a i n a r t i f i c i a l l y r e h e a t e d and f e a t h e r s q u i c k l y s t r i p p e d o f f , t h e c a r c a s s r e h e a t e d the l a s t few degrees t o normal c o r e t e m p e r a t u r e , and t h e n a l l o w e d t o c o o l w i t h o u t f e a t h e r s . S u r f a c e a r e a s o f d e f e a t h e r e d b i r d c a r c a s s e s were d e t e r m i n e d by c o v e r i n g t h e c a r c a s s w i t h a t h i n l a y e r o f Dow-Corning S i l i c o n e S e a l a n t . The s e a l a n t was a l l o w e d t o cur e and was removed i n a manner s i m i l a r t o s k i n n i n g . The c a r c a s s mold was t h e n c u t i n t o s e c t i o n s , p i n n e d o u t f l a t and t r a c e d . A p o l a r p l a n i m e t e r was employed t o d e t e r m i n e t h e s u r f a c e a r e a o f the t r a c i n g . S u r f a c e a r e a d a t a o b t a i n e d i n t h i s manner were compared w i t h t h o s e 2 /3 c a l c u l a t e d u s i n g the f o r m u l a o f Meeh (1897: S.A.=kw ' ) and t h e c o n s t a n t (k) o b t a i n e d by Rubner (1902: k=10.4). 18 RESULTS N e s t i n g The S t a r l i n g N e s t b u i l d i n g by s t a r l i n g s i n t h e Vancouver a r e a began i n t h e second o r t h i r d week i n March. F i r s t eggs were u s u a l l y l a i d i n the second week o f A p r i l , however, d u r i n g 1970, s t a r -l i n g s began n e s t i n g e a r l i e r and f i r s t eggs were l a i d i n the f i r s t week o f A p r i l (See F i g u r e 4 ) . The mean c l u t c h s i z e f o r a l l f i r s t n e s t i n g s was 5.45 ± .12 eggs (n=76). S t a r -l i n g s a re not s t r o n g l y n e s t s i t e t e n a c i o u s , b u t 8 females d i d occupy t h e same box f o r two c o n s e c u t i v e y e a r s . T h i r t y -n i n e p e r c e n t o f a l l s t a r l i n g s i n t h i s s t u d y s u c c e s s f u l l y n e s t e d t w i c e . These second c l u t c h e s were s t a r t e d i n l a t e May w i t h the peak of egg l a y i n g near 1 Jun e , and e x c l u s i v e of r e n e s t i n g s t h e y averaged 4.73 ± .30 eggs (n=32). The Myna The f i r s t myna n e s t i n g a c t i v i t y began i n t h e second o r t h i r d week o f March. Males p e r c h e d n e a r t h e p r o s p e c t i v e n e s t s i t e and v o c a l i z e d l o u d l y . I n most c a s e s mynas seemed a l r e a d y p a i r e d when n e s t i n g a c t i v i t y was i n i t i a t e d . P a i r i n g p r o b a b l y o c c u r r e d i n the r o o s t o r away from t h e n e s t i n l a t e w i n t e r o r e a r l y s p r i n g . O l d e r mynas a r e s t r o n g l y n e s t s i t e t e n a c i o u s , w i t h some n e s t s o c c u p i e d by a t l e a s t 1 member of t h e same p a i r f o r the t h r e e y e a r s t u d y p e r i o d . Mynas are v e r y a g g r e s s i v e b i r d s 19 F i g u r e 4. Dates o f f i r s t eggs i n f i r s t and second c l u t c h e s f o r Vancouver S t u r n i d a e . 20 and r e a d i l y k i l l any n e s t l i n g s and d r i v e o f f p a r e n t b i r d s of o t h e r s p e c i e s w h i c h e s t a b l i s h t h e m s e l v e s i n a p r o s p e c t i v e myna n e s t . Myna n e s t s a r e t r u l y t r a d i t i o n a l ; we were i n f o r m e d t h a t one n e s t had been o c c u p i e d by b r e e d i n g p a i r s f o r o v e r t h i r t y y e a r s . These o l d e r n e s t s were q u i t e l a r g e and gaudy w i t h b r i g h t p a p e r s , n y l o n s t o c k i n g s , p l a s t i c bags, b a l l o o n s , b r i g h t f e a t h e r s , mummified g o l d f i n c h and s w a l l o w c a r c a s s e s , r e c o r d e r tape and candy wrappers- p r o t r u d i n g from the n e s t h o l e . Few mynas a c c e p t e d any e x p e r i m e n t a l n e s t b o x e s the f i r s t summer (1968) o f t h i s s t u d y , b u t more e s t a b l i s h e d t h e m s e l v e s i n t h e s e boxes d u r i n g 1969 and 1970. By p l a c i n g a ced a r n e s t b o x o v e r the e n t r a n c e t o an e s t a b l i s h e d myna n e s t , mynas would n e s t i n t h e boxes, t h e r e b y making t h e i r a c t i v i t i e s e a s i e r t o m o n i t o r . Mynas l a y 1 egg/day w i t h the mean f o r a l l f i r s t c l u t c h e s 4.85 ± .80 e g g s / c l u t c h (n=31). F i r s t eggs were found from the second week o f A p r i l , w i t h no major peak i n egg l a y i n g o b s e r v e d . F i r s t e g g s / n e s t were s t i l l b e i n g found i n l a t e May when s t a r l i n g s were s t a r t i n g second c l u t c h e s . Only f i v e p o s i t i v e second n e s t i n g s ( e x c l u s i v e o f r e n e s t i n g s ) were o b s e r v e d i n t h e t h r e e y e a r s t u d y and t h e s e were s c a t t e r e d from l a t e May t h r o u g h e a r l y A ugust ( F i g u r e 4 ) , and t h e y averaged 3.83 ± .47 eggs. 21 I n c u b a t i o n The S t a r l i n g P a i r s r o o s t e d away from the n e s t and c o n t i n u e d t o r o o s t i n communal r o o s t s u n t i l i n c u b a t i o n began a f t e r t h e l a s t egg was l a i d . B o th sexes i n c u b a t e d d u r i n g the day, b u t o n l y f e m ales a t n i g h t . Some males f l e w t o a d i s t a n t communal r o o s t a t n i g h t d u r i n g t h e i n c u b a t i o n . p e r i o d , w h i l e o t h e r s r o o s t e d s i n g l y near th e n e s t . I n c u b a t i o n i n s t a r l i n g s l a s t e d from 10-13 d a y s , w i t h 11 and 12 days most common. A c t u a l i n c u b a t i o n t e m p e r a t u r e s were n o t m o n i t o r e d b u t the t e m p e r a t u r e i n t h e egg c l u s t e r averaged 33.0°C f o r s t a r l i n g s ( F i g u r e 5) w i t h a mean d a i l y n e s t a t t e n t i v e n e s s (% t i m e eggs covered) o f 77% (n=4 n e s t s ; 13 days) f o r f i r s t broods (70% d u r i n g d a y l i g h t p e r i o d ; 0300-2100). The maximum number of eggs s u c c e s s f u l l y i n c u -b a t e d was 7 of a c l u t c h o f 9. The- Myna I n c u b a t i o n began a f t e r the l a s t egg was l a i d , and b o t h sexes i n c u b a t e d d u r i n g the day. S e x i n g mynas i n t h e f i e l d was a l m o s t i m p o s s i b l e and t o o much t a m p e r i n g w i t h i n c u b a t i n g a d u l t s always r e s u l t e d i n n e s t d e s e r t i o n , t h e r e f o r e i t was n o t a s c e r t a i n e d which of the p a i r took most of the r e s p o n -s i b i l i t y f o r i n c u b a t i o n . . The b i r d n o t i n c u b a t i n g u s u a l l y 22 F i g u r e 5. N e s t a t t e n t i v e n e s s and mean (+ s.e.) d a i l y maximum and minimum tem p e r a t u r e i n the egg c l u s t e r o f Vancouver S t u r n i d a e f o r the complete i n c u b a t i o n p e r i o d (o = s t a r l i n g ; © = c r e s t e d myna). T I M E O F DAY 23 r o o s t e d near the n e s t a t n i g h t . I n c u b a t i o n i n mynas l a s t e d from 12-15 days w i t h 14 days most common. As w i t h s t a r l i n g s , a c t u a l egg t e m p e r a t u r e s d u r i n g i n c u b a t i o n were n o t m o n i t o r e d b u t t e m p e r a t u r e i n t h e egg c l u s t e r d u r i n g i n c u b a t i o n averaged 29.6°C ( F i g u r e 5) w i t h a mean a t t e n t i v e n e s s (% time eggs covered) o f 59% o v e r the whole 2 4 hour p e r i o d and 47% d u r i n g the d a y l i g h t p e r i o d (n=4 n e s t s ; 14 d a y s ) . The maximum number of eggs s u c c e s s f u l l y i n c u b a t e d was 5 o f a c l u t c h o f 6. H a t c h i n g and F l e d g i n g The S t a r l i n g - H a t c h i n g H a t c h i n g s u c c e s s s h o u l d be d e f i n e d as t h a t p e r c e n t o f a l l eggs t h a t s u r v i v e d i n the n e s t a t l e a s t as l o n g as the normal i n c u b a t i o n p e r i o d . F a i l u r e t o h a t c h was a t t r i b u t e d t o p a r e n t a l c a u s e s , i n f e r t i l e eggs, c r a c k e d eggs and p r e -d a t i o n : Undetermined P a r e n t a l I n f e r t i l e C r a c k e d P r e d a t i o n Causes % Causes % Eggs % Eggs % % C r e s t e d M y n a ( 3 9 % ) : 2 4 70 12 11 3 S t a r l i n g ( 1 6 % ) 2 3 5 83 8 1 The m a j o r i t y o f a l l p r e d a t i o n was by humans (mostly c h i l d r e n ) however, c r e s t e d mynas r e a d i l y e v i c t e d any o t h e r b i r d s a t t e m p t i n g t o occupy a t r a d i t i o n a l myna n e s t . I n g e n e r a l , p r e d a t i o n was low and as R i c k l e f s (1969a) has shown, P a r e n t a l Causes i n c l u d e s d e s e r t i o n and c h i l l i n g o f eggs P e r c e n t of a l l eggs w h i c h d i d not h a t c h 23A the p r e d a t i o n component o f egg and n e s t l i n g m o r t a l i t y i s low f o r h o l e o r c a v i t y n e s t e r s . S t a r l i n g s h a r t c h e d 84% o f a l l eggs l a i d as f i r s t c l u t c h e s (76 n e s t s ) d u r i n g t h i s s t u d y and a 69% h a t c h i n g s u c c e s s was o b s e r v e d f o r second c l u t c h e s (32 n e s t s ) . From the time s h e l l s were p i p p e d t o complete escape from the egg sometimes took 2 4 h o u r s , b u t u s u a l l y o n l y 8-10 hours was r e q u i r e d . The mean w e i g h t o f n e s t l i n g s i m m e d i a t e l y a f t e r h a t c h i n g was 5.7 ± .81 gms (18 o b s e r v a t i o n s ) . H a t c h l i n g s t u r n i d s a re t y p i c a l a l t r i c i a l n e s t l i n g s ( e c t o t h e r m i c ) , and c o r e t e m p e r a t u r e s ( p r o v e n t r i c u l a r ) a t h a t c h i n g v a r i e d (34.2 t o 40.2°C) w i t h the n e s t t e m p e r a t u r e and amount o f b r o o d i n g d u r i n g h a t c h i n g . S t a r l i n g s h a t c h e d w i t h l o n g s t r a n d s o f down (1.0-1.5 cm) p r e s e n t on t h e c a p i t a l , f e m o r a l and s p i n a l p t e r y l a e and w i t h s h o r t e r down (0.25-0.50 cm) found on the a l a r and humeral p t e r y l a e . N e s t l i n g M o r t a l i t y F a c t o r s N e s t l i n g m o r t a l i t y was a t t r i b u t e d a l m o s t s o l e l y t o d e s e r t i o n ( s t a r v a t i o n and e x p o s u r e ) , however, s e v e r e m i t e i n f e s t a t i o n s i n l o c a l i z e d n e s t s i t e s r e s u l t e d i n some n e s t l i n g l o s s e s , and wounds i n f l i c t e d by p a r e n t b i r d s a l s o r e s u l t e d i n a few l o s s e s . A d u l t s t u r n i d s p r o m p t l y remove dead n e s t l i n g s from t h e n e s t and d e t a i l e d a n a l y s e s o f c a r c a s s e s was i m p o s s i b l e i n most cases 24 F l e d g i n g Seventy-one p e r c e n t o f a l l eggs i n f i r s t c l u t c h e s l a i d by s t a r l i n g s e v e n t u a l l y f l e d g e d ; a 68% s u c c e s s was o b s e r v e d f o r eggs i n second c l u t c h e s . J u s t p r i o r t o f l e d g i n g , t h e mean n e s t l i n g w e i g h t d e c r e a s e d ( F i g u r e 6) as a r e s u l t of r e d u c e d c a l o r i c i n t a k e , i n c r e a s e d a c t i v i t y , and because some o f the h e a v i e r n e s t l i n g s f l e d g e d e a r l y . A d u l t f e e d i n g s / n e s t l i n g - h r d e c r e a s e d d r a m a t i c a l l y j u s t p r i o r t o f l e d g i n g and young b i r d s became v e r y a c t i v e around days 19-21. N e s t l i n g s f l u t t e r e d up t o the n e s t h o l e and were commonly seen w i t h head and b r e a s t o u t o f the box. T h i s i n c r e a s e d a c t i v i t y by n e s t l i n g s i n f l u e n c e d the a c t i v i t y r e c o r d i n g s , t h e r e f o r e a f t e r day 19, e vent r e c o r d i n g s were no t t r u l y r e p r e s e n t a t i v e o f a d u l t f e e d i n g s ( F i g u r e 10) and t o o b t a i n t h i s i n f o r m a t i o n a c t u a l f e e d i n g s were o b s e r v e d a t d i f f e r e n t t i m e s of the day ( a f t e r day 18) w i t h a s p o t t i n g scope. N e s t P a r a s i t i s m Many t i m e s f l e d g l i n g s t a r l i n g s from o t h e r n e s t s p a r a s i t i z e d n e s t c a v i t i e s a l r e a d y o c c u p i e d by l e s s d e v e l o p e d n e s t l i n g s . I n one such c a s e , a n e s t p a r a s i t e was found t o be an abandoned l a t e h a t c h i n g i n d i v i d u a l i n a l a t e s t a g e o f development from a nearby n e s t b o x . I n some i n s t a n c e s t h e s e n e s t p a r a s i t e s a c t u a l l y consumed the m a j o r i t y o f f o o d b r o u g h t by the p a r e n t b i r d s , w h i c h r e s u l t e d i n d e a t h o f the o r i g i n a l b r o o d . 25 F i g u r e 6. Growth and plumage development o f n e s t l i n g Vancouver S t u r n i d a e (o = s t a r l i n g ; © = c r e s t e d myna). (suuo) H19N31 AUVWIHd 26 F o r s e v e r a l days a f t e r l e a v i n g t h e n e s t b o x , j u v e n i l e s t a r l i n g s are f e d by p a r e n t b i r d s i n t h e f i e l d , and t h e m a j o r i t y o f n e s t p a r a s i t e s are t h o u g h t t o be t h e s e f l e d g e d j u v e n i l e s who became s e p a r a t e d from t h e i r p a r e n t s and r e t u r n e d t o any a c t i v e n e s t b o x f o r p a r e n t a l c a r e . N e s t p a r a s i t i s m o f t h i s type was not uncommon; 28 d i f f e r e n t i n s t a n c e s were o b s e r v e d d u r i n g the 3-year s t u d y p e r i o d . A f t e r j u v e n i l e s t a r l i n g s became s e l f - s u f f i c i e n t , t h e y g a t h e r e d i n t o s m a l l f l o c k s w h i c h f i r s t became e v i d e n t i n the Vancouver a r e a i n l a t e June, when second c l u t c h e s were h a t c h i n g . As the summer p r o g r e s s e d t h e s e s u b - a d u l t f l o c k s c o n g r e g a t e d and e n l a r g e d , u n t i l l a t e J u l y o r e a r l y August when the second broods f l e d g e d and j o i n e d them. The f l o c k s c o n t i n u e d t o e n l a r g e w i t h t h e a d d i t i o n o f a d u l t b i r d s . D u r i n g t h i s f l o c k f o r m a t i o n p e r i o d the m o l t o c c u r r e d and s i g n i f i c a n t numbers o f b i r d s resumed use o f communal r o o s t i n g a r e a s . W i t h t h e coming of f a l l and lower temper-a t u r e s , l o c a l f l o c k s and communal r o o s t s e n l a r g e d a g a i n w i t h t h e i n f l u x o f m i g r a n t b i r d s from the i n t e r i o r o f B r i t i s h C olumbia. Peak numbers of s t a r l i n g s p r o b a b l y o c c u r r e d from mid-September t o mid-October; l a t e r t h e numbers began t o d e c r e a s e as t h e m i g r a n t s c o n t i n u e d t h e i r j o u r n e y South. 27 The Myna - H a t c h i n g Mynas h a t c h e d 61% o f a l l eggs l a i d as f i r s t c l u t c h e s (32 n e s t s ) d u r i n g t h e t h r e e y e a r s o f s t u d y , and a 58% h a t c h i n g s u c c e s s was o b s e r v e d f o r 5 second c l u t c h e s . H a t c h i n g u s u a l l y took 8-10 h o u r s ; the mean n e s t l i n g w e i g h t i m m e d i a t e l y a f t e r h a t c h i n g was 5.92 ± .42 gms (11 o b s e r -v a t i o n s ) . Mynas h a t c h w i t h s h o r t down (0.25-0.50 cms) on t h e c a p i t a l , s p i n a l , f e m o r a l , a l a r and humeral p t e r y l a e . H a t c h l i n g mynas l o o k v e r y s i m i l a r t o s t a r l i n g s e x c e p t t h a t the c r a n i u m appears l e s s rounded t h a n s t a r l i n g s , t h e s k i n i s pigmented more h e a v i l y g i v i n g the n e s t l i n g a "suntanned" appearance, and t h e down i s s h o r t e r . F l e d g i n g N e s t l i n g mynas were n o t as a c t i v e as n e s t l i n g s t a r l i n g s p r i o r t o f l e d g i n g , however, i n c r e a s e d a c t i v i t y s t i l l i n f l u -enced a c t i v i t y r e c o r d i n g s ( F i g u r e 10) and n e c e s s i t a t e d d i r e c t o b s e r v a t i o n s o f n e s t s d u r i n g t h e l a t e s t a g e s of n e s t l i n g development. Young b i r d s f l e d g e d near day 22 and f l e w t o nearby t r e e s o r t a l l s hrubs where they were f e d by p a r e n t b i r d s . Mynas formed s t r o n g f a m i l y bonds and f a m i l y groups were s t i l l seen i n l a t e f a l l . W h i l e l e a v e s and f r u i t remained on d e c i d u o u s t r e e s , mynas c o n g r e g r a t e d i n t o l o c a l 28 communal r o o s t s , b u t when t h e l e a v e s and f r u i t d r opped, t h e s e b i r d s l e f t and j o i n e d l a r g e r communal r o o s t s w i t h s t a r l i n g s and o t h e r mynas. F o r t y - s i x p e r c e n t o f myna eggs i n f i r s t c l u t c h e s produced young t h a t e v e n t u a l l y f l e d g e d and 35% o f t h e eggs from t h e f i v e second c l u t c h e s produced young t h a t f l e d g e d . Growth and Development The S t a r l i n g - Growth S t a r l i n g growth f o l l o w s a s i g m o i d c u r v e ( F i g u r e 6) d e s c r i b e d by the l o g i s t i c e q u a t i o n : W = 78.56  , , - 0.416(t-5.3) 1 + e where W i s w e i g h t i n gms; 0.416 i s the growth r a t e c o n s t a n t (K); 5.3 (days) i s the p o i n t of i n f l e c t i o n o f the c u r v e ; and 7 8.56 gms i s the a s y m p t o t i c w e i g h t . F i g u r e 7 i l l u s t r a t e s s t u r n i d growth u s i n g the method d e s c r i b e d by R i c k l e f s (1967). Development of f l i g h t f e a t h e r s , a l t h o u g h n o t e x a c t l y s y n c h r o n i z e d w i t h t o t a l c o n t o u r f e a t h e r development, i s a handy i n d e x o f plumage development. F i g u r e 6 a l s o e x p r e s s e s t h e mean l e n g t h o f the l o n g e s t p r i m a r y on t h e r i g h t wing of g r owing n e s t l i n g s t a r l i n g s . The p a t t e r n o f f e a t h e r g r o w t h , e x p r e s s e d as l e n g t h o f a s i n g l e f e a t h e r f o l l o w s an a r i t h -29 F i g u r e 7. Growth o f n e s t l i n g Vancouver S t u r n i d a e , p r e s e n t e d i n t h e manner d e s c r i b e d by R i c k l e f s (1967) (o = s t a r l i n g ; © = c r e s t e d myna). H O l O V d N 0 I S U 3 A N 0 0 0 I 1 S I 9 0 1 30 m e t i c i n c r e a s e , however, i f w e i g h t o f a l l the d e v e l o p i n g plumage were p l o t t e d a g a i n s t d a y s , a g e o m e t r i c i n c r e a s e , s i m i l a r t o body w e i g h t , would p r o b a b l y be d e m o n s t r a t e d . The e n t i r e c l u t c h o f eggs u s u a l l y h a t c h e d t h e same day and w e i g h t s of a l l the n e s t l i n g s i n c r e a s e d s i m i l a r l y d u r i n g growth. O c c a s i o n a l l y one egg h a t c h e d b e f o r e o r a f t e r the r e s t i n w h i c h case t h a t n e s t l i n g always had a c l e a r advantage o r d i s a d v a n t a g e w i t h r e s p e c t t o growth o r s u r v i v a l , depending on t h e t o t a l brood s i z e . The b o d i e s of n e s t l i n g s t a r l i n g s were not c o m p l e t e l y c o v e r e d w i t h f e a t h e r s u n t i l day 13 o r 14; f e a t h e r e l o n g a t i o n was s t i l l t a k i n g p l a c e when t h e b i r d s l e f t t h e n e s t . J u v e n i l e s t a r -l i n g s m o l t e d t h e i r d u l l grey-brown plumage from l a t e J u l y ( f i r s t broods) t h r o u g h e a r l y O c t o b e r , w i t h some j u v e n i l e f e a t h e r s s t i l l found on t h e c a p i t a l and s p i n a l t r a c t i n l a t e December. Development of Endothermy and Homeothermy N e s t l i n g s t a r l i n g s were t r u l y p o i k i l o t h e r m i c u n t i l days 13-15 a f t e r h a t c h i n g . F i g u r e 8 shows t h e development of endothermy i n growing s t u r n i d s o f d i f f e r e n t w e i g h t c l a s s e s . N e s t l i n g s t a r l i n g s do n o t show a s u s t a i n e d h e a t p r o d u c t i o n u n t i l f e a t h e r s were a l m o s t f u l l y d e v e l o p e d (60-70 gms) and a b l e t o t r a p h e a t produced by t h e i n c r e a s e i n m e t a b o l i c 31 F i g u r e 8. Development o f i n t e r n a l h e a t p r o d u c t i o n (endothermy) i n n e s t l i n g Vancouver S t u r n i d a e ; oxygen consumption a t v a r y i n g ambient temper-a t u r e s by b i r d s i n d i f f e r e n t w e i g h t c l a s s e s (0,©,A / & , • / © , r e p r e s e n t b i r d s w e i g h i n g between 10-20, 20-30, 30-40, 40-50, 50-60 and 60-70 gms,- r e s p e c t i v e l y ) . OXYGEN CONSUMPTION (cc02/gm-hr) 3 2 a c t i v i t y . A l t h o u g h h e a t p r o d u c t i o n i n c r e a s e d i n t h e 60-70 gm n e s t l i n g w e i g h t c l a s s , complete homeothermy was not a t t a i n e d u n t i l b i r d s had a l m o s t r e a c h e d a s y m p t o t i c w e i g h t s ( F i g u r e 9 ) . N e s t l i n g s t a r l i n g s w i t h s t o o d a m a z i n g l y extreme d e c r e a s e s i n body t e m p e r a t u r e . A l l i n d i v i d u a l s t e s t e d a t -5°C f o r 30 minutes s u r v i v e d , and one newly h a t c h e d s t a r l i n g (6.6 gms) s u r v i v e d extreme hypothermy ( t ^ = 2.8°C) f o r 20 m i n u t e s , a f t e r w h i c h t i m e i t was r e -h e a t e d t o +34°C and r e p l a c e d i n i t s n e s t b o x t o e v e n t u a l l y f l e d g e . N e s t l i n g Food I n t a k e D u r i n g t h e growth p e r i o d , t h e r a t e o f f o o d i n t a k e o f n e s t l i n g s i n c r e a s e d , as i s i l l u s t r a t e d by t h e i n c r e a s e i n a c t i v i t y ( F i g u r e 10) a t two ne s t b o x e s (1 i n 1969 and 1 i n 1970) d u r i n g i n c u b a t i o n and growth. From h a t c h i n g u n t i l about day 10, a s t e a d y i n c r e a s e i n v i s i t s t o t h e n e s t was m o n i t o r e d . From o b s e r v i n g n e s t b o x e s w i t h a 30X s p o t t i n g scope, a p p r o x i m a t e l y 90% (91.6%) o f a l l t r i p s by b o t h p a r e n t s t o the n e s t box r e s u l t e d i n an a c t u a l f e e d i n g . A p p l y i n g t h i s v a l u e t o F i g u r e 10 we a r r i v e a t an i n i t i a l f e e d i n g r a t e o f 2.5 t o 3.0 f e e d i n g / n e s t l i n g h o u r (18 hour f e e d i n g day) a t h a t c h i n g day (day 0) up t o 8.0 f e e d i n g s / n e s t l i n g -hour a t days 10-12 (18 hour f e e d i n g d a y ) . 