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The breeding ecology and management of white pelicans at Stum Lake, British Columbia Dunbar, David Leonard 1982

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THE BREEDING ECOLOGY AND MANAGEMENT OF WHITE PELICANS AT STUM . LAKE, BRITISH COLUMBIA by DAVID LEONARD DUNBAR B . S c U n i v e r s i t y Of B r i t i s h C o l u m b i a , 1976 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Department Of F o r e s t r y We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA O c t o b e r 1982 © D a v i d L e o n a r d Dunbar, 1982 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y of B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head of my D e partment or by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D epartment of F o r e s t r y The U n i v e r s i t y of B r i t i s h C o l u m b i a 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5 D a t e : O c t o b e r 15, 1982 i i ABSTRACT T h i s s t u d y was c o n d u c t e d t o i d e n t i f y a s p e c t s o f t h e b r e e d i n g e c o l o g y of w h i t e p e l i c a n s ( P e l e c a n u s e r y t h r o r h y n c h o s ) i n B r i t i s h C o l u m b i a and t o d e v e l o p a management p l a n t o p r e s e r v e and enhance w h i t e p e l i c a n s and t h e i r h a b i t a t i n B r i t i s h C o l u m b i a . F i e l d s t u d i e s were c o n d u c t e d d u r i n g t h e b r e e d i n g s e a s o n s from 1977 t o 1980. The major m i g r a t o r y r o u t e of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a o c c u r s i n t h e Okanagan V a l l e y . P e l i c a n s a r r i v e a t Stum L a k e , t h e o n l y known b r e e d i n g l o c a t i o n i n B r i t i s h C o l u m b i a , i n mid A p r i l and r e m a i n on t h e F r a s e r P l a t e a u u n t i l l a t e September. E i g h t y - t h r e e p e r c e n t of a l l p e l i c a n s o b s e r v e d i n B r i t i s h C o l u m b i a d u r i n g t h e summer were l o c a t e d w i t h i n 80 km of t h e b r e e d i n g l a k e . C h i l c o t i n L a k e , a p p r o x i m a t e l y 70 km west of Stum L a k e , was t h e p r i m a r y f o r a g i n g s i t e d u r i n g t h e s t u d y . I d e n t i f i c a t i o n of bone samples c o l l e c t e d on t h e b r e e d i n g i s l a n d i n d i c a t e t h a t p e l i c a n s i n B r i t i s h C o l u m b i a p r e y c h i e f l y on non-game f i s h s p e c i e s , s u c h a s s u c k e r ( C a t o s t o m u s s p p . ) . P e l i c a n s a t Stum Lake s e l e c t e d f l a t u n v e g e t a t e d a r e a s t o n e s t . The p r e s e n c e of h e r r i n g g u l l s ( L a r u s a r g e n t a t u s ) d i d not a p p e a r t o a f f e c t t h e i r n e s t i n g d i s t r i b u t i o n . I n t e r - n e s t d i s t a n c e s were c a l c u l a t e d i n 1977 and 1978 and f o u n d t o be s i m i l a r t o d i s t a n c e s r e c o r d e d f o r o t h e r w h i t e p e l i c a n c o l o n i e s i n N o r t h A m e r i c a . Mean c l u t c h s i z e of w h i t e p e l i c a n s a t Stum Lake d u r i n g y e a r s w i t h o u t d i s t u r b a n c e was 1.95 ± 0.21. Mean egg m o r t a l i t y was 10% of a l l eggs l a i d . N e s t abandonment was t h e majo r m o r t a l i t y f a c t o r . N e s t l i n g and f l e d g l i n g m o r t a l i t y c l a i m e d a i i i further 26% and 20% respectively, of a l l eggs l a i d . Total mortality of young during 1977 and 1978 was 56% of a l l eggs produced. In years when coyote predation or human disturbance occurred, survivorship of young, and ove r a l l productivity of the colony was reduced. The potential impact of coyote predation and human disturbance were examined over longer periods by using a simple simulation model. The results of thi s study were discussed in terms of potential management practices that would enhance white pelicans in B r i t i s h Columbia. i v TABLE OF CONTENTS ABSTRACT i i L I S T OF TABLES v i i i L I S T OF FIGURES i x ACKNOWLEDGEMENTS x i i CHAPTER 1. INTRODUCTION 1 CHAPTER 2. DESCRIPTION OF STUDY AREA 5 2.1 L o c a t i o n and H a b i t a t 5 2.2 C l i m a t e 7 CHAPTER 3. DISTRIBUTION AND ABUNDANCE OF WHITE PELICANS IN BRITISH COLUMBIA 11 3 . 1 I n t r o d u c t i o n 11 3.2 Methods 13 3.2.1 D i s t r i b u t i o n of White P e l i c a n s i n - W e s t e r n N o r t h A m e r i c a 13 3.2.2 P o p u l a t i o n S t a t u s 13 3.3 R e s u l t s 14 3.3.1 W i n t e r i n g A r e a s and M i g r a t i o n R o u t e s o f White P e l i c a n s i n W e s t e r n N o r t h A m e r i c a 14 3.3.2 H i s t o r y , P r e s e n t S t a t u s , and P o p u l a t i o n T r e n d s 20 3 .4 D i s c u s s i o n 23 CHAPTER 4. FORAGING DISTRIBUTION, HABITAT CHARACTERISTICS, AND FOOD HABITS OF WHITE PELICANS IN BRITISH COLUMBIA 25 4.1 I n t r o d u c t i o n 25 4.2 Methods 27 4.2.1 F o r a g i n g D i s t r i b u t i o n of White P e l i c a n s i n V B r i t i s h C o l u m b i a 27 4.2.2 Movements o f P e l i c a n s 28 4.2.3 Fo o d H a b i t A n a l y s e s 29 4.3 R e s u l t s 29 4.3.1 F o r a g i n g D i s t r i b u t i o n o f W h i t e P e l i c a n s i n B r i t i s h C o l u m b i a 29 4.3.2 Movements of P e l i c a n s 34 4.3.3 H a b i t a t C h a r a c t e r i s t i c s of F o r a g i n g L a k e s ..... 36 4.3.4 Fo o d H a b i t s 39 4.4 D i s c u s s i o n 39 CHAPTER 5. CHARACTERISTICS OF THE NESTING HABITAT 43 5.1 I n t r o d u c t i o n 43 5.2 Methods 44 5.2.1 Measurements of t h e B r e e d i n g H a b i t a t 44 5.2.2 S p a t i a l D i s t r i b u t i o n o f N e s t s 45 5.2.3 A e r i a l S u r v e y s . . .' 45 5.3 R e s u l t s 46 5.3.1 P h y s i c a l C h a r a c t e r i s t i c s of t h e B r e e d i n g H a b i t a t a t Stum Lake 46 5.3.2 N e s t i n g D i s t r i b u t i o n of W h i t e P e l i c a n s a t Stum Lake 50 5.3.3 A l t e r n a t i v e N e s t i n g H a b i t a t 57 5.4 D i s c u s s i o n 58 CHAPTER 6. REPRODUCTIVE SUCCESS OF WHITE PELICANS AT STUM LAKE, BRITISH COLUMBIA 62 6.1 I n t r o d u c t i o n 62 6.2 Methods 63 6.2.1 P o p u l a t i o n E s t i m a t e s 64 v i 6.3 R e s u l t s 65 6.3.1 C o l o n y O c c u p a t i o n 65 6.3.2 E a r l y N e s t i n g P h e n o l o g y 68 6.3.3 Commencement o f Egg L a y i n g and H a t c h i n g 71 6.3.4 C l u t c h S i z e s 71 6.3.5 R e p r o d u c t i v e S u c c e s s 74 6.3.6 P r e d a t i o n 78 6.3.7 Human D i s t u r b a n c e 80 6.3.8 S u r v i v o r s h i p and P r o d u c t i v i t y i n r e l a t i o n t o C l u t c h S i z e 81 6.4 D i s c u s s i o n 83 6.4.1 C o m p a r i s o n o f R e p r o d u c t i v e S u c c e s s w i t h o t h e r White P e l i c a n C o l o n i e s i n N o r t h A m e r i c a 83 6.4.2 E f f e c t s of P r e d a t i o n and D i s t u r b a n c e a t White P e l i c a n N e s t i n g C o l o n i e s 86 6.4.3 I m p l i c a t i o n s o f C l u t c h S i z e 89 CHAPTER 7. BEHAVIOUR OF WHITE PELICANS AT STUM LAKE 91 7.1 I n t r o d u c t i o n 91 7.2 Methods 92 7.3 R e s u l t s 93 7.3.1 I n t r a s p e c i f i c I n t e r a c t i o n s 93 7.3.2 I n t e r s p e c i f i c R e l a t i o n s 97 7 . 4 D i s c u s s i o n 100 CHAPTER 8. MANAGEMENT RECOMMENDATIONS AND RECOVERY PLAN FOR WHITE PELICANS IN BRITISH COLUMBIA 104 8.1 I n t r o d u c t i o n 104 8.1.1 B a c k g r o u n d 104 8.1.2 Need and J u s t i f i c a t i o n F o r P r o t e c t i o n 105 v i i 8.2 S u s p e c t e d Or P r o v e n Reasons F o r Changes In S t a t u s ....106 8.3 R e c o v e r y P l a n Of White P e l i c a n s In B r i t i s h C o l u m b i a ..114 8.3.1 P r o t e c t i o n And M a i n t e n a n c e Of The Stum Lake P e l i c a n C o l o n y 115 8.3.2 Enhancement T e c h n i q u e s 120 8.3.2.1 M a i n t e n a n c e And Enhancement Of P r e s e n t F e e d i n g L a k e s 120 8.3.2.2 S t o c k i n g Stum Lak e W i t h S u i t a b l e C o a r s e F i s h 122 8.3.2.3 Improvement Of P r e s e n t B r e e d i n g H a b i t a t At Stum Lake 123 8.3.2.4 P r e d a t o r C o n t r o l 125 8.3.3 R e c o v e r y T e c h n i q u e s f o r White P e l i c a n s 126 LITERATURE CITED 131 APPENDIX I : 138 APPENDIX II : 1 39 v i i i L I S T OF TABLES T a b l e Page 1 Food abundance o f s e v e r a l l a k e s and f r e q u e n c y o f f o r a g i n g by w h i t e p e l i c a n s from Stum L a k e , B.C. .. 37 2 Numbers of a d u l t s , n e s t s , c l u t c h s i z e s , p r o d u c t i v i t y and s u r v i v o r s h i p f o r w h i t e p e l i c a n s a t Stum L a k e , B.C 73 3 C h r o n o l o g y of known d i s t u r b a n c e s t o t h e w h i t e p e l i c a n c o l o n y a t Stum L a k e , B.C 107 4 P a r a m e t e r v a l u e s employed i n t h e s i m u l a t i o n model and a s s o c i a t e d r a t e s of change i n t h e s i m u l a t e d p o p u l a t i o n 109 i x L I S T OF FIGURES F i g u r e Page 1 L o c a t i o n and c o n f i g u r a t i o n o f Stum L a k e , B r i t i s h C o l u m b i a 6 2 D a i l y minimum and maximum t e m p e r a t u r e s f o r Stum Lake and t h e A l e x i s C r e e k - T a u t r i C r e e k Weather S t a t i o n 8 3 Mean m o n t h l y minimum and maximum t e m p e r a t u r e s f o r A l e x i s C r e e k - T a u t r i C r e e k Weather S t a t i o n f r o m 1971 t o 1979 10 4 P r i n c i p a l w i n t e r i n g a r e a s f o r w h i t e p e l i c a n s west of t h e Rocky M o u n t a i n s 15 5 M i g r a t o r y r o u t e of w h i t e p e l i c a n s b r e e d i n g west of t h e Rocky M o u n t a i n s 17 6 M i g r a t o r y r o u t e of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a 18 7 Numbers of n e s t s and p e l i c a n s o b s e r v e d a t Stum Lake, B r i t i s h C o l u m b i a ( i n 1959 e x a c t numbers a r e not a v a i l a b l e and a range i s g i v e n ) 22 8 F o r a g i n g s i g h t i n g s of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a 30 9 C u m u l a t i v e f r e q u e n c y o f p e l i c a n s i g h t i n g s i n r e l a t i o n t o d i s t a n c e from t h e c o l o n y 31 10 Summer f o r a g i n g r a n g e of w h i t e p e l i c a n s b r e e d i n g a t Stum L a k e , B r i t i s h C o l u m b i a * 33 F i g u r e Page 11 V a n i s h i n g b e a r i n g s of w h i t e p e l i c a n s d e p a r t i n g f r o m Stum L a k e . A) Mean d i r e c t i o n of w h i t e p e l i c a n s p r i n g movements, 1979 and 1980; B) Mean d i r e c t i o n o f w h i t e p e l i c a n summer movements, 1977 and 1978 35 12 Water d e p t h s between t h e main b r e e d i n g i s l a n d ( I s l a n d Two) and t h e m a i n l a n d 47 13 H a b i t a t map of I s l a n d Two a t Stum Lake, B r i t i s h C o l u m b i a d u r i n g 1977 and 1978 49 14 N e s t s i t e s e l e c t i o n by w h i t e p e l i c a n s on I s l a n d Two a t Stum Lake, B.C. d u r i n g 1977 and 1978 51 15 S p a t i a l d i s t r i b u t i o n o f n e s t i n g g r o u p s a t Stum L a k e , B.C. from 1977 t o 1980 53 16 Group s i z e and mean i n t e r - n e s t d i s t a n c e s a t Stum L a k e , B.C. d u r i n g 1977 and 1978 (1 = d a t a from Knopf 1975) 55 17 D i s t r i b u t i o n of d i s t a n c e s between n e s t c e n t e r s a t Stum L a k e , B.C. d u r i n g 1977 and 1978 56 18 C o l o n y o c c u p a t i o n and n e s t s i t e e s t a b l i s h m e n t d u r i n g s p r i n g 1979 a t Stum L a k e , B r i t i s h C o l u m b i a 66 19 C o l o n y o c c u p a t i o n and n e s t s i t e e s t a b l i s h m e n t d u r i n g s p r i n g 1980 a t Stum L a k e , B r i t i s h C o l u m b i a 67 20 H a t c h i n g d a t e s of w h i t e p e l i c a n eggs a t Stum L a k e , B.C 72 x i F i g u r e Page 21 C l u t c h s i z e f r e q u e n c i e s of w h i t e p e l i c a n s a t Stum Lake d u r i n g 1977 and 1978 . 75 22 S u r v i v o r s h i p o f w h i t e p e l i c a n s a t Stum L a k e , B r i t i s h C o l u m b i a d u r i n g 1977 and 1978 77 23 C l u t c h s i z e i n r e l a t i o n t o p r o d u c t i v i t y and s u r v i v o r s h i p of young a t Stum L a k e , d u r i n g 1977 and 1978 82 24 A g g r e s s i v e i n t e r a c t i o n r a t e among a d u l t w h i t e p e l i c a n s a t Stum Lake, B r i t i s h C o l u m b i a 94 25 S i m u l a t e d c h a n g e s i n p e l i c a n numbers r e s u l t i n g f r o m a i r c r a f t d i s t u r b a n c e a t d i f f e r e n t f r e q u e n c i e s 111 26 S i m u l a t e d c h a n g e s i n p e l i c a n numbers r e s u l t i n g from c o y o t e p r e d a t i o n a t d i f f e r e n t f r e q u e n c i e s ... 112 ACKNOWLEDGEMENTS Sincere appreciation is extended to my supervisor Dr. Fred L. Bunnell for his patience and guidance during the course of the study and in the preparation of this thesis. I am also grateful for the advice and helpful reviews I received of e a r l i e r drafts from my committee members: Drs. Jamie Smith, David Shackleton, Chris Shank, and Wayne Campbell. I would further l i k e to acknowledge Grant Hazelwood (B.C. Parks Branch) who, along with Fred Bunnell, i n i t i a t e d the study. Wayne Campbell of the B.C. P r o v i c i a l Museum supplyed me with h i s t o r i c a l records of white pelicans in B r i t i s h Columbia, and for t h i s I am gra t e f u l . I would also l i k e to thank Fred Bunnell and Mike Gillingham for their help in designing the simulation model. Funding for the study was provided by grants to F.L. Bunnell from the Canadian W i l d l i f e Service, the World W i l d l i f e Fund, and the University of B r i t i s h Columbia. I was supported in part by the B r i t i s h Columbia Fish and W i l d l i f e Branch , B r i t i s h Columbia Parks Branch, the University of B r i t i s h Columbia, and the Canadian Forest Products Fellowship in W i l d l i f e Management. I especially thank Alton Harestad for his endless encouragement and assistance in interpreting data. I would also l i k e to thank everyone at Header House for their moral support. I g r a t e f u l l y acknowledge Cathi Lowe for typing the thesis and Darline M i l l e r for reviewing the manuscript. I wish to acknowledge my parents for their constant support while I attended university. . Lastly, but most importantly, I thank L i a n a Koza, who a s s i s t e d i n e v e r y phase o f t h i s s t u d y . 1 CHAPTER 1. INTRODUCTION Two s p e c i e s o f p e l i c a n s o c c u r i n N o r t h A m e r i c a . The brown p e l i c a n ( P e l e c a n u s o c c i d e n t a l i s ) i s s t r i c t l y m a r i n e w h i l e t h e w h i t e p e l i c a n ( P e l e c a n u s e r y t h r o r h y n c h o s ) o c c u p i e s b o t h m a r i n e and f r e s h w a t e r h a b i t a t s . P r e s e n t l y b o t h s p e c i e s o f p e l i c a n a r e s u f f e r i n g p o p u l a t i o n d e c l i n e s t h r o u g h o u t a l l o r p a r t of t h e i r b r e e d i n g r a n g e . The d e c l i n e o f t h e brown p e l i c a n a p p e a r s t o be a s s o c i a t e d p r i m a r i l y w i t h r e p r o d u c t i v e f a i l u r e s r e s u l t i n g f r o m t h e a c c u m u l a t i o n of c h e m i c a l r e s i d u e s ( B l u s e_t aJL. 1974, A n d e r s o n and A n d e r s o n 1976, and A n d e r s o n e t a_l. 1977). The d e c l i n e of t h e w h i t e p e l i c a n s a p p e a r s due t o s e v e r a l f a c t o r s t h a t d i f f e r between c o l o n i e s . F a c t o r s l i m i t i n g t h e p r o d u c t i v i t y of w h i t e p e l i c a n c o l o n i e s i n N o r t h A m e r i c a i n c l u d e mammalian p r e d a t i o n ( S c o t t 1960, B l o k p o e l 1971), f l u c t u a t i n g w ater l e v e l s ( H o s f o r d 1965, Evans 1972), human-induced d i s t u r b a n c e ( H a l l 1925, M a n s e l l 1965, C a r s o n 1966, Vermeer 1970a), p a r a s i t e s and d i s e a s e ( G r e i c h u s and G r e i c h u s 1973, Wobeser e t a l . 1974), s i b l i n g r i v a l r y a n d / o r s t a r v a t i o n (Knopf 1975, J o h n s o n 1976), and a d v e r s e weather c o n d i t i o n s (Bartholomew e_t a_l. 1953, L i e s and B e h l e 1966, A d o l p h s o n and A d o l p h s o n 1968, Bremer 1977). 2 In Canada, a t l e a s t 20 w h i t e p e l i c a n c o l o n i e s have been abandoned o v e r t h e p a s t 80 y e a r s . T h i s l o s s r e p r e s e n t s a l m o s t one h a l f o f t h e 46 c o l o n i e s p r e s e n t a t t h e t u r n of t h e c e n t u r y (Vermeer 1970a). S i n c e V e r m e e r ' s s t u d y an a d d i t i o n a l 6 c o l o n i e s have been abandoned i n A l b e r t a . The r e m a i n i n g 7 c o l o n i e s i n A l b e r t a o c c u r o n l y i n t h e more n o r t h e r n , u n s e t t l e d r e g i o n s o f t h e p r o v i n c e (Markham and B r e t c h e l 1978). T h e r e i s some e v i d e n c e t h a t w h i t e p e l i c a n c o l o n i e s abandoned d u r i n g one y e a r can be r e - o c c u p i e d i n f o l l o w i n g y e a r s (Vermeer 1970a, Roney 1978, Roney 1979). In g e n e r a l , however, t h e r e a p p e a r s t o be a g r o w i n g number of abandoned c o l o n i e s i n Canada t h a t a r e not b e i n g r e - c o l o n i z e d or r e l o c a t e d . W h i t e p e l i c a n s a r e now c l a s s i f i e d as ' t h r e a t e n e d ' i n Canada. A ' t h r e a t e n e d s p e c i e s ' i s d e f i n e d as 'any i n d i g e n o u s s p e c i e s of f a u n a o r f l o r a t h a t i s l i k e l y t o become e n d a n g e r e d i n Canada i f t h e f a c t o r s a f f e c t i n g i t s v u l n e r a b l i t y do not become r e v e r s e d ' (Committee on t h e S t a t u s of E n d a n g e r e d W i l d l i f e i n C a n a d a ) . In B r i t i s h C o l u m b i a , t h e o n l y known b r e e d i n g c o l o n y o c c u r s a t Stum Lake a p p r o x i m a t e l y 70 km west of W i l l i a m s L a k e . P e l i c a n s were t h o u g h t t o have b r e d a t s e v e r a l o t h e r l o c a l i t i e s i n B r i t i s h C o l u m b i a (Thompson 1933); however, t h e s e p o s s i b l e b r e e d i n g r e c o r d s r e m a i n u n c o n f i r m e d . At p r e s e n t , fewer t h a n 300 p e l i c a n s n e s t a t t h e Stum Lake c o l o n y . P r i o r t o my s t u d y , t h e s t a t u s of t h e p o p u l a t i o n was u n c e r t a i n and i n f o r m a t i o n on t h e i r b r e e d i n g e c o l o g y was f r a g m e n t a r y . P r e v i o u s d a t a i n d i c a t e t h a t t h e b r e e d i n g p o p u l a t i o n a t Stum Lake may have been l a r g e r t h a n p r e s e n t p o p u l a t i o n l e v e l s . D u r i n g t h e l a s t 10 y e a r s , however, t h e p o p u l a t i o n a p p e a r s t o have s t a b i l i z e d s l i g h t l y and may even 3 be i n c r e a s i n g . In r e c o g n i t i o n t h a t h i s t o r i c a l p o p u l a t i o n l e v e l s may have been l a r g e r , and t h a t t h e p o p u l a t i o n has s u c h a r e s t r i c t e d b r e e d i n g d i s t r i b u t i o n w i t h i n t h e p r o v i n c e , t h e w h i t e p e l i c a n was o f f i c i a l l y d e s i g n a t e d as an ' e n d a n g e r e d s p e c i e s ' i n B r i t i s h C o l u m b i a as of March 1980. An 'endangered s p e c i e s ' i s d e f i n e d as 'a p o p u l a t i o n i m m e d i a t e l y f a c i n g e x t i n c t i o n i n B r i t i s h C o l u m b i a and r e q u i r i n g s p e c i a l enhancement measures o r b o t h t o e n s u r e t h e i r s u r v i v a l ' (B.C. F i s h and W i l d l i f e B r a n c h ) . My s t u d y had two b r o a d o b j e c t i v e s : 1) To d e t e r m i n e t h e p r e s e n t s t a t u s and t o document t h e n a t u r a l h i s t o r y of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a , and 2) To d e v e l o p a p l a n t o manage and enhance w h i t e p e l i c a n s and t h e i r h a b i t a t i n B r i t i s h C o l u m b i a ( C h a p t e r 8 ) . S p e c i f i c o b j e c t i v e s were: 1) To d e t e r m i n e t h e p r e s e n t s t a t u s , d i s t r i b u t i o n , and t r e n d s i n t h e p o p u l a t i o n ( C h a p t e r 3 ) ; 2) To d e t e r m i n e t h e l o c a t i o n o f f o r a g i n g s i t e s and t h e c h a r a c t e r i s t i c s of t h e s e f e e d i n g a r e a s ( C h a p t e r 4 ) ; 3) To d e t e r m i n e t h e c h a r a c t e r i s t i c s of t h e b r e e d i n g h a b i t a t and t o l o c a t e a l t e r n a t i v e b r e e d i n g s i t e s s u i t a b l e f o r m o d i f i c a t i o n ( C h a p t e r 5 ) ; 4) To document t h e b r e e d i n g c o l o n y ' s r e p r o d u c t i v e s u c c e s s ( C h a p t e r 6 ) ; 5) To a s s e s s t h e r o l e of i n t r a s p e c i f i c b e h a v i o u r and i n t e r s p e c i f i c r e l a t i o n s on t h e i r b r e e d i n g s u c c e s s ( C h a p t e r 7 ) ; and, 4 6) To r e l a t e t h e p r e c e d i n g 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 t o p o t e n t i a l management p r a c t i c e s t h a t would enhance w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a ( C h a p t e r 8 ) . 5 CHAPTER 2. DESCRIPTION OF STUDY AREA 2.1 L o c a t i o n and H a b i t a t W h ite P e l i c a n P r o v i n c i a l Park i s l o c a t e d on t h e F r a s e r P l a t e a u i n c e n t r a l B r i t i s h C o l u m b i a (52° 16'N by 123° 3'W), a p p r o x i m a t e l y 70 km west of W i l l i a m s Lake ( F i g . 1 ) . The l a n d s u r r o u n d i n g t h e l a k e i s f o r e s t e d and g e n t l y s l o p i n g . The d ominant t r e e s p e c i e s a r e l o d g e p o l e p i n e ( P i n u s c o n t o r t a ) , t r e m b l i n g a s p e n ( P o p u l u s t r e m u l o i d e s ) , and w h i t e s p r u c e ( P i c e a  g l a u c a ) . The l a k e l i e s a t an e l e v a t i o n of 1218 m e t e r s . I t c o v e r s a p p r o x i m a t e l y 900 ha and has a mean d e p t h of a p p r o x i m a t e l y 2.5 m ( B u r n s and K l e i n 1973). The water i s s l i g h t l y a l k a l i n e , ( p H = 8.6) and s u p p o r t s a l a r g e number of l a k e chub ( C o u e s i u s  p l u m b e n s ) . F i v e s m a l l i s l a n d s l i e w i t h i n t h e l a k e , t h r e e of w h i c h have been u s e d ' f o r n e s t i n g by p e l i c a n s . The n e s t i n g i s l a n d s a r e I s l a n d One, I s l a n d Two, and Scaup I s l a n d ( F i g . 1 ) . B o t h Scaup I s l a n d and I s l a n d One a r e low, e x p o s e d , r o c k y o u t c r o p p i n g s , and a r e 300 and 600 m e t e r s r e s p e c t i v e l y from t h e n e a r e s t m a i n l a n d . T h e s e i s l a n d s have v e r y l i t t l e v e g e t a t i o n , e x c e p t f o r s m a l l p a t c h e s of s t i n g i n g n e t t l e ( U r t i c a d i o i c a ) , w a t er hemlock ( C i c u t a d o u q l a s i i ) , a nd v a r i o u s s e d g e s ( C a r e x spp.) g r o w i n g a l o n g t h e s h o r e l i n e . Scaup I s l a n d i s t h e s m a l l e s t o f t h e t h r e e n e s t i n g i s l a n d s and has an a r e a of o n l y a b o u t 90 m2, whereas I s l a n d One has an a r e a of a p p r o x i m a t e l y 400 m 2. The l a r g e s t and most commonly u s e d i s l a n d f o r n e s t i n g i s I s l a n d Two. 6 - - - - - - - Park Boundary SCALE: KILOMETERS -I ' I ' I I 0.5 10 Figure 1. Location and configuration of Stun Lake, British Columbia. 7 I t has an a r e a of a p p r o x i m a t e l y 1000 m 2 and r i s e s g r a d u a l l y from i t s s h o r e t o i t s h i g h e s t p o i n t (6.7 m above l a k e l e v e l ) . I t i s s i t u a t e d o n l y 84 m from t h e m a i n l a n d . The r e m a i n i n g two i s l a n d s ( C r e s c e n t and Ryder) on t h e l a k e a r e h e a v i l y v e g e t a t e d and a r e not u s e d by t h e p e l i c a n s f o r n e s t i n g o r r o o s t i n g . H e r r i n g g u l l s ( L a r u s a r g e n t a t u s ) a l s o n e s t on I s l a n d One and, t o a l e s s e r e x t e n t , on Scaup I s l a n d . O t h e r b i r d s t h a t o c c a s i o n a l l y n e s t on I s l a n d Two i n c l u d e common l o o n s ( G a v i a  immer), Canada geese ( B r a n t a c a n a d e n s i s ) , m a l l a r d s (Anas  p l a t y r h y n c h o s ) , l e s s e r s c a u p ( A y t h y a a f f i n i s ) , r i n g - n e c k e d d u c k s ( A y t h y a c o l l a r i s ) , t r e e s w a l l o w s ( I r i d o p r o c n e b i c o l o r ) , and w h i t e - c r o w n e d s p a r r o w s ( Z o n o t r i c h i a l e u c o p h r y s ) . F o r a more d e t a i l e d d e s c r i p t i o n of t h e b i r d s and p l a n t c o m m u n i t i e s of White P e l i c a n P r o v i n c i a l P a r k , r e f e r t o Koza ( 1 9 8 1 ) . 2.2 C l i m a t e The c l i m a t e a t Stum Lake i s c h a r a c t e r i s t i c of t h e s l i g h t l y c o o l e r s ub-zone of t h e C a r i b o o - A s p e n - L o d g e p o l e P i n e B i o g e o c l i m a t i c Zone s e n s u K r a j i n a ( 1 9 5 9 ) . Weather d a t a were c o l l e c t e d a t t h e A l e x i s C r e e k - T a u t r i C r e e k Weather S t a t i o n (52° 33'N by 123° 11'W) l o c a t e d 30 km n o r t h w e s t o f Stum L a k e . The weather s t a t i o n l i e s a t an e l e v a t i o n of 1219 m e t e r s . D a t a c o v e r t h e p e r i o d from 1971 t o 1980. D a i l y minimum and maximum t e m p e r a t u r e s r e c o r d e d d u r i n g s p r i n g , 1979, d i f f e r e d o n l y s l i g h t l y between Stum Lake and t h e weather s t a t i o n ( F i g . 2 ) . D a i l y maximum t e m p e r a t u r e s r e c o r d e d a t Stum Lake a v e r a g e d a b o u t 2°C c o o l e r t h a n t h o s e a t t h e weather s t a t i o n . 8 Figure 2. Daily ntinimum and maximum temperatures for Stum Lake and the Alexis Creek-Tautri Creek Weather Station. 9 Mean d a i l y minimum and maximum t e m p e r a t u r e s r a n g e d from -6°C t o 8°C r e s p e c t i v e l y i n A p r i l , i n c r e a s i n g s t e a d i l y u n t i l J u l y when mean d a i l y minimum and maximum t e m p e r a t u r e s r a n g e d between 3°C and 20°C ( F i g . 