33. F i g u r e 9. Development o f homeothermy i n n e s t l i n g Vancouver S t u r n i d a e e x p r e s s e d as t h e change i n body t e m p e r a t u r e ( d u r i n g 30 minute t r i a l s a t - 5 C) o f n e s t l i n g s a t v a r y i n g s t a g e s o f development (o = s t a r l i n g ; © = c r e s t e d myna) 3Cy o o LO I • -0— o o _ Q <3 - 2 0 - 1 0 Ol 5 o o o 9 O O n © © O o o J i 10 20 30 4 0 5 0 60 7 0 8 0 9 0 100 WEIGHT (gms) 3 4 F i g u r e 10. A d u l t a c t i v i t y a t 2 s t a r l i n g (1 i n 1969 and 1 i n 1970) n e s t b o x e s . 1000 800 600 400 FLEDGE 20 JULY 1970 4 YOUNG A A A A A A A A 0 . A < Q v. CO or 2 0 0 INCUBATION 5 EGGS A A , 1970 ^ * FLEDGE 7 JULY 4 YOUNG 1968 A A- 4 HATCH 28 JUNE 1970 4 EGGS HATCH 18 JUNE 1969 4 EGGS . A o x I00| LU Q 801 A A ' >-> 60 A o INCUBATION 4 EGGS 1969 2 401 10 15 20 25 30 35 DAYS 35 The mean c a l o r i c v a l u e o f f o o d i t e m s c o l l e c t e d from n e s t l i n g s t a r l i n g s was 5.18 ± .09 k c a l / g m (39 s a m p l e s ) ; a mean d r y w e i g h t o f 0.112 ± .019 gms/ f e e d i n g was o b s e r v e d f o r t h o s e same f o o d i t e m s . Sample s i z e s were s m a l l i n any one w e i g h t o r age c l a s s , t h e r e f o r e d a t a were p o o l e d t o o b t a i n mean v a l u e s . These v a l u e s can s i m i l a r l y be a p p l i e d t o F i g u r e 10 w i t h the r e s u l t i n g d e s c r i p t i o n o f g r o s s energy i n t a k e (G.E.) o f n e s t l i n g s t a r l i n g s . G.E. i n t a k e i n c r e a s e d from 1.45 k c a l / n e s t l i n g - h o u r (26.10 k c a l / n e s t l i n g - d a y ) a t h a t c h i n g day up t o 4.64 k c a l / n e s t l i n g - h o u r (83.52 k c a l / n e s t l i n g - d a y ) a t day 10-12. There were d i f f e r e n c e s i n f o o d i t e m s o f n e s t l i n g s t a r -l i n g s depending upon l o c a t i o n o f the n e s t and time o f y e a r . I f t h e n e s t was l o c a t e d near f r u i t t r e e s l a t e i n summer, f r u i t ( e s p e c i a l l y c h e r r i e s and b e r r i e s ) c o n t r i b u t e d g r e a t l y t o t h e d i e t o f gr o w i n g b i r d s . Most f i r s t b r o o d s , however, were f e d p r i m a r i l y a n i m a l m a t t e r , and r e g a r d l e s s o f the time o f the y e a r , v e r y young n e s t l i n g s (up t o 5-6 days o l d ) were f e d a l m o s t e x c l u s i v e l y a n i m a l m a t t e r ( h i g h p r o t e i n ) . The mean c a l o r i c v a l u e o f s t a r l i n g f o o d i t e m s r e p r e s e n t s samples o f b o t h a n i m a l and p l a n t f o o d , t h e r e f o r e i t may n o t be r e p r e s e n t a t i v e o f c a l o r i c i n t a k e o f l a t e broods f e d al m o s t e x c l u s i v e l y c h e r r i e s p a s t day 5-6. 3 6 The Myna - Growth Myna growth f o l l o w s a s i g m o i d c u r v e ( F i g u r e 6) d e s c r i b e d by the l o g i s t i c e q u a t i o n : W = 88.59  ± + e - 0 . 2 8 4 ( t - 7 . 5 ) where W i s w e i g h t i n gms; 0.2 84 i s the growth r a t e c o n s t a n t (K); 7.5 (days) i s t h e p o i n t o f i n f l e c t i o n o f the growth c u r v e ; 88.59 gms i s t h e a s y m p t o t i c w e i g h t . F i g u r e 7 r e p r e s e n t s b o t h s t a r l i n g and myna growth u s i n g t h e method d e s c r i b e d by R i c k -l e f s (1967). F i g u r e 6 e x p r e s s e s growth o f myna plumage u s i n g l e n g t h o f t h e l o n g e s t p r i m a r y as an i n d e x o f t o t a l f e a t h e r development. As w i t h s t a r l i n g s , myna eggs u s u a l l y h a t c h on the same day, w i t h w e i g h t s o f a l l n e s t l i n g s i n c r e a s i n g s i m i l -a r l y d u r i n g growth. However, i f an egg h a t c h e d more th a n 1 day a f t e r the r e s t o f the c l u t c h , t h a t n e s t l i n g u s u a l l y d i e d , depending upon t h e t o t a l b r ood s i z e . The b o d i e s o f n e s t l i n g mynas a r e n o t c o m p l e t e l y c o v e r e d w i t h f e a t h e r s u n t i l days 18-20, w i t h f e a t h e r e l o n g a t i o n s t i l l o c c u r r i n g a t f l e d g i n g . Development o f Endothermy and Homeothermy N e s t l i n g mynas a r e p o i k i l o t h e r m i c u n t i l day 14-16 (60-70 gm w e i g h t c l a s s ) when i n c r e a s e d m e t a b o l i c a c t i v i t y and d e v e l o p i n g plumage e n a b l e d the b i r d t o t r a p a l a y e r o f warm a i r f o r i n s u l a t i o n . A l t h o u g h h e a t p r o d u c t i o n i n c r e a s e d ( s i m i l a r t o s t a r l i n g s , F i g u r e 8) n e s t l i n g s were n o t c o m p l e t e l y 37 homeothermic u n t i l 80-85 gms. N e s t l i n g mynas a l s o w i t h -s t o o d extreme hypothermy d u r i n g 30-minute t r i a l s a t -5°C ( F i g u r e 9 ) . N e s t l i n g Food I n t a k e D u r i n g the growth p e r i o d , the r a t e o f f o o d i n t a k e o f n e s t l i n g mynas i n c r e a s e d a t a r a t e s i m i l a r t o s t a r l i n g n e s t l i n g s . F i g u r e 11 i l l u s t r a t e s a c t i v i t y a t two myna n e s t b o x e s (1 i n 1969 and 1 i n 1970) d u r i n g i n c u b a t i o n and growth. From h a t c h i n g u n t i l days 12-14, a s t e a d y i n c r e a s e i n a c t i v i t y was r e c o r d e d . Mynas were n o t as i n d u s t r i o u s a t f e e d i n g young as s t a r l i n g s . Only an 81% f e e d i n g r a t i o was o b s e r v e d ( a c t u a l f e e d i n g s / t o t a l t r i p s t o t h e n e s t b o x ) . By a p p l y i n g t h i s f e e d i n g r a t i o t o F i g u r e 11, we a r r i v e a t an i n i t i a l f e e d i n g r a t e o f 0.80 f e e d i n g s / n e s t l i n g - h o u r (18 hour f e e d i n g d a y ) , and a r a t e o f 8.1 f e e d i n g s / n e s t l i n g -hour a t days 14-16 (18 hour f e e d i n g d a y ) . The mean ( p o o l e d f o r a l l p e r i o d s ) c a l o r i c v a l u e o f n e s t l i n g f o o d m a t e r i a l s was 4.97 + .612 kca l / g m (37 samples a n a l y z e d ) and t h e mean d r y w e i g h t o f thos e f o o d i t e m s was 0.10 ± .048 gm s / f e e d i n g . A p p l y i n g t h e s e v a l u e s , i n t u r n , t o F i g u r e 11 we o b t a i n a d e s c r i p t i o n o f G.E. i n t a k e f o r n e s t l i n g mynas t h r o u g h o u t t h e growth p e r i o d . T h i s G.E. i n c r e a s e d f rom 0.402 k c a l / n e s t l i n g - h o u r (7.22 k c a l / n e s t l i n g - d a y ) a t h a t c h i n g day t o 4.02 k c a l / n e s t l i n g - h o u r (72.30 k c a l / n e s t l i n g - d a y ) a t day 14-16. 3 8 F i g u r e 11. A d u l t a c t i v i t y a t 2 myna (1 i n 1969 and 1 i n 1970) n e s t b o x e s . 1000 8 0 0 6 0 0 4 0 0 5 2 0 0 Q \ CO CL or 100 X LU Q 80 z ; >- 60 > < 40 FLEDGED 6 JULY 1970 3 YOUNG A A A A A • • A A • * A A • A A o A e • • A • e A • FLEDGED II JUNE 1969 3 YOUNG INCUBATION 4 EGGS 0 • • A _^J369 x • A • A t A A HATCH 4 EGGS 19 MAY 1969 • A e • • A-—HATCH 3 EGGS 14 JUNE 1970 INCUBATION 5 EGGS 1970 10 15 20 DAYS 25 30 35 39 N e s t and Egg M a n i p u l a t i o n E x p e r i m e n t s C r o s s - f o s t e r i n g Between S p e c i e s D i f f e r e n c e s between s t a r l i n g and myna i n c u b a t i o n and f l e d g i n g s u c c e s s prompted egg s w i t c h i n g e x p e r i m e n t s between the two s p e c i e s t o d e t e r m i n e i f t h e s e d i f f e r e n c e s a r o s e from d i f f e r e n c e s i n (1) egg q u a l i t y o r (2) t h e e f f e c t i v e n e s s of t h e a d u l t b i r d s as i n c u b a t o r s and p a r e n t s . F i v e myna and f i v e s t a r l i n g c l u t c h e s (5 eggs) w h i c h were s y n c h r o n i z e d (± 1 day) i n t h e i r i n c u b a t i o n c y c l e s were s w i t c h e d a t day 2 and f o l l o w e d t h r o u g h i n c u b a t i o n t o h a t c h i n g and f l e d g i n g . As F i g u r e 12 shows, a 90% h a t c h i n g s u c c e s s was o b s e r v e d f o r myna eggs i n c u b a t e d by s t a r l i n g s w h i l e o n l y 62% o f the s t a r -l i n g eggs i n c u b a t e d by mynas h a t c h e d . Growth r a t e s o f the c r o s s - f o s t e r e d n e s t l i n g s were not s i g n i f i c a n t l y d i f f e r e n t from t h o s e d e s c r i b e d e a r l i e r ( r a i s e d by t h e i r own p a r e n t s ) . Heated Nestboxes Inasmuch as one o f the s t r i k i n g d i f f e r e n c e s between the n e s t performance o f the two s p e c i e s was the h i g h e r average egg t e m p e r a t u r e m a i n t a i n e d by t h e s t a r l i n g , I i n v e s t i g a t e d t h e i n f l u e n c e o f n e s t t e m p e r a t u r e upon h a t c h i n g s u c c e s s i n t h e myna. To do t h i s , 5 h e a t e d n e s t -boxes were p l a c e d i n l o c a t i o n s where mynas had a l r e a d y 40 F i g u r e 12. R e s u l t s o f egg s w i t c h i n g e x p e r i m e n t s and subsequent a d u l t i n c u b a t i o n by Vancouver S t u r n i d a e . 19/21 = 90% 13/21= 62% 41 e s t a b l i s h e d t hemselves as n e s t b o x b r e e d e r s . These boxes were t h e r m o s t a t i c a l l y r e g u l a t e d t o keep egg l e v e l temper-a t u r e s from d r o p p i n g below 28°C. As shown i n F i g u r e 13 a 92% h a t c h i n g s u c c e s s was o b s e r v e d i n t h e h e a t e d n e s t -boxes, and a 6 3% h a t c h i n g s u c c e s s was o b s e r v e d i n t h e c o n t r o l s (2 c o n t r o l n e s t s were n o t i n n e s t b o x e s , b u t i n n a t u r a l t r e e c a v i t i e s ) . T h i s s u c c e s s i n t h e c o n t r o l s was n o t s i g n i f i c a n t l y d i f f e r e n t from the 61% s u c c e s s o b s e r v e d i n 31 f i r s t c l u t c h e s r e p o r t e d e a r l i e r . The Energy C y c l e The S t a r l i n g - Gross Energy S t u r n i d g r o s s energy (G.E.) i n t a k e and cage a r e a ambient t e m p e r a t u r e f l u c t u a t i o n s t h r o u g h o u t t h e one-year e x p e r i m e n t a l p e r i o d a r e r e p r e s e n t e d i n Appendix F i g u r e 1. Mean G.E. v a l u e s d u r i n g the e x c r e t o r y s a m p l i n g p e r i o d s a r e p r e s e n t e d on a monthly b a s i s i n F i g u r e 14. S t a r l i n g G.E. i n t a k e g r a d u a l l y d e c r e a s e d f rom J a n u a r y t h r o u g h December w i t h h i g h v a l u e s r a n g i n g between 118.8 and 128.32 k c a l / b i r d - d a y r e c o r d e d between J a n u a r y and A p r i l . Low i n t a k e s o f 94.2, 99.1 and 97.6 k c a l / b i r d - d a y were r e c o r d e d d u r i n g O c t o b e r , November and December, r e s p e c t i v e l y . 42 F i g u r e 13. R e s u l t s o f h e a t e d n e s t b o x e x p e r i m e n t s . Myna n e s t b o x t e m p e r a t u r e s were p r e v e n t e d from d r o p p i n g below 2 8°C; t h e r e s u l t i n g h a t c h i n g s u c c e s s i s compared w i t h c o n t r o l n e s t s . to power supply H E A T E R B O X C O N T R O L 2 5 / 2 7 = 9 2 % 1 4 / 2 3 = 6 4 % 43 E x c r e t o r y Energy S t a r l i n g e x c r e t o r y energy (E.E.) i s i l l u s t r a t e d g r a p h i c a l l y i n F i g u r e 14 a l s o . H i g h e s t E.E. v a l u e s f o r s t a r l i n g s were o b t a i n e d d u r i n g March and A p r i l ; 73.1 and 68.9 k c a l / b i r d - d a y , r e s p e c t i v e l y , and the l o w e s t v a l u e was o b t a i n e d from t h e November sample; 40.9 k c a l / b i r d - d a y . E x c r e t o r y energy f l u c t u a t e d more t h a n G.E. t h e r e f o r e the r e s u l t i n g m e t a b o l i z a b l e energy (M.E.) f l u c t u a t e d g r e a t l y a l s o ( F i g u r e 14).. M e t a b o l i z a b l e Energy The h i g h e s t s t a r l i n g M.E. (G.E. - E.E. = M.E.) was r e c o r d e d i n F e b r u a r y (60.9 k c a l / b i r d - d a y ) and t h e l o w e s t d u r i n g O c t o b e r (41.88 k c a l / b i r d - d a y ) . E f f i c i e n c y o f Food C o n v e r s i o n C a l o r i c v a l u e o f s t u r n i d e x c r e t o r y m a t e r i a l and d i g e s t i o n e f f i c i e n c y (M.E./G.E. x 100 = d i g e s t i o n e f f i c -i e n c y ) b o t h i n d i c a t e t h e e f f i c i e n c y o f f o o d c o n v e r s i o n ( F i g u r e 1 5 ) . The mean monthly energy c o n t e n t o f s t a r l i n g e x c r e t o r y m a t e r i a l f l u c t u a t e d between 4.03 kca l / g m (March sample) and 4.19 k c a l / g m (October s a m p l e ) . E x c e p t f o r h i g h November v a l u e s ( 5 8 . 7 8 % ) , s t a r l i n g d i g e s t i o n e f f i c i e n c y was r e l a t i v e l y c o n s t a n t t h r o u g h o u t the y e a r . 44 M o l t The m o l t i s p o t e n t i a l l y a p e r i o d o f s u b s t a n t i a l energy d r a i n from the b i r d , t h e r e f o r e c o n s i d e r a t i o n s h o u l d be g i v e n t h i s s u b j e c t d u r i n g e x p o s i t i o n o f r e s u l t s p e r t a i n i n g t o t h e energy c y c l e . N o r t h A m e rican s t u r n i d s m o l t once each y e a r d u r i n g l a t e summer and e a r l y f a l l . F i g u r e 14 i l l u s t r a t e s t h e p a t t e r n o f m o l t i n s t u r n i d s h e l d c a p t i v e a t Vancouver, B r i t i s h C o l u m b i a , d u r i n g t h e 1969 s t u d y p e r i o d . M o l t i n d e x i s s i m p l y t h e number o f f e a t h e r s / d a y s e p a r a t e d from t h e e x c r e t a c o l l e c t i o n s . S t a r l i n g s b e g i n t h e i r m o l t i n l a t e June and t e r m i n a t e i t i n l a t e A u g ust, w i t h most f e a t h e r s l o s t between l a t e J u l y and e a r l y August. S l e a k i r i d e s c e n t c o n t o u r f e a t h e r s a r e l o s t f i r s t and r e p l a c e d by the w h i t e -t i p p e d w i n t e r plumage; remiges and r e c t r i c e s a r e r e p l a c e d l a t e r , w i t h p r i m a r i e s 7, 8 and 9 and t h e o u t e r r e c t r i c e s n o t c o m p l e t e l y hardened u n t i l l a t e September. Weight Dynamics Weight dynamics are good i n d i c a t o r s o f whether b i r d s a r e m a i n t a i n i n g energy b a l a n c e . S t a r l i n g w e i g h t s were r e l a t i v e l y s t a b l e t h r o u g h o u t t h e y e a r l o n g e x p e r i m e n t a l p e r i o d ; v a l u e s ranged from 86.6 gms i n l a t e O c t o b e r t o 80.0 gms d u r i n g the m o l t i n e a r l y A u g u s t , w i t h a y e a r l y mean o f 83.7 gms ( F i g u r e 14). S i g n i f i c a n t d i f f e r e n c e s were 45 F i g u r e 14. D e p i c t i o n o f s t u r n i d g r o s s energy i n t a k e (G.E.), e x c r e t o r y o u t p u t (E.E.) and m e t a b o l i z a b l e energy (M.E.) ( a l l i n K c a l / b i r d - d a y ) , w i t h m o l t , w e i g h t and ambient t e m p e r a t u r e changes (o = s t a r l i n g ; & = c r e s t e d myna). 46 not observed for mean s t a r l i n g weights between or within sexes during the year. S t a t i s t i c a l Treatment of Energetics Data Having described and presented the values for energy u t i l i z a t i o n by s t a r l i n g s , a s t a t i s t i c a l analysis of mean energy values can now be considered. Appendix Table 2 presents an analysis of variance of energy balance data. Bioenergetics data of s t a r l i n g s and mynas show i d e n t i c a l trends from month to month (except for the low value for mynas i n February) therefore means of both species were lumped for ease i n s t a t i s t i c a l treatment. Calculated monthly constants, presented i n an ordered array, when summed with the appropriate species constant (in t h i s case, s t a r l i n g ) and the calculated estimate of the mean, w i l l y i e l d a s t a t i s t i c which approximates the monthly parameter sought. The F values, with appropriate degrees of freedom, designate the s i g n i f i c a n c e of d i f f e r e n t energy values between species (myna and st a r l i n g ) and within months (any two months). Monthly values not connected by the same underscoring are those d i f f e r e n t from each other. In the case of s t a r l i n g G.E., the mean standard error of the difference between two months was 7.09 kcal/bird-day, therefore, values d i f f e r e n t by more than 7.09 (1 standard 47 e r r o r ) , were c o n s i d e r e d d i f f e r e n t . D u r i n g J a n u a r y t h r o u g h May, t h e g r e a t e s t amount o f energy was consumed. C o n t r a s t -i n g l y , June and O c t o b e r t h r o u g h December were the p e r i o d s of l o w e s t energy consumption. S t a r l i n g E.E. v a l u e s were t r e a t e d i n the same manner and a r e a l s o p r e s e n t e d i n Appendix T a b l e 2. The mean s t a n -d a r d e r r o r o f the d i f f e r e n c e between any two months was 3.51 k c a l / b i r d - d a y . The c a l c u l a t e d s p e c i e s c o n s t a n t and e s t i m a t e o f the mean are 0.24 and 5 8.64 k c a l / b i r d - d a y , r e s p e c t i v e l y . March E.E. was h i g h e s t f o r s t a r l i n g s and the November v a l u e was l o w e s t . The a n a l y s i s o f M.E. v a l u e s y i e l d s r e s u l t s v e r y s i m i l a r t o t h o s e f o r G.E. (Appendix T a b l e 2 ) . J a n u a r y t h r o u g h May were t h e months when t h e most energy was m e t a b o l i z e d , e x c e p t f o r t h e u n e x p l a i n e d i n c r e a s e i n M.E. d u r i n g November. C o n t r a s t i n g l y , O c t o b e r and December were t h e months o f l o w e s t energy m e t a b o l i s m . The mean s t a n d a r d e r r o r o f the d i f f e r e n c e between any two months was 5.30 k c a l / b i r d - d a y and t h e c a l c u l a t e d e s t i m a t e o f the mean was 55.6 4 k c a l / b i r d - d a y . The Myna - Gross Energy Appendix F i g u r e 1 a l s o i l l u s t r a t e s myna G.E. and temper-a t u r e f l u c t u a t i o n s d u r i n g the one y e a r e x p e r i m e n t a l p e r i o d . 