3 ) . Mean minimum and maximum t e m p e r a t u r e s d e c r e a s e d t o -1°C and 15°C r e s p e c t i v e l y by September. D u r i n g t h e p e r i o d when p e l i c a n s were a t Stum Lake ( A p r i l t o September) t h e mean d a i l y t e m p e r a t u r e was 7.8°C. The a v e r a g e number of f r o s t - f r e e d a y s p e r y e a r was 79; however, f r o s t has been r e c o r d e d i n e v e r y month o f t h e y e a r . The s t u d y a r e a r e c e i v e s an a v e r a g e t o t a l p r e c i p i t a t i o n o f 448 mm ± 41 mm (sd) p e r y e a r , w i t h a p p r o x i m a t e l y 251 mm ± 68 mm (sd) of p r e c i p i t a t i o n d u r i n g t h e b r e e d i n g s e a s o n from A p r i l t o September. B r e a k - u p of i c e a t Stum Lake o c c u r r e d between 2 May and 3 May i n 1978, l a t e r t h a n 8 May ( e s t i m a t e d between 10 May and 12 May) i n 1979, and between 30 A p r i l and 1 May i n 1980. The mean d a t e of b r e a k - u p a t Stum Lake f o r t h o s e 3 b r e e d i n g s e a s o n s , a s s u m i n g my e s t i m a t e d u r i n g 1979 i s a c c u r a t e , was 4 May. 10 Mean Maximum Temp. Mean Minimum Temp —f 1 1 1 1 1 APRIL MAY JUNE JULY AUGUST SEPTEMBER Figure 3. Mean monthly minimum and maximum temperatures for Alexis Creek-Tautri Creek Weather Station from 1971 to 1979. 11 CHAPTER 3 . DISTRIBUTION AND ABUNDANCE OF WHITE PELICANS IN BRITISH COLUMBIA 3.1 I n t r o d u c t i o n P r i o r to.my s t u d y , t h e s t a t u s of t h e w h i t e p e l i c a n p o p u l a t i o n i n B r i t i s h C o l u m b i a was u n c e r t a i n . The c o l o n y had been s u r v e y e d d u r i n g 11 b r e e d i n g s e a s o n s ; however, more t h a n s e v e n d i f f e r e n t g r o u p s had p a r t i c i p a t e d i n t h e c o u n t s . C o n s e q u e n t l y , t h e t i m i n g of t h e s u r v e y s , t h e methods of d a t a c o l l e c t i o n , and t h e r e s u l t i n g d a t a v a r i e d c o n s i d e r a b l y . D u r i n g t h e 11 b r e e d i n g s e a s o n s , a d u l t s were e s t i m a t e d o n l y two t i m e s ; n e s t s , o n l y two t i m e s ; a c c u r a t e n e s t c o u n t s , t h r e e t i m e s ; and a c c u r a t e n e s t c o u n t s a s w e l l as 'an e s t i m a t e of a d u l t s , f o u r t i m e s . D u r i n g a t l e a s t two s u r v e y s , p e l i c a n s were f o r c e d t o abandon t h e b r e e d i n g l a k e w h i l e c o u n t s of n e s t s and eggs were c o n d u c t e d . E a r l i e r d a t a s u g g e s t t h a t t h e p r e s e n t w h i t e p e l i c a n p o p u l a t i o n a t Stum Lake i s s m a l l e r t h a n h i s t o r i c a l l e v e l s . Heavy l o s s e s o f young, r e s u l t i n g from c o y o t e p r e d a t i o n and human-induced d i s t u r b a n c e s , were r e c o r d e d from 1971 t o 1974. The number of v i s i t o r s a t t h e l a k e a l s o a p p e a r e d t o be g r o w i n g d u r i n g t h e same p e r i o d . In view of t h e s e p o i n t s , t h e r e was i n c r e a s i n g c o n c e r n r e g a r d i n g t h e a b i l i t y of t h e c o l o n y t o s u r v i v e . 12 In a d d i t i o n , r e l a t i v e l y l i t t l e was known c o n c e r n i n g t h e m i g r a t o r y r o u t e s and summer d i s t r i b u t i o n o f p e l i c a n s n e s t i n g i n B r i t i s h C o l u m b i a . I n f o r m a t i o n r e g a r d i n g t h e m i g r a t o r y r o u t e s t h r o u g h t h e U n i t e d S t a t e s and w i n t e r i n g a r e a s of w h i t e p e l i c a n s b r e e d i n g west of t h e Rocky M o u n t a i n s was a l s o i n s u f f i c i e n t . At p r e s e n t , t h e o n l y p u b l i s h e d a c c o u n t of w h i t e p e l i c a n m i g r a t i o n s west of t h e Rocky m o u n t a i n s i s t h a t p r e s e n t e d by Vermeer ( 1 9 7 7 ) . The s u g g e s t e d m i g r a t o r y r o u t e , however, i s l i m i t e d t o o n l y s e v e n b a n d i n g r e t u r n s from p e l i c a n s t h a t f l e d g e d a t Stum L a k e . The major o b j e c t i v e a d d r e s s e d i n t h i s c h a p t e r was t o d e t e r m i n e t h e p r e s e n t s t a t u s , d i s t r i b u t i o n , and t r e n d s i n t h e p e l i c a n p o p u l a t i o n i n B r i t i s h C o l u m b i a . S p e c i f i c o b j e c t i v e s were t o : 1. D e t e r m i n e t h e w i n t e r i n g a r e a s and m i g r a t o r y r o u t e s of p e l i c a n s b r e e d i n g west of t h e Rocky M o u n t a i n s , 2. D e t e r m i n e t h e m i g r a t o r y r o u t e and t h e summer d i s t r i b u t i o n o f w h i t e p e l i c a n s b r e e d i n g a t Stum Lake and, 3. D e t e r m i n e t h e h i s t o r y , p r e s e n t s t a t u s , and p o p u l a t i o n t r e n d o f w h i t e p e l i c a n s a t Stum L a k e . D u r i n g t h e s t u d y , s e v e r a l e a r l i e r p o p u l a t i o n r e c o r d s ( n e s t s a n d / o r a d u l t s ) were l o c a t e d , t h e e a r l i e s t from 1953. These e a r l i e r c o u n t s were used t o d e t e r m i n e l o n g - t e r m t r e n d s i n t h e p o p u l a t i o n . 13 3.2 Methods 3.2.1 D i s t r i b u t i o n of White P e l i c a n s i n W e s t e r n N o r t h A m e r i c a White p e l i c a n s i g h t i n g s r e c o r d e d d u r i n g t h e s p r i n g and f a l l i n B r i t i s h C o l u m b i a were o b t a i n e d from t h e B.C. P r o v i n c i a l Museum. R e c o r d s r a n g i n g from 1922 t o 1978 were examined and mapped t o d e t e r m i n e t h e major m i g r a t i o n r o u t e of w h i t e p e l i c a n s t h r o u g h B r i t i s h C o l u m b i a . The m i g r a t o r y r o u t e o f p e l i c a n s s o u t h of t h e Canada-U.S. b o r d e r were d e t e r m i n e d by mapping s p r i n g and f a l l s i g h t i n g s l i s t e d i n t h e J o u r n a l of A m e r i c a n B i r d s (1965 t o 1978) . T o t a l numbers of b i r d s o b s e r v e d were d i v i d e d by t h e number of y e a r s of d a t a t o p r o v i d e a y e a r l y a v e r a g e . W i n t e r i n g a r e a s were d e t e r m i n e d by mapping p e l i c a n s c e n s u s e d d u r i n g t h e M e x i c o W i n t e r W a t e r f o w l S u r v e y (U.S. F i s h and W i l d l i f e S e r v i c e 1979) , and by l o c a t i o n s l i s t e d i n t h e J o u r n a l of A m e r i c a n B i r d s . 3.2.2 P o p u l a t i o n S t a t u s H i s t o r i c a l r e c o r d s of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a were l o c a t e d a t t h e B r i t i s h C o l u m b i a P r o v i n c i a l Museum i n V i c t o r i a . I n f o r m a t i o n g a t h e r e d t h e r e i n c l u d e d e a r l y r e c o r d s of f o r a g i n g s i g h t i n g s , numbers of a d u l t s a t Stum L a k e , c l u t c h s i z e s , and numbers o f young f l e d g e d . I s t u d i e d t h e c o l o n y f r o m 1977 t o 1980 and r e c o r d e d c o l o n y o c c u p a t i o n , minimum numbers of a d u l t s , c l u t c h s i z e s , numbers of n e s t s , t h e p r o d u c t i v i t y of n e s t s (young f l e d g e d / n e s t ) , and s u r v i v o r s h i p of t h e young (young f l e d g e d / e g g l a i d ) . 14 3.3 R e s u l t s 3.3.1 W i n t e r i n g A r e a s and M i g r a t i o n R o u t e s o f White P e l i c a n s i n W e s t e r n N o r t h A m e r i c a The m a j o r i t y of w h i t e p e l i c a n b r e e d i n g c o l o n i e s o c c u r i n c e n t r a l Canada and n o r t h c e n t r a l U n i t e d S t a t e s ( a b o u t 3 0 ) , w h i l e o n l y 6-7 c o l o n i e s o c c u r west of t h e C o n t i n e n t a l D i v i d e . B a n d i n g r e c o v e r i e s i n d i c a t e t h a t t h e r e i s l i t t l e m i x i n g between t h e two p o p u l a t i o n s on t h e i r summer and w i n t e r r a n g e s (Vermeer 1977). The w i n t e r range f o r t h e e a s t e r n p o p u l a t i o n s l i e s a l o n g t h e c o a s t a l r e g i o n s of t h e G u l f of M e x i c o and t h e e a s t c o a s t of M e x i c o ( S t r a i t and S l o a n 1975). The p r i n c i p a l w i n t e r i n g g r o u n d s f o r w h i t e p e l i c a n s t h a t b r e e d west of t h e Rocky M o u n t a i n s l i e a l o n g t h e c o a s t s of s o u t h e r n C a l i f o r n i a and w e s t e r n M e x i c o ( F i g . 4 ) . Seven r e c o v e r i e s of p e l i c a n s banded a t Stum Lake i n 1968 a l s o i n d i c a t e an autumn m i g r a t i o n t o w a r d s t h e s o u t h e r n C a l i f o r n i a c o a s t l i n e (Vermeer 1977). O t h e r c o l o n i e s west of t h e C o n t i n e n t a l D i v i d e t h a t a r e known t o m i g r a t e s o u t h and w i n t e r a l o n g t h e west c o a s t s of C a l i f o r n i a and M e x i c o i n c l u d e p e l i c a n s f r o m G r e a t S a l t L a k e , U t a h ( B e h l e 1958), P y r a m i d L a k e , Nevada ( K r i d l e r 1960) and t h o s e from t h e Warner V a l l e y , Oregon (S. E l e f a n t p e r s . comm.). P e l i c a n s of t h e Y e l l o w s t o n e Lake c o l o n y , Wyoming, s i t u a t e d i n t h e Rocky M o u n t a i n s , f l y m a i n l y t o s o u t h e r n C a l i f o r n i a and t h e west c o a s t of M e x i c o d u r i n g t h e i r f a l l m i g r a t i o n ; however some f l y t o Te x a s and e a s t e r n M e x i c o (Diem 1967). Figure 4 . Principal wintering areas for white pelicans west of the Rocky Mountains. 16 The n o r t h w e s t m i g r a t i o n d u r i n g t h e s p r i n g b e g i n s i n March and c o n t i n u e s u n t i l A p r i l or May (P a l m e r 1962). The m i g r a t o r y r o u t e t h r o u g h t h e w e s t e r n U n i t e d S t a t e s i s not c l e a r l y d e f i n e d , p r o b a b l y due t o t h e d i s p e r s a l of b i r d s t o t h e i r p a r t i c u l a r b r e e d i n g c o l o n i e s ( F i g . 5 ) . S i n c e p e l i c a n s no l o n g e r b r e e d i n W a s h i n g t o n , c o n s i s t e n t s p r i n g and f a l l m i g r a t i o n r e c o r d s from McNary W i l d l i f e Refuge i n s o u t h e r n W a s h i n g t o n i n d i c a t e t h a t t h e b i r d s f r o m Stum Lake p a s s t h r o u g h t h i s a r e a . F l o c k s of 20 o r more w h i t e p e l i c a n s have been r e c o r d e d d u r i n g t h e summer i n e a s t e r n W a s h i n g t o n ; however, t h e s e b i r d s a r e p r o b a b l y non-b r e e d e r s ( B r i t t e l 1976). N o n - b r e e d i n g p e l i c a n s have a l s o been o b s e r v e d d u r i n g t h e summer a t t h e McNary R e f u g e . The l a s t n e s t i n g r e c o r d s of white, p e l i c a n s i n W a s h i n g t o n o c c u r r e d d u r i n g t h e e a r l y 1930's. P r i o r t o t h a t p e r i o d , t h e y b r e d r e g u l a r l y i n e a s t e r n W a s h i n g t o n , p r i m a r i l y - i n t h e Moses Lake a r e a ( B r i t t e l 1976). The major m i g r a t o r y r o u t e o f w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a o c c u r s i n t h e Okanagan V a l l e y . The b i r d s c o n t i n u e t o t r a v e l n o r t h w e s t t h r o u g h t h e N i c o l a V a l l e y t o w a r d s t h e F r a s e r P l a t e a u ( F i g . 6 ) . P e l i c a n s have f r e q u e n t l y been o b s e r v e d r e s t i n g o v e r n i g h t a t Stump Lake (R. Howie P e r s . Comm.), a p p r o x i m a t e l y 35 km s o u t h of Kamloops, i n t h e N i c o l a V a l l e y . The c o a s t does not a p p e a r t o be a major m i g r a t o r y r o u t e f o r p e l i c a n s d u r i n g t h e s p r i n g or f a l l m i g r a t i o n . The s e v e r a l c o a s t a l s i g h t i n g s a r e g e n e r a l l y o l d e r r e c o r d s and u s u a l l y r e p r e s e n t s i n g l e b i r d s or v e r y s m a l l g r o u p s . In t h e lower m a i n l a n d , p e l i c a n s a r e c o n s i d e r e d as ' c a s u a l ' d u r i n g t h e summer, o n l y o c c u r r i n g one o r two t i m e s p e r decade ( C h e c k l i s t of Figure 5 . Migratory route of white pelicans breeding west of the Rocky Mountains. F i g u r e 6 . Migratory route of white p e l i c a n s i n B r i t i s h Columbia. 19 V a n c o u v e r B i r d s 1975). The a p p r o x i m a t e t i m e of a r r i v a l o f t h e b i r d s g e n e r a l l y c o i n c i d e s w i t h t h e s p r i n g m e l t . The p e l i c a n s f i r s t a r r i v e i n the C h i l c o t i n r e g i o n i n m i d - A p r i l , one t o two weeks b e f o r e t h e i c e l e a v e s Stum L a k e . R e g u l a r s i g h t i n g s have been r e c o r d e d a t A l k a l i Lake ( a b o u t 80 km s o u t h e a s t o f Stum La k e ) d u r i n g t h i s p e r i o d . The mean d a t e o f a r r i v a l f o r p e l i c a n s a t Stum Lak e (two b r e e d i n g s e a s o n s ) i s 17 A p r i l , w h i l e t h e mean d a t e o f i c e b r e a k -up a t t h e b r e e d i n g l a k e ( t h r e e s e a s o n s ) i s 4 May ( r e f e r t o S e c t i o n 6.3.1 f o r d e t a i l s ) . D u r i n g t h e summer, t h e p e l i c a n s u s e d s e v e r a l l a k e s on t h e F r a s e r P l a t e a u as f o r a g i n g s i t e s . E i g h t y - t h r e e p e r c e n t of w h i t e p e l i c a n s o b s e r v e d d u r i n g t h e summer (260 of t h e 315 p e l i c a n s s i g h t e d ) were w i t h i n 80 km of t h e b r e e d i n g l a k e ( r e f e r t o S e c t i o n 4.3.1 f o r d e t a i l s ) . The l a t e s t d a t e t h a t p e l i c a n s have been r e c o r d e d ' i n t h e a r e a was 14 September d u r i n g 1973. F a l l m i g r a t i o n s i g h t i n g s i n d i c a t e t h a t t h e b i r d s g e n e r a l l y f o l l o w t h e i r s p r i n g m i g r a t o r y r o u t e . One p e l i c a n banded a t Stum Lake was s h o t n e a r V a n c o u v e r i n O c t o b e r 1968, w h i l e two o t h e r s were r e c o v e r e d i n December i n s o u t h e r n W a s h i n g t o n and c e n t r a l U t a h (Vermeer 1970b). 