48 Temperature and energy b a l a n c e d a t a a re a l s o compared on a monthly b a s i s ( F i g u r e 1 4 ) . C r e s t e d myna G.E. showed a d e c r e a s e from J a n u a r y t h r o u g h June, a f t e r w h i c h i t l e v e l e d o f f and remained r e l a t i v e l y c o n s t a n t . The h i g h e s t v a l u e r e c o r d e d f o r myna G.E. was 143.7 k c a l / b i r d - d a y d u r i n g J a n u a r y . The l o w e s t v a l u e s were 97.96 and 102.96 k c a l / b i r d - d a y d u r i n g F e b r u a r y and December, r e s p e c t i v e l y . E x c r e t o r y Energy Myna E.E. was more e r r a t i c t h r o u g h o u t t h e y e a r t h a n G.E. High v a l u e s o f 66.7 and 69.7 and 64.3 k c a l / b i r d - d a y were r e c o r d e d f o r J a n u a r y , March and A p r i l E.E., r e s p e c t -i v e l y . The l o w e s t v a l u e s r e c o r d e d were 43.5 and 48.0 k c a l / b i r d - d a y , d u r i n g F e b r u a r y and November, r e s p e c t i v e l y . M e t a b o l i z a b l e Energy Myna M.E. f l u c t u a t e d g r e a t l y a l s o , e s p e c i a l l y d u r i n g t h e . s e c o n d h a l f o f 1969. The h i g h myna M.E. v a l u e s o f 76.9, 73.0 and 71.2 k c a l / b i r d - d a y o c c u r r e d d u r i n g J a n u a r y , September and November, r e s p e c t i v e l y . Low v a l u e s o f 49.9 and 46.9 k c a l / b i r d - d a y were r e c o r d e d d u r i n g F e b r u a r y and O c t o b e r , r e s p e c t i v e l y . 49 E f f i c i e n c y of Food C o n v e r s i o n The mean monthly c a l o r i c v a l u e s o f myna e x c r e t o r y m a t e r i a l a r e p r e s e n t e d i n F i g u r e 15. The l o w e s t and h i g h e s t r e c o r d e d v a l u e s were 4.06 k c a l / g m d u r i n g May and 4.18 k c a l / g m d u r i n g September. D i g e s t i o n e f f i c i e n c y of mynas (M.E./G.E.xlOO = d i g e s t i o n e f f i c i e n c y ) i s p r e s e n t e d i n F i g u r e 14 a l s o . S i m i l a r t o s t a r l i n g s , myna e f f i c i e n c y was h i g h e s t d u r i n g November (62%) and l o w e s t d u r i n g t h e month of O c t o b e r (45.94%). The t r e n d i n d i g e s t i o n e f f i c i e n c y f o r mynas was i d e n t i c a l t o t h a t f o r s t a r l i n g s ( F i g u r e 1 5 ) . V a l u e s f o r J a n u a r y t h r o u g h August were r e l a t i v e l y s t a b l e and v a l u e s f o r September t h r o u g h December were u n s t a b l e . M o l t The p a t t e r n o f m o l t i n c r e s t e d mynas c l o s e l y o v e r l a p p e d t h a t o f s t a r l i n g s . The m o l t began i n m i d - J u l y w i t h l o s s o f the c r e s t and f a c i a l f e a t h e r s , and c o n t i n u e d t h r o u g h t o mid-October w i t h t h e peak i n f e a t h e r l o s s d u r i n g l a t e A ugust and e a r l y September. The l a s t r e c t r i c e s and remiges d i d n o t c o m p l e t e l y harden u n t i l e a r l y November. Weight Dynamics Weight dynamics o f c a p t i v e mynas are e x p r e s s e d i n 50 F i g u r e 15. Energy c o n t e n t of e x c r e t a and d i g e s t i o n e f f i c i e n c y d u r i n g the 1 y e a r e x p e r i m e n t a l p e r i o d (o = s t a r l i n g ; ® = c r e s t e d myna). 51 F i g u r e 14 a l s o . Myna w e i g h t s , as t h o s e o f s t a r l i n g s , were r e l a t i v e l y c o n s t a n t t h r o u g h o u t 1969; o n l y the w e i g h t s r e c o r d e d i n e a r l y May (111.4 gms) were s i g n i f i c a n t l y h e a v i e r t h a n the l i g h t e s t w e i g h t s r e c o r d e d i n September d u r i n g t h e m o l t (101.3 gms). I t was d i f f i c u l t t o d e t e r m i n e sex o f c r e s t e d mynas w i t h o u t s a c r i f i c i n g b i r d s , however, peaks i n a b i m o d a l d i s t r i b u t i o n o f w e i g h t s o f w i l d s h o t mynas were s i g n i f i c a n t l y d i f f e r e n t and were p r o b a b l y c o r r e l a t e d w i t h e i t h e r sex o r age. E i g h t female mynas weighed 107.2 ± 1.56 gms (mean ± s t a n d a r d e r r o r o f the mean); 9 males weighed 115.3 ± 1.2 8 gms. B i r d s were c o l l e c t e d i n w i n t e r and e a r l y s p r i n g . D e t e r m i n a t i o n of age by s k u l l g r a n u l a t i o n was n o t at t e m p t e d , t h e r e f o r e any i n f l u e n c e o f sex on t h i s d i s t r i -b u t i o n c o u l d be masked by t h o s e o f age. S t a t i s t i c a l Treatment o f E n e r g e t i c s Data The s t a t i s t i c a l t r e a t m e n t of myna e n e r g e t i c s d a t a i s h a n d l e d e x a c t l y as d e s c r i b e d f o r s t a r l i n g s (Appendix T a b l e 2 ) . C a l c u l a t e d monthly c o n s t a n t s w h i c h a r e p r e s e n t e d i n an o r d e r e d a r r a y , when summed w i t h the a p p r o p r i a t e s p e c i e s c o n s t a n t and the c a l c u l a t e d e s t i m a t e of t h e mean, w i l l y i e l d the e s t i m a t e o f e i t h e r G.E., E.E. o r M.E. The v a l u e s n o t co n n e c t e d by t h e same u n d e r s c o r i n g were c o n s i d e r e d d i f f e r e n t from o t h e r s . F o r myna G.E., t h e mean s t a n d a r d e r r o r o f the d i f f e r e n c e between any two months i s s t i l l 7.09 k c a l / b i r d -day. The c a l c u l a t e d e s t i m a t e o f the mean remains 114.29 52 k c a l / b i r d - d a y , however, th e s p e c i e s c o n s t a n t has now changed t o 4.37 k c a l / b i r d - d a y . F o r myna E.E., the c a l c u l a t e d e s t i m a t e o f t h e mean (58.6 k c a l / b i r d - d a y ) and monthly c o n s t a n t s a l s o r e m a i n the same as d e s c r i b e d f o r s t a r l i n g s , however, th e s p e c i e s c o n s t a n t has changed t o -0.24 k c a l / b i r d - d a y . The mean s t a n d a r d e r r o r o f the d i f f e r e n c e between two months remains 3.51 k c a l / b i r d - d a y , and as t h e F v a l u e f o r months i n d i c a t e s ( 1 2 . 4 5 w i t h 11 and 372 d.f.) some months a r e d i f f -e r e n t from o t h e r s . The months c o n s i d e r e d d i f f e r e n t are t h o s e n o t u n d e r s c o r e d by the same l i n e (Appendix T a b l e 2 ) . Myna M.E. d a t a a r e t r e a t e d i n the same manner as above. The c a l c u l a t e d s p e c i e s c o n s t a n t i s now 4.62 k c a l / b i r d - d a y , w h i l e t h e r e m a i n i n g v a l u e s (55.64 k c a l / b i r d - d a y = e s t i m a t e of the mean; 5.30 k c a l / b i r d - d a y = mean s t a n d a r d e r r o r o f t h e d i f f e r e n c e between two months) a r e l e f t unchanged, e x c e p t f o r the F v a l u e s . The p e r i o d s of h i g h e s t and l o w e s t energy i n p u t , o u t p u t and u t i l i z a t i o n are the same f o r b o t h mynas and s t a r l i n g s . T h i s s i m p l y i n d i c a t e s t h a t b o t h s p e c i e s responded i n a s i m i l a r manner t o v a r i a b l e s a s s o c i a t e d w i t h the t i m e o f y e a r , and i s the j u s t i f i c a t i o n used f o r lumping t h e two s p e c i e s f o r s t a t i s t i c a l t r e a t m e n t . 53 Thermal Response t o the E x t e r n a l E n v i r o n m e n t The S t a r l i n g - E f f e c t s o f Ambient Temperature on Energy U t i l i z a t i o n R e s u l t s o f a r e g r e s s i o n a n a l y s i s of t e m p e r a t u r e a g a i n s t G.E., E.E. and M.E. are p r e s e n t e d i n o r d e r t o i s o l a t e t he e f f e c t s o f ambient t e m p e r a t u r e on the energy c y c l e o f c a p t i v e s t u r n i d s . Energy v a l u e s g r a p h i c a l l y p r e s e n t e d i n F i g u r e 14 were p l o t t e d a g a i n s t t h e mean monthly cage a r e a ambient t e m p e r a t u r e f o r the t o t a l , f i r s t and second h a l f y e a r p e r i o d s (Appendix T a b l e 3 ) . F o r t h e f i r s t h a l f y e a r (January t h r o u g h June, 1969), o n l y M.E. was n e g a t i v e l y c o r r e l a t e d ( a l t h o u g h weakly) w i t h t e m p e r a t u r e , t h a t i s , as te m p e r a t u r e d e c r e a s e d , energy u t i l i z a t i o n i n c r e a s e d (r=0.79). A l l s t a r l i n g energy v a l u e s f o r the second h a l f y e a r o f 1969 ( J u l y t h r o u g h December) were p o s i t i v e l y c o r r e l a t e d w i t h t e m p e r a t u r e , however, o n l y t e m p e r a t u r e v e r s u s G.E. showed a s t r o n g c o r r e l a t i o n (r=0.80). Year l o n g t e m p e r a t u r e was n o n s i g n i f i c a n t l y and n e g a t i v e l y c o r r e l a t e d w i t h G.E., E.E. and M.E. (r=0.29, 0.00 and 0.45, r e s p e c t i v e l y ) . The Myna - E f f e c t s o f Ambient Temperature on Energy U t i l i z a t i o n A r e g r e s s i o n a n a l y s i s o f c r e s t e d myna G.E., E.E. and M.E. a g a i n s t mean monthly cage a r e a ambient t e m p e r a t u r e 54 showed c o r r e l a t i o n s weaker th a n t h o s e f o r s t a r l i n g s d u r i n g t h e same p e r i o d (Appendix T a b l e 4 ) . M e t a b o l i z a b l e energy f o r the f i r s t h a l f y e a r showed the s t r o n g e s t n e g a t i v e c o r r e l a t i o n w i t h t e m p e r a t u r e (r=0.63). Energy u t i l i z a t i o n d a t a a n a l y z e d f o r the second h a l f and t o t a l y e a r p e r i o d s showed weak c o r r e l a t i o n s w i t h mean m o n t h l y cage a r e a ambient t e m p e r a t u r e . L a b o r a t o r y S t u d i e s o f Thermal Response The S t a r l i n g - Oxygen Consumption L a b o r a t o r y i n v e s t i g a t i o n s o f s t u r n i d t h e r m a l r e s p o n s e were conducted t o supplement e n e r g e t i c s d a t a c o l l e c t e d i n the a v i a r y . F i g u r e 16 i l l u s t r a t e s t h e s t a r l i n g t h e r m a l r e s p o n s e c u r v e . The t h e r m a l n e u t r a l zone l i e s near +20°C. E x p e r i m e n t a l l y o b t a i n e d and c a l c u l a t e d l o w e r c r i t i c a l t e m p e r a t u r e s are p r e s e n t e d . The p o i n t where the t h e r m a l -n e u t r a l zone i n t e r s e c t s the l e a s t s q u a r e s l i n e s h o u l d t h e o r e t i c a l l y be t h e LCT. T h i s v a l u e can be checked by u s i n g t h e f o r m u l a : LCT = t b~BMR/q, where q i s t h e v a l u e f o r conductance o b t a i n e d from c o o l i n g e x p e r i m e n t s ( K l e i b e r 1965:165). F o r s t a r l i n g s , the c a l c u l a t e d LCT o f 14.70°C, u s i n g a body t e m p e r a t u r e o f 40.66°C (n=38) and a BMR o f 55 F i g u r e 16. S t u r n i d t h e r m a l r e s p o n s e c u r v e s i l l u s t r a t i n g t h e o r e t i c a l LCT and e x p e r i m e n t a l l y o b s e r v e d LCT, and l e a s t s q uares r e g r e s s i o n l i n e s e x t r a p o l a t e d t o o b s e r v e d body t e m p e r a t u r e s . A c t u a l body t e m p e r a t u r e s a t +20°C a r e 40.66°C and 39.93°C f o r s t a r l i n g s (n=38) and mynas (n=32), r e s p e c t i v e l y (o = s t a r l i n g , © = myna; v e r t i c l e b a r t h r o u g h symbol = ± 1 s . e . ) . AMBIENT TEMPERATURE (°C) 56 12.6 cal/gm-hr, i s v e r y c l o s e t o the e x p e r i m e n t a l l y o b t a i n e d v a l u e ( F i g u r e 16; LCT). L e t h a l Temperature The L D 5 Q f o r upper t e m p e r a t u r e t o l e r a n c e by s t a r l i n g s was n o t o b t a i n e d i n t h i s s t u d y . S t a r l i n g s w i t h s t o o d + 40°C f o r 3 hours even though body t e m p e r a t u r e s i n c r e a s e d an average of 2.5°C ov e r the v a l u e o b t a i n e d b e f o r e b i r d s were s u b j e c t e d t o e x p e r i m e n t a l t e m p e r a t u r e s ( T a b l e 1 ) . No f a c i l i t i e s were a v a i l a b l e f o r t e s t i n g b i r d s below -20°C, t h e r e f o r e no l o w e r t o l e r a n c e l i m i t s c o u l d be d e t e r m i n e d . Weight l o s s d u r i n g m e t a b o l i c t r i a l s was a t t r i b u t e d t o w a t e r l o s s , t i s s u e o x i d a t i o n and e x c r e t i o n . No attempt was made t o measure r e s p i r a t o r y w ater l o s s . E x c r e t a l o s t w e i g h t d u r i n g m e t a b o l i c t r i a l s , t h e r e f o r e no v a l u e s f o r t i s s u e o x i d a t i o n c o u l d be o b t a i n e d from w e i g h t measurements. S e a s o n a l E f f e c t s on M e t a b o l i s m S t a r l i n g m e t a b o l i c t r i a l s were c o n d u c t e d a t -20°C and +30°C i n b o t h l a t e s p r i n g (June) and l a t e f a l l (Novem-ber) . 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 m e t a b o l i c r a t e s were found between t h e s e d i f f e r e n t seasons. T a b l e 1. Change i n body tem p e r a t u r e ( t b ) and body w e i g h t d u r i n g m e t a b o l i s m e x p e r i m e n t s . E x p e r i m e n t a l t - t, (°C) W - W, (gms/hr) Temperature (°C) o p l ° 1 S t a r l i n g Myna S t a r l i n g Myna -20 .42 + .085 -.11 + .182 1.18 + .033 1.73 + .099 -10 .48 + .167 -.04 + .225 .91 + .106 1. 44 + .078 0 .53 + .257 -.04 + .340 .83 + .090 1.25 + .173 10 .80 + .284 .51 + .158 1.09 + .051 1.29 + .058 20 1.12 + .157 1.94 + .411 .43 + .028 .59 + .037 30 1.51 + .120 1.40 + .193 1.63 + .119 1.69 + .086 40 2.58 + .187 3.57 + .120 2 2.02 + .076 3.77 + .714 1 4.70 + • 286 3 2.08 + .194 2 4.20 + 4 .279 3. 04 + 3 .517 Mean ± s t a n d a r d e r r o r o f the mean B i r d s t h a t s u r v i v e d (n=4) B i r d s t h a t d i e d (n=4) T o t a l b i r d s t h a t l i v e d and d i e d (n=8) 58 R e s p i r a t o r y Q u o t i e n t s and S h i v e r i n g R e s p i r a t o r y q u o t i e n t s (R.Q.) d e t e r m i n e d a t -20°C and +20°C f o r s t a r l i n g s (0.74 ± 0.07 and 0.73 ± 0.06, r e s p e c t -i v e l y ) were n o t s i g n i f i c a n t l y d i f f e r e n t from each o t h e r . O b s e r v a t i o n s o f s t a r l i n g s d u r i n g m e t a b o l i s m e x p e r i m e n t s r e v e a l e d s h i v e r i n g a t and below 0°C. S h i v e r i n g was n o t o b s e r v e d above 0°C. The Myna - Oxygen Consumption The c r e s t e d myna t h e r m a l r e s p o n s e c u r v e i s a l s o shown i n F i g u r e 16. , The c a l c u l a t e d LCT o f 15.34°C f o r mynas, u s i n g a body t e m p e r a t u r e o f 39.93°C (n=32), i s s i m i l a r t o the v a l u e o b t a i n e d from t h e l e a s t s q u a r e s l i n e i n F i g u r e 16. T h i s LCT, a l o n g w i t h the BMR (9.5 cal/gm-hr) p l a c e d t h e myna t h e r m a l n e u t r a l zone around 20°C. L e t h a l Temperature The L D J-Q f o r upper t e m p e r a t u r e t o l e r a n c e i n c r e s t e d mynas was between 30°C and 40°C (n=8 b i r d s ) ; 4 d i e d a f t e r c o n s i d e r a b l e l o s s o f w e i g h t and d u r i n g h y p e r t h e r m y , when t e s t e d f o r 3 hours a t +40°C. S e a s o n a l E f f e c t s on M e t a b o l i s m The e f f e c t o f season on myna m e t a b o l i c r a t e s was t e s t e d by measuring myna m e t a b o l i s m i n l a t e s p r i n g and 59 l a t e f a l l ; as w i t h s t a r l i n g s , no such change was o b s e r v e d . Myna R.Q. a t +20°C (0.74 ± 0.08) was n o t s i g n i f i c a n t l y h i g h e r than a t -20°C (0.71 ± 0.09). S h i v e r i n g d u r i n g m e t a b o l i c t r i a l s was n o t i c e d f o r c r e s t e d mynas a t and below 0°C. I n s u l a t i o n and Thermal Conductance C o o l i n g E x p e r i m e n t s S i n c e m e t a b o l i c t r i a l s s u g g e s t e d mynas were p r o d u c i n g p r o p o r t i o n a l l y more h e a t t h a n s t a r l i n g s a t b o t h low and h i g h t e m p e r a t u r e s ( F i g u r e 1 6 ) , an attempt was made t o d e t e r m i n e the e f f e c t i v e n e s s of plumage as an i n s u l a t i v e l a y e r f o r b o t h s p e c i e s . The r e s u l t s o f c o o l i n g e x p e r i m e n t s were p l o t t e d and r e g r e s s i o n l i n e s r e l a t i n g c o o l i n g r a t e t o e x t e r n a l t e m p e r a t u r e were c o n s t r u c t e d f o r f e a t h e r e d and u n f e a t h e r e d s t a r l i n g s and mynas (Appendix F i g u r e s 2 and 3, r e s p e c t i v e l y ) . Thermal conductance v a l u e s were o b t a i n e d u s i n g methods s i m i l a r t o t h o s e d e s c r i b e d by M o r r i s o n and 2 T i e t z (1957) and a r e e x p r e s s e d i n c a l / c m -hr-°C. The s p e c i f i c h e a t o f b i r d t i s s u e was assumed t o be c l o s e t o 0.83 cal/°C-gm, w h i c h i s the v a l u e g i v e n by M o r r i s o n and T i e t z (1957) f o r s m a l l mammal t i s s u e . T a b l e 2 p r e s e n t s the p e r t i n e n t d a t a from which t h e r m a l conductance v a l u e s T a b l e 2. Conductance v a l u e s o b t a i n e d from c o o l i n g c u r v e s o f s t u r n i d s Weight (gms) F e a t h e r e d Weight (gms) U n f e a t h e r e d F e a t h e r Weight C a l c u l a t e d S u r f a c e A r e a from U n f e a t h e r e d Weight (cm^) C o o l i n g Thermal C o n s t a n t s Conductance ( h r ~ 5 (cal/cm 2-hr-°C) S t a r l i n g (n=5) F e a t h e r e d U n f e a t h e r e d 88.2±.77 X 79.8i.95 6.3±.32 195.711.55 .62+.035 1.741.114 .211.012 Myna (n=4) 112.4±5.62 100.6±1.53 10.5±.35 228.112.43 .501.030 1.561.141 .181.012 1: A l l v a l u e s a r e e x p r e s s e d as means ± s t a n d a r d e r r o r s o f means. O 61 were c a l c u l a t e d . A l l c a l c u l a t i o n s f o r t h e r m a l c onductance are based on u n f e a t h e r e d w e i g h t s . S u r f a c e A r e a S u r f a c e a r e a v a l u e s were c a l c u l a t e d f rom u n f e a t h e r e d w e i g h t s a f t e r a s e r i e s o f e x p e r i m e n t s were c o n d u c t e d t o t e s t the a c c u r a c y o f the f o r m u l a g i v e n by Meeh (1897) : 2 2/3 S u r f a c e A r e a (cm ) = kW ' . A v a l u e o f 10.4 was g i v e n by Rubner (1902) f o r k, t h e r e f o r e the f o r m u l a used was S.A. = 2/3 1 0 . 4 ( u n f e a t h e r e d W) , where W i s e x p r e s s e d i n gms (See F i g u r e 1 7 ) . In o r d e r t o e v a l u a t e plumage q u a l i t y , t h e v a l u e L was d e r i v e d as f o l l o w s : L = ( q 2 ~ q ^ ) ( s p e c i f i c h e a t ) ( u n f e a t h e r e d w e i g h t ) ( s u r f a c e a r e a ) ( f e a t h e r w e i g h t ) where and q^ are c o o l i n g c o n s t a n t s f o r u n f e a t h e r e d and f e a t h e r e d c a r c a s s e s , r e s p e c t i v e l y ( T able 2 ) . Thus, the v a l u e L r e p r e s e n t s the amount o f h e a t ( c a l o r i e s ) c o n s e r v e d 2 by one gram o f f e a t h e r s o v e r 1 cm o f s u r f a c e a r e a i n 1 hour f o r e v e r y 1°C o f t e m p e r a t u r e g r a d i e n t ( tj-,~ t a) • S t a r l i n g L = 6.2 ± .05 x 1 0 ~ 2 cal/gm-hr-°C-cm 2, w h i l e t h e mean plumage w e i g h t o f s t a r l i n g s (n=5) c o l l e c t e d f o r c o o l i n g e x p e r i m e n t s was 6.3 ± .32 gms (7% o f t o t a l body w e i g h t ) . 62 Figure 17. Comparison of e x p e r i m e n t a l l y obtained (o) and t h e o r e t i c a l (Meeh 1897: 10.4 W2/3) surface area values f o r 9 b i r d s ranging i n s i z e from a juvenal barn swallow to an a d u l t rock dove. WEIGHT IN GRAMS 63 Myna L = 3.4 i .40 x 10 2 cal/gm-hr-°C-cm 2, and mean plumage w e i g h t (n=4) was 10.5 ± .35 gms (9.4% o f t h e t o t a l body w e i g h t ) . 64 DISCUSSION This study has been devoted to exploring the compar-ative performance of two passeriformes, belonging to the family Sturnidae, as colonizers i n a new environment i n western North America. One of the species (Sturnus  vulgaris) i s of north temperate o r i g i n , the other (Sturnus  c r i s t a t e l l u s ) i s predominantly subtropical. Preliminary consideration of known facts of the l i f e h i s t o r y of the two species led to the proposition that the most probable differences i n performance i n the colonizing success of the species was concerned with u t i l i z a t i o n of the energy resources of the environment and i n adaptation to thermal constraints. To explore these areas, observations and experiments were designed to examine reproductive e f f i c i e n c y through the nesting period; rate of growth and course of develop-ment, with p a r t i c u l a r reference to the a c q u i s i t i o n of endothermy; the energy cycle during the winter; metabolism under controlled thermal conditions, and the i n s u l a t i v e q u a l i t y of the plumage. 