20 3.3.2 H i s t o r y , P r e s e n t S t a t u s , and P o p u l a t i o n T r e n d s The w h i t e p e l i c a n has been a r e g u l a r b r e e d e r i n B r i t i s h C o l u m b i a f o r many y e a r s . The f i r s t r e c o r d e d i n f o r m a t i o n f o r t h e s p e c i e s i n B.C. o c c u r r e d i n 1892 from t h e C a r i b o o - C h i l c o t i n r e g i o n of t h e p r o v i n c e . P e l i c a n s were r e p o r t e d by Rhoads (1893) as common d u r i n g m i g r a t i o n on Lac La Hache (110 km from Stum L a k e ) . S e v e r a l s p r i n g and f a l l s i g h t i n g s were r e c o r d e d a l o n g t h e Okanagan V a l l e y i n t h e e a r l y 1900's (B.C. P r o v i n c i a l Museum R e c o r d s ) . Munro (1930) r e p o r t e d t h e s p e c i e s a s o c c u r r i n g r e g u l a r l y d u r i n g m i g r a t i o n s i n t h e N i c o l a V a l l e y i n t h e l a t e 1920's. In a s u r v e y of w h i t e p e l i c a n b r e e d i n g c o l o n i e s i n N o r t h A m e r i c a from 1931 t o 1932, Thompson (1933) l i s t e d s e v e r a l l o c a l i t i e s i n B.C. where p e l i c a n s were t h o u g h t t o have b r e d . T h e s e i n c l u d e d Swan ( P a n t a g e ) , S u c k e r , Anahim, P u n t z i , T z e n z a i c u t , and P e l i c a n L a k e s . These l a k e s a r e a l l remote and t h e r e has been no c o n f i r m a t i o n t h a t p e l i c a n s a c t u a l l y n e s t e d a t any o f them. The f i r s t c o n f i r m e d b r e e d i n g o b s e r v a t i o n f o r w h i t e p e l i c a n s i n B.C. o c c u r r e d on 1 J u l y , 1939 a t Stum L a k e . Eggs and young were p h o t o g r a p h e d a t t h a t t i m e , a l t h o u g h numbers o f n e s t s and young were not r e c o r d e d . S i n c e t h a t t i m e , Stum L a k e has r e m a i n e d t h e o n l y known b r e e d i n g c o l o n y of w h i t e p e l i c a n s i n B.C. No f u r t h e r r e c o r d s o f n e s t i n g e x i s t u n t i l t h e b r e e d i n g s e a s o n of 1950. P e l i c a n eggs were c o l l e c t e d t w i c e d u r i n g 1950, but p o p u l a t i o n c o u n t s were not made. 21 In 1953, I.McT. Cowan made t h e f i r s t p o p u l a t i o n c e n s u s a t t h e Stum Lake c o l o n y and c o u n t e d 140 n e s t s . S i x y e a r s l a t e r , L.G. Sugden o b s e r v e d t h e c o l o n y and c o u n t e d 59 e ggs, 70 l i v e young, and 9 dead young on two i s l a n d s . He e s t i m a t e d 100 t o 150 a d u l t s on t h e l a k e but d i d not r e c o r d t h e number of n e s t s . In l a t e May of i 9 6 0 , G. Van T e t s v i s i t e d t h e n e s t i n g i s l a n d and f o u n d i t d e s e r t e d w i t h many b r o k e n p e l i c a n e g g s . He e s t i m a t e d t h e t o t a l number o f abandoned n e s t s a t 239. Numbers o f n e s t s were n o t c o u n t e d i n 1963, a l t h o u g h two c o l o n i e s were r e p o r t e d t o have 130 and 150 a d u l t s ( L i e s and B e h l e 1966). In 1964, a minimum c o u n t of 146 n e s t s was o b t a i n e d by t h r e e s u r v e y i n g p a r t i e s . N e s t c o u n t s i n 1964 a r e not c l e a r s i n c e s e v e r a l c o n f l i c t i n g r e c o r d s e x i s t . I t a p p e a r s , however, t h a t t h e r e were a t l e a s t 146 n e s t s d u r i n g t h a t y e a r . R.T. W r i g h t v i s i t e d t h e c o l o n y i n 1967 and 1969, and f o u n d 153 and 87 n e s t s r e s p e c t i v e l y on one i s l a n d . In b o t h y e a r s , p e l i c a n s were f o r c e d t o l e a v e t h e i r n e s t s d u r i n g t h e n e s t s u r v e y . K. Vermeer banded 45 of t h e 83 n e s t l i n g s i n 1968 and c o u n t e d 85 n e s t s . From 1971 t o 1974, G.R. Ryder was a p a r k warden a t t h e c o l o n y and f o u n d 104, 116, 118, and 108 n e s t s r e s p e c t i v e l y . He was t h e f i r s t t o r e c o r d t h e s u r v i v a l of young i n t h e c o l o n y . The t o t a l a d u l t p o p u l a t i o n was a l s o e s t i m a t e d d u r i n g t h o s e y e a r s . My s t u d y e x t e n d e d from 1977 t o 1980. T o t a l numbers o f n e s t s f o r t h e s e f o u r y e a r s were 86, 105, 96, and 120. The h i s t o r i c a l abundance of t h e c o l o n y a t Stum Lake i s i l l u s t r a t e d i n F i g u r e 7 w h i c h summarizes t h e number of a d u l t s and n e s t s r e c o r d e d from 1953 t o 1980. 22 Figure 7. Number of nests and pelicans'.observed at Stum Lake, B r i t i s h Columbia (in ]959 exact numbers are not available and a range i s given). 23 The t r e n d i n t h e p o p u l a t i o n i s more a c c u r a t e u s i n g numbers of n e s t s r a t h e r t h a n a d u l t s . The number o f a d u l t s p r e s e n t a t t h e c o l o n y f l u c t u a t e s d a i l y and c h a n g e s d r a m a t i c a l l y w i t h i n a s i n g l e b r e e d i n g s e a s o n . Numbers o f n e s t s however change o n l y s l i g h t l y d u r i n g t h e i n c u b a t i o n and b r o o d i n g p e r i o d s , and t h e r e f o r e p r o v i d e a b e t t e r i n d e x o f t h e r e p r o d u c t i v e l y - a c t i v e a d u l t p o p u l a t i o n . A l t h o u g h th e c o l o n y i s g e n e r a l l y l o w e r i n numbers of n e s t s i n r e c e n t y e a r s compared w i t h t h e 3 e a r l i e s t b r e e d i n g r e c o r d s (1953, 1964, and 1967), a l o n g - t e r m d e c l i n i n g t r e n d i s not e v i d e n t i n t h e p o p u l a t i o n . From 1967 t o 1968, t h e r e was a s u b s t a n t i a l d r o p i n t h e number of n e s t s a t Stum L a k e . D u r i n g t h e y e a r s from 1968 t o 1974, t h e c o l o n y f l u c t u a t e d m i l d l y , but g e n e r a l l y r e m a i n e d r e l a t i v e l y s t a b l e a t a b o u t 103 ± 14 n e s t s / y e a r . D u r i n g my s t u d y p e r i o d from 1977 t o 1980, t h e p o p u l a t i o n a p p e a r s t o have i n c r e a s e d s l i g h t l y . 3.4 D i s c u s s i o n The w i n t e r i n g a r e a s of w h i t e p e l i c a n s b r e e d i n g a t Stum Lake a p p e a r t o l i e a l o n g t h e c o a s t s of s o u t h e r n C a l i f o r n i a and w e s t e r n M e x i c o . The m a j o r i t y of w h i t e p e l i c a n s i g h t i n g s a l o n g t h e c o a s t o c c u r r e d i n b r a c k i s h e s t u a r i e s and p r o t e c t e d b a y s , m a r s h e s , and l a g o o n s . The San F r a n c i s c o Bay a r e a a p p e a r e d t o be t h e most i m p o r t a n t w i n t e r i n g a r e a a l o n g t h e C a l i f o r n i a c o a s t . However, t h e m a j o r w i n t e r i n g a r e a s f o r w h i t e p e l i c a n s b r e e d i n g west of the Rocky M o u n t a i n s a r e i n t h e G u l f of C a l i f o r n i a and e x t e n d s o u t h t o G u a d a l a j a r a , M e x i c o . The few i n l a n d s i g h t i n g s o f w i n t e r i n g w h i t e p e l i c a n s u s u a l l y - were i n marshes and l a g o o n s w i t h i n N a t i o n a l W i l d l i f e R e f u g e s . 24 M i g r a t o r y r o u t e s of w h i t e p e l i c a n s t h r o u g h t h e U n i t e d S t a t e s a r e n ot c l e a r , and p e l i c a n s may f o l l o w two g e n e r a l f l y - w a y s . One r o u t e seems t o e x t e n d n o r t h w a r d f r o m w i n t e r i n g a r e a s i n t h e San F r a n c i s c o Bay a r e a t o i n l a n d and n o r t h e r n s t a t e s . The o t h e r f l y - w a y a p p e a r s t o be more i n l a n d from t h e G u l f o f C a l i f o r n i a , n o r t h w a r d t h r o u g h A r i z o n a , Nevada, U t a h , and I d a h o . T h i s l a t t e r f l y - w a y c l o s e l y r e s e m b l e s t h e r o u t e t a k e n by p e l i c a n s from Stum Lake as i n d i c a t e d from V e r m e e r ' s (1977) s e v e n b a n d i n g r e t u r n s . The m i g r a t o r y r o u t e t h r o u g h B r i t i s h C o l u m b i a i s w e l l d e f i n e d . The m a j o r i t y o f t h e b i r d s t r a v e l t h r o u g h t h e Okanagan and N i c o l a V a l l e y s , t h e n n o r t h w e s t t o w a r d s t h e F r a s e r P l a t e a u . T h i s r o u t e t h r o u g h B r i t i s h C o l u m b i a i s a l s o a major f l y - w a y f o r Canada geese and o t h e r w a t e r f o w l s p e c i e s (Myres and C a n n i n g s 1971 ) . White p e l i c a n s u n d o u b t e d l y have been r e g u l a r b r e e d e r s i n B r i t i s h C o l u m b i a f o r many y e a r s . Rhoads (1892) l i s t e d w h i t e p e l i c a n s a s 'common' d u r i n g m i g r a t i o n on Lac La Hache a l m o s t a c e n t u r y ago. D u r i n g t h e l a s t d ecade t h e c o l o n y a p p e a r s t o have been s t a b l e , and may be i n c r e a s i n g . However, numbers of b r e e d i n g a d u l t s have not y e t r e a c h e d t h e l e v e l s r e c o r d e d p r i o r t o 1968. F a c t o r s t h a t w a r r a n t i t s e n d a n g e r e d s t a t u s i n B r i t i s h C o l u m b i a under p r e s e n t l e g i s l a t i o n i n c l u d e : t h e v e r y r e s t r i c t e d b r e e d i n g r a n g e o f t h e p o p u l a t i o n , ( o n l y one l o c a t i o n i n B r i t i s h C o l u m b i a ) ; t h e s m a l l s i z e of t h e p o p u l a t i o n , ( l e s s t h a n 300 i n d i v i d u a l s ) ; t h e low r e p r o d u c t i v e p o t e n t i a l of t h e p o p u l a t i o n , (age a t f i r s t b r e e d i n g i s t h r e e y e a r s ) ; and t h e t a x o n o m i c i m p o r t a n c e of t h e p o p u l a t i o n , ( o n l y r e p r e s e n t a t i v e of the F a m i l y P e l e c a n i d a e i n B r i t i s h C o l u m b i a ) . 25 CHAPTER 4. FORAGING DISTRIBUTION, HABITAT CHARACTERISTICS, AND FOOD HABITS OF WHITE PELICANS IN BRITISH COLUMBIA 4 . 1 I n t r o d u c t i o n The f e e d i n g h a b i t s o f w h i t e p e l i c a n s i n N o r t h A m e r i c a have been p o o r l y u n d e r s t o o d f o r many y e a r s . T h i s l a c k of knowledge p r o b a b l y has been an i n d i r e c t but i m p o r t a n t f a c t o r c o n t r i b u t i n g t o t h e i r d e c l i n e i n N o r t h A m e r i c a . S i n c e t h e mid-1800's p e l i c a n s have been p e r s e c u t e d r e p e a t e d l y on t h e i r n e s t i n g g r o u n d s by p e o p l e who b e l i e v e d t h e b i r d s consumed l a r g e numbers of i m p o r t a n t game f i s h . Henshaw (1879) r e p o r t e d t h a t w h i t e p e l i c a n c o l o n i e s i n t h e s o u t h w e s t e r n U n i t e d S t a t e s were c o n t i n u a l l y h a r a s s e d f o r t h i s r e a s o n . At Y e l l o w s t o n e Lake, Wyoming, t h e w h i t e p e l i c a n p o p u l a t i o n was c o n t r o l l e d from 1923 t o 1932 i n an e f f o r t t o r e d u c e t h e b i r d s ' impact on t h e number of t r o u t i n t h e l a k e (Anon. 1932). A c t i n g under t h e o r d e r s from t h e Park S u p e r i n t e n d e n t , two r a n g e r s d e s t r o y e d eggs and c l u b b e d young t o d e a t h . D u r i n g 1931, t h e Montana Government removed s t a t e p r o t e c t i o n f o r w h i t e p e l i c a n s and made an a p p e a l t o h u n t e r s t o e x t e r m i n a t e t h e b i r d s (Anon. 1932). A Montana newspaper, d e s c r i b i n g t h e b i r d s , s t a t e d : " M e a s u r i n g some seven f e e t of wingspan on an a v e r a g e , t h e b i r d s not o n l y e a t f i s h f o r f o o d and s t o r e o t h e r s f o r s h o r t t i m e s i n t h e i r b e a k s , but k i l l f i s h f o r t h e p u r e l o v e of k i l l i n g . " 26 In Canada, t h e s i t u a t i o n r e m a i n e d much t h e same as i n t h e U n i t e d S t a t e s . In 1964, f i s h e r m e n c a u s e d w h i t e p e l i c a n s n e s t i n g a t S u g g i L a k e , S a s k a t c h e w a n , t o c o m p l e t e l y abandon t h e i r c o l o n y f o r t h e s e a s o n ( C a r s o n 1966). T h i s c o l o n y was d i s t u r b e d a g a i n by f i s h e r m e n i n 1970, c a u s i n g t h e p e l i c a n s t o d e s e r t i t p e r m a n e n t l y (Vermeer 1971). A l t h o u g h w h i t e p e l i c a n s a r e " t h r e a t e n e d " i n Canada (Committee on t h e S t a t u s of E n d a n g e r e d W i l d l i f e i n Canada 1979) and m i g r a t e between U n i t e d S t a t e s and Canada, t h e y s t i l l a r e n o t p r o t e c t e d by t h e f e d e r a l M i g r a t o r y B i r d C o n v e n t i o n A c t of 1916. The b e l i e f t h a t t h e b i r d s consumed l a r g e q u a n t i t i e s of e c o n o m i c a l l y v a l u a b l e f i s h was t h e p r i m a r y r e a s o n f o r t h e i r e x c l u s i o n f r o m t h e a c t (Vermeer 1971). P r o t e c t i o n of t h e w h i t e p e l i c a n has been c o n s i d e r e d u n n e c e s s a r y b e c a u s e t h e s p e c i e s has no m onetary v a l u e . R e c e n t s t u d i e s have begun t o r e f i n e our c o n c e p t s of t h e f o o d h a b i t s and f o r a g i n g r e q u i r e m e n t s of w h i t e p e l i c a n s . I n v e s t i g a t i o n s have been c a r r i e d o ut a t Chase L a k e , N o r t h D a k o t a ( J o h n s o n 1976, L i n g l e and S l o a n 1980), G r e a t S a l t L a k e , U t a h (Low e t a_l. 1950), Lake of t h e Woods, O n t a r i o ( M a n s e l l 1965), P r i n c e A l b e r t N a t i o n a l P a r k , S a s k a t c h e w a n ( T r o t t i e r e_t a l . 1980), and B i r c h L a k e , A l b e r t a ( E a l e y 1979). The m a j o r i t y o f t h e s e s t u d i e s have shown t h a t w h i t e p e l i c a n s do not consume e c o n o m i c a l l y v a l u a b l e game f i s h , b u t c o a r s e f i s h i n s t e a d . In B r i t i s h C o l u m b i a , r e l a t i v e l y l i t t l e i s known c o n c e r n i n g t h e f o r a g i n g h a b i t s and a c t i v i t i e s o f w h i t e p e l i c a n s . 27 S p e c i f i c o b j e c t i v e s of t h e f o r a g i n g a c t i v i t i e s s t u d y were: 1. To p r o v i d e i n f o r m a t i o n on t h e f o r a g i n g d i s t r i b u t i o n and movements of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a ; 2. To document t h e c h a r a c t e r i s t i c s of f o r a g i n g a r e a s , t o d e t e r m i n e s p e c i f i c h a b i t a t r e q u i r e m e n t s ; and, 3. To a n a l y s e f o o d h a b i t s o f p e l i c a n s n e s t i n g a t Stum L a k e . T h e s e o b j e c t i v e s were s e c o n d a r y t o my e f f o r t s t o document p e l i c a n numbers and p r o d u c t i v i t y . 4.2 Methods 4.2.1 F o r a g i n g D i s t r i b u t i o n o f White P e l i c a n s i n B r i t i s h C o l u m b i a I c o n d u c t e d 3 a e r i a l s u r v e y s of s e l e c t e d l a k e s on t h e F r a s e r P l a t e a u d u r i n g t h e 1977 b r e e d i n g s e a s o n (27 J u n e , 5 A u g u s t , 25 A u g u s t ) . The s u r v e y s were c o n d u c t e d t o d e t e r m i n e t h e f o r a g i n g and b r e e d i n g d i s t r i b u t i o n of w h i t e p e l i c a n s i n B.C. and t o f i n d p o t e n t i a l n e s t i n g h a b i t a t s u i t a b l e f o r m a n i p u l a t i o n ( r e f e r t o S e c t i o n 5 . 3.3). I s e l e c t e d l a k e s on t h e b a s i s of t h e i r d i s t a n c e from Stum L a k e , t h e abundance of f i s h , and t h e p r e s e n c e of i s l a n d s . I n i t i a l l y , B.C. F i s h and W i l d l i f e B r a n c h Lake S u r v e y s were u s e d t o d e t e r m i n e f i s h abundance, and a e r i a l p h o t o g r a p h s were u s e d t o l o c a t e l a k e s w i t h i s l a n d s . The m a j o r i t y o f t h e l a k e s s u r v e y e d were n o r t h of Highway 20 between R i s k e C r e e k and Anahim L a k e . S u r v e y s were f l o w n between 11:00 and 15:00 h o u r s u s i n g f i x e d - w i n g a i r c r a f t ( C e s s n a 185) a t an a l t i t u d e o f 28 a p p r o x i m a t e l y 350 m. Two o b s e r v e r s r e c o r d e d t i m e , l o c a t i o n , number o f b i r d s , and h a b i t a t c h a r a c t e r i s t i c s of t h e l a k e s and i s l a n d s . H a b i t a t f e a t u r e s n o t e d i n c l u d e d t h e w ater d e p t h between t h e i s l a n d and t h e m a i n l a n d , e s t i m a t e d v i s u a l l y from t h e a i r c r a f t or o b t a i n e d from p r e v i o u s F i s h and W i l d l i f e Lake S u r v e y s , and p r e s e n c e o r a b s e n c e of l o a f i n g s i t e s ( s a n d b a r s , i s l a n d s , e t c . ) . The f o r a g i n g d i s t r i b u t i o n was mapped u s i n g t h e d a t a c o l l e c t e d from 3 a e r i a l s u r v e y s and from o l d e r r e c o r d s of summer s i g h t i n g s (1 June t o 30 A u g u s t ) o b t a i n e d from t h e B.C. P r o v i n c i a l Museum. 4.2.2 Movements of P e l i c a n s D u r i n g t h e s p r i n g ( 1.979 and 1980) and summer (1977 and 1978) s u r v e y s , I r e c o r d e d movements of p e l i c a n s d e p a r t i n g from t h e n e s t i n g l a k e . The measurements were r e c o r d e d t o p r o v i d e a d d i t i o n a l i n s i g h t i n t o t h e l o c a t i o n of f o r a g i n g a r e a s f o r w h i t e p e l i c a n s on t h e F r a s e r P l a t e a u . I assumed t h a t t h e s e p e l i c a n movements were p r i m a r i l y a s s o c i a t e d w i t h f o r a g i n g e x c u r s i o n s b e c a u s e p e l i c a n s d i d not f o r a g e a t Stum L a k e . I r e c o r d e d t h e t i m e , number of b i r d s , and t h e d i r e c t i o n of f l i g h t . 29 4.2.3 F o o d H a b i t A n a l y s e s In l a t e A u g u s t 1978, a f t e r t h e p e l i c a n s had l e f t t h e n e s t i n g i s l a n d , I examined t h e i s l a n d f o r r e m a i n s of f o o d t h a t had been p a r t i a l l y consumed by t h e b r e e d i n g b i r d s . S i x r i g h t - o p e r c u l a r b o nes, one r i g h t c l e i t h r u m bone, two c a u d a l f i n bones, and 133 v e r t e b r a e were c o l l e c t e d . The bones were i d e n t i f i e d a t t h e Department of Z o o l o g y ' s O e s t e o l o g y Museum, U.B.C. 4.3 R e s u l t s 4.3.1 F o r a g i n g D i s t r i b u t i o n of White P e l i c a n s i n B r i t i s h C o l u m b i a In B r i t i s h C o l u m b i a t h e f o r a g i n g r a n g e of w h i t e p e l i c a n s d u r i n g t h e summer was c h i e f l y c o n f i n e d t o t h e l a k e s of t h e F r a s e r P l a t e a u ( F i g . 8 ) . The p e l i c a n s d i d not f o r a g e a t Stum L a k e . A p p e n d i c e s I and I I c o n t a i n summer s i g h t i n g s r e c o r d e d d u r i n g 3 a e r i a l s u r v e y s i n 1977 and f o r a g i n g r e c o r d s from t h e p e r i o d 1920 t o 1978 o b t a i n e d from t h e B.C. P r o v i n c i a l Museum, r e s p e c t i v e l y . E i g h t y - t h r e e p e r c e n t (260 p e l i c a n s ) o f a l l w h i t e p e l i c a n s s i g h t e d d u r i n g t h e summer on t h e F r a s e r P l a t e a u ( not i n c l u d i n g p e l i c a n s s i g h t e d a t Stum Lake o r d u r i n g m i g r a t i o n s ) were w i t h i n 80 km o f Stum Lake ( F i g . 9 ) . The o t h e r s i g h t i n g s i n B r i t i s h C o l u m b i a r e c o r d e d d u r i n g t h e b r e e d i n g s e a s o n , e x c l u d i n g t h o s e on t h e F r a s e r P l a t e a u , o c c u r r e d a l o n g t h e Okanagan V a l l e y (4) and s o u t h e r n c o a s t l i n e ( 5 ) . Th e s e 9 s i g h t i n g s a r e a l l g r e a t e r t h a n 300 km from Stum Lake and p r o b a b l y r e p r e s e n t t h e l e s s c o n s t r a i n e d movements o f n o n - b r e e d i n g s u b - a d u l t s (one and Figure 8. Foraging sightings of white pelicans i n B r i t i s h Columbia. Figure 9. Cumulative frequency of pelican sightings in relation to distance from the colony. 32 two y e a r o l d s ) from Stum Lake o r o t h e r c o l o n i e s s o u t h of B r i t i s h C o l u m b i a . F o r example, a n o n - b r e e d i n g 2-year o l d p e l i c a n , banded and wing-marked i n t h e Warner V a l l e y , O r e g o n , was o b s e r v e d a t Stum Lake on 22 June 1977. T h i s s u b - a d u l t was a p p r o x i m a t e l y 1000 km from i t s n a t a l c o l o n y . D u r i n g t h e 1977 and 1978 b r e e d i n g s e a s o n s , f o r a g i n g p e l i c a n s t r a v e l l e d d i s t a n c e s r a n g i n g from 3 km, one way, ( B e a v e r L a k e ) t o 142 km, one way (Towdystan L a k e ) . The l a k e u s e d most c o n s i s t e n t l y f o r f e e d i n g d u r i n g t h e b r e e d i n g s e a s o n was C h i l c o t i n L a k e , 71 km west of t h e c o l o n y . T h i s heavy use by p e l i c a n s of C h i l c o t i n L a k e , i n d i c a t e d by my a e r i a l s u r v e y s , was l a t e r c o n f i r m e d by E. Hennan ( P e r s . Comm.) who o b s e r v e d t h e b i r d s t h e r e d a i l y t h r o u g h o u t " t h e summer of 1978. The ' f o r a g i n g home r a n g e ' f o r p e l i c a n s b r e e d i n g a t Stum Lake was d e f i n e d as t h e a r e a e n c o m p a s s i n g t h e l a k e s t h a t had mo d e r a t e t o heavy use by p e l i c a n s ( F i g . 10). Lake i m p o r t a n c e was d e f i n e d by t h e number and f r e q u e n c y of use by p e l i c a n s . L a k e s were c l a s s i f i e d as h a v i n g l i g h t , m o d e r a t e , or heavy u s e : l i g h t u s e , o n l y one or two p e l i c a n s s i g h t e d on t h e l a k e ; m o derate use, between t h r e e and 14 p e l i c a n s r e p o r t e d on t h e l a k e , n ot n e c e s s a r i l y d u r i n g e v e r y s u r v e y ; and heavy use, a t o t a l of 15 o r more p e l i c a n s o b s e r v e d a n d / o r b i r d s a l w a y s p r e s e n t . The l a k e s of p r i m a r y i m p o r t a n c e f o r f o r a g i n g p e l i c a n s d u r i n g t h e summer were B e a v e r and A l e x Graham l a k e s t o t h e s o u t h , R o s i t a and T a u t r i l a k e s t o t h e n o r t h , and t h e A l e x i s Lake c h a i n , P a l m e r , and C h i l c o t i n l a k e s t o t h e west. SCALE: kilometers I I 1 I 1 0 20 40 Figure 10. Surmer foraging range of white pelicans breeding at Stum Lake, British Columbia. LO LO 34 4.3.2 Movements of P e l i c a n s The movements of p e l i c a n f l o c k s d e p a r t i n g from Stum Lake were s t u d i e d t o p r o v i d e a d d i t i o n a l i n f o r m a t i o n c o n c e r n i n g i m p o r t a n t f o r a g i n g a r e a s d u r i n g t h e b r e e d i n g s e a s o n . To d e t e r m i n e i f s e a s o n a l d i f f e r e n c e s e x i s t e d , movements were c l a s s i f i e d a s o c c u r r i n g p r i o r t o o r a f t e r b r e a k - u p a t Stum L a k e . D u r i n g t h e s p r i n g , w h i l e i c e c o v e r e d Stum Lake, I r e c o r d e d t h e v a n i s h i n g b e a r i n g s of 283 p e l i c a n s i n 26 f l o c k s a s t h e y l e f t Stum L a k e . F l o c k s i z e s r a n g e d f r o m s o l i t a r y i n d i v i d u a l s t o one v e r y l a r g e f l o c k of 48 b i r d s ( a v e r a g e f l o c k s i z e was 10.9 b i r d s ) . The mean d i r e c t i o n of movement d u r i n g t h e s p r i n g f o r th e 26 f l o c k s o b s e r v e d l e a v i n g Stum Lake was 108° ( F i g . 11-A). T r a v e l d u r i n g t h e s p r i n g ( p r i o r t o i c e b r e a k u p ) was s t r o n g l y d i r e c t i o n a l , u s i n g R a y l e i g h ' s t e s t (P < 0.001; F i g . 11-A). Movements b a s e d on t h e 283 i n d i v i d u a l p e l i c a n s were s i m i l a r and a l s o h i g h l y d i r e c t i o n a l . D u r i n g t h e summer ( a f t e r i c e b r e a k - u p ) , I o b s e r v e d 315 p e l i c a n s i n 50 f l o c k s d e p a r t i n g f r o m Stum L a k e . F l o c k s r a n g e d from 1 t o 25 b i r d s , w i t h an a v e r a g e f l o c k s i z e o f 6.3 b i r d s . The mean d i r e c t i o n of t r a v e l d u r i n g t h e summer was 289° from Stum Lake and was a l s o s i g n i f i c a n t l y d i r e c t i o n a l (P < 0.001; F i g . 11-B). A n a l y s e s of t h e 315 i n d i v i d u a l s p r o v i d e d s i m i l a r r e s u l t s . 35 (180*1 S Figure 11. Vanishing bearings of white pelicans departing from Stum Lake. A) Mean direction of white pelican spring movements, 1979 and 1980; B) Mean direction of white pelican summer movements, 1977 and 1978. 36 4.3.3 H a b i t a t C h a r a c t e r i s t i c s of F o r a g i n g L a k e s White p e l i c a n s have been o b s e r v e d f e e d i n g on r e l a t i v e l y few l a k e s , compared w i t h t h e h u n d r e d s of l a k e s t h a t l i e on t h e F r a s e r P l a t e a u . S e v e n t y - e i g h t p e r c e n t (60 of 77 b i r d s ) of t h e p e l i c a n s s i g h t e d d u r i n g t h e 3 a e r i a l s u r v e y s were o b s e r v e d on o n l y two l a k e s . I t seems a p p a r e n t t h a t p e l i c a n s a r e s e l e c t i v e i n t h e i r c h o i c e of f o r a g i n g l a k e s , as 15 or more l a k e s o f c o m p a r a b l e s i z e o c c u r w i t h i n t h e i r r a n g e . One i m p o r t a n t f a c t o r i n t h e s e l e c t i o n of f o r a g i n g s i t e s was t h e d i s t a n c e between t h e f o r a g i n g s i t e and t h e c o l o n y . In g e n e r a l , l a k e s f u r t h e r f r o m t h e c o l o n y were n o t as f r e q u e n t l y u s e d as l a k e s c l o s e r t o t h e c o l o n y . O n l y 17% (53 of 315 b i r d s ) o f a l l p e l i c a n s s i g h t e d d u r i n g t h e summer i n B r i t i s h C o l u m b i a , were r e c o r d e d a t d i s t a n c e s g r e a t e r t h a n 80 km f r o m Stum Lake ( F i g . 9 ) . The abundance of f o o d a l s o a p p e a r s t o have a major i n f l u e n c e on t h e s e l e c t i o n o f f o r a g i n g s i t e s . D a t a from t h e B r i t i s h C o l u m b i a F i s h and W i l d l i f e B r a n c h Lake S u r v e y s s u g g e s t t h a t f o r a g i n g p e l i c a n s from t h e Stum Lake c o l o n y s e l e c t l a k e s w i t h a g r e a t e r abundance of f o o d ( T a b l e 1 ) . A l t h o u g h C h i l c o t i n Lake was not s u r v e y e d by t h e B r i t i s h C o l u m b i a F i s h and W i l d l i f e B r a n c h , t h e l a k e i s w e l l known f o r i t s abundant s u p p l y of t r o u t and c o a r s e f i s h ( J . L e g g a t P e r s . Comm.). 