65 N e s t i n g N e s t i n g a c t i v i t i e s by mynas and s t a r l i n g s s t a r t e d about the same time time i n t h e Vancouver a r e a , and the d a t e s of f i r s t eggs l a i d were a l s o s i m i l a r f o r b o t h s p e c i e s , b u t s t a r l i n g a c t i v i t i e s were s y n c h r o n i z e d i n t o d e f i n i t e peaks f o r the whole b r e e d i n g s e a s o n . The o n s e t o f egg l a y i n g by mynas was v e r y s i m i l a r t o t h a t found by MacKay and Hughes (1963) f o r c r e s t e d mynas i n t h e Vancouver a r e a i n 1959 and 1960; f i r s t eggs were found i n t h e second week i n A p r i l . They r e p o r t e d a l o w e r c l u t c h s i z e t h a n t h a t found i n t h i s s t u d y (Table 3 ) . The l a r g e s t number of myna n e s t s had 5 eggs ( 4 7 % ) , w i t h 4 eggs second most common ( 2 6 % ) , w h i c h compares f a v o u r a b l y w i t h r e s u l t s r e p o r t e d by MacKay and Hughes (1963:159). I t i s i n t e r e s t i n g t o note t h a t i n the Hong Kong a r e a , where f i r s t eggs were r e p o r t e d from 15 A p r i l onward, a 4 egg c l u t c h was most common f o r t h i s s p e c i e s (Vaughn and Jones 1913). S m a l l e r c l u t c h s i z e i n t r o p i c a l s p e c i e s i s common (Skutch 1949), however, i t i s i n t e r e s t i n g t h a t a t r o p i c a l b i r d appears t o have i n c r e a s e d i t s c l u t c h s i z e when moved t o a temperate e n v i r o n m e n t . W i l k i n s o n (1929:124) r e p o r t e d t h a t two broods a y e a r i s t y p i c a l o f c r e s t e d mynas i n C h i n a . MacKay and Hughes r e p o r t e d no c e r t a i n second c l u t c h e s f o r c r e s t e d mynas i n 66 the Vancouver area, but several instances suggested that second clutches were l a i d . Only f i v e c e r t a i n two brood nests were found i n t h i s study, which also suggests that second nestings are not common i n the Vancouver area. Scheffer and Cottam (1935) suggested the small number of second broods i s the r e s u l t of a lengthened period of a c t i v i t y associated with the f i r s t nesting. They observed a 14-day nest b u i l d i n g period for Vancouver crested mynas, followed by a 15-day period for egg laying and incubation. The young l e f t the nest when about 27 days old, thus the t o t a l nesting period lasted about 66 days. Nest building took as long as two weeks for f i v e pairs i n my study, and most juveniles l e f t the nest at 22-23 days. A t o t a l of 49-59 days lapsed from i n i t i a t i o n of nest b u i l d i n g to independence of the f i r s t brood. I n i t i a t i o n of s t a r l i n g nesting a c t i v i t y was e a r l i e r than noticed for mynas, although not as early as reported for s t a r l i n g s i n Arizona (Royall 1966) or M i s s i s s i p p i and V i r g i n i a (Kessel 1957). Starlings i n the Vancouver area (49° N latitude) s t a r t f i r s t clutches e a r l i e r than suggested by the schedule of laying at 4 8-50° N l a t i t u d e for Eastern North America (Kessel 1957:270). However, peaks of egg laying by s t a r l i n g s i n Czechoslovakia (Havlin personal communication 19 6 8), Scotland (Anderson 1961) and Denver, 67 C o l o r a d o (DeHaven p e r s o n a l communication 196 9) a r e c l o s e t o t h o s e o b s e r v e d i n Vancouver (15-30 A p r i l ) . C l u t c h s i z e f o r f i r s t n e s t i n g s of t h e European s t a r -l i n g i n Vancouver (Table 3) were s i m i l a r t o t h o s e i n New York ( K e s s e l 1957), H o l l a n d (Lack 1948) and S c o t l a n d (Anderson 1961), b u t h i g h e r t h a n r e p o r t e d i n A r i z o n a ( R o y a l l 1966) and N o r t h e r n E n g l a n d (Lack 1948). S i m i l a r l y , c l u t c h s i z e i n second n e s t i n g s was g e n e r a l l y h i g h e r i n Vancouver s t a r l i n g s than r e p o r t e d e l s e w h e r e , w i t h t h e e x c e p t i o n of. c e r t a i n l o c a t i o n s and y e a r s i n A r i z o n a ( R o y a l l 1966) and S c o t l a n d (Anderson 1961). I n c u b a t i o n C r e s t e d mynas i n c u b a t e d a p p r o x i m a t e l y two days l o n g e r than s t a r l i n g s (14 and 12 d a y s , r e s p e c t i v e l y ) , w i t h t h e mean a t t e n t i v e n e s s d u r i n g d a y l i g h t hours (0300-2100 h r s ) f o r mynas 47% compared t o 70% f o r s t a r l i n g s (59% and 77% r e s p e c t i v e l y , f o r t h e whole 24-hour p e r i o d ) . Myna a t t e n t -i v e n e s s was s i g n i f i c a n t l y l o w e r e x c e p t f o r t h e 1800-2100 hour p e r i o d when no s i g n i f i c a n t d i f f e r e n c e was o b s e r v e d between the two s p e c i e s . D e l v i n g t (1963) r e p o r t e d a 78% a t t e n t i v e n e s s ( d u r i n g a 24-hour p e r i o d ) f o r s t a r l i n g s i n B e l g i u m , w h i c h compares f a v o u r a b l y w i t h 77% o b t a i n e d i n t h i s s t u d y . 68 A l s o , n e s t b o x t e m p e r a t u r e a t egg l e v e l was l o w e r f o r i n c u b a t i n g mynas t h a n f o r s t a r l i n g s . However, no d a t a were found i n t h e l i t e r a t u r e c o n c e r n i n g i n c u b a t i o n t e m p e r a t u r e s f o r s t a r l i n g s . No i n f o r m a t i o n was found c o n c e r n i n g i n c u b a t i o n f o r c r e s t e d mynas, b u t Sengupta (1968) d e s c r i b e d i n c u b a t i o n f o r the s i m i l a r common myna ( A c r i d o t h e r e s t r i s t i s t r i s t i s L.) i n West B e n g a l as i r r e g u l a r (mean extreme a i r temperature= 20° and 32°C), w i t h i n c u b a t i o n l e f t t o the h e a t o f the sun and s h o r t s i t t i n g p e r i o d s d u r i n g t h e day. H a t c h i n g and F l e d g i n g C r e s t e d mynas h a t c h e d f a r fewer eggs t h a n s t a r l i n g s i n t h i s s t u d y (Table 3 ) . A s i m i l a r low h a t c h i n g s u c c e s s was o b s e r v e d f o r t h e c r e s t e d myna i n the Vancouver a r e a by MacKay and Hughes (1963). They found a 37% h a t c h i n g s u c c e s s f o r a l l eggs i n 1959 and 1960 w i t h about 73% o f the f a i l u r e s a t t r i b u t e d t o i n c u b a t i o n f a i l u r e and 20% due t o egg d e s t r u c t i o n ; t h i s y i e l d s an i n c u b a t i o n s u c c e s s of 49%, s t i l l l o w e r t h a n t h a t found i n t h i s s t u d y . However, MacKay and Hughes o b s e r v e d a h i g h e r f l e d g i n g r a t e f o r young mynas, from h a t c h i n g , t h a n i n t h i s s t u d y . These h a t c h i n g , f l e d g i n g and n e s t i n g s u c c e s s v a l u e s a r e much lower t h a n r e p o r t e d by Sengupta (1968) f o r common mynas T a b l e 3. C o m p a r a t i v e r e p r o d u c t i v e d a t a f o r s t a r l i n g s a n d m y n a s S o u r c e C l u t c h s i z e H a t c h i n g s u c c e s s N e s t i n g s u c c e s s ( M e a n e g g s / c l u t c h ) (% h a t c h e d ) (% f l e d g e d o f c l u t c h ) S t a r l i n g T h i s s t u d y 5.5 ( 4 . 8 ) 1 84 ( 6 9 ) 76 ( 7 1 ) K e s s e l ( 1 9 5 7 ) 5.5 ( 4 . 1 ) 81 ( 7 1 ) 81 (68 ) A n d e r s o n ( 1 9 6 1 ) 5.2 ( 4 . 6 ) 88 ( 8 3 ) 80 ( 8 0 ) D u n n e t ( 1 9 5 5 ) 5.1 ( 4 . 6 ) 88 ( 8 6 ) 82 (72 ) L a c k ( 1 9 4 8 ) 2 5.2 ( 4 . 3 ) 85 ( 8 6 ) 83 ( 7 8 ) R o y a l l ( 1 9 6 6 ) 4.4 84 57 ( 4 7 ) r n a T h i s s t u d y 4.9 ( 3 . 8 ) 61 ( 5 8 ) 46 (39 ) M a c K a y a n d H u g h e s ( 1 9 6 3 ) 4.4 37 31 S e n g u p t a ( 1 9 6 8) 3.8 98 76 • — _ L a m b a ( 1 9 6 3 ) - — 87 V a l u e s i n p a r e n t h e s e s a r e f o r s e c o n d n e s t i n g s ( e x c l u s i v e o f r e n e s t i n g s ) ^ For D u t c h s t a r l i n g s o n i v 70 i n West B e n g a l . He o b s e r v e d a h a t c h i n g s u c c e s s o f 9 8% f o r 45 eggs i n 12 c l u t c h e s , w h i c h i s e x t r e m e l y h i g h , even when compared t o the 87% h a t c h i n g s u c c e s s o b s e r v e d f o r t h e same s p e c i e s i n a d i f f e r e n t p a r t o f I n d i a (Lamba 1963). The o v e r a l l n e s t i n g s u c c e s s o b s e r v e d f o r common mynas was 75.55% (Sengupta 1968). N e s t i n g s u c c e s s f o r e a r l y n e s t i n g s t a r l i n g s i n Vancouver was l o w e r t h a n t h a t r e p o r t e d f o r t h i s s p e c i e s by K e s s e l (1957) i n New Yo r k , Anderson (1961) i n S c o t l a n d and by Lack (1948) f o r Dutch s t a r l i n g s . A r i z o n a b i r d s ( R o y a l l 1966) had a lo w e r n e s t i n g s u c c e s s f o r f i r s t c l u t c h e s which was p r o b a b l y a r e s u l t of human i n t e r f e r e n c e , e c t o p a r a s i t i c ( f o w l m i t e s ) i n f e s t a t i o n s and o v e r h e a t i n g i n t h e n e s t b o x e s ( R o y a l l 1966:201). Second c l u t c h e s o f s t a r l i n g eggs i n Vancouver y i e l d e d a l o w e r n e s t i n g s u c c e s s t h a n t h e f i r s t , however, the p e r c e n t f l e d g i n g from eggs o f second c l u t c h e s i s w i t h i n the range o f e x p e r i e n c e e l s e w h e r e (See T a b l e 3 ) . Growth The r a t e o f s t a r l i n g growth (K = 0.416) i s f a s t e r t h a n t h a t o b s e r v e d f o r c r e s t e d mynas (K = 0.284) and p a s t day 3, r e g r e s s i o n l i n e s c o n s t r u c t e d from l o g i s t i c c o n v e r s i o n f a c t o r s ( F i g u r e 7) a r e s i g n i f i c a n t l y d i f f e r e n t (a = 0.10) from each o t h e r . The r a t e o f s t a r l i n g growth i n Vancouver i s s i m i l a r 71 t o t h a t r e p o r t e d by R i c k l e f s (1968:110) f o r Czech s t a r l i n g s (K = 0.412) and s l i g h t l y f a s t e r than r e p o r t e d f o r S c o t t i s h s t a r l i n g s (K = 0.396). A l s o , s t a r l i n g g rowth f i t s n i c e l y i n t o R i c k l e f s 1 (1969:1032) r e g r e s s i o n l i n e o f a d u l t body w e i g h t and growth r a t e (K) f o r temperate zone p a s s e r i n e s . The growth r a t e of the t r o p i c a l c r e s t e d myna i n Vancouver i s much lo w e r t h a n p r e d i c t e d from h i s c u r v e , w h i c h i s c o n s i s t e n t w i t h t h e h y p o t h e s i s and r e s u l t s p r e s e n t e d by R i c k l e f s f o r o t h e r t r o p i c a l b i r d s . I t i s i n t e r e s t i n g t o note t h a t t r o p i c a l common mynas began i n c u b a t i o n b e f o r e l a y i n g t h e l a s t egg (Sengupta 1968). T h i s r e s u l t e d i n some n e s t l i n g s h a t c h i n g e a r l i e r t h a n o t h e r s , t h e r e b y i n c r e a s i n g t h e r a t e o f growth i n t h e s e e a r l i e r h a t c h e d n e s t l i n g s . D e s p i t e t h e s e d i f f e r e n c e s i n r a t e o f growth between n e s t l i n g s , development o f plumage was s t i l l s y n c h r o n i z e d w i t h age, and f l e d g i n g s u c c e s s was h i g h . The above-mentioned phenomenon was n o t o b s e r v e d i n Vancouver c r e s t e d mynas, where t h e growth r a t e o f a l l n e s t l i n g s was s i m i l a r . T h e r e f o r e , comparisons o f grow t h r a t e s o f common and c r e s t e d mynas u s i n g the method d e s c r i b e d by R i c k l e f s would n o t be r e a l i s t i c . L o g i s t i c c o n v e r s i o n f a c t o r s c o u l d be c a l c u l a t e d f o r each i n d i v i d u a l n e s t l i n g u s i n g d i f f e r e n t a s y m p t o t i c v/eights measured a t the n e s t , b u t t h e s e would no t r e p r e s e n t o r be comparable t o n e s t l i n g s which r e a c h near a d u l t w e i g h t w h i l e s t i l l i n t h e n e s t . 72 Few s t u d i e s o f c o m p a r a t i v e e n e r g e t i c s have been made on c l o s e l y r e l a t e d s p e c i e s from d i f f e r e n t g e o g r a p h i c r e g i o n s , however, Maher (1964) p r e s e n t s d a t a showing t h a t t h e growth r a t e o f two a r c t i c b r e e d i n g e m b e r i z i n a e a t Barrow, A l a s k a , were not d i f f e r e n t even though the a d u l t w e i g h t of one s p e c i e s was 30% h e a v i e r t h a n t h e o t h e r . He went on t o compare growth r a t e s o f the two a r c t i c b r e e d i n g f r i n g i l l i d s w i t h f i v e temperate b r e e d i n g r e l a t i v e s and c o n c l u d e d t h a t t h e r e was no e v i d e n c e f o r a d a p t a t i o n i n growth r a t e s i n w i d e l y d i s p e r s e d members o f the same f a m i l y . C r e s t e d mynas and European s t a r l i n g s , a l t h o u g h s i m i l a r l y r e l a t e d , have e v o l v e d i n two d i f f e r e n t c l i m a t i c and e c o l o g i c ( t r o p i c a l and temperate) r e g i o n s . I have shown t h e r a t e s o f growth t o be d i f f e r e n t as a l s o d e m o n s t r a t e d by R i c k l e f s (1969a); t h i s r e i n f o r c e s t h e s u g g e s t i o n t h a t d i f f e r e n c e s between t r o p i c a l and temperate r e g i o n s are much g r e a t e r t h a n t h o s e between a r c t i c and temperate r e g i o n s , w i t h r e s p e c t t o t h e e v o l u t i o n o f b r e e d i n g systems, m o r t a l i t y , and the growth o f p a s s e r i f o r m b i r d s . N e s t l i n g Energy I n t a k e V a l u e s f o r s t u r n i d f e e d i n g r a t e s a r e g i v e n by H a v l i n and F o l k (1964), K l u i j v e r (1933) and Dunnet (1955) f o r s t a r l i n g s and by Sengupta (1968) f o r mynas i n West B e n g a l . 73 Dunnet l i s t e d o n l y wet w e i g h t s o f f o o d , w h i c h c o n s i s t e d m o s t l y o f c r a n e f l y l a r v a e (80%) and earthworms ( 1 6 % ) . Assuming a maximum o f 80% w a t e r c o n t e n t f o r t h e s e f o o d i t e m s , we can e s t i m a t e an average o f 0.366 gms/feeding from Dunnet's T a b l e 3 f o r a n e s t of t h r e e 18 day o l d n e s t l i n g s , w h i c h i s about t h r e e times the v a l u e o b t a i n e d from c a l c u l a t i o n s i n t h i s s t u d y . Dunnet mentioned t h a t h i s d a t a d i d not s u b s t a n t i a t e K l u i j v e r ' s o b s e r v a t i o n t h a t t h e average s i z e o f the f e e d i n c r e a s e d g r a d u a l l y u n t i l t h e n e s t l i n g s were 12-15 days o l d . However, he d i d ment i o n t h a t the d a i l y amount o f f o o d n e c e s s a r y f o r a n e s t l i n g t o f o l l o w t h e mean growth c u r v e r i s e s q u i c k l y t o a maximum a t about day 10, and t h i s i s m a i n t a i n e d u n t i l a few days b e f o r e t h e n e s t l i n g s l e a v e the n e s t a t about 22 days o l d . R e c o r d i n g s o f a d u l t f e e d i n g a c t i v i t y i n my s t u d y ( F i g u r e 10) s u b s t a n t i a t e Dunnet's l a s t s t a t e m e n t and a l s o show t h e same t r e n d f o r myna f e e d i n g a c t i v i t y . A l t h o u g h the s i z e o f the f o o d i t e m s t h e o r e t i c a l l y c o u l d i n c r e a s e as the n e s t l i n g ' s a p p e t i t e and mouth s i z e i n c r e a s e , my d a t a s u g g e s t s t h a t most o f the i n c r e a s e i n n e s t l i n g f o o d i n t a k e was the r e s u l t o f an i n c r e a s e d f e e d i n g r a t e r a t h e r t han an i n c r e a s e i n t h e s i z e o f the fo o d i t e m s s u p p l i e d . 74 K l u i j v e r (1933) found t h a t the wet w e i g h t o f f o o d s / f e e d i n g never exceeded 1 gm. The maximum d r y w e i g h t s o f f e e d i n g s r e p o r t e d by him c o u l d n o t have been l a r g e r t h a n 0.20 gms/feeding i f we s t i l l assume an 80% w a t e r c o n t e n t f o r f o o d b r o u g h t by. Dutch s t a r l i n g s ( p r i m a r i l y c r a n e f l y l a r v a e ) ; thus h i s v a l u e s were p r o b a b l y lower t h a n t h o s e r e p o r t e d by Dunnet. Weights o f f e e d i n g s i n my s t u d y a pproximate those r e p o r t e d by K l u i j v e r , however, t h e d i f f e r e n c e i n l o c a t i o n o f s t u d y a r e a s , and the number o f assumptions i n v o l v e d make d i r e c t comparisons r i s k y . A l s o , as mentioned e a r l i e r , v a l u e s p r e s e n t e d i n t h i s s t u d y a r e averages f o r t h e whole growth p e r i o d . H a v l i n and F o l k (1964) o b s e r v e d l a t e broods o f s t a r -l i n g s i n C z e c h o s l o v a k i a and e s t i m a t e d 750 gms of c h e r r i e s (Prunus c e r a s u s ) consumed by 5 f u l l - g r o w n , b u t n e s t l i n g , s t a r l i n g s i n one day. T h i s v a l u e y i e l d s 24.3 g m s / n e s t l i n g -day o f p i t l e s s d r i e d c h e r r i e s consumed, w h i c h i n t u r n y i e l d s a p p r o x i m a t e l y 120 k c a l / n e s t l i n g - d a y o f G.E. i n t a k e f o r l a t e broods o f s t a r l i n g s i n C z e c h o s l o v a k i a . T h i s e s t i m a t e i s h i g h e r t h a n the 83.50 k c a l / n e s t l i n g - d a y o b t a i n e d f o r f i r s t b roods o f s t a r l i n g s i n t h i s s t u d y . The d i s c r e p a n c y may a r i s e , i n p a r t from the v a l u e s used by me i n c o n v e r t i n g H a v l i n and F o l k ' s (1964) g r o s s w e i g h t s i n t o e n e r g e t i c terms. I used v a l u e s o b t a i n e d from c u l t i v a t e d Byng c h e r r i e s i n t h e 75 Vancouver a r e a where w a t e r c o n t e n t was 78%; p i t s r e p r e s e n t e d 5.7% o f the t o t a l c h e r r y w e i g h t , and energy c o n t e n t was 5.01 kcal/gm. W e s t e r t e r p (1971) has made e x t e n s i v e s t u d i e s o f energy b a l a n c e d u r i n g growth of n e s t l i n g s t a r l i n g s i n H o l l a n d . Compared w i t h r e s u l t s from h i s more d e t a i l e d a n a l y s i s , my e s t i m a t e s o f energy i n t a k e by n e s t l i n g s , i n t h e Vancouver a r e a a r e about 20% h i g h e r i n the e a r l i e r s t a g e s o f growth and about 40% h i g h e r a t l a t e r s t a g e s o f growth. The e s t i -mates I o b t a i n e d by c a l c u l a t i o n from t h e d a t a o f H a v l i n and F o l k (1964) are o v e r 100% h i g h e r than W e s t e r t e r p ' s e s t i m a t e s f o r Dutch s t a r l i n g s a t comparable w e i g h t s . A l t h o u g h the r a t e o f n e s t l i n g growth, as r e c o r d e d by W e s t e r t e r p , i s a l m o s t i d e n t i c a l t o t h a t r e c o r d e d i n t h i s s t u d y , the a s y m p t o t i c w e i g h t s o f Vancouver n e s t l i n g s a r e a l m o s t 10 gms h e a v i e r than the Dutch b i r d s . A l s o , m o r t a l i t y was h i g h among the Dutch s t a r l i n g s ; a f t e r sub-t r a c t i n g known m o r t a l i t y as a r e s u l t o f i n v e s t i g a t o r i n t e r f e r e n c e , s t i l l o n l y 30% t o 49% o f a l l eggs l a i d r e s u l t e d i n f l e d g e d young. However, the most s i g n i f i c a n t f a c t o r a f f e c t i n g the d i s c r e p a n c y i n energy i n t a k e v a l u e s between t h e two s t u d i e s i s p r o b a b l y the d i f f e r e n c e i n n e s t l i n g energy m e t a b o l i s m by Vancouver s t a r l i n g s compared w i t h those i n v e s t -75A i g a t e d by .Westerterp. Even a f t e r c o r r e c t i n g f o r the f a c t t h a t W e s t e r t e r p 1 s b i r d s were grouped d u r i n g m e t a b o l i s m t r i a l s (See B r e i t e n b a c k and B a s k e t t , 196 ), Vancouver n e s t -l i n g s i n the 60-70 gms w e i g h t c l a s s produced h e a t a t a r a t e o v e r 1.5 t i m e s (See F i g u r e 9. 35 k c a l / n e s t l i n g - d a y compared w i t h 18 k c a l / n e s t l i n g - d a y ) t h a t of the Dutch b i r d s i n t h e same w e i g h t range. Both Dutch and Vancouver b i r d s w e i g h i n g l e s s than 40 gms had a s i m i l a r energy e x p e n d i t u r e (10 t o 15 k c a l / n e s t l i n g - d a y ) . Sengupta (1968) found t h a t f e e d i n g rates, i n t h e t r o p i c a l common myna i n West B e n g a l i n c r e a s e d s t e a d i l y w i t h growth and development. He r e p o r t e d 1.96 f e e d i n g s / n e s t l i n g - h o u r a t day 1 and 4.26 f e e d i n g s / n e s t l i n g - h o u r a t day 16, thus h i s v a l u e s f o r common mynas were h i g h e r than mine f o r c r e s t e d mynas d u r i n g the e a r l y s t a g e s o f growth and l o w e r i n l a t e r s t a g e s . S t a r l i n g f o o d h a b i t s i n Europe and N o r t h A m e r i c a have been d e s c r i b e d by Dunnet (1955), Anderson (1961), H a v l i n and F o l k (1964), S z i j j (1957), Kalmbach and G a b r i e l s o n (1921), B e s s e r , D e G r a z i o and G u a r i n o (1968) and o t h e r s . However, o n l y a few f o o d h a b i t s s t u d i e s have been made of c r e s t e d mynas ( S c h e f f e r and Cottam 1935; Wood 1924). No s t u d i e s have been made o f c o m p a r a t i v e f o o d h a b i t s of s y m p a t r i c mynas and s t a r l i n g s , however, t h e d a t a o f S c h e f f e r 76 and Cottam are b e s t s u i t e d f o r such a comp a r i s o n . They found t h a t mynas consumed more v e g e t a b l e (61.11%) than a n i m a l m a t t e r (38.89%); s t a r l i n g s c o l l e c t e d d u r i n g the same p e r i o d b u t a t d i f f e r e n t l o c a t i o n s consumed more a n i m a l (62.29%) than v e g e t a b l e m a t t e r (37.71%). S p e c i e s d i f f e r e n c e s i n f o o d s e l e c t i o n have been demon-s t r a t e d i n the p r e s e n t s t u d y where mynas and s t a r l i n g s f e d ov e r t h e same r e g i o n . I n g e n e r a l mynas i n c l u d e d a h i g h e r p e r c e n t a g e o f low energy and low p r o t e i n c o n t e n t v e g e t a b l e foods i n the n e s t l i n g d i e t . E a r l y i n the n e s t i n g s e a s o n , b o t h a d u l t s t a r l i n g s and mynas i n c l u d e d a n i m a l m a t t e r as the major p o r t i o n o f f o o d d e l i v e r e d t o young. A n a l y s i s of t h e s e f o o d i t e m s d e l i v e r e d p r i o r t o 1 J u l y r e v e a l e d t h a t n e s t l i n g s t a r l i n g s were f e d 69% a n i m a l m a t t e r , 19% v e g e t a b l e m a t t e r , w i t h the r e m a i n i n g 2% composed o f u n d i -g e s t i b l e s y n t h e t i c s and m i n e r a l . Mynas f e d t h e i r n e s t l i n g s 66% a n i m a l and 24% v e g e t a b l e m a t t e r d u r i n g the same p e r i o d . A f t e r 1 J u l y , s t a r l i n g s f e d t h e i r young 61.5% a n i m a l m a t t e r and 3 8.5% v e g e t a b l e m a t t e r . However, v e g e t a b l e and a n i m a l m a t e r i a l r e p r e s e n t e d 67.2% and 22.8% r e s p e c t i v e l y , o f t h e myna d i e t d u r i n g the same p e r i o d . Both a d u l t and l a r v a e Hymenoptera and L e p i d o p t e r a , l a r v a e T i p u l i d a e and a d u l t o l i g o c h a e t s were t h e major a n i m a l f o o d f e d n e s t l i n g s t h r o u g h o u t the b r e e d i n g season by b o t h s p e c i e s . F r u i t s , m o s t l y c u l t i v a t e d and w i l d 76A Prunus spp., Rubus spp., c u l t i v a t e d Malus spp., and Vaccinium oxycoccos were the primary components of the vegetable diets of both myna and s t a r l i n g n e s t l i n g s , with heaviest use of these species occurring l a t e r i n the nesting season. Development and Plumage of Endothermy The development of s t a r l i n g plumage follows the des-c r i p t i o n given by Kessel (1957) for s t a r l i n g s i n New York. The rate of growth of the longest primary was used as a general index of plumage development. That rate i s s i m i l a r i n both s t a r l i n g s and crested mynas, however, f i r s t appear-ance of primaries i s on day 5 for s t a r l i n g s and days 6-7 for mynas. Primaries began to develop i n common mynas (Sengupta 1968) on day 7 - 8 , which i s l a t e r than that obser-ved for crested mynas i n Vancouver (Figure 6). The rate of growth of primaries i n the common myna i n West Bengal i s greater than that of birds I studied. Thus, at 10 days post hatching the common myna had a primary length of 4 cm compared to 2 cm for Vancouver crested mynas on the same day. This difference may r e f l e c t species differences or factors associated with the environment. Contour feather development i s very s i m i l a r i n common and crested mynas with both species almost f u l l y fledged by days 22-24, afte r which both species are fed and protected by both parents. This period lasted for nearly one 77 and a h a l f months ^ f o r b o t h t h e common myna (Sengupta 1969) i n West B e n g a l and the c r e s t e d myna i n Vancouver. E n d o t h e r m i c c o n t r i b u t i o n t o the o v e r a l l h e a t b a l a n c e of n e s t l i n g a l t r i c i a l b i r d s i s s m a l l , w i t h most h e a t p r o v i d e d by b r o o d i n g p a r e n t s ( B a l d w i n and Kendeigh 1932). F i g u r e 8 d e m o n s t r a t es the g r a d u a l i n c r e a s e i n t h i s endo-t h e r m i c c o n t r i b u t i o n d u r i n g growth o f b o t h s p e c i e s o f n e s t l i n g s . Complete homeothermy by Vancouver s t u r n i d s was n o t a c h i e v e d u n t i l a s y m p t o t i c w e i g h t was n e a r l y a t t a i n e d . Oxygen consumption of n e s t l i n g s i n d i f f e r e n t w e i g h t c l a s s e s has shown the p a t t e r n o f development of homeothermy t h r o u g h -o u t the growth p e r i o d . An i n c r e a s e d oxygen consumption r e p r e s e n t s an a t t e m p t by the n e s t l i n g t o i n c r e a s e h e a t p r o d u c t i o n , w h i l e t h e development o f plumage e n a b l e s t h i s h e a t t o be c a p t u r e d f o r i n s u l a t i o n and subsequent m a i n t -enance of a c o n s t a n t body t e m p e r a t u r e . As can be seen from F i g u r e s 8 and 9,. an i n c r e a s e i n endothermy d i d n o t o c c u r or even become p a r t i a l l y e f f e c t i v e u n t i l a f t e r days 10-12 f o r s t a r l i n g n e s t l i n g s and days 12-14 f o r c r e s t e d myna n e s t l i n g s . There i s c o n s i d e r a b l e d i v e r s i t y i n the r a t e a t w h i c h endothermy i s a c h i e v e d by n e s t l i n g s of a l t r i c i a l b i r d s . Dawson and Evans (1957) found the development o f endothermy i n s e v e r a l s p e c i e s o f p a s s e r i n e s f o l l o w e d a p a t t e r n s i m i l a r t o t h a t h e r e d e s c r i b e d . B r i e t e n b a c h and 78 B a s k e t t (1967) showed a s i m i l a r development o f endothermy f o r t h e mourning dove ( Z e n a i d u r a m a c r o u r a ) , and Maher (1964) found a r c t i c b r e e d i n g f r i n g i l l i d n e s t l i n g s t o be e s s e n t i a l l y e c t o t h e r m i c from 0-4 days o f age. B r e n n e r , however, (196 4) r e p o r t e d endothermy i n red-winged b l a c k b i r d s ( A g e l a i u s  p h o e n i c e u s ) a t 1-3 days o f age. N e s t l i n g myna m e t a b o l i s m was l o w e r than t h a t o f s t a r -l i n g s a t most t e m p e r a t u r e s (3-7 n e s t l i n g s t e s t e d a t each t ), b u t o n l y s t a t i s t i c a l l y d i f f e r e n t (a = 0.10) i n t h e 3. 4 0-5 0 gms w e i g h t c l a s s . Myna body growth and plumage d e v e l -opment was s l o w e r t h a n t h a t o b s e r v e d f o r s t a r l i n g s , and mynas l e f t t h e n e s t a t an e a r l i e r s t a g e o f development t h a n s t a r l i n g s , t h e r e f o r e , d i f f e r e n c e s i n n e s t l i n g m e t a b o l i c r a t e s a r e n o t s u r p r i s i n g . F u r t h e r , i f n e s t l i n g m e t a b o l i c r a t e s f o r s t a r l i n g s and mynas i n the 4 0-5 0 gms w e i g h t c l a s s a re compared on the b a s i s o f p e r c e n t t o t a l plumage development, no d i f f e r e n c e i s d e t e c t e d . S i m i l a r l y , i t i s e v i d e n t t h a t t h e development o f endothermy i s n o t d i f f e r e n t f o r d e v e l o p i n g s t a r l i n g s and mynas (See F i g u r e 8 ) . N e s t and Egg M a n i p u l a t i o n E x p e r i m e n t s Egg s w i t c h i n g e x p e r i m e n t s emphasized t h e e f f e c t s o f low n e s t a t t e n t i v e n e s s and consequent low mean egg l e v e l t e m p e r a t u r e e x h i b i t e d by mynas (See F i g u r e 1 1 ) . These 79 e x p e r i m e n t s o f f e r answers t o a v a r i e t y of q u e s t i o n s i n v o l v i n g egg l a y i n g s p e c i e s i n which a s p e c t s o f p a r e n t a l b e h a v i o u r a r e c r i t i c a l i n t h e s u r v i v a l o f b o t h t h e young and t h e s p e c i e s . Thus, i n c u b a t i o n b e h a v i o u r was s u s p e c t e d t o be the weak p o i n t i n t h e myna b r e e d i n g c y c l e . I n a t r o p i c a l e n v ironment where t e m p e r a t u r e s d u r i n g the n e s t i n g season are h i g h e r t h a n i n Vancouver ( F i g u r e 3 ) , a s t r i c t i n c u b a t i o n s c h e d u l e would n o t be c r i t i c a l . T h i s i s s u p p o r t e d by Sengupta (1968) who r e p o r t e d a 97.77% h a t c h i n g s u c c e s s by t h e common myna i n West B e n g a l , even though n e s t a t t e n t i v e n e s s was low. Egg s w i t c h i n g e x p e r i m e n t s i n d i c a t e d t h a t t h e d i f f e r -e n t i a l h a t c h i n g s u c c e s s was due t o an a s p e c t o f i n c u b a t i o n b e h a v i o u r . When h e a t e r s were i n s t a l l e d t o m a i n t a i n egg l e v e l t e m p e r a t u r e above 2 8°C, h a t c h i n g s u c c e s s was t h e same f o r b o t h s p e c i e s . The r e s u l t s from t h e s e e x p e r i m e n t s s u b s t a n t i a t e the f i n d i n g s o f n e s t t e m p e r a t u r e r e c o r d i n g s which i n d i c a t e d t h a t egg l e v e l t e m p e r a t u r e m i g h t be the c r i t i c a l a s p e c t a f f e c t i n g low h a t c h i n g s u c c e s s i n Vancouver mynas. I n c u b a t i o n rhythm was n o t m o n i t o r e d m e c h a n i c a l l y , b u t checks were made on h e a t e d n e s t b o x e s p e r i o d i c a l l y ; no e v i d e n c e was found t h a t mynas were more n e s t a t t e n t i v e i n h e a t e d t h a n i n unheated n e s t b o x e s . Von Hartmann (1956) 80 suggested that such changes in incubation behaviour appear when nest temperature is changed. He showed that when nest temperatures were raised experimentally, incubating adult pied flycatchers (Ficedula hypoleuca) shortened si t t i n g periods. However, an adaptation of this sort or the inverse of i t has not been demonstrated in tropical hole nesters. Growth rates of nestlings hatched by foster parents were measured and found to be the same as for nestlings reared by their own parents. Even though egg colours differed between the two species, nest cavities were dark, egg sizes were similar and both species readily accepted each others eggs. Vocalizations of the nestling mynas are similar to those of starlings at hatching; later myna food calls became harsh and much louder than those of nestling starlings. Because of this, i t was i n i t i a l l y expected that foster parents would abandon the nestlings, however, this only occurred in one instance when a pair of starlings abandoned half-grown mynas before fledging. A l l cross-fostered nestlings were colour marked to make observations of post fledging behaviour easier. However, no cross-fostered nestlings were seen after fledging. 81 I t i s i n t e r e s t i n g t o s p e c u l a t e on t h e consequences o f i n n a t e v e r s u s l e a r n e d b e h a v i o u r i n c r o s s - f o s t e r e d n e s t l i n g s . E x p e r i m e n t s o f t h i s k i n d c o u l d i n c r e a s e knowledge c o n c e r n i n g t h e o r i g i n o f c e r t a i n a v i a n behav-i o u r a l t r a i t s ; e s p e c i a l l y i m p o r t a n t and r e v e a l i n g would be c r o s s - f o s t e r i n g e x p e r i m e n t s d e s i g n e d t o t e s t t h e o r i g i n o f r e p r o d u c t i v e i s o l a t i n g mechanisms. The Energy C y c l e i n the A v i a r y Gross energy i n t a k e d e c r e a s e d g r a d u a l l y t h r o u g h o u t t h e e n t i r e 1 y e a r e x p e r i m e n t a l p e r i o d . Both s t a r l i n g and myna e x c r e t o r y energy was more e r r a t i c t h a n G.E. f o r t h e second h a l f y e a r o f 1969, t h e r e b y y i e l d i n g e r r a t i c v a l u e s f o r m e t a b o l i z a b l e energy (M.E.). C r e s t e d mynas i n g e s t e d s i g n i f i c a n t l y more energy than s t a r l i n g s d u r i n g t h e y e a r l o n g e x p e r i m e n t a l p e r i o d . A l s o , myna M.E. was s i g n i f i c a n t l y h i g h e r t h a n t h a t f o r s t a r l i n g s f o r t h e same p e r i o d . However, 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 i n e x c r e t o r y energy o u t p u t between the two s p e c i e s , as e v i d e n c e d by t h e F v a l u e f o r s p e c i e s i n Appendix T a b l e 2. S i n c e t e m p e r a t u r e s were c o l d i n t h e e a r l y h a l f o f 1969, r e g r e s s i o n a n a l y s e s were conducted f o r t h e o n e - h a l f y e a r p e r i o d s as w e l l as f o r t h e t o t a l y e a r p e r i o d t o i s o l a t e t h e e f f e c t o f te m p e r a t u r e on t h e energy c y c l e o f t h e s e two 82 s t u r n i d s . Only the mean monthly s t a r l i n g M.E. f o r the f i r s t h a l f o f 1969 was s i g n i f i c a n t l y c o r r e l a t e d ( n e g a t i v e l y ) w i t h mean monthly cage a r e a ambient t e m p e r a t u r e (a = 0.10). S i m i l a r l y , o n l y myna M.E. f o r the f i r s t h a l f y e a r was s i g n i f i c a n t l y c o r r e l a t e d w i t h ambient t e m p e r a t u r e . A l l myna energy a g a i n s t t e m p e r a t u r e c o r r e l a t i o n s were weaker than t h o s e f o r s t a r l i n g s . Second h a l f y e a r energy v a l u e s f o r b o t h mynas and s t a r l i n g s were weakl y and p o s i t i v e l y c o r r e l a t e d w i t h cage a r e a ambient t e m p e r a t u r e . Only G.E. showed a s t r o n g s t a t i s t i c a l c o r r e l a t i o n w i t h ambient t e m p e r a t u r e . No s i g n i f i c a n t c o r r e l a t i o n e x i s t e d between s t a r l i n g G.E., E.E. and M.E. v a l u e s and y e a r l o n g mean cage a r e a ambient t e m p e r a t u r e . There i s i n most cases a s t r o n g e r c o r r e l a t i o n between t e m p e r a t u r e and M.E. u t i l i z a t i o n f o r the f i r s t h a l f of 1969 t h a n f o r e i t h e r t h e t o t a l o r t h e l a s t h a l f o f 1969. T h i s s u g g e s t s t h a t i n a normal y e a r , warmer w i n t e r ambient t e m p e r a t u r e w o u l d p l a y a minor r o l e i n r e g u l a t i n g energy e x p e n d i t u r e o f t h e s e b i r d s . Even though t h e w i n t e r o f 1968-69 was one o f t h e c o l d e s t r e c o r d e d f o r t h e Vancouver a r e a , no d r a m a t i c t e m p e r a t u r e - i n d u c e d f l u c t u a t i o n s i n energy m e t a b o l i s m o c c u r r e d . A l s o , d a t a p r e s e n t e d i n Appendix T a b l e 1 s u g g e s t s t h a t s t a r l i n g s and mynas were 83 s i m i l a r l y i n f l u e n c e d by ambient t e m p e r a t u r e . The v a r i a -b i l i t y i n E.E. r e s u l t e d i n a s i m i l a r v a r i a b i l i t y i n M.E. f o r b o t h s p e c i e s , e x c e p t f o r the f i r s t 6 months o f 1969 when t e m p e r a t u r e g r a d i e n t s ( t ^ - t ) were extreme enough t o w e a k l y i n f l u e n c e energy m e t a b o l i s m . S t a r l i n g s had no a p p a r e n t advantage o v e r mynas; G.E. and E.E. were about e q u a l l y (weakly) c o r r e l a t e d w i t h t e m p e r a t u r e . The f a c t t h a t t h e t o t a l y e a r M.E. was nega-t i v e l y c o r r e l a t e d w i t h t e m p e r a t u r e i n d i c a t e s t h a t a g e n e r a l t r e n d ( a l t h o u g h s t a t i s t i c a l l y i n s i g n i f i c a n t ) o f i n c r e a s e d energy m e t a b o l i s m d u r i n g c o l d e r weather was e v i d e n t . A l s o , b o t h G.E. and E.E. were n e g a t i v e l y c o r r e l a t e d w i t h temper-a t u r e , w h i c h i n d i c a t e s t h a t a t l e a s t i n p a r t , the b i r d s compensated f o r c o l d by i n c r e a s i n g the volume o f energy p r o c e s s e d r a t h e r than i n c r e a s i n g the e f f i c i e n c y o f u t i l i z a t i o n . No s i g n i f i c a n t c o r r e l a t i o n was d e t e c t e d between e i t h e r t e m p e r a t u r e and c a l o r i c v a l u e o f e x c r e t a o r t e m p e r a t u r e and d i g e s t i v e e f f i c i e n c y . T h i s agrees w i t h the f i n d i n g s of Kendeigh (1949), D a v i s (1955), West (I960) and Zimmerman (1965). However, i t d i s a g r e e s w i t h r e s u l t s p r e s e n t e d by Owen (1970) f o r b l u e - w i n g e d t e a l (Anas d i s c o r s ) , W i l l i a m s (1965) f o r Canada geese ( B r a n t a c a n a d e n s i s ) and Brooks (1968) f o r r e d p o l l s ( A c a n t h i s s p p . ) . 84 No s i g n i f i c a n t c o r r e l a t i o n c o u l d be found between m o l t i n d e x o r energy c o n t e n t o f the e x c r e t a and d i g e s t i v e e f f i c i e n c y . However, a h i g h e r M.E. was o b s e r v e d d u r i n g the m o l t and a subsequent lower v a l u e o b s e r v e d a f t e r t e r m i n a t i o n o f the m o l t , s u g g e s t i n g t h a t t h e e x p e r i m e n t a l b i r d s d i d i n c r e a s e t h e i r M.E. d u r i n g t h i s p e r i o d . T h i s i s s u r p r i s i n g s i n c e t h e i r d i e t c o n t a i n e d 20% p r o t e i n , w h i c h i s more t h a n s u f f i c i e n t t o accommodate m o l t i n c a p t i v e b i r d s ( M a r t i n 1968). A l s o i t i s s u r p r i s i n g t h a t , i n f a c t , t h e l o w e s t w e i g h t s r e c o r d e d were d u r i n g t h e m o l t p e r i o d . The low mean s t a r l i n g w e i g h t o f 80.0 gms d u r i n g e a r l y August ( a l t h o u g h n o t s i g n i f i c a n t l y l o w e r t h a n any o t h e r p e r i o d ) f a l l s d u r i n g the peak o f f e a t h e r r e p l a c e m e n t ( F i g u r e 1 3 ) . The h i g h mean s t a r l i n g w e i g h t of 96.6 gms o c c u r r e d i n l a t e O c t o b e r , a f t e r c o m p l e t i o n o f the m o l t . C r e s t e d mynas s i m i l a r l y r e a c h e d t h e i r l i g h t e s t w e i g h t s i n mid-September (mean=101.3 gms; n=18) d u r i n g the peak o f f e a t h e r r e p l a c e m e n t . The h i g h e s t mean w e i g h t ( s i g n i f i c a n t l y h i g h e r t h a n t h e low w e i g h t r e c o r d e d i n September) was r e c o r d e d f o r e a r l y May (111.4 gms), however, a f t e r the m o l t i n l a t e f a l l , myna w e i g h t s a l s o i n c r e a s e d (See F i g u r e 1 3 ) . D u r i n g June, when the mean cage a r e a ambient temper-a t u r e was 20°C, s t a r l i n g and myna m e t a b o l i s m i n the 85 a v i a r y was about e q u a l : 21.95 cal/gm-hr and 20.99 c a l / gm-hr, r e s p e c t i v e l y . A t t h e same te m p e r a t u r e i n the e n v i r o n m e n t a l c a b i n e t , p o s t a b s o r p t i v e and r e s t i n g s t a r -l i n g s and mynas m e t a b o l i z e d 12.6 and 9.5 cal/gm-hr, r e s p e c t i v e l y , a t n i g h t . Assuming t h e l a t t e r v a l u e s are minimum r a t e s a t t h e s e t e m p e r a t u r e s , a r e m a i n d e r o f 9.13 and 11.27 cal/gm-hr e x i s t s f o r s t a r l i n g s and mynas, r e s p e c t i v e l y , t o c a r r y out a c t i v i t i e s i n t h e i r c ages. I n A p r i l , the mean cage a r e a ambient t e m p e r a t u r e was 10°C and s t a r l i n g s and mynas m e t a b o l i z e d 28.44 and 22.13 cal/gm-hr i n t h e i r c ages. D u r i n g r e s p i r o m e t r i c t r i a l s a t 10°C, s t a r l i n g s m e t a b o l i z e d 15.02 cal/gm-hr compared t o a v a l u e o f 12.97 cal/gm-hr f o r c r e s t e d mynas, l e a v i n g 13.42 and 10.6 4 cal/gm-hr o f energy a v a i l a b l e f o r d a i l y a c t i v i t i e s f o r the r e s p e c t i v e s p e c i e s . D u r i n g J a n u a r y , the mean cage a r e a ambient t e m p e r a t u r e of -2°C was c l o s e enough t o 0°C t o make f u r t h e r s i m i l a r c omparisons p o s s i b l e . The v a l u e s a t -2°C f o r energy meta-b o l i z e d o u t s i d e were v e r y s i m i l a r f o r b o t h s p e c i e s w i t h s t a r l i n g s m e t a b o l i z i n g 31.26 cal/gm-hr and mynas m e t a b o l i z i 31.12 cal/gm-hr. D u r i n g r e s p i r o m e t r i c t r i a l s s t a r l i n g s m e t a b o l i z e d 20.26 cal/gm-hr compared t o 13.59 cal/gm-hr f o r c r e s t e d mynas, l e a v i n g a r e m a i n d e r o f 11.00 and 17.53 cal/gm-hr, r e s p e c t i v e l y , f o r a c t i v i t y i n the cages. 86 Thus, t h e remainder ( a c t i v i t y energy) i s about e q u a l f o r s t a r l i n g s and mynas a t 20 and 10°C, however a t -2°C, r e q u i r e m e n t s f o r mynas are about 50% g r e a t e r than t h o s e f o r s t a r l i n g s . These c a l c u l a t i o n s would i n d i c a t e t h a t c r e s t e d mynas are e i t h e r more a c t i v e t h a n s t a r l i n g s i n the cages d u r i n g c o l d t e m p e r a t u r e s o r t h e y have t r o u b l e m a i n t a i n i n g energy b a l a n c e a t t h e c o l d e r t e m p e r a t u r e s . A l t h o u g h r e c o r d e r s were n o t used t o m o n i t o r a c t i v i t y , b i r d s were watched a l m o s t d a i l y and I f e l t t h a t mynas were n o t more a c t i v e t h a n s t a r l i n g s i n t h e cage a r e a d u r i n g t h i s s t u d y . S t a r l i n g s were more r e s t l e s s than mynas and s p e n t more time p r e e n i n g and f l u t t e r i n g i n e a r l y morning h o u r s . When w i l d mynas came i n t o o r r e s t e d near t h e cage a r e a , and e s p e c i a l l y when they v o c a l i z e d , caged mynas became e x c i t e d and f l u t t e r e d from p e r c h t o p e r c h . A l s o , on s e v e r a l o c c a s i o n s , norway r a t s ( R a t t u s n o r v e g i c u s ) h a r a s s e d caged b i r d s and on one o c c a s i o n r a t s k i l l e d and a t e 2 s t a r l i n g s t h r o u g h the cage w i r e s . The l a t e F e b r u a r y E.E. c o l l e c t i o n c o i n c i d e d w i t h t h i s p e r i o d o f r a t harassment, and a reduced amount of e x c r e t a was o b s e r v e d as a r e s u l t . A l s o , d u r i n g A p r i l an a d u l t female Cooper's Hawk ( A c c i p i t e r  c o o p e r i i ) made v i s i t s t o the cage a r e a f o r s e v e r a l days (See Appendix F i g u r e 1; A p r i l ' G . E . ) b e f o r e she was c a p t u r e d 87 and r e l e a s e d e l s e w h e r e . Under such c o n d i t i o n s o f s t r e s s , b i r d s became v e r y e x c i t e d and a t e l i t t l e f o o d . However, b o t h s p e c i e s were s u b j e c t e d t o t h e same c o n d i t i o n s and i t i s f e l t t h a t mynas d i d n o t show a g r e a t e r r e a c t i o n d u r i n g t h e s e p e r i o d s o f s t r e s s . Kendeigh (1970) p r e s e n t s a f o r m u l a d e s c r i b i n g e x i s t e n c e energy (M.E. when w e i g h t b a l a n c e i s m a i n t a i n e d ) r e q u i r e m e n t s f o r 15 p a s s e r i n e s p e c i e s a t 30°C (M = 1.5720 W 0* 6 2 1; where M = e x i s t e n c e energy, and W = we i g h t i n gms), f o r 9 n o n - p a s s e r i n e s p e c i e s a t 30°C (M = 0.5404 W 0 , 7 5 4 5 ) , and f o r b o t h groups a t 0°C (M =4.3372 W^*^ 3^). A l t h o u g h s t u r n i d s a r e p a s s e r i n e b i r d s , no mean monthly v a l u e near 30°C was r e c o r d e d i n t h i s s t u d y , t h e r e f o r e comparisons were made between my d a t a f o r s t u r n i d s c o l l e c t e d o u t s i d e a t -2°C ( J a n u a r y , 1969) and Kendeigh's p r e d i c t e d v a l u e s c a l c u l a t e d from M = 4.3372 w 0 , 5 3 0 0 f o r a l l s p e c i e s a t 0°C. The p r e d i c t e d v a l u e s f o r s t a r l i n g s and mynas r e s p e c t i v e l y a r e 45.09 and 50.60 k c a l / b i r d - d a y . Kendeigh i n c l u d e s s t a n d a r d m e t a b o l i s m , s p e c i f i c dynamic a c t i o n and l o c o m o t o r a c t i v i t y w i t h i n the cages as p a r t o f h i s e x i s t e n c e energy. K e n d e i g h s t a t e d t h a t cages used f o r h o u s i n g b i r d s " v a r i e d i n s i z e t o p e r m i t a p p r o x i m a t e l y the same amount o f f r e e movement; e.g. h o p p i n g b u t not f l i g h t ( M a r t i n 19 6 7 ) " . Cages used i n my st u d y were l a r g e enough t o p e r m i t f l i g h t f o r s e v e r a l 88 f e e t and b i r d s d i d so r e a d i l y . The d i s c r e p a n c y between v a l u e s o b t a i n e d i n my s t u d y (59.4 and 76.0 k c a l / b i r d - d a y , r e s p e c t i v e l y , f o r s t a r l i n g s and mynas) and thos e p r e d i c t e d by Kendeigh's e q u a t i o n c o u l d be a t t r i b u t e d t o i n c r e a s e d a c t i v i t y by my b i r d s . More e x p e r i m e n t s need t o be u n d e r t a k e n w i t h f e e d i n g c o n ducted a t c o n s t a n t t e m p e r a t u r e s i n c o n t r o l l e d e n v i r o n -ment c a b i n e t s . A l t h o u g h the v a l u e s p r e s e n t e d g i v e i n d i c a -t i o n s o f g e n e r a l t r e n d s , many v a r i a b l e s c o u l d be e l i m i n a t e d o r measured by c o n d u c t i n g more c l o s e l y c o n t r o l l e d e x p e r i m e n t s . M e t a b o l i s m Under L a b o r a t o r y C o n d i t i o n s M e t a b o l i c c u r v e s ( F i g u r e 6) i n d i c a t e t h a t c r e s t e d myna me t a b o l i s m was lo w e r than t h a t of s t a r l i n g s e x c e p t a t the extreme ends o f the e x p e r i m e n t a l t e m p e r a t u r e spectrum. Mynas had d i f f i c u l t y k e e p i n g warm a t -20°C and k e e p i n g c o o l a t +40°C. The upper t e m p e r a t u r e t o l e r a n c e l e v e l (LD^Q) f o r a t h r e e hour p e r i o d was 40°C f o r c r e s t e d mynas (n=8 b i r d s ) , w h i c h i s l o w e r t h a n r e p o r t e d (46-47°C) by Kendeigh (1969) f o r s e v e r a l o t h e r s p e c i e s o f p a s s e r i n e b i r d s . Myna l e t h a l t e m p e r a t u r e was a l s o l o w e r t h a n r e p o r t e d f o r b l u e -winged t e a l by Owen (1970), b u t s i m i l a r t o t h a t o f Canada geese (41°C) r e p o r t e d by W i l l i a m s . S t a r l i n g s s u r v i v e d t e m p e r a t u r e s s l i g h t l y above 40°C 8 9 f o r t h r e e hours showing no n o t i c e a b l e a d v e r s e e f f e c t s , however, above 30°C b o t h s p e c i e s panted v i g o r o u s l y . R e l a t i v e h u m i d i t y i n t h e r e s p i r a t i o n chamber was c l o s e t o 20% d u r i n g a l l t e s t s . B oth s p e c i e s e x h i b i t e d v i s i b l e s h i v e r i n g a t t e m p e r a t u r e s c o l d e r than 0°C, b u t mynas e l e v a t e d m e t a b o l i c r a t e s a t c o l d e r t e m p e r a t u r e s f a s t e r t h a n s t a r l i n g s . West (1962) s u g g e s t e d t h a t most h e a t p r o d u c t i o n i n b i r d s i s a r e s u l t o f m u s c u l a r a c t i v i t y . H i s e x p e r i m e n t s w i t h e v e n i n g g r o s b e a k s ( H e s p e r i p h o n a v e s p e r t i n a ) have shown t h a t i n b o t h summer and w i n t e r t h e s e b i r d s s h i v e r a l l n i g h t o u t - o f - d o o r s a t a l l t e m p e r a t u r e s below t h e r m a l -n e u t r a l i t y , and t h e i n t e n s i t y o f s h i v e r i n g i n c r e a s e s as the ambient t e m p e r a t u r e f a l l s (West 1962:299). A l t h o u g h s t a r l i n g s s h i v e r e d a t and below 0°C, t h e y m a i n t a i n e d and even overcompensated t o g i v e a n e t i n c r e a s e i n body temper-a t u r e (Table 3 ) , w h i c h c o n t r a s t e d w i t h the n e t t e m p e r a t u r e d e c r e a s e e x h i b i t e d by c r e s t e d mynas below 0°C (Table 1 ) . H a r t (1962) conducted m e t a b o l i c t e s t s (1 hour t r i a l s ) on s t a r l i n g s a t t e m p e r a t u r e s near -70°C w h i c h d i d n o t pr o v e f a t a l . However, h i s c o l d r e s i s t a n c e t e s t s a re n o t compar-a b l e t o mine because he used t i m e as t h e v a r i a b l e ( a t -48°C) r a t h e r t h a n t e m p e r a t u r e . 90 Only two o t h e r s o u r c e s o f m e t a b o l i c d a t a a r e a v a i l a b l e f o r s t u r n i d s . H a r t (1962) made e s t i m a t e s o f s t a r l i n g meta-b o l i s m between -65 and +38°C. A l l h i s measurements were made d u r i n g d a y l i g h t hours ( i n a da r k e n e d chamber). H i s v a l u e s a t 38°C and 30°C (1962:22) compare f a v o u r a b l y w i t h t h o s e i n t h i s s t u d y a t 40°C and 30°C, b u t v a l u e s a t 12, 0 and -15°C a r e h i g h e r t h a n t h o s e o b t a i n e d i n t h i s s t u d y a t s i m i l a r t e m p e r a t u r e s . I t s h o u l d be p o i n t e d o u t t h a t H a r t ' s oxygen consumption v a l u e s f o r e v e n i n g g r o s b e a k s a r e a l s o m a r k e d l y h i g h e r t h a n t h o s e found by Dawson and T o r d o f f (1959). B r e n n e r (1965) a l s o measured m e t a b o l i c r a t e s o f s i n g l e r o o s t i n g s t a r l i n g s a t 2-4°C and 24-30°C. H i s v a l u e s a g a i n a r e v e r y c l o s e t o mine a t h i s 24-30°C ra n g e , b u t d i f f e r e n t a t t h e 2-4°C range . A s c h o f f and P o h l (1970) have compared m e t a b o l i c d a t a o b t a i n e d i n darkened chambers d u r i n g day ( A c t i v i t y p e r i o d ) and n i g h t ( R e s t i n g p e r i o d ) and found a mean d i f f e r e n c e o f 23% w i t h day v a l u e s h i g h e r . Thus, even though r e s p i r a t i o n chambers a r e dark e n e d , b i r d s have a b u i l t - i n rhythm w h i c h i s n o t i n t e r r u p t e d m e r e l y by t u r n i n g o u t the l i g h t s . L e wies and Dyer (1969) i l l u s t r a t e t h i s pheaiomenon most c l e a r l y (pp. 293-294). I t i s a l s o i n t e r e s t i n g t o note t h a t a t warmer t e m p e r a t u r e s t h e d i f f e r e n c e s between day and n i g h t m e t a b o l i s m a r e l e s s t h a n a t c o l d e r t e m p e r a t u r e s . 91 F o r example (Lewies and Dyer 1969), the mean minimum day and n i g h t m e t a b o l i s m v a l u e s f o r male red-winged b l a c k b i r d s ( A g e l a i u s p h oeniceus ) were 3.61 cc C>2/gm-hr a t 42.5°C and 3.04 cc 02/gm-hr between 43 and 45°C, r e s p e c t i v e l y , w i t h day 16% h i g h e r t h a n n i g h t . The mean maximum v a l u e s f o r day and n i g h t were 7.9 8 and 5.38 c c 0 2/gm-hr a t 5 and 0°C, r e s p e c t i v e l y , w i t h day and n i g h t v a l u e s d i f f e r e n t by 23%. F o r female r e d -winged b l a c k b i r d s the d i f f e r e n c e was even more extreme. The mean minimum day and n i g h t m e t a b o l i c v a l u e s were 3.05 and 2.47 c c 02/gm-hr a t 45 and 42°C, r e s p e c t i v e l y , w hich i s a d i f f e r e n c e of 19%. The mean maximum day and n i g h t m e t a b o l i s m v a l u e s f o r female red-wings were 9.52 and 3.23 cc 02/gm-hr a t 0° and 2°C, r e s p e c t i v e l y , w h i c h i s a d i f f e r e n c e o f 65%. Thus i t seems the warmer the ambient t e m p e r a t u r e d u r i n g e x p e r i m e n t a t i o n , the s m a l l e r the d i f f e r e n c e i n v a l u e s o f m e t a b o l i c r a t e between day and n i g h t . T h i s i n p a r t , c o u l d ex-p l a i n t h e d i f f e r e n c e between my v a l u e s and t h o s e o f H a r t . How-e v e r , i t remains e v i d e n t t h a t m e t a b o l i c d a t a o b t a i n e d from t h i s s t u d y are h i g h e r t h a n p r e s e n t e d by H a r t (See T a b l e 4 ) , whose c o r r e c t e d b a s a l m e t a b o l i s m v a l u e s h o u l d be a p p r o x i m a t r l y 17% l o w e r t h a n p r e s e n t e d (based on t h e 16.6% d i f f e r e n c e s p r e s e n t e d by Lewies and Dyer 1969). The d a t a o f B r e n n e r (1965) show much the same d i s c r e p a n c y from my d a t a as t h a t o f H a r t . B r e n n e r ( p e r s o n a l communication) p e r f o r m e d m e t a b o l i s m t r i a l s i n l a t e a f t e r n o o n and e a r l y e v e n i n g , p o s s i b l y making h i s v a l u e s h i g h a l s o . 92 I n v i ew o f t h e s e d i f f e r e n c e s p r e s e n t e d by A s c h o f f and P o h l , and i l l u s t r a t e d by Lewies and Dyer, comparisons drawn between u n c o r r e c t e d day and n i g h t m e t a b o l i c d a t a a r e i n a p p r o p r i a t e . I t i s i m p e r a t i v e t h a t r e s e a r c h e r s g i v e d e t a i l e d i n f o r m a t i o n about time of day and t e c h n i q u e s used d u r i n g m e t a b o l i s m e x p e r i m e n t s . , i S t a r l i n g and myna s t a n d a r d m e t a b o l i s m compares f a v o u r -a b l y w i t h the f o r m u l a : M = 0.867 W 0 , 7 2 4; where M i s r e s t i n g m e t a b o l i s m i n K c a l / b i r d - d a y f o r p a s s e r i n e b i r d s and W i s w e i g h t i n gms (Kendeigh 1970). Weights o f 82.9 and 10 7.7 gms r e s p e c t i v e l y , f o r s t a r l i n g s and mynas p r i o r t o 20°C m e t a b o l i s m t r i a l s were used t o o b t a i n t h e s e c a l -c u l a t e d v a l u e s (See T a b l e 4 ) . B a s a l m e t a b o l i c r a t e s c a l c u l a t e d f r om t h e f o l l o w i n g e q u a t i o n : BMR (cal/gm-hr) = ( S p e c i f i c h e a t ) ( W e i g h t ) ( q 1 ) ( t ^ - L C T ) ( h r s / d a y ) ; ( W e i g h t ) ( h r s / d a y ) y i e l d s v a l u e s o f 12.8 and 10.4 cal/gm-hr r e s p e c t i v e l y , f o r s t a r l i n g s and mynas. These v a l u e s a re c l o s e t o 12.6 and 9.5 cal/gm-hr o b t a i n e d i n my r e s p i r a t i o n t r i a l s . The above e q u a t i o n , when r e a r r a n g e d c o u l d a l s o be used t o e s t i m a t e the c o o l i n g c o n s t a n t (q^) f o r a f e a t h e r e d b i r d c a r c a s s . C a l c u l a t e d ( K l e i b e r 1961) lo w e r c r i t i c a l t e m p e r a t u r e s (LCT) o f 14.07 and 15.34°C agree w i t h v a l u e s e s t i m a t e d f rom 93 T a b l e 4. Comparisons o f s t u r n i d r e s t i n g m e t a b o l i c r a t e s . Source R e s t i n g M e t a b o l i c R a t e 3 ( c a l / g m - h r ) S t u r n u s v u l g a r i s S t u r n u s c r i s t a t e l l u s T h i s s t u d y 12.6 § 20°C 9.5 @ 20°C H a r t (1962) 1 2 b @ 20°C Bren n e r (1965) 1 0 . 5 b @ 20-24°C Kendeigh (1970) 10.7° 9.8° M e t a b o l i c r a t e i n t h e t h e r m a l n e u t r a l zone d u r i n g t h e r e s t p e r i o d . C o r r e c t e d v a l u e s t o e l i m i n a t e e f f e c t s o f a c t i v i t y - r e s t i n g c y c l e ( A s c h o f f and P o h l 1970). C a l c u l a t e d s t a n d a r d m e t a b o l i s m from body w e i g h t s . 94 F i g u r e 16. E x t r a p o l a t i o n o f m e t a b o l i s m s l o p e s t h r o u g h LCTs was at t e m p t e d t o o b t a i n e s t i m a t e s o f body temper-a t u r e s f o r s t a r l i n g s and mynas. T h i s t e c h n i q u e was f a i r l y a c c u r a t e f o r s t a r l i n g s , b u t l e s s s a t i s f a c t o r y f o r t h e mynas ( F i g u r e 1 6 ) . Mynas d i d n o t i n c r e a s e t h e i r m e t a b o l i s m as r a p i d l y when t e m p e r a t u r e s became c o l d e r , w h i c h might r e f l e c t t h e s l i g h t d i f f e r e n c e s i n m e t a b o l i c s l o p e below t h e LCT. S i n c e m e t a b o l i c r e q u i r e m e n t s a r e g r e a t e r f o r a v i a r y mynas th a n a v i a r y s t a r l i n g s , t h i s w ould seem i n c o n s i s t e n t , h o w e v e r , s t a n d a r d m e t a b o l i s m a t n i g h t i s n o t a measure o f e x i s t e n c e m e t a b o l i s m d u r i n g the day. A l s o , myna body t e m p e r a t u r e d e c r e a s e d below normal a t c o l d t e m p e r a t u r e s d u r i n g m e t a b o l i s m t r i a l s (See T a b l e 1 ) . Myna m e t a b o l i s m i n c r e a s e d s h a r p l y a t t h e -20°C l e v e l s u g g e s t i n g t h a t t h e s e b i r d s p r o b a b l y c o u l d n o t w i t h s t a n d l o n g t e r m d r o p s i n body t e m p e r a t u r e . T h i s i s s u b s t a n t i a t e d by the f a c t t h a t two mynas were found f r o z e n t o d e a t h i n t h e i r cages i n l a t e December, 1968, when ambient t e m p e r a t u r e s were near -20°C. A l s o , mynas commonly h u d d l e near chimney h e a t e f f l u e n t w i t h house sparrows ( P a s s e r d o m e s t i c u s ) on c o l d w i n t e r days. These f a c t o r s would s u g g e s t t h a t mynas are n o t w e l l adapted f o r a c o l d c l i m a t e and t h a t t h e y have n o t e v o l v e d any s p e c i a l p h y s i o l o g i c a l a d a p t a t i o n s f o r c o l d . 95 Plumage Q u a l i t y and Thermal Conductance The q u a l i t y o f plumage as an i n s u l a t o r was i n v e s t i -g a t e d f o r b o t h s p e c i e s . Conductance v a l u e s and c o o l i n g c o n s t a n t s are p r e s e n t e d i n T a b l e 2. L a w i e s k i e t a l (1967) s t a t e d "because t h e r m a l conductance i n c l u d e s e v a p o r a t i o n , c o n d u c t i o n , c o n v e c t i o n and r a d i a t i o n h e a t l o s s , and t h e s e avenues are f a r from u n i f o r m over the s u r f a c e o f a n i m a l b o d i e s , we f e e l t h a t a t t e m p t s t o e x p r e s s t h e r m a l c o n d u c t -ance on t h e b a s i s of s u r f a c e a r e a ( g e n e r a l l y c a l c u l a t e d from body w e i g h t ) i n s m a l l homeotherms a r e o f t e n u n r e a l -i s t i c " . However, i f one i s e x p r e s s l y t r y i n g t o measure the v a l u e o f plumage as an i n s u l a t o r , and r e c o g n i z i n g t h a t plumage p l a y s a l a r g e p a r t i n r e g u l a t i n g h e a t l o s s e s by c o n d u c t i o n , c o n v e c t i o n and r a d i a t i o n , s u r f a c e a r e a would seem the a p p r o p r i a t e u n i t . Weight i s s i m i l a r l y a v a r i a b l e u n i t , depending upon the degree o f f a t n e s s of the specimen o r whether the c r o p o r g u t i s f u l l . Meeh's f o r m u l a was found t o be a c c u r a t e f o r e s t i m a t i n g s u r f a c e a r e a f rom b i r d w e i g h t s ( F i g u r e 1 7 ) , and v a l u e s o b t a i n e d by t h i s f o r m u l a were used i n my c a l c u l a t i o n s . Thermal conductance e q u a t i o n s have been p u b l i s h e d by H e r r i e d and K e s s e l (1967) and L a s i e w s k i e t a l (1967) f o r v a r i o u s p a s s e r i n e and n o n - p a s s e r i n e b i r d s . My v a l u e s 96 are not s i g n i f i c a n t l y d i f f e r e n t from p r e d i c t e d v a l u e s . H e r r i e d and K e s s e l c a l c u l a t e d thermal conductance s i m i l a r to the method described by Morrison and T i e t z (1957) , whereas L a s i e w s k i e t a l c a l c u l a t e d thermal conductance i n d i r e c t l y from metabolic r a t e s . T h e o r e t i c a l l y , these two techniques should produce s i m i l a r r e s u l t s . The exact surface from which body heat i s r e l e a s e d can be argued, however the s k i n should be the standard surface accepted. This would e l i m i n a t e the e f f e c t s of grad i e n t s between the s k i n and feathers which vary w i t h the posture and b a s i c s t r u c t u r e of the f e a t h e r s . The advantages of using l i v e b i r d s are obvious and giv e some support to the technique of La s i e w s k i e t a l (1967) , and Wallgren (1954), however, i f the feathers are to be removed i n an e f f o r t to evaluate plumage q u a l i t y , l i v e b i r d s cannot be used. Therefore i t i s u s e f u l to explore the technique using f r e s h b i r d carcasses. I f the s k i n s urface i s to be accepted as the standard s u r f a c e , the unfeathered weight should be employed i n a l l c a l c u l a t i o n s . Feathers do not c o n t r i b u t e s i g n i f i c a n t l y i n s p e c i f i c heat determinations of b i r d t i s s u e , t h e r e f o r e , t h e i r i n c l u s i o n i n such c a l c u l a t i o n s i s qu e s t i o n a b l e . The mean value (n=4) f o r myna plumage q u a l i t y i s -2 2 3.4 ± .40 x 10 cal/gm-hr-°C-cm compared to 6.2 + .50 97 x 10 cal/gm-hr-°C-cm (n=5) for s t a r l i n g plumage. These values suggest r e a l differences i n basic plumage q u a l i t y of s t a r l i n g s and crested mynas. I t i s i n t e r e s t i n g to note that both mynas and s t a r l i n g s have more feathers, by weight, than predicted by Kendeigh 1s (1970) equation: 0 95 = 0.068 W " ; where i s weight of the feathers i n gms, and W i s body weight of the b i r d i n gms. This equation i s based on Wetmore's (1936) data, which d i d not include values for sturnids. I t i s also i n t e r e s t i n g to note that mynas i n t h i s geographic region have more feathers as a percent of body weight (9.4%) than do s t a r l i n g s (7.0%). Mynas also have more feathers than s t a r l i n g s i f calculations are based on t o t a l surface area: 4.6 and 3.2%, respectively, for mynas and s t a r l i n g s . Thus, the i n s u l a t i v e q u a l i t y of myna plumage seems to be i n f e r i o r to that of s t a r l i n g s . These differences are s i g n i f i c a n t and since they cannot be explained on the basis of plumage weight, some more subtle factors may be involved. Measurements of plumage q u a l i t y using the techniques described above are i n f e r i o r i n that they do not measure the actual changes i n plumage posture which the b i r d i n i t i a t e s when exposed to d i f f e r e n t temperatures. Possibly the use of a helium environment during metabolism experiments could e s s e n t i a l l y produce a featherless b i r d . A technique 98 has been t r i e d and found s u c c e s s f u l by M o r r i s o n and Rose-mann ( p e r s o n a l communication) i n s m a l l mammal work i n whi c h t h e y r e p l a c e t h e normal ^ e n v i r o n m e n t ( a p p r o x i -m a t e l y 80% of room a i r ) w i t h He; the d i f f u s i c i t y o f the warmed gas i n t h e dead a i r spaces i n c r e a s e s d r a m a t i c a l l y , and the a n i m a l cannot t h e r m o r e g u l a t e . Thus, by e x p o s i n g the two s p e c i e s t o a common c o l d t e m p e r a t u r e i n an He env i r o n m e n t w h i c h e s s e n t i a l l y r e n d e r s them f e a t h e r l e s s , m e t a b o l i c r a t e s o b t a i n e d would be tho s e r e p r e s e n t i n g a l i v e f e a t h e r l e s s b i r d ; t h e s e r a t e s c o u l d be compared a g a i n s t s i m i l a r r a t e s o b t a i n e d i n t h e normal N 2 e n v i r o n -ment and b o t h o f t h e s e r a t e s c o u l d be compared between the two s p e c i e s . I t i s a p p a r e n t t h a t i n many o f the components o f t h e i r l i f e h i s t o r i e s , t h e two s p e c i e s p e r f o r m d i f f e r e n t l y . The s u b t r o p i c a l myna i s found t o be l e s s w e l l adapted t o the c l i m a t i c and p h e n o l o g i c a l c h a r a c t e r i s t i c s o f the a r e a of s o u t h w e s t e r n B r i t i s h C o l u m b i a i n w h i c h i t became i n t r o -duced t h a n i s the common s t a r l i n g w h i c h i n t r o d u c e d i t s e l f . The summary e f f e c t of a l l t h e d i f f e r e n c e s a l r e a d y exposed, p r o b a b l y supplemented by o t h e r s n o t y e t s t u d i e d , has l e d t o the g r e a t e r e f f e c t i v e n e s s of the s t a r l i n g i n i t s new env i r o n m e n t . A t t h e same time the myna i s s u c c e s s f u l i n t h a t i t has s u r v i v e d h e r e f o r some 80 y e a r s , t h e l a s t 12 of w h i c h have been i n c o m p e t i t i o n w i t h an e x p a n d i n g 99 s t a r l i n g p o p u l a t i o n . P o s s i b l y b e h a v i o u r a l f e a t u r e s r e l a t e d t o n i c h e s e l e c t i o n are r e s p o n s i b l e f o r s u r v i v a l o f t h e myna d e s p i t e i t s a p p a r e n t i n a b i l i t y t o a c h i e v e t h e r m a l a d a p t a t i o n o f the k i n d found i n t h e s t a r l i n g . 100 SUMMARY AND CONCLUSIONS 1. The n e s t i n g season f o r s t a r l i n g s was s y n c h r o n i z e d i n t o d e f i n i t e peaks of n e s t b u i l d i n g , egg l a y i n g , h a t c h i n g and f l e d g i n g , w h i c h was n o t t h e case f o r c r e s t e d mynas. 2. C l u t c h and brood s i z e s were h i g h e r i n s t a r l i n g s t h a n mynas. S t a r l i n g s s u c c e s s f u l l y r e a r e d more (38%) second broods t h a n mynas ( 9 % ) . 3. Egg t r a n s p l a n t and h e a t e r n e s t b o x e x p e r i m e n t s i n d i -c a t e d t h a t t h e poor n e s t a t t e n t i v e n e s s and low i n c u b a t i o n t e m p e r a t u r e s m a i n t a i n e d by c r e s t e d mynas, r e s u l t e d i n a low h a t c h i n g and consequent low f l e d g i n g s u c c e s s . 4 . S t a r l i n g r e s t i n g m e t a b o l i s m was h i g h e r t h a n t h a t o b s e r v e d f o r mynas. 5. D u r i n g m e t a b o l i s m e x p e r i m e n t s a t t e m p e r a t u r e s below 0°C, a d u l t mynas d i d n o t m a i n t a i n p o s i t i v e h e a t b a l a n c e . 6. A c t i v e mynas housed o u t s i d e a t c o l d t e m p e r a t u r e s have h i g h e r energy r e q u i r e m e n t s t h a n s t a r l i n g s under th e same c o n d i t i o n s . 7. C o o l i n g e x p e r i m e n t s i n d i c a t e d myna plumage was n o t as e f f e c t i v e an i n s u l a t o r a g a i n s t c o l d as s t a r l i n g plumage. 101 Ideas f o r m u l a t e d e a r l y i n t h i s r e s e a r c h were co n c e r n e d w i t h the r e a s o n s f o r the poor c o l o n i z i n g s u c c e s s by S t u r n u s  c r i s t a t e l l u s c r i s t a t e l l u s compared t o S t u r n u s v u l g a r i s  v u l g a r i s , b o t h i n t r o d u c e d t o N o r t h A m e r i c a i n t h e 1890's. I t was h y p o t h e s i z e d t h a t d i f f e r e n c e s i n t h e r m a l a d a p t a b i l i t y m i ght be i n f l u e n c i n g f a c t o r s . The most i m p o r t a n t f a c t o r s u p p o r t i n g my h y p o t h e s i s was t h e low h a t c h i n g s u c c e s s caused by poor n e s t a t t e n t -i v e n e s s and i n c u b a t i o n s u c c e s s by c r e s t e d mynas compared t o b o t h the s t a r l i n g l i v i n g i n the same e n v i r o n m e n t and the c l o s e l y r e l a t e d common myna l i v i n g i n West B e n g a l , I n d i a . A low h a t c h i n g s u c c e s s f o r c r e s t e d mynas i n Vancouver was f i r s t d e s c r i b e d by MacKay and Hughes (1963: 158-159). These r e s u l t s s u g g e s t t h a t mynas have n o t adapted an i n c u b a t i o n rhythm n e c e s s a r y f o r h i g h e r h a t c h i n g s u c c e s s i n the Vancouver e n v i r o n m e n t . T h i s i s a p p a r e n t when one compares th e n e s t i n g s u c c e s s of Vancouver c r e s t e d mynas w i t h t h a t o f t h e t r o p i c a l common myna and i t s s i m i l a r poor n e s t a t t e n t i v e n e s s b u t e x t r e m e l y h i g h h a t c h i n g s u c c e s s (98%) i n t h e t r o p i c s . R e s t i n g m e t a b o l i s m i n mynas does n o t d e v i a t e s i g n i -f i c a n t l y from t h e e x p e c t e d v a l u e s f o r b i r d s o f s i m i l a r w e i g h t , however, a d u l t and n e s t l i n g myna m e t a b o l i c r e s p o n s e 102 t o d e c r e a s i n g t e m p e r a t u r e i s s l o w e r t h a n t h a t o b s e r v e d f o r s t a r l i n g s . E x p e r i m e n t s i n d i c a t e d myna plumage was i n f e r i o r t o t h a t o f s t a r l i n g s , and a l t h o u g h mynas d i d s u f f e r d u r i n g c o l d p e r i o d s , some b i r d s seem t o have adap t e d s p e c i a l b e h a v i o u r a l t r a i t s t o compensate f o r c o l d . N e s t l i n g mynas were s u p p l i e d more low energy c o n t e n t v e g e t a b l e foods t h a n s t a r l i n g s and t h e r a t e o f f o o d con-sumption and G.E. i n t a k e was lo w e r than f o r n e s t l i n g s t a r l i n g s . S u b s e q u e n t l y n e s t l i n g myna growt h was s l o w e r than s t a r l i n g s o c c u p y i n g the same e n v i r o n m e n t . A l t h o u g h t h e above f a c t o r s do s u p p o r t the o r i g i n a l h y p o t h e s i s , some f a c t o r s have n ot been i n v e s t i g a t e d t h a t c o u l d be i m p o r t a n t . The e f f e c t s o f human d i s t u r b a n c e on c r e s t e d myna n e s t i n g a c t i v i t i e s have n ot been f u l l y s t u d i e d . P o s s i b l y s t a r l i n g s were s i m p l y more t o l e r a n t o f d i s t u r b -ances near t h e n e s t , and t h e r e f o r e were more n e s t a t t e n t i v e when d i s t u r b a n c e s ' ( i n c l u d i n g b i o l o g i c a l i n v e s t i g a t i o n s ) o c c u r r e d , d u r i n g t h e i n c u b a t i o n p e r i o d . An i n c r e a s e i n t h e myna p o p u l a t i o n t o a h i g h o f a p p r o x i m a t e l y 20,000 b i r d s i n the l a t e 1920s i n d i c a t e d a more s u c c e s s f u l p o p u l a t i o n i n c r e a s e t h a n o b s e r v e d i n t h i s s t u d y . However, t h i s i n i t i a l i n c r e a s e and subsequent d e c r e a s e i s t h e g e n e r a l t r e n d f o r s p e c i e s i n v a d i n g new 103 h a b i t a t ( E l t o n 1958), and a s i m i l a r p a t t e r n has been o b s e r v e d f o r s t a r l i n g s i n e a s t e r n N o r t h A m e r i c a . The o r i g i n a l i n c r e a s e i n myna numbers came a t a time when t h e a g r i c u l t u r a l d i s t r i c t s n ear V a n c o u v e r were b e i n g d e v e l o p e d . A s i m i l a r p a t t e r n of s t a r l i n g p o p u l a t i o n i n c r e a s e e x i s t s f o r Europe ( D e l v i n g t 1961) . T h i s s u g g e s t s t h a t t h e i n i t i a l i n c r e a s e i n stu u r n i d p o p u l a -t i o n b o t h i n N o r t h A m e r i c a and Europe m i g l i t have been r e l a t e d t o i n c r e a s e d f e e d i n g a r e a s ( a g r i c u l t u r a l d i s t r i c t s ) . Peak myna numbers were o b s e r v e d i n t h e m i d - l a t e 1920s and e a r l y 1930s, l o n g b e f o r e any myna-s t a r l i n g c o m p e t i t i o n was p o s s i b l e . S t a r l i n g s had h a r d l y s p r e a d from e a s t e r n N o r t h A m e r i c a by 1930 (See F i g u r e 1 ) . However, i t s t i l l remains e v i d e n t t h a t t h e p o p u l a t i o n has n o t e x h i b i t e d t h e d r a m a t i c s u c c e s s f u l c o l o n i z a t i o n t h a t has been e v i d e n c e d by s t a r l i n g s . F i e l d o b s e r v a t i o n s made c l e a r t h e f a c t t h a t mynas were a g g r e s s i v e d u r i n g t h e n e s t i n g p e r i o d ; e x p e r i e n c e d b r e e d e r s r e a d i l y e j e c t e d o t h e r s p e c i e s f r o m f o r m e r n e s t s i t e s , however l i t t l e i s known o f c o m p e t i t i v e r e l a t i o n -s h i p s o f y e a r l i n g mynas s e e k i n g n e s t s i t e s f o r the f i r s t t i m e . S i m i l a r l y , l i t t l e i s known o f p o s s i b l e c o m p e t i t i o n between B.C. s t u r n i d s and o t h e r p a s s e r i f o m m s p e c i e s . C o m p e t i t i o n c e r t a i n l y cannot be e l i m i n a t e d as a f a c t o r 104 r e g u l a t i n g growth o f the s t u r n i d p o p u l a t i o n i n t h e lo w e r m a i n l a n d , however, a comprehensive s t u d y of such com-p e t i t i o n i s n o t w i t h i n t h e scope of t h i s s t u d y . G e n e r a l i n t e r p r e t a t i o n o f r e s u l t s p e r t a i n i n g t o e n e r g e t i c s t h e o r y s h o u l d be g i v e n c o n s i d e r a t i o n h e r e as t h e y seem p a r a d o x i c a l i n many i n s t a n c e s . I n t r u e homeo-therms, h e a t p r o d u c t i o n s h o u l d e q u a l h e a t l o s s , o r the o p p o s i t e , t h e r e b y h a v i n g m i n i m a l a f f e c t on body t e m p e r a t u r e . D u r i n g c o l d s t r e s s , a n i m a l s l o s e h e a t a t a f a s t e r r a t e t h r o u g h c o n d u c t i o n , c o n v e c t i o n , r a d i a t i o n and e v a p o r a t i o n , and h e a t p r o d u c t i o n i s t h e r e f o r e i n c r e a s e d . I t i s i n t e r e s t i n g t o n o t e t h a t h e a t p r o d u c t i o n by mynas (cal/gm-hr) i s lo w e r t h a n t h a t of s t a r l i n g s a t the same c o l d t e m p e r a t u r e s . T h i s would s u g g e s t , i f we f o l l o w the above e q u a t i o n , t h a t mynas e i t h e r (1) l o s e l e s s h e a t t o t h e environment ( b e t t e r i n s u l a t i o n ) o r (2) t h e y a r e n o t t r u l y m a i n t a i n i n g a c o n s t a n t body t e m p e r a t u r e . O t h e r e x p e r i m e n t s s u g g e s t e d t h a t myna plumage was i n f e r i o r t o t h a t o f s t a r l i n g s f o r c o n s e r v i n g h e a t ; t h i s e l i m i n a t e s i n s u l a t i o n as a f a c t o r and T a b l e 1 shows t h a t mynas d i d no t m a i n t a i n homeothermy a t c o l d t e m p e r a t a i r e s . A t 40°C, the L D 5 Q f o r e x p e r i m e n t a l mynas had been r e a c h e d . I t seems p a r a d o x i c a l t h a t a b i r d of s u b t r o p i c a l o r i g i n t o l e r a t e s warm t e m p e r a t u r e s l e s s w e l l t h a n one 105 i n t r o d u c e d from a temperate environment. P o s s i b l y r e c e n t a d a p t a t i o n s t o t h e c o l d e n v ironment by mynas may have r e d u c e d t o l e r n a c e . a t the o t h e r end o f the t e m p e r a t u r e spectrum. Or p o s s i b l y , a t 20% r e l a t i v e h u m i d i t y , mynas c o u l d n o t t o l e r a t e the e v a p o r a t i v e w a t e r l o s s (not measured); b u t th e n u n l e s s s t a r l i n g s have e v o l v e d s p e c i a l p h y s i o l o g i c a l o r b e h a v i o u r a l a d a p t a t i o n s , why then s h o u l d they be b e t t e r a b l e t o t o l e r a t e h i g h h e a t and w a t e r l o s s ? I t would seem c l e a r t h a t a b i r d w h i c h e v o l v e d i n a t r o p i c a l e c osystem would have a h i g h e r LCT ( l o w e r c r i t i c a l t e m p e r a t u r e ) than one o r i g i n a t i n g from a temperate c l i m a t e . However, t h e myna LCT i s n o t d i f f e r e n t from t h a t o f s t a r l i n g s . Mynas and s t a r l i n g s have been i n N o r t h A m e r i c a o n l y about 80 y e a r s . The amount o f change, m o r p h o l o g i c a l l y , p h y s i o l o g i c a l l y , o r b e h a v i o u r a l l y ( a l l o f t h e s e under g e n e t i c c o n t r o l ) i s q u e s t -i o n a b l e . The m o r p h o l o g i c a l changes t h a t have o c c u r r e d i n house sparrows ( P a s s e r domesticus) s i n c e i n t r o d u c t i o n i n 1850, i n d i c a t e the t y p e o f r a p i d e v o l u t i o n t h a t can o c c u r i n b i r d s i n a r e -l a t i v e l y s h o r t time p e r i o d ( S e l a n d e r and J o h n s t o n , 1967; J o h n s t o n and S e l a n d e r , 1964 and 1971). The d a t a i n t h i s t h e s i s on myna c l u t c h s i z e i n d i c a t e t h a t an e v o l u t i o n a r y change may a l -ready have o c c u r r e d i n t h i s t r a i t i n t h e Vancouver a r e a . The d a t a a l s o i n d i c a t e s t h a t n e s t a t t e n t i v e n e s s i s under s e v e r e s e l e c t i v e p r e s s u r e and y e t t h e r e does n o t appear t o have been an e v o l u t i o n a r y r e s p o n s e . 106 I t seems o b v i o u s t h a t t h e t r o p i c a l myna i n c u b a t i o n rhythm has changed l i t t l e ; s i m i l a r l y , mynas e x h i b i t a slow growth r a t e , a l s o t y p i c a l o f many t r o p i c a l s p e c i e s . These two f a c t o r s , a l o n g w i t h the b e h a v i o u r a l a d a p t a t i o n s a s s o c i a t e d w i t h r e l a t i v e l y c o o l Vancouver w i n t e r s , i n d i c a t e t h a t N o r t h American c r e s t e d mynas have n o t e v o l v e d a com-p l e t e new l i f e s t y l e , b u t s t i l l r e t a i n many t r a i t s o f sub-t r o p i c a l o r i g i n . I t i s t r u l y u n f o r t u n a t e t h a t l i t t l e p h y s i o l o g i c a l r e s e a r c h has been done on any r e s i d e n t t r o p i c a l b i r d s . 107 LITERATURE CITED A l i , S. 1949. Indian h i l l b i r d s . Oxford Univ. Press, London. 188 pp. Amadon, D. 1943. The genera of s t a r l i n g s and t h e i r r e l a t i o n s h i p s . Amer. Mus. Novitates, No. 1247. Anderson, A. 1960. The breeding of the s t a r l i n g i n Aberdeenshire. The Scottish Nat. 70(l):60-74. Aschoff, J . and H. Pohl. 1970. Der ruheumsatz von vogeln als funktion der tagesqueit und der korper-grosse. J . fur Ornith. 1(111):38-47. Baldwin, S.P. and S.W. Kendeigh. 1932. Physiology of the temperature of b i r d s . S c i . Publ. Cleveland Mus. Nat. His t . 3:1-196. Barnes, I.R. 1951. The s t a r l i n g ' s conquest: I I . A t l a n t i c Nat. 6(4):151-158. Besser, J.F., J.W. De Grazio and J.L. Guarino. 1968. Costs of wintering s t a r l i n g s and red-winged blackbirds at feedlots. J . W i l d l . Mgmt. 32(9):179-180. Breitenbach, R.P., and T.S. Baskett. 1967. Ontogeny of thermoregulation i n the mourning dove. Physiol. Zool. 40(3):207-217. Brenner, F.J. 1964. Growth, f a t deposition and development of endothermy i n n e s t l i n g red-winged blackbirds. J. Scient. Labs Denison Univ. 46:81-89. 108 Brody, S. 1945. B i o e n e r g e t i c s and growth. R e i n h a r t Pub. Co., New York. 1032 pp. B r o o k s , W.S. 196 8. Comparative a d a p t a t i o n s o f a l a s k a n r e d p o l l s t o t h e a r c t i c e n v i r o n m e n t . W i l s o n B u l l . 80:253-280. Cooke, May T. 1928. The s p r e a d o f t h e European s t a r l i n g i n N o r t h A m e r i c a . U.S. Dept. o f Ag. C i r c . No. 40. Cowan, I . McT., and C.J. G u i g u e t . 1965. The mammals o f B r i t i s h C o l u m b i a . B.C. P r o v . Mus. Dept. o f Rec. and Conserv. Handbook No. 11. 414 pp. Cummings, R.A. 1925. O b s e r v a t i o n s on t h e Chinese s t a r l i n g ( E t h i o s p a r c r i s t a t e l l u s ) . Can. F i e l d N at. 39:187-190. . 1932. B i r d s o f t h e Vancouver d i s t r i c t , B r i t i s h C o lumbia. M u r r e l e t 1 3 ( 1 ) : 3 - 1 5 . D a v i s , E.A. 1955. S e a s o n a l changes i n t h e energy b a l a n c e o f t h e E n g l i s h sparrow. Auk 72:385-411. Dawson, W.R., and R.C. Evans. 1957. R e l a t i o n o f growth and development t o t e m p e r a t u r e r e g u l a t i o n i n n e s t l i n g f i e l d and c h i p p i n g s p a r r o w s . P h y s i o l . Z o o l . 30 (4):315-327. ., and H. T o r d o f f . 1959 . R e l a t i o n o f oxygen consumption t o t e m p e r a t u r e i n e v e n i n g g r o s b e a k s . Condor 61:388-396. D e l y i n g t , W. 1961. Sur 1 ' e v o l u t i o n des p o p u l a t i o n s europeennes de S t u r n u s v u l g a r i s d e p u i s un s i e c l e . 109 A n n a l e s de l a S o c i e t e R o y a l e de Z o o l o g i e de B e l g i q u e 91:29-38. . 1963. E c o l o g i e de l ' a c t i v i t e i n c u b a t r i c e d'un c o u p l e d'etourneaux, S t u r n u s v u l g a r i s . A r d e a 51:196-211. Dunnet, G.M. 1955. The b r e e d i n g o f the s t a r l i n g S t u r n u s  v u l g a r i s i n r e l a t i o n t o i t s f o o d s u p p l y . I b i s 97: 619-662. E l t o n , C S . 1958. E c o l o g y o f i n v a s i o n s by a n i m a l s and p l a n t s . J . W i l e y and Sons, New York. 181 pp. F o r b u s h , E.H. 1916. The s t a r l i n g . Mass. S t a t e B o a r d o f Ag. C i r c . 45. 23 pp. G a b r i e l s o n , I.N., and S.G. J e w e t t . 1940. B i r d s o f Oregon. Oregon S t a t e C o l l e g e P r e s s , C o r v a l l i s . 650 pp. H a r t , J.S. 1962. S e a s o n a l a c c l i m a t i z a t i o n i n f o u r s p e c i e s o f s m a l l w i l d b i r d s . P h y s i o l . Z o o l . 35:224-236. Hartmann, L. von. 1956. E i n f l u s s d e r t e m p e r a t u r auf den b r u t r h y t h m u s . O r n i s F e n n i c a . 33:100-107. H a v l i n , J . , and C. F o l k . 1961. The b r e e d i n g s eason and number o f young i n the s t a r l i n g S t u r n u s v u l g a r i s L., i n C z e c h o s l o v a k i a . Z o o l . L i s t y 1 0 ( l ) : 6 7 - 8 4 . . 1965. P o t r a v a a vyznam s p a c k a obecneho, S t u r n u s v u l g a r i s L. Z o o l . L i s t y 1 4 ( 3 ) : 193-208. 110 H e r r e i d , C.F., I I , and B r i n a K e s s e l . 1967. Thermal conductance i n b i r d s and mammals. Comp. Biochem. P h y s i o l . 21:405-414. J e w e t t , S.C., W.P. T a y l o r , W.T. Shaw and J.W. A l d r i c h . 1953. B i r d s o f Washington S t a t e . U n i v . o f Wash. P r e s s , S e a t t l e . 767 pp. Johnson, S.R. 1971. A c o l o u r e d l e g t a g f o r n e s t l i n g and a d u l t b i r d s . B i r d b a n d i n g . 4 2 ( 2 ) : 129-131. J o h n s t o n , R.F. and R.K. S e l a n d e r . 1964. House Sparrows: R a p i d e v o l u t i o n o f r a c e s i n N o r t h A m e r i c a . S c i e n c e 144: 548-550. J o h n s t o n , R.F. and R.K. S e l a n d e r . 1971. E v o l u t i o n i n the House Sparrows. I I . A d a p t i v e d i f f e r e n t i a t i o n i n N o r t h American p o p u l a t i o n s . E v o l u t i o n 25: 1-2 8. Kalmbach, E.R., and I.N. G a b r i e l s o n . 1921. Economic v a l u e o f the s t a r l i n g i n the U n i t e d S t a t e s . U.S. Dept. o f Ag. B u l l . , 868. 66 pp. K e l l y , W.N. 1927. The Japanese s t a r l i n g i n Vancouver, B.C. M u r r e l e t 8 ( 1 ) : 14. Kend e i g h , S.C. 1949. E f f e c t o f te m p e r a t u r e and season on t h e energy r e s o u r c e s o f the E n g l i s h sparrow. Auk 66:113-127. . 1969. Energy r e s p o n s e s o f b i r d s t o t h e r m a l e n v i r o n m e n t s . W i l s o n B u l l . 81: 441-449. . 1970. Energy r e q u i r e m e n t s f o r e x i s t e n c e i n r e l a t i o n t o s i z e o f b i r d . Condor 72: 60-65. Kermode, F. 1921. Notes on t h e C h i n e s e s t a r l i n g ( A c r i d o t h e r e s c r i s t a t e l l u s ) . B.C. P r o v . Mus. Nat. H i s t . Rept. 1920. R. 20-R. 21. (Review o f Rept., s i g n e d P.A.T. 1922, i n Canad. F i e l d Nat. 36 ( 3 ) : 54. I l l K e s s e l , B r i n a . 1951. C r i t e r i a f o r s e x i n g and a g i n g European s t a r l i n g s ( S t u r n u s v u l g a r i s ) . B i r d b a n d i n g 22:16-23. . 19 57. B r e e d i n g b i o l o g y o f the s t a r l i n g i n N o r t h A m e r i c a . Amer. M i d i . N a t. 58:257-331. K i n g , J.R., and D.S. F a r n e r . 1961. I n . B i o l o g y and c o m p a r a t i v e p h y s i o l o g y o f b i r d s . I I . Ed. A . J . M a r s h a l l . Academic P r e s s , New York and London. K l e i b e r , M. 1961. The f i r e o f l i f e . An i n t r o d u c t i o n t o a n i m a l e n e r g e t i c s . John W i l e y and Sons, New York. 454 pp. K l u i j v e r , H.N. 1933. B i j d r a g e t o t de b i o l o g i e en de e c o l o g i e van den Spreeuw ( S t u r n u s v u l g a r i s v u l g a r i s L.) gedurende z i j n v o o r t p l a n t i n g s t i j d . V e r s l . P l z i e k t . D i e n s t . Wageningen 69:1-145. La c k , D. 1948. N a t u r a l s e l e c t i o n and f a m i l y s i z e i n the s t a r l i n g . E v o l u t i o n 2(2):95-110. Lamba, B.S. 1963. The n i d i f i c a t i o n o f some common I n d i a n b i r d s . 4. The common myna. Res. B u l l . P u njab U n i v . , 14:11-20. L a s i e w s k i , R.C., and W.R. Dawson. 1967. R e e x a m i n a t i o n o f the r e l a t i o n between s t a n d a r d m e t a b o l i c r a t e and body w e i g h t i n b i r d s . Condor 69:13-23. ., W.W. Weathers and M.H. B e r n s t e i n . 1967. P h y s i o l o g i c a l r e s p o n s e s o f the g i a n t hummingbird 112 (Patagona g i g a s ) . Comp. Biochem. P h y s i o l . 23:797-813. L e w i e s , R.W., and M.I. Dyer. 1969. R e s p i r a t o r y meta-b o l i s m of the red-winged b l a c k b i r d i n r e l a t i o n t o ambient t e m p e r a t u r e . Condor 71(3):291-298. MacKay, V i o l e t M., and W.M. Hughes. 1963. C r e s t e d myna i n B r i t i s h C o l u m b i a . Canad. F i e l d N a t. 77(3):154-162. Maher, W.J. 196 4. Growth r a t e and development o f endo-thermy i n t h e snow b u n t i n g ( P l e c t r o p h e n a x n i v a l i s ) and l a p l a n d l o n g s p u r ( C a l c a r i u s i a p p o n i c u s ) a t Barrow, A l a s k a . E c o l o g y 45(3):520-528. McGregor, R.C. 1920. Some f e a t u r e s o f the P h i l i p p i n e o r n i s . ( O r i g i n a l n o t seen. From Wood, C A . 1924. The s t a r l i n g f a m i l y a t home and abroad. Condor 26(4):123-136.) M a r t i n , E.W. 196 7. An improved cage d e s i g n f o r e x p e r i -m e n t a t i o n w i t h p a s s e r i f o r m b i r d s . W i l s o n B u l l . 79:335-338. . 1968. The e f f e c t s o f d i e t a r y p r o t e i n on the energy and n i t r o g e n b a l a n c e of the t r e e sparrow ( S p i z e l l a a r b o r e a a r b o r e a ) . P h y s i o l . Z o o l . 41(3):313-331. Meeh, K. 1897. Oberflachenmessungen des m e n s c h l i c h e n k o r p e r s . Z t s c h r . B i o l . 15:425-458. 113 M o r r i s o n , P.R., and W.J. T i e t z . 1957. C o o l i n g and t h e r m a l conductance i n t h r e e s m a l l a l a s k a n mammals. J . Mammal. 3 8 ( 1 ) : 7 8-86. Munro, J.A. 1922. The "Japanese s t a r l i n g " i n Vancouver, B r i t i s h C o l u m b i a . Canad. F i e l d N a t. 1 6 ( 2 ) : 32-33. • • . 1930. The Japanese S t a r l i n g i n A l e r t Bay, B.C. Canad. F i e l d Nat. 44(2):30 Owen, R.B. J r . , 1970. The b i o e n e r g e t i c s o f c a p t i v e b l u e - w i n g e d t e a l under c o n t r o l l e d and o u t d o o r c o n d i t i o n s . Condor 72: 153-163. P h i l l i p s , J.C. 1928. W i l d b i r d s i n t r o d u c e d o r t r a n s -p l a n t e d i n N o r t h A m e r i c a . U.S. Dept. o f Ag. Tech. B u l l . No.61. Racey, K. 1924. Japanese s t a r l i n g i n Vancouver, B.C. M u r r e l e t . 5 (2):12. R i c k l e f s , R.E. 1967. A g r a p h i c a l method o f f i t t i n g e q u a t i o n s t o growth c u r v e s . E c o l o g y . 48 (6):978-983. . 1968. P a t t e r n s o f growth i n b i r d s . I b i s 110(4):419-451. 1969. a. P r e l i m i n a r y models f o r growth r a t e s o f a l t r i c i a l b i r d s . E c o l o g y 50(6):1031-1039. 1969. b. An a n a l y s i s o f n e s t i n g m o r t a l i t y i n b i r d s . S m i t h s o n i a n C o n t r . Z o o l . 9:1-48. R o y a l l , W.C. J r . 1966. B r e e d i n g o f t h e s t a r l i n g i n C e n t r a l A r i z o n a . Condor 6 8 ( 2 ) : 196-205. 114 Rubner, M. 1902. The laws o f energy consumption i n n u t r i t i o n . F r a n z D e u t i c k e , L e i p z i g and V i e n n a . T r a n s , by M a r k o f f , A., and A. S a n d r i - W h i t e . Ed. R.J.T. J o y , U.S. Army Rs. I n s t , o f E n v i r o n . Med., N a t i c k , Mass. (1968). Saunders, W.E. 1930. Japanese s t a r l i n g a t A l e r t Bay. Canad. F i e l d Nat. 44(1):24. S c h e f f e r , T.H. 1931. A week o f mynah b i r d s a t Vancouver, B r i t i s h C o l u m b i a . M u r r e l e t 12 ( 3 ) : 84-85. . 1955. P r e s e n t s t a t u s o f t h e i n -t r o d u c e d E n g l i s h s k y l a r k on Vancouver I s l a n d and of the C h i n e s e mynah on Vancouver m a i n l a n d . M u r r e l e t 36:28-29. , and C. Cottam. 1935. The c r e s t e d mynah, o r C h i e n e s e s t a r l i n g i n the P a c i f i c N o r t h w e s t . U.S. Dept. of Ag. Tech. B u l l . 467. 1-27. S c h o l a n d e r , P.F. 1955. E v o l u t i o n o f c l i m a t i c a d a p t a t i o n s i n homeotherms. E v o l u t i o n 9 ( 1 ) : 15-26. . 1956. C l i m a t i c r u l e s . E v o l u t i o n 9 ( 1 ) : 15-26. S e l a n d e r , R.K., and R.F. J o h n s t o n . 1967. E v o l u t i o n i n the House S p a r r o w . I . I n t r a p o p u l a t i o n v a r i a t i o n i n N o r t h A m e r i c a . Condor 69:217-258. Sengupta, S. 196 8. S t u d i e s on the l i f e o f t h e common myna A c r i d o t h e r e s t r i s t i s t r i s t i s ( L i n n a e u s ) (Aves: P a s s e r i f o r m e s : S t u r n i d a e ) . P r o c . Z o o l . Soc. C a l c u t t a 21:1-27 115 • . 1 9 6 9 . S t u d i e s o n t h e l i f e o f t h e common m y n a A c r i d o t h e r e s t r i s t i s t r i s t i s ( L i n n a e u s ) ( A v e s : P a s s e r i f o r m e s : S t u r n i d a e ) . 2. S o c i a l B e h a v i o u r . P r o c . Z o o l . S o c . C a l c u t t a . 2 2 : 1 2 9 - 1 3 7 . S k u t c h . , A . F . 1 9 4 9 . Do t r o p i c a l b i r d s r e a r a s m any y o u n g a s t h e y c a n n o u r i s h ? I b i s 9 1 : 4 3 0 - 4 5 8 . S m y t h i e s , B . E . 1 9 5 3 . T h e b i r d s o f B u r m a . O l i v e r a n d B o y d , E d i n b u r g h . 6 68 p p . S t o n e r , D. 1 9 2 3 . T h e m y n a A s t u d y i n a d a p t a t i o n . A u k 4 0 : 3 2 8 - 3 3 0 . S z i j j i , J . 1 9 5 6 . T h e f o o d b i o l o g y o f t h e s t a r l i n g a n d i t s a g r i c u l t u r a l i m p o r t a n c e . A q u i l a 6 3 / 6 4 : 7 1 - 1 0 0 . V a u g h n , R . E . a n d K.H. J o n e s . 1 9 1 3 . T h e b i r d s o f H o n g K o n g , M a c a o , a n d t h e W e s t R i v e r o r S i K i a n g i n S o u t h e a s t e r n C h i n a , w i t h s p e c i a l r e f e r e n c e t o t h e i r n i d i f i c a t i o n a n d s e a s o n a l m o v e m e n t s . P a r t I I . I b i s , 1 0 t h s e r i e s , N o . I I , 1 7 4 - 1 7 5 . W a l l g r e n , H. 1 9 5 4 . E n e r g y m e t a b o l i s m o f t w o s p e c i e s o f t h e g e n u s E m b e r i z a a s c o r r e l a t e d w i t h d i s t r i b u t i o n a n d m i g r a t i o n . A c t a Z o o l o g i c a l F e n n i c a . 84:1-110. W e s t , G . C , 1 9 6 0 . S e a s o n a l v a r i a t i o n i n t h e e n e r g y b a l a n c e o f t h e t r e e s p a r r o w i n r e l a t i o n t o m i g r a t i o n . A u k 7 7 : 3 0 6 - 3 2 9 116 . 1962. Responses and a d a p t a t i o n s o f w i l d b i r d s t o e n v i r o n m e n t a l t e m p e r a t u r e . pp.291-333. I n J.P. Hannon and E. V i e r e c k (eds.) Comparative p h y s i o l o g y o f t e m p e r a t u r e r e g u l a t i o n , P a r t 3. A r c t i c A e r o m e d i c a l Lab., F o r t W a i n w r i g h t , A l a s k a . W e s t e r t e r p , K. 1971. V e r s l a g over h e t onderzoek naar de e n e r g i e b a l a n s van de spreeuw ( s t u r n u s v u l g a r i s L.) aan h e t I n s t i t u t Voor O e c o l o g i s c h Onderzoek t e Arnhem i n de b r o e d s e i z o e n e n van 1968, 1969 en 1970 (duur 12 maaden). 42 pp. mimeo. Wetmore, A. 1936. The number o f c o n t o u r f e a t h e r s i n p a s s e r -i f o r m and r e l a t e d b i r d s . Auk 53:159-169. . 1964. Song and garden b i r d s o f N o r t h A m e r i c a . Nat. G e o g r a p h i c S o c i e t y . Wash. D.C. 400 pp. W h i s t l e r , H. 1949. P o p u l a r handbook o f I n d i a n b i r d s . Gurney and J a c k s o n . London and E d i n b u r g h . 560 pp. W i l d a s h , P. 1968. B i r d s o f South Vietnam. C h a r l e s E. T u t t l e . R u t l a n d , V t . , and Tokyo, Japan. 234 pp. W i l k i n s o n , E.S. 1929. Shanghai b i r d s , a s t u d y o f b i r d l i f e i n Shanghai and s u r r o u n d i n g d i s t r i c t s . S h anghai. 243 pp. W i l l i a m s , J.E. 1965. Energy r e q u i r e m e n t s o f t h e Canada goose ( B r a n t a c a n a d e n s i s i n t e r i o r ) i n r e l a t i o n t o d i s t r i b u t i o n and m i g r a t i o n . D i s s . A b s t r . 2 6 ( 1 ) : 566-567. Wood, C A . 1924. The s t a r l i n g f a m i l y a t home and abroad. Condor 2 6 ( 4 ) : 123-136. Zimmerman, J . L . 1965. B i o e n e r g e t i c s o f the d i c k -c i s s e l , S p i z a americana. P h y s i o l . Z o o l . 38:370-389. 117 -2 APPENDIX 118 Appendix F i g u r e 1. Computer p l o t o f mean cage a r e a ambient t e m p e r a t u r e (°C maximum and minimum) and s t u r n i d G.E. i n t a k e f o r the p e r i o d 1 J a n u a r y 1969 t o 1 J a n u a r y 1970. GROSS ENERGY INTAKE CAGE AREA AMBIENT (KCAL / BIRD-DAY) TEMPERATURE C° O o « i S D i § S B ^ § 3 I S g S o 6 8 8 & 119 Appendix Figure 2 . Plot of heat loss from feathered (f) and unfeathered (uf) starling carcasses cooled at 0°C. STARLING YF= 3-7209 + -O0101X N = 50 i \ U F •- Y = 3-7219 + -0.0291X N = 50 UF 1 1 1 1 1— f 1 1 ! r 0 » 0 10 '0 EO'O 3 0 » 0 40*0 50*0 G 0 « 0 7 0 « 0 B 0 » 0 30*0 100-0 TIME (MINUTES) Appendix F i g u r e 3. P l o t of h e a t l o s s from f e a t h e r e d ( f ) and u n f e a t h e r e d (uf) myna c a r c a s s e s c o o l e d a t 0°C. m m a i P j - H - H o o (Do) 3dniva3diAi3i N i Appendix Table 1. Meteorological Data for Lower Mainland Areas, British Columbia, 1969 Experimental Cage Area Vivarium, UBC UBC Weather Station Vancouver International Airport Month Temperature (°C) Temperature Precipitation (cm) Temperature Precipitation Mean Max. Min. Mean Max. Min. Rain Snow Total^ Mean Max. Min. Rain Snow Total Jan. -2.1 1.3 -5.5 -2.4 0.3 -5.2 9.4 54.3 14.8 -3.0 0.0 -6.0 7.3 65.0 12.8 Feb. 4.7 8.3 1.0 3.5 6.4 0.5 5.6 2.6 5.8 3.5 6.5 -0.5 4.4 6.9 5.0 Mar. 6.4 10.3 2.5 6.3 9.6 3.0 9.8 9.8 6.0 10.1 1.8 9.0 9.0 Apr. 9.0 12.8 5.1 7.9 10.9 4.9 13.0 13.0 8.4 11.9 4.9 10.8 10.8 May 14.8 20.6 8.9 13.1 17.0 9.1 3.4 3.4 . 13.0 17.5 8.5 2.8 2.8 June 20.1 26.3 13.8 16.8 20.0 13.5 2.2 2.2 17.4 21.5 13.3 1.7 1.7 July 20.4 27.7 13.1 16.5 20.3 12.6 2.0 2.0 17.3 22.0 12.5 1.2 1.2 Aug 17.4 22.3 12.5 15.5 18.3 11.8 6.2 6.2 15.8 20.0 11.6 5.2 5.2 Sept. 14.9 20.1 9.6 14.1 16.7 11.5 15.7 15.7 14.1 17.6 10.6 14.0 14.0 Oct. 11.4 16.8 5.9 10.1 13.1 7.0 10.1 10.1 9.6 13.4 5.8 10.4 . 10.4 Nov. 7.4 10.7 4.0 7.1 9.4 4.9 9.4 9.4 6.5 9.4 3.6 9.9 9.9 Dec. 5.4 8.6 2.2 5.6 7.4 3.8 17.7 ____ 17.7 5.2 8.0 2.4 15.4 15.4 ^ 10 cm snow = 1 cm rain Appendix Table 2. Results of an analysis of variance on energy balance data. GROSS ENERGY: March Jan. 18.62 14.37 Calculated monthly constants presented in an ordered array (Kcal/bird-day)  April May Aug. Feb. July Sept. Nov. June 8.23 4.91 0.12 -0.57 -1.04 -1.68 -7.54 -9.97 Mean standard error of difference between two months - 7.09 Mean standard error of difference between two species = 2.74 F value for months = 4.41 with 11 and 372 d.f. A F value for species = 6.74 with 1 and 372 d.f. Oct. -11.00 Calculated species constants: Starlings (Kcal/bird-day) -4.37 Calculated estimate of mean: 114.29 (Kcal/bird-day) Dec. -14.44 Mynas +4.37 FECAL ENERGY: March 13.08 Apri l 8.09 Calculated monthly constants presented in an ordered array (Kcal/bird-day) Oct. 3.26 Jan. 2.93 May 2.63 1.78 July 1.60 Mean standard error of difference between two months = 3.51 Mean standard.error of difference between two species =1.36 F value for months = 12.45 with 11 and 372 d.f. F value for species = 0.12 with 1 and 372 d.f. Dec. -2.28 June -3.15 Feb. -3.25 Calculated species constants: (Kcal/bird-day) Calculated estimate of mean: (Kcal/bird-day) Sept. -8.11 Starlings +0.24 58.64 Nov. -16.53 Mynas -0.24 to \ Appendix Table 2 (continued). Results of an analysis of variance on energy balance data. METABOLIZED ENERGY Calculated monthly constants presented in an ordered array (Kcal/bird-day)  Jan. Nov. Sept. March Feb. May April Aug. July June Dec. Oct. 11.45 8.99 6.43 5.57 2.63 2.27 0.14 -1.60 -2.66 -6.80 -12.16 -14.27 Mean standard error of difference between two months = 5.30 Mean standard error of difference between two species = 2.05 F value for months = 3.82 with 11 and 372 d.f. Calculated species constants: Starlings Mynas F value for species ,= 15.82* with 1 and 372 d.f. (Kcal/bird-day) -4.62 +4.62 Calculated estimate of mean: 55.64 (Kcal/bird-day) Values joined by solid lines are not significantly different from each other Designates significance (P = .10) \ Appendix T a b l e 3. R e s u l t s o f a r e g r e s s i o n a n a l y s i s o f t e m p e r a t u r e a g a i n s t G.E., E.E. and M.E. f o r s t a r l i n g s . C o r r e l a t i o n C o e f f i c i e n t s R e g r e s s i o n C o e f f i c i e n t s N ( P r o d u c t moment r) (b i n Y = bX+a) Temperature v s . G.E. T o t a l Y e a r Jan.-June J u l y - D e c . Temperature v s . E.E. T o t a l Year Jan.-June J u l y - D e c . Temperature v s . M.E. T o t a l Y e a r Jan.-June J u l y - D e c . 0.28 0.56 0.79 0.00 0.10 0.53 0.45 0.78 0.12 -0. 49 -0.68 +0.88 -0.03 -0.09 + 0.75 -0.46 -0.59 + 0.14 12 6 6 12 6 6 12 6 6 Appendix T a b l e 4. R e s u l t s o f a r e g r e s s i o n a n a l y s i s o f t e m p e r a t u r e a g a i n s t G.E., E.E. and M.E. f o r mynas. C o r r e l a t i o n C o e f f i c i e n t s R e g r e s s i o n C o e f f i c i e n t s N (P r o d u c t moment r) (b i n Y = bX+a) Temperature v s . G.E. T o t a l Year Jan.-June J u l y - D e c . Temperature v s . E.E. T o t a l Year Jan.-June J u l y - D e c . Temperature v s . M.E. T o t a l Year Jan.-June J u l y - D e c . 0.25 0. 50 0.66 0.10 0.29 0.56 0.27 0.63 0.18 -0. 48 -0.12 + 0. 89 -0.11 -0.31 +0.56 -0.37 -0. 83 + 0.31 12 6 6 12 6 6 12 6 6 126 THE INFLUENCE OF BODY SIZE ON METABOLIC RATE W a l l g r e n ( A c t a Z o o l . Fenn., 84:110 pp., 1954) d i s -c u s s e d the p r a c t i c a l and t h e o r e t i c a l a s p e c t s o f e x p r e s s i n g r e s u l t s o f a v i a n m e t a b o l i c e x p e r i m e n t s (pp. 14-15) i n terms of e i t h e r W"'"*0, W"7^, W*^7, or some o t h e r f u n c t i o n of body w e i g h t (W). S i n c e the mean l i v e w e i g h t s o f the two s t u r n i d s mentioned h e r e i n were r e l a t i v e l y s i m i l a r (Myna W=107.8 ± .12 gms, n=152; S t a r l i n g W=83.3 ± .09 gms, n=189), as were t h e two s p e c i e s s t u d i e d by W a l l g r e n , and s i n c e n o n - s i g n i f i c a n t w e i g h t v a r i a t i o n s were o b s e r v e d i n t h e e x p e r i m e n t a l b i r d s t e s t e d , my m e t a b o l i c d a t a a r e p r e s e n t e d p r i m a r i l y i n t h e form of c a l / g m " 1 " 0 0 - h r . I t s h o u l d be mentioned however, t h a t a t the time of W a l l g r e n s work, i n s u f f i c i e n t a v i a n (more s p e c i f i -c a l l y p a s s e r i f o r m ) m e t a b o l i c d a t a were a v a i l a b l e t o c o n s t r u c t d e t a i l e d l i n e a r r e g r e s s i o n s r e l a t i n g I n m e t a b o l i c r a t e t o I n body w e i g h t (W). I n the l a s t 20-25 y e a r s more a v i a n m e t a b o l i c r a t e s have been d e s c r i b e d and as a r e s u l t r e l a t i o n s h i p s between m e t a b o l i s m and body w e i g h t have been made more c l e a r . The most r e c e n t s e r i e s o f such e q u a t i o n s a re th o s e p r e s e n t e d by L a s i e w s k i and Dawson (Condor 69:12-23, 1967). Appendix F i g u r e 4 compares m e t a b o l i c r a t e s of a d u l t S. v u l g a r i s and S_. c r i s t a t e l l u s based on t h e i r r e s p e c t i v e p h y s i o -l o g i c a l o r m e t a b o l i c body w e i g h t s ( W ° * 7 2 4 ; based on L a s i e w s k i 127 and Dawson's (Op. C i t . ) e q u a t i o n r e l a t i n g m e t a b o l i s m t o body w e i g h t i n p a s s e r i f o r m s p e c i e s ) . No s i g n i f i c a n t changes o c c u r i n my r e s u l t s as a r e s u l t o f t h i s n o r m a l i z a t i o n p r o c e s s ( e x c e p t t h a t myna m e t a b o l i s m a t +30°C i s now n o n - s i g n i f i c a n t l y g r e a t e r t h a n s t a r l i n g m e t a b o l i s m a t +30°C). Other than t h o s e by S a l t ( E c o l . Monogr. 22:121-152, 1952), W a l l g r e n (Op. C i t . ) , L a s i e w s k i ( P h y s i o l . Z o o l . 36:122-140, 1963) and t h i s s t u d y , few c o m p a r a t i v e e n e r g e t i c ^ s t u d i e s o f c l o s e l y r e l a t e d s p e c i e s have been co n d u c t e d . I n a l l o f t h e s e s t u d i e s and, i n f a c t , i n the m a j o r i t y o f a v i a n m e t a b o l i c work, r e s u l t s have been e x p r e s s e d i n terms o f W^'00. However, i t remains a p p a r e n t t h a t i n any c o m p a r a t i v e s t u d y o f a v i a n m e t a b o l i s m , body s i z e must be c o n s i d e r e d as an i n f l u e n c e , and i t c o u l d be argued t h a t c o m p a r a t i v e d a t a s h o u l d be based on m e t a b o l i c or p h y s i o l o g i c a l w e i g h t s . A more complex p r o b l e m e x i s t s when comparisons are made between d i f f e r e n t w e i g h t c l a s s e s o f growing o r d e v e l o p i n g b i r d s . Comparisons o f m e t a b o l i c r a t e s f o r d e v e l o p i n g a l t r i c i a l and p r e c o c i a l b i r d s p r e s e n t s an even more complex p r o b l e m t o t h e e x p e r i m e n t e r because o f p o s s i b l e d i f f e r e n t r e a c t i o n s o f the two t y p e s o f ambient t e m p e r a t u r e changes. 128 Appendix F i g u r e 4. S t u r n i d t h e r m a l r e s p o n s e c u r v e s 724 e x p r e s s e d i n terms o f cal/gm* - h r . LCT d e s i g n a t e s e m p i r i c a l l y o b t a i n e d v a l u e f o r l o w e r t e m p e r a t u r e ( K l e i b e r , 1965: 165) (o = s t a r l i n g ; o = c r e s t e d myna). ( j q - w6/|D0) NOIldlMlSNOO 20 

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