37 TABLE 1. Food abundance of several lakes and frequency of foraging by white pelicans from Stum Lake, B.C. Lake Food Abundance 1 (Kg) Pelican U t i l i z a t i o n 2 C h i l c o t i n Palmer Alex Graham Taharti Beaver Stum very high (unsurveyed) 81.5 56.0 32.0 28.0 2.4 high moderate moderate low low n i l 1 Calculated from B.C. Fish and W i l d l i f e Lake Surveys (Nets set for a 12 hour period) 2 Lake use by white pelicans determined from a e r i a l surveys conducted during 1977. (See Appendix I) 38 Not o n l y d i d p e l i c a n s s e l e c t l a k e s w i t h an o v e r a l l h i g h abundance of f i s h , but t h e y a l s o s e l e c t e d l a k e s o f f e r i n g a g r e a t e r a v a i l a b i l i t y of f i s h , t h a t i s , s h a l l o w l a k e s . F o r example, C h i l c o t i n L a k e , a t w h i c h 40 o f t h e 77 f e e d i n g o b s e r v a t i o n s were r e c o r d e d , i s v e r y s h a l l o w . Mean d e p t h o f t h e l a k e i s a b o u t 1 t o 2 m and f i s h a r e h i g h l y a c c e s s i b l e t o a s u r f a c e - f e e d i n g b i r d . The m a j o r i t y o f p e l i c a n s o b s e r v e d f o r a g i n g d u r i n g 1977 and 1978 were i n s h a l l o w w ater c l o s e t o s h o r e . At C h i l c o t i n L a k e , p e l i c a n s u s u a l l y f o r a g e d i n t h e s h a l l o w s a l o n g t h e s h o r e l i n e , a t c r e e k mouths, and o c c a s i o n a l l y swam up t h o s e c r e e k s . A n o t h e r i m p o r t a n t component o f t h e f o r a g i n g h a b i t a t was t h e p r e s e n c e of ' l o a f i n g ' s i t e s . G r o u p s of 3 t o 20 b i r d s f r e q u e n t l y u t i l i z e d s u c h a r e a s f o r r e s t i n g and p r e e n i n g a t C h i l c o t i n and R o s i t a L a k e s . I t was not d e t e r m i n e d whether t h e s e were us e d as n i g h t r o o s t s ( p e l i c a n s from Stum Lake d i d s t a y away from t h e b r e e d i n g c o l o n y f o r p e r i o d s g r e a t e r t h a n 24 h r ) . The most commonly u s e d l o a f i n g s i t e s were t h e d e l t a s and sand b a r s a t r i v e r mouths. In a l l c a s e s , t h e s e l o a f i n g s i t e s were low and f l a t and had l i t t l e o r no v e g e t a t i o n , t h e r e b y g i v i n g t h e b i r d s an u n o b s t r u c t e d view of t h e s u r r o u n d i n g s . 39 4.3.4 Food H a b i t s W h i t e p e l i c a n s b r e e d i n g a t Stum Lake a p p e a r t o be u t i l i z i n g p r i m a r i l y non-game o r ' c o a r s e f i s h ' as t h e i r major f o o d s o u r c e . The s i x r i g h t - o p e r c l e s , one c l e i t h r u m , and two c a u d a l f i n s d i s c o v e r e d on t h e b r e e d i n g i s l a n d were a l l i d e n t i f i e d as bones from s u c k e r ( C a t o s t o m u s s p p . ) , p r o b a b l y l a r g e s c a l e s u c k e r (C. m a c r o c h e i l u s ) . S e v e r a l v e r t e b r a e of n o r t h e r n s q u a w f i s h ( P t y c h o c h e i l u s o r e g o n e n s i s ) were a l s o p r e s e n t among t h e bone s a m p l e s . A minimum number o f 7 f i s h were r e c o r d e d (6 s u c k e r and 1 n o r t h e r n s q u a w f i s h ) . They were e s t i m a t e d t o be between 30 and 40 cm l o n g ( J . D . M c P h a i l p e r s . comm.). Bones f r o m game s p e c i e s ( t r o u t , c h a r , e t c . ) were not f o u n d i n t h e sample. 4.4 D i s c u s s i o n The m a j o r i t y o f w h i t e p e l i c a n summer f o r a g i n g s i g h t i n g s i n B r i t i s h C o l u m b i a o c c u r r e d on t h e F r a s e r P l a t e a u . P e l i c a n s n e s t i n g a t Stum Lake f o r a g e d on l a k e s r a n g i n g from 3 km t o 142 km d i s t a n t (one way). The one-way t r a v e l l i n g d i s t a n c e s t o f o r a g i n g a r e a s f o r t h e Stum Lake c o l o n y a r e s i m i l a r t o t h o s e r e c o r d e d f o r o t h e r w h i t e p e l i c a n c o l o n i e s i n N o r t h A m e r i c a . One-way f o r a g i n g d i s t a n c e s a t G r e a t S a l t L a k e , U t a h , r a n g e d from 48 t o 160 km ( B e h l e 1958) and t h o s e a t B i r c h L a k e , A l b e r t a , r a n g e d from 30 t o 69 km ( E a l e y 1979). On t h e b a s i s of f i s h t a g r e c o v e r i e s , J o h n s o n (1976) f o u n d t h a t one-way f o r a g i n g d i s t a n c e s f o r t h e Chase L a k e , N o r t h D a k o t a , c o l o n y r a n g e d from 50 t o 307 km. However, 28 o f t h e 31 f i s h t a g s r e c o v e r e d (90%) had t h e i r o r i g i n w i t h i n 127 km of t h e c o l o n y . 40 D u r i n g t h e s p r i n g and summer, d r a m a t i c d i f f e r e n c e s were r e c o r d e d i n t h e movements of p e l i c a n f l o c k s d e p a r t i n g f r o m Stum L a k e . D u r i n g t h e s p r i n g ( p r i o r t o i c e b r e a k - u p ) t h e mean d i r e c t i o n o f movement from Stum Lake was 108°, w h i l e t h e mean d i r e c t i o n o f movement d u r i n g t h e summer ( a f t e r i c e b r e a k - u p ) was 289° from Stum L a k e . The d i f f e r e n c e i n t h e p r e f e r r e d f l i g h t d i r e c t i o n s s u g g e s t a t l e a s t two e x p l a n a t i o n s . D u r i n g t h e s p r i n g , t h e l o w e r e l e v a t i o n l a k e s t o t h e s o u t h e a s t may become f r e e of i c e s o o n e r t h a n o t h e r l a k e s i n t h e s u r r o u n d i n g a r e a . The c l o s e s t l o w e r e l e v a t i o n l a k e s ( a p p r o x i m a t e l y 945 m e l e v a t i o n ) a r e i n t h e d i r e c t i o n of t h e o b s e r v e d s p r i n g movements and a r e o n l y 35 km from Stum L a k e . T h e s e l o w e r l a k e s , s u c h as Meldrum, Knox, D e s t e r , and N a t s y L a k e s , may p r o v i d e an i m p o r t a n t f o o d s o u r c e p r i o r t o t h e e n e r g y demanding p e r i o d s of c o u r t s h i p and egg l a y i n g . I n o t h e r w a t e r b i r d s c l u t c h s i z e s a r e known t o v a r y i n r e l a t i o n t o f o o d s u p p l y (Klomp 1970, B e n g s t o n 1971, R a v e l i n g 1979). T h e r e f o r e , i t i s p o s s i b l e t h a t t h e s e l a k e s t o t h e s o u t h e a s t of Stum Lake c o u l d have a d i r e c t i n f l u e n c e on t h e o v e r a l l p r o d u c t i v i t y of t h e c o l o n y . A s e c o n d e x p l a n a t i o n f o r t h e s o u t h e a s t e r l y f o r a g i n g d i r e c t i o n d u r i n g t h e s p r i n g i s t h a t i n t h a t r e g i o n l e s s t i m e may be r e q u i r e d f o r p e l i c a n s t o l o c a t e l a k e s f r e e of i c e . At t h i s t i m e , t h e b i r d s have j u s t p a s s e d t h r o u g h t h e s e a r e a s on t h e i r m i g r a t i o n t o Stum L a k e . 41 The c o m p l e t e r e v e r s a l of p r e f e r r e d f o r a g i n g d i r e c t i o n d u r i n g t h e summer p r o b a b l y r e s u l t s f r o m p e l i c a n s l o c a t i n g more p r o d u c t i v e f o r a g i n g l a k e s no l o n g e r c o v e r e d w i t h i c e . O b s e r v e d f l i g h t d i r e c t i o n s of p e l i c a n s d e p a r t i n g from Stum Lake d u r i n g t h e summer ( g e n e r a l l y n o r t h w e s t of t h e c o l o n y ) c o r r e l a t e v e r y w e l l w i t h a c t u a l f o r a g i n g s i g h t i n g s r e c o r d e d d u r i n g t h e a e r i a l s u r v e y s . The l a k e w i t h by f a r t h e g r e a t e s t use ( C h i l c o t i n L a k e ) , l i e s a p p r o x i m a t e l y 280° ( n o r t h w e s t ) from Stum L a k e . W h i t e p e l i c a n s b r e e d i n g a t Stum Lake a p p e a r e d t o be h i g h l y s e l e c t i v e i n t h e i r c h o i c e of f o r a g i n g l a k e s . Of t h e 26 l a k e s s u r v e y e d from t h e a i r , 78% (60 o f 77 b i r d s ) o f t h e t o t a l number of p e l i c a n s s i g h t e d were o b s e r v e d on o n l y two l a k e s . P e l i c a n s s e l e c t e d l a k e s w i t h an o v e r a l l h i g h abundance o f f i s h as w e l l as t h o s e l a k e s o f f e r i n g a g r e a t e r a v a i l a b i l i t y of f o o d , t h a t i s , l a k e s w i t h e x t e n s i v e l i t t o r a l a r e a s f o r f e e d i n g . P e l i c a n s o b s e r v e d f o r a g i n g o f t e n used s h a l l o w a r e a s c l o s e t o s h o r e l i n e and c r e e k mouths. D i n and E l t r i n g h a m (1974) o b s e r v e d A f r i c a n w h i t e p e l i c a n s (P. o n o c r o t a l u s ) f o r a g i n g i n t h i s manner and c o n c l u d e d t h a t t h e b i r d s were d r i v i n g f i s h i n t o s h a l l o w e r a r e a s where t h e y c o u l d be c a u g h t more e a s i l y . L o a f i n g s i t e s a p p e a r e d t o be an i m p o r t a n t component of t h e f o r a g i n g h a b i t a t . E a l e y (1979) f o u n d t h a t p e l i c a n s i n n o r t h e r n A l b e r t a s p e n t a g r e a t d e a l o f t h e i r t i m e l o a f i n g when away, from t h e b r e e d i n g c o l o n y . The m a j o r i t y o f t h e t i m e s p e n t l o a f i n g i n c l u d e d ' p r e e n i n g and r e s t i n g . A key c h a r a c t e r i s t i c of t h e l o a f i n g s i t e s a t C h i l c o t i n Lake was t h e a b s e n c e of v e g e t a t i o n on t h e i s l a n d s . D i n and E l t r i n g h a m (1974) f e l t t h a t t h e major f a c t o r i n t h e c h o i c e of an a r e a f o r l o a f i n g A f r i c a n w h i t e and 42 p i n k - b a c k e d p e l i c a n s (P. r u f e s c e n s ) was a f l a t a r e a which l a c k e d c o v e r t h a t m i g h t c o n c e a l t h e a p p r o a c h of p r e d a t o r s . They a l s o n o t e d t h a t t h e b i r d s would a v o i d s t e e p or h e a v i l y v e g e t a t e d a r e a s . Bone sa m p l e s c o l l e c t e d on t h e b r e e d i n g i s l a n d a t Stum Lak e were i d e n t i f i e d a s bones from s u c k e r and n o r t h e r n s q u a w f i s h . Remains f r o m game f i s h were n o t r e c o r d e d . T h e s e s p a r s e r e s u l t s s u p p o r t o t h e r f o o d h a b i t s t u d i e s of w h i t e p e l i c a n s i n N o r t h A m e r i c a . H a l l (1925) and Bond (1940) f o u n d t h a t w h i t e p e l i c a n s a t P y r a m i d L a k e , Nevada, consumed 97% and 89% non-game s p e c i e s r e s p e c t i v e l y . Low e_t a_l. (1950) d i d not p r o v i d e d a t a but s t a t e d t h a t p e l i c a n s a t G r e a t S a l t L a k e , U t a h , f e d a l m o s t e x c l u s i v e l y on non-game f i s h . P e l i c a n s a t Lake of the Woods, O n t a r i o , consumed 87% non-game s p e c i e s ( M a n s e l l 1965). S p e c i e s t a k e n by p e l i c a n s i n t h e s e s t u d i e s i n c l u d e d minnow, chub, s t i c k l e b a c k , b u l l h e a d , c a r p , p e r c h , l i n g , c a t f i s h , s u c k e r , and c r u s t a c e a n s . B o t h f i s h s p e c i e s f o u n d on t h e b r e e d i n g i s l a n d a t Stum L a k e , l i k e o t h e r c o a r s e f i s h , have h i g h upper l e t h a l t e m p e r a t u r e s ( a p p r o x i m a t e l y 29°C) and a r e o f t e n f o u n d a t d e p t h s o f o n l y a few f e e t f r o m t h e s u r f a c e ( S c o t t and Crossman 1973). C o n v e r s e l y , game f i s h s u c h a s t r o u t , have l o w e r upper l e t h a l t e m p e r a t u r e s ( a p p r o x i m a t e l y 2 4 ° C ) and c o n s e q u e n t l y a r e f o u n d i n d e e p e r c o l d e r water i n l a k e s and s t r e a m s . B e c a u s e of t h e d i f f e r e n c e s i n t e m p e r a t u r e r e q u i r e m e n t s between game and non-game f i s h , and t h e f a c t t h a t w h i t e p e l i c a n s f e e d o n l y by c a t c h i n g p r e y from t h e s u r f a c e , i t seems l o g i c a l t h a t t h e y w i l l c a t c h more c o a r s e f i s h ( s q u a w f i s h , s u c k e r s , e t c . ) t h a n t h e y w i l l game s p e c i e s ( t r o u t , c h a r ) . 43 CHAPTER 5. CHARACTERISTICS OF THE NESTING HABITAT 5.1 I n t r o d u c t i o n The p r i m a r y n e s t i n g h a b i t a t r e q u i r e m e n t s o f w h i t e p e l i c a n s i n N o r t h A m e r i c a a r e r e l a t i v e l y w e l l u n d e r s t o o d . I s o l a t e d l a k e s w h i c h c o n t a i n a t l e a s t one i s l a n d a r e p r o b a b l y t h e major r e q u i r e m e n t . The n e s t i n g l a k e s must be n e a r a l o c a l f o o d s o u r c e ; however, c l o s e p r o x i m i t y of f i s h i s o f t e n l e s s i m p o r t a n t t h a n t h e i s o l a t i o n of t h e n e s t i n g s i t e (Vermeer 1970a). Water b a r r i e r s a r o u n d t h e i s l a n d ( s ) of s u f f i c i e n t d e p t h and d i s t a n c e from t h e m a i n l a n d a l s o a r e n e c e s s a r y t o r e d u c e mammalian p r e d a t i o n . T h e s e water l e v e l s must remain r e l a t i v e l y s t a b l e f o r s u c c e s s f u l r e p r o d u c t i o n (Evans 1972). In y e a r s o f low w a t e r , n e s t i n g i s l a n d s can become c o n t i n u o u s w i t h t h e m a i n l a n d , e x p o s i n g n e s t i n g b i r d s and t h e i r n e s t c o n t e n t s t o t h e t h r e a t o f mammalian p r e d a t i o n ( S c o t t 1962, H o u s t o n 1966, L a p p 1976). When water l e v e l s become t o o h i g h , f l o o d i n g can o c c u r , c a u s i n g n e s t s and eggs t o be washed away (Ho u s t o n 1962, Evans 1972). N e s t i n g i s l a n d s v a r y a g r e a t d e a l i n s i z e and form; however, t h e m a j o r i t y of w h i t e p e l i c a n i s l a n d s a r e low, r e l a t i v e l y f l a t , s p a r s e l y v e g e t a t e d , and t r e e l e s s (Vermeer 1970a). 44 The b r e e d i n g range of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a i s v e r y r e s t r i c t e d . At p r e s e n t t h e e n t i r e p o p u l a t i o n b r e e d s o n l y a t Stum L a k e . A l t h o u g h w h i t e p e l i c a n s have n e s t e d a t Stum Lake f o r a t l e a s t 40 y e a r s , i n f o r m a t i o n r e g a r d i n g t h e i r b r e e d i n g h a b i t a t i s l i m i t e d . To b e t t e r u n d e r s t a n d th e n e s t i n g h a b i t a t r e q u i r e m e n t s of p e l i c a n s a t Stum L a k e , t h e c u r r e n t n e s t i n g h a b i t a t must f i r s t be d e s c r i b e d and e v a l u a t e d . Once e v a l u a t e d , i t m i g h t be d e s i r a b l e e i t h e r t o make h a b i t a t improvements o r t o c r e a t e a d d i t i o n a l n e s t i n g h a b i t a t . The p r e s e n c e o f a l t e r n a t i v e b r e e d i n g h a b i t a t c o u l d r e d u c e t h e r i s k of " h a v i n g a l l t h e p e l i c a n eggs i n B r i t i s h C o l u m b i a i n one b a s k e t " . O b j e c t i v e s a d d r e s s e d i n t h i s c h a p t e r were: 1. To d e t e r m i n e t h e c h a r a c t e r i s t i c s of w h i t e p e l i c a n n e s t i n g h a b i t a t a t Stum L a k e ; and, 2. To recommend a l t e r n a t i v e n e s t i n g s i t e s s u i t a b l e f o r man i p u l a t i o n . 5.2 Methods 5.2.1 Measurements of t h e B r e e d i n g H a b i t a t I r e c o r d e d c h a r a c t e r i s t i c s of n e s t i n g h a b i t a t a t Stum Lake i n A u g u s t 1977 and 1978 a f t e r t h e a d u l t s and f l e d g l i n g s had l e f t t h e n e s t i n g i s l a n d . The h e i g h t of l a n d above t h e l a k e l e v e l and t h e i s l a n d a r e a were d e t e r m i n e d f o r t h e t h r e e i s l a n d s used f o r n e s t i n g by p e l i c a n s . The water d e p t h and d i s t a n c e between the major b r e e d i n g i s l a n d ( I s l a n d Two) and t h e m a i n l a n d were a l s o m e asured. I e s t i m a t e d d i s t a n c e s between the m a i n l a n d and t h e 45 s e c o n d a r y n e s t i n g i s l a n d s ( I s l a n d One and Scaup I s l a n d ) from a e r i a l p h o t o g r a p h s . T o p o g r a p h y and v e g e t a t i v e c o v e r of t h e t h r e e i s l a n d s were r e c o r d e d . F o r e a c h n e s t s i t e , I r e c o r d e d a s p e c t , s l o p e , s u b s t r a t e , and v e g e t a t i v e and p h y s i c a l f e a t u r e s ( l o g s , r o c k s , s t u m p s ) . 5.2.2 S p a t i a l D i s t r i b u t i o n of N e s t s D u r i n g 1977 and 1978, I measured t h e i n t e r - n e s t d i s t a n c e s ( t h e d i s t a n c e between c e n t e r s of a d j a c e n t n e s t mounds) i n l a t e A u g u s t a f t e r t h e p e l i c a n s had l e f t t h e i s l a n d . D u r i n g t h e f o u r b r e e d i n g s e a s o n s , I r e c o r d e d t h e s p a t i a l c o n f i g u r a t i o n o f t h e d i f f e r e n t n e s t i n g g r o u p s and mapped t h e s e i n r e l a t i o n t o t h e p h y s i c a l a t t r i b u t e s o f t h e i s l a n d s . 5.2.3 A e r i a l S u r v e y s I c o n d u c t e d t h r e e a e r i a l s u r v e y s i n 1977 t o l o c a t e a l t e r n a t i v e b r e e d i n g s i t e s o r p o t e n t i a l n e s t i n g h a b i t a t s u i t a b l e f o r m o d i f i c a t i o n ( d e t a i l s of t h e f l i g h t s a r e d i s c u s s e d i n S e c t i o n 4 . 2.1). S e v e r a l l a k e s w i t h i s l a n d s were r e c o r d e d . I r a t e d t h e i s l a n d s ' p o t e n t i a l as p e l i c a n n e s t i n g h a b i t a t as e i t h e r good, m o d e r a t e , or p o o r . The c r i t e r i a u s e d t o r a t e t h e i s l a n d s were, i n o r d e r of i m p o r t a n c e : i s o l a t i o n , water d e p t h between t h e i s l a n d ( s ) and t h e m a i n l a n d , d i s t a n c e from t h e m a i n l a n d , i s l a n d t o p o g r a p h y , and v e g e t a t i v e c o v e r . Water d e p t h , d i s t a n c e ( s ) between t h e i s l a n d ( s ) and t h e m a i n l a n d , and i s l a n d t o p o g r a p h y were e i t h e r o b t a i n e d from B r i t i s h C o l u m b i a F i s h and W i l d l i f e B r a n c h Lake S u r v e y s or were e s t i m a t e d v i s u a l l y from t h e 46 a i r c r a f t . I a l s o r e c o r d e d t h e p r e s e n c e or a b s e n c e of v e g e t a t i o n on t h e i s l a n d s . 5.3 R e s u l t s 5.3.1 P h y s i c a l C h a r a c t e r i s t i c s o f t h e B r e e d i n g H a b i t a t a t Stum Lake F i v e s m a l l i s l a n d s l i e w i t h i n Stum Lake, t h r e e o f w h i c h have been u s e d as n e s t i n g s i t e s by w h i t e p e l i c a n s ( F i g . l ) . Two of t h e i s l a n d s were u s e d as n e s t i n g s i t e s f o r o n l y 3 and 4 y e a r s ( S c a u p I s l a n d and I s l a n d One r e s p e c t i v e l y ) d u r i n g t h e 13 y e a r s f o r w h i c h d a t a a r e a v a i l a b l e . The i s l a n d u t i l i z e d c o n s i s t e n t l y i n a l l 13 y e a r s was t h e l a r g e s t one, I s l a n d Two. 'The two r e m a i n i n g i s l a n d s i n t h e l a k e , C r e s c e n t and Ryder I s l a n d s , a r e h e a v i l y v e g e t a t e d and a r e not u s e d by p e l i c a n s . D u r i n g my s t u d y , p e l i c a n s n e s t e d on I s l a n d Two e v e r y y e a r . The main b r e e d i n g i s l a n d ( I s l a n d Two) i s 84 m from t h e n e a r e s t m a i n l a n d ( F i g . 12). The i s l a n d s l o p e s g r a d u a l l y up from the s o u t h - f a c i n g s h o r e s t o t h e h i g h e s t p o i n t n e a r i t s c e n t e r , 6.7 m e t e r s above the l a k e l e v e l . About h a l f of t h e i s l a n d ' s t o t a l a r e a r a n g e s between z e r o and f i v e p e r c e n t s l o p e . The i s l a n d i s a p p r o x i m a t e l y 86 m i n l e n g t h by 42 m i n w i d t h , and has a t o t a l a r e a of a b o u t 1,000 m 2. Water d e p t h s (when water l e v e l i s 1.91 m below bench mark) between t h e b r e e d i n g i s l a n d and t h e m a i n l a n d i n c r e a s e g r a d u a l l y f o r t h e f i r s t 5 t o 10 m from t h e i r s h o r e l i n e s , t h e n i n c r e a s e more r a p i d l y t o a maximum d e p t h of 5.4 m ( F i g . 12).. Figure 12. Water depths between the main breeding island (Island Two) and the mainland. 48 The dominant p l a n t s p e c i e s on t h e l o w e r s o u t h e r n s h o r e s of I s l a n d Two i n c l u d e s t i n g i n g n e t t l e ( U r t i c a d i o i c a ) , f i r e w e e d ( E p i l o b i u m a n g u s t i f o l i u m ) , and w i l d r a s p b e r r y (Rubus i d a e u s ) . G o o s e b e r r y ( R i b e s l a c u s t r e ) and w i l l o w ( S a l i x spp.) were most abundant on t h e s t e e p e r n o r t h e r n s h o r e ( F i g . 13). The h i g h e r r e g i o n s o f t h e i s l a n d were e i t h e r b a r r e n o r s u p p o r t e d a c o v e r o f s e v e r a l s p e c i e s of g r a s s . B are g r o u n d a c c o u n t e d f o r a b o u t 25% of t h e i s l a n d ' s a r e a . A number of f a l l e n snags l a y ' s c a t t e r e d i n t h e s e b a r e a r e a s . S e v e r a l s t a n d i n g s nags and a few l i v i n g l o d g e p o l e p i n e ( P i n u s c o n t o r t a ) and w h i t e s p r u c e ( P i c e a g l a u c a ) o c c u r r e d c l o s e t o s h o r e . The two o t h e r i s l a n d s t h a t have been u s e d by p e l i c a n s a t Stum Lake ( I s l a n d One and Scaup I s l a n d ) a r e low, e x p o s e d , r o c k y o u t c r o p p i n g s . B o t h i s l a n d s a r e f l a t and have l i t t l e v e g e t a t i o n , e x c e p t f o r s m a l l p a t c h e s of s t i n g i n g n e t t l e ( U r t i c a d i o i c a ) , water hemlock ( C i c u t a d o u g l a s i i ) , and v a r i o u s s e d g e s ( C a r e x spp.) g r o w i n g a l o n g t h e s h o r e l i n e . I s l a n d One i s a b o u t 600 m from t h e n e a r e s t m a i n l a n d and has an a r e a of a p p r o x i m a t e l y 400 m 2. The i s l a n d i s 63 m i n l e n g t h by 13 m i n w i d t h and i s 1.5 m above t h e l a k e l e v e l . D u r i n g my s t u d y , p e l i c a n s n e s t e d on I s l a n d One o n l y once ( 1 9 7 9 ) . However, p e l i c a n s u s e d t h e i s l a n d a g r e a t d e a l d u r i n g t h e c o u r t s h i p p e r i o d , e s p e c i a l l y w h i l e i c e s t i l l c o v e r e d t h e l a k e , and l a t e r i n t h e b r e e d i n g s e a s o n a f t e r t h e young had f l e d g e d . Scaup I s l a n d , t h e s m a l l e s t of t h e t h r e e i s l a n d s i s 300 m f r o m t h e n e a r e s t m a i n l a n d . The i s l a n d i s o n l y 12 m i n l e n g t h by 6 m i n w i d t h and has an a r e a of a b o u t 90 m 2. I t i s a p p r o x i m a t e l y 1 m above l a k e l e v e l . H e r r i n g g u l l s b r e d on b o t h I s l a n d One (about 100 n e s t s ) and Scaup I s l a n d (3 t o 4 ISLAND T W O {""""""ItAHE GROUND f^^GHASS Figure 13. Habitat map of Island Two at Stum Lake, British Columbia during 1977 and 1978. 50 n e s t s ) d u r i n g my s t u d y . 5.3.2 N e s t i n g D i s t r i b u t i o n of W h i t e P e l i c a n s a t Stum Lake W h i t e p e l i c a n s a t Stum Lake g e n e r a l l y s e l e c t e d n e s t i n g s i t e s t h a t were l o c a t e d i n r e l a t i v e l y f l a t a r e a s on I s l a n d Two. S e v e n t y - o n e p e r c e n t (61 of 86 n e s t s ) o f a l l n e s t s i n 1977 and 79% (83 of 105 n e s t s ) of a l l n e s t s i n 1978 were b u i l t i n a r e a s r a n g i n g from 0 t o 5% s l o p e ( F i g . 14). A p p r o x i m a t e l y 50% of t h e i s l a n d r a n g e d between 0 and 5% s l o p e . C o m b i n i n g d a t a f o r b o t h y e a r s , p e l i c a n s u t i l i z e d n e s t i n g a r e a s w i t h s l o p e s < 5% i n g r e a t e r p r o p o r t i o n t h a n t h e i r a v a i l a b i l i t y ( C h i - S q u a r e One Sample T e s t P < 0.001). D u r i n g 1978, o n l y 1% (1 i n 83) of t h e n e s t s i t e s l o c a t e d on s l o p e s < 5% had an egg r o l l from a n e s t , w h i l e 14% (3 i n 22) of t h e n e s t s i t e s on s l o p e s > 5% had eggs r o l l f r o m t h o s e n e s t s . In a d d i t i o n t o s e l e c t i n g n e s t s i t e s i n f l a t a r e a s , p e l i c a n s a l s o a p p e a r e d t o p r e f e r a r e a s w i t h b a r e g r o u n d . D u r i n g 1977 and 1978, 77% (147 of 191 n e s t s ) of a l l n e s t s a t Stum Lake were b u i l t on b a r e g r o u n d . These u n v e g e t a t e d a r e a s a c c o u n t e d f o r o n l y a b o u t 25% of t h e i s l a n d ' s t o t a l a r e a . B a r e - g r o u n d a r e a s were u s e d s i g n i f i c a n t l y more o f t e n t h a n would be e x p e c t e d i n terms of t h e i r a v a i l a b i l i t y i n r e l a t i o n t o v e g e t a t e d a r e a s C h i -S q u a r e One Sample T e s t P < 0.001). The o t h e r 44 n e s t s were b u i l t among f i r e w e e d p a t c h e s . N e s t s b u i l t among f i r e w e e d were e s t a b l i s h e d i n e a r l y s p r i n g and young f i r e w e e d p l a n t s were p r o b a b l y k i l l e d by a c o m b i n a t i o n of t r a m p l i n g and guano d e p o s i t i o n . The p r e s e n c e of r o o t s i n d i c a t e d t h a t g r a s s e s and h e r b a c e o u s p l a n t s had p r e v i o u s l y o c c u p i e d n e a r l y a l l t h e n e s t 51 too -90 BO 70 V> £2 60 z z 5 0 LU a. 40 LU a 30 20 10 0 II 1977 86 NESTS 21 0 - 5 6-10 11-15 16-20 PERCENT SLOPE 100 90 80 70 tn t— ifi iu 60 Z _ 50 Z iu > 40 UJ a. 301 20 10 0 • 3 1978 105 NESTS it 0 - 5 6-10 11-15 16-20 PERCENT SLOPE 20 Figure 14. Nest site selection by white pelicans on Island Two at Stum Lake, British Columbia during 1977 and 1978. 52 s i t e s . P h y s i c a l b a r r i e r s ( l o g s , r o c k s , stumps, and v e g e t a t i o n ) between n e s t i n g b i r d s and a d j a c e n t t o n e s t s a l s o a p p e a r e d t o i n f l u e n c e t h e n e s t i n g d i s t r i b u t i o n . Logs were t h e most common form o f b a r r i e r between n e s t i n g p e l i c a n s a t Stum L a k e . S i x t y p e r c e n t of t h e n e s t s i n 1977 and 45% of t h e n e s t s i n 1978 were b u i l t w i t h i n 50 cm of b a r r i e r s . The s p a t i a l d i s t r i b u t i o n o f t h e n e s t i n g g r o u p s a t Stum Lake c h a n g e d d r a m a t i c a l l y from y e a r t o y e a r . The p e l i c a n s n e s t e d i n 7 d i s t i n c t g r o u p s i n 1977, 3 g r o u p s i n 1978, 7 g r o u p s i n 1979, and 3 g r o u p s i n 1980 ( F i g . 15). N e s t i n g g r o u p s r a n g e d i n s i z e f r o m o n l y 3 p a i r s (1979) t o 83 p a i r s ( 1 9 8 0 ) . From t h e 1977 b r e e d i n g s e a s o n t o t h e 1978 b r e e d i n g s e a s o n , 69% (72 of 105) of t h e n e s t s were l o c a t e d i n a r e a s unused th e p r e v i o u s y e a r . From 1978 t o 1979 and from 1979 t o 1980, 78% (63 of 81) and 82% (99 of 120) of t h e n e s t s , r e s p e c t i v e l y , were c o n s t r u c t e d i n a r e a s u n u s e d t h e p r e v i o u s y e a r . D u r i n g t h e f o u r b r e e d i n g s e a s o n s , an a v e r a g e of 76% of t h e n e s t s were c o n s t r u c t e d i n a r e a s unused i n t h e p r e v i o u s y e a r . One f a c t o r t h a t i n f l u e n c e d t h e n e s t i n g g r o u p d i s t r i b u t i o n a t Stum Lake was d i s t u r b a n c e by p r e d a t o r s . C o y o t e h a r a s s m e n t c a u s e d t h e p e l i c a n s t o abandon t h e i r n e s t s i t e s and i n i t i a t e new s i t e s on s e v e r a l o c c a s i o n s d u r i n g 1979 and 1980. E a r l y i n t h e b r e e d i n g s e a s o n of 1979, t h e m a j o r i t y of t h e p e l i c a n s had e s t a b l i s h e d t h e i r n e s t i n g s i t e s i n one l a r g e g r o u p on I s l a n d Two. C o l o n y d i s r u p t i o n by c o y o t e s , o n l y one t o two d a y s p r i o r t o egg l a y i n g , f o r c e d p e l i c a n s t o l a y t h e i r eggs and n e s t on I s l a n d One. 53 Figure 15. Spatial distribution of nesting groups at Stum lake, British Columbia from 1977 to 1980. 54 Human d i s t u r b a n c e a l s o had a s i m i l a r a f f e c t on t h e n e s t i n g d i s t r i b u t i o n s of t h e g r o u p s . D u r i n g 1979, a l o w - f l y i n g a i r c r a f t c a u s e d t h e d i s r u p t i o n of s e v e r a l n e s t i n g g r o u p s d u r i n g t h e c o u r t s h i p and egg l a y i n g p e r i o d s . The s o c i a l e n v i r o n m e n t (where a few b i r d s a t t r a c t o t h e r s t o a s i t e ) may be e x t r e m e l y i m p o r t a n t i n t h e f o r m a t i o n of n e s t i n g g r o u p s . D u r i n g t h e c o u r t s h i p p e r i o d a t Stum L a k e , p e l i c a n s o f t e n f l e w from i s l a n d t o i s l a n d t o j o i n o t h e r g r o u p s of c o u r t i n g b i r d s . B i r d s w i t h newly i n i t i a t e d n e s t s would o c c a s i o n a l l y abandon t h e i r s i t e s t o j o i n c o u r t i n g f l o c k s . B i r d s w i t h e s t a b l i s h e d n e s t s or t h o s e w i t h eggs g e n e r a l l y would not j o i n c o u r t i n g f l o c k s . At Stum L a k e , h e r r i n g g u l l s d i d not a p p e a r t o i n f l u e n c e p e l i c a n n e s t i n g a c t i v i t y . The p e l i c a n s u t i l i z e d a l l t h r e e i s l a n d s d u r i n g t h e i r c o u r t s h i p a t Stum Lake i n - 1 9 7 9 , and t h e p r e s e n c e o r a b s e n c e of g u l l s d i d not seem t o c a u s e any d e v i a t i o n s f r o m t h e i r n o r m a l b e h a v i o u r . A l t h o u g h t h e g u l l s had a r r i v e d and begun n e s t i n g b e f o r e t h e p e l i c a n s , c o u r t i n g p e l i c a n s o f t e n d i s p l a c e d g u l l s f r o m t h e i r n e s t s . A l t h o u g h n e s t i n g g r o u p s i z e s v a r i e d a g r e a t d e a l , mean i n t e r - n e s t d i s t a n c e s ( d i s t a n c e between c e n t e r s of a d j a c e n t n e s t s ) d i f f e r e d o n l y s l i g h t l y between 1977 and 1978 a t Stum L a k e . No r e l a t i o n s h i p was f o u n d between n e s t i n g g r o u p s i z e and mean i n t e r - n e s t d i s t a n c e s ( F i g . 1 6 ) . The d i s t a n c e t o n e a r e s t n e i g h b o u r r a n g e d from 52.0 cm t o 732.0 cm (a s o l i t a r y n e s t ) i n 1977 and from 68.0 cm t o 186.0 cm i n 1978. The mean i n t e r - n e s t d i s t a n c e s f o r a l l n e s t s a t Stum Lake was 92.3 ± 23.8 (SD) cm i n 1977 and 99.1 ± 23.1 (SD) cm i n 1978 ( F i g . 17). Mean i n t e r - n e s t 55 120 H g 100-' _ " ' u C 80-(0 % 60-e c E 40-o S 20-- i 1 1 1 1 1 — i 1 r 10 20 30 40 60 60 V 1 140 150 160 Nest Qroup Size Figure 16. Group size and mean inter-nest distances at Stun Lake, B.C. during 1977 and 1978 (1 - data from Knopf 1975). 10 . 5 . 0 5 0 . 4 5 . 4 0 . 1977 70 NESTS MEAN 82.3+ 23.8 Cm i i I 3 .6 .9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 12. 7.3 1978 105 NESTS MEAN 99.1123.1 cm .3 .6 .9 1.2 1.5 1.8 2.1 DISTANCE (meters) Figure 17. Distribution of distances between nest centers at Stum Lake, British Columbia during 1977 and 1978. 57 d i s t a n c e s a p p r o x i m a t e t h r e e p e l i c a n b i l l l e n g t h s (mean b i l l l e n g t h i s 34.7 cm, G o d f r e y 1966). 5.3.3 A l t e r n a t i v e N e s t i n g H a b i t a t I c o n d u c t e d t h r e e a e r i a l s u r v e y s d u r i n g 1977 t o l o c a t e p o t e n t i a l n e s t i n g h a b i t a t . S e v e r a l l a k e s w h i c h c o n t a i n e d i s l a n d s were o b s e r v e d ; however, t h e i r s u i t a b l i t y a s n e s t i n g h a b i t a t was e x t r e m e l y v a r i a b l e . T a h a r t i L a k e , a p p r o x i m a t e l y 20 km n o r t h e a s t of Stum Lake (52° 27'N by 122° 53'W) a p p e a r e d t o be t h e b e s t s u i t e d as p o t e n t i a l p e l i c a n h a b i t a t . The l a k e i s a b o u t 2 km l o n g by 0.5 km w ide. The s m a l l e r of t h e two i s l a n d s i n t h e l a k e i s r e l a t i v e l y f l a t and l o c a t e d 213 m from t h e n e a r e s t m a i n l a n d . The a r e a of t h e i s l a n d i s a b o u t 1.3 ha. The maximum d e p t h of t h e l a k e i s 5.5 m w i t h a minimum d e p t h of 4.9 m o c c u r r i n g a r o u n d the i s l a n d . The i s l a n d i s h e a v i l y t i m b e r e d , however r e m o v a l of p a r t of t h e t r e e c o v e r would not be d i f f i c u l t . In a d d i t i o n , w h i t e p e l i c a n s o c c a s i o n a l l y use t h i s l a k e a s a f o r a g i n g s i t e ( B r i t i s h C o l u m b i a F i s h and W i l d l i f e B r a n c h Lake S u r v e y s ). A l t h o u g h th e l a k e was r e l a t i v e l y i s o l a t e d from human a c t i v i t y a t t h e t i m e of t h e s u r v e y , a r e c e n t B r i t i s h C o l u m b i a F o r e s t S e r v i c e a c c e s s r o a d may l i m i t t h e l a k e ' s p o t e n t i a l as a s e c o n d a r y n e s t i n g s i t e . 58 5.4 D i s c u s s i o n The n e s t i n g h a b i t a t of w h i t e p e l i c a n s i n N o r t h A m e r i c a v a r i e s c o n s i d e r a b l y . P e l i c a n s u t i l i z e b o t h n a t u r a l and man-made i s l a n d s . N a t u r a l i s l a n d s i n c l u d e low l y i n g g r a v e l b a r s ( H o s f o r d 1965, E v a n s 1972), r o c k y o u t c r o p p i n g s ( S c h a l l e r 1964, Vermeer 1970a, t h i s s t u d y ) , f l o a t i n g t u l e beds ( F i n l e y 1907), and h i l l y i s l a n d s w i t h g e n t l e s l o p e s ( M a n s e l l 1965, Vermeer 1970a, J o h n s o n 1976). Man-made n e s t i n g s i t e s i n c l u d e i s l a n d s of d r e d g e d m a t e r i a l ( L a n d i n and S o o t s 1977) and t h o s e c r e a t e d by water impoundments (L a p p 1977, Domenick 1979). I n f r e q u e n t l y p e l i c a n s w i l l n e s t on narrow p e n i n s u l a s ( H o s f o r d 1965, T a i t e t al. 1978) and l a k e s h o r e l i n e s ( S c h a l l e r 1964); however, t h e s e s i t e s a r e u s u a l l y u n p r o d u c t i v e . The s i z e s of n e s t i n g i s l a n d s c an range from s m a l l g r a v e l b a r s t h a t a r e s u b j e c t t o f l o o d i n g i n y e a r s w i t h h i g h w a t e r , t o l a r g e h i l l y i s l a n d s s u c h as G u n n i s o n I s l a n d a t G r e a t S a l t L a k e , U t a h (66 ha i n a r e a and 88 m above l a k e l e v e l , Knopf 1975). In B r i t i s h C o l u m b i a , p e l i c a n s a t Stum Lake have n e s t e d on t h r e e n a t u r a l i s l a n d s . The most c o n s i s t e n t l y u s e d i s l a n d has an a r e a of ab o u t 1000 m2 and i s l o c a t e d 84 m from t h e w e s t e r n m a i n l a n d . I t s l o p e s g e n t l y and has two u n v e g e t a t e d a r e a s n e a r t h e c e n t e r . S h r u b s and s e v e r a l t r e e s and snags o c c u r on t h e i s l a n d ' s p e r i p h e r y , w h i l e g r a s s e s o c c u p y t h e c e n t e r r e g i o n s of th e i s l a n d . As i n o t h e r c o l o n i e s i n N o r t h A m e r i c a , p e l i c a n s a t Stum Lake n e s t e d on t h e u n v e g e t a t e d , g e n t l e s l o p e s of t h e i s l a n d . Knopf (1975) o b s e r v e d t h a t w h i t e p e l i c a n s a t G r e a t S a l t L a k e s e l e c t e d s i m i l a r s i t e s , b u t u s u a l l y o n l y t h o s e w i t h i n a few v e r t i c a l m e t e r s of t h e water l e v e l . 59 The p r e f e r e n c e shown by p e l i c a n s t o w a r d r e l a t i v e l y f l a t n e s t i n g a r e a s may be an a d a p t a t i o n t o r e d u c e t h e l o s s of eggs t h a t r o l l f r o m n e s t s . D u r i n g 1978, egg l o s s e s a t Stum Lak e were much h i g h e r i n n e s t s on s l o p e s > 5% compared w i t h n e s t s on s l o p e s < 5% ( r e f e r t o S e c t i o n 5 . 3 . 2 ) . The s p a t i a l d i s t r i b u t i o n of n e s t i n g g r o u p s a t Stum Lak e c h a n g e d d r a m a t i c a l l y from y e a r t o y e a r . S h i f t s s u c h as t h e s e have been r e c o r d e d f o r many w h i t e p e l i c a n c o l o n i e s i n N o r t h A m e r i c a ( H a l l 1925, Bond 1940, L i e s and B e h l e 1966, Knopf 1975, Bea v e r and B a l l a n t y n e 1979, Diem 1979, T r o t t i e r e t a l . 1980). Such c h a n g e s i n n e s t i n g p a t t e r n s a r e not w e l l u n d e r s t o o d and may o c c u r f o r more t h a n one r e a s o n . One f a c t o r t h a t i n f l u e n c e d t h e n e s t i n g g r o u p d i s t r i b u t i o n of w h i t e p e l i c a n s a t Stum Lake was c o y o t e h a r a s s m e n t . T h e r e i s some e v i d e n c e t o s u g g e s t t h a t c o y o t e h a r a s s m e n t d u r i n g t h e s p r i n g may i n c r e a s e t h e s p a t i a l d i s p e r s i o n of t h e n e s t i n g g r o u p s . D u r i n g 1979, one l a r g e n e s t i n g g r o u p on I s l a n d Two was s p l i t i n t o s e v e r a l s m a l l e r g r o u p s on two i s l a n d s a f t e r a c o y o t e a t t a c k . Weather a p p e a r s t o i n d i r e c t l y i n f l u e n c e t h e r a t e of d i s t u r b a n c e by c o y o t e s . D u r i n g c o o l e r s p r i n g s a t Stum L a k e , i c e r e m a i n e d on t h e l a k e l o n g e r and p r o v i d e d c o y o t e s w i t h a c c e s s t o th e i s l a n d s . Human d i s t u r b a n c e a l s o a p p e a r s t o have a s i m i l a r ' s c a t t e r i n g ' a f f e c t on t h e n e s t i n g g r o u p s a t Stum L a k e . 60 A n o t h e r f a c t o r t h a t may i n f l u e n c e t h e s p a t i a l d i s t r i b u t i o n of t h e n e s t i n g g r o u p s i s t h e w ater l e v e l of t h e l a k e . Water l e v e l s a t B i r c h L a k e , A l b e r t a , f l u c t u a t e w i d e l y f r o m y e a r t o y e a r . D u r i n g y e a r s o f low w ater t h e i s l a n d ' s a r e a i n c r e a s e d d r a m a t i c a l l y and, as a r e s u l t , n e s t i n g g r o u p s were e s t a b l i s h e d f a r t h e r a p a r t ( B e a v e r and B a l l a n t y n e 1979). Water l e v e l s a t Stum L a k e , however, have r e m a i n e d r e l a t i v e l y s t a b l e d u r i n g my s t u d y .* T r o t t i e r e t a l . (1980) s u g g e s t e d t h a t t h e p r e s e n c e o f h e r r i n g g u l l s n e s t s may a f f e c t t h e n e s t i n g d i s t r i b u t i o n of w h i t e p e l i c a n s a t P r i n c e A l b e r t N a t i o n a l P a r k , S a s k a t c h e w a n . At Stum Lake however, h e r r i n g g u l l s d i d n o t a p p e a r t o a f f e c t t h e n e s t i n g d i s t r i b u t i o n . A c t i v i t y and movements of c o u r t i n g p e l i c a n s d i d not change a c c o r d i n g t o whether g u l l s were p r e s e n t or n o t . In 1979, p e l i c a n s o c c a s i o n a l l y c o u r t e d on i s l a n d s where h e r r i n g g u l l s were a l r e a d y on n e s t s . D u r i n g t h e s e p e r i o d s , t h e g u l l s i m m e d i a t e l y l e f t t h e i r n e s t s . Knopf (1975) a l s o n o t e d s i m i l a r b e h a v i o u r by C a l i f o r n i a g u l l s ( L a r u s c a l i f o r n i c u s ) i n t h e p r e s e n c e of w h i t e p e l i c a n s . At Stum Lake, mean i n t e r - n e s t d i s t a n c e s were 92.3 cm i n 1977 (70 n e s t s ) and 99.1 cm i n 1978 (105 n e s t s ) . Knopf ( 1 9 7 5 ) , a t G r e a t S a l t Lake, U t a h , f o u n d t h a t t h e d i s t a n c e between n e s t edges (153 n e s t s ) was 59.0 ± 16.2 cm. R e c a l c u l a t i n g K n o p f ' s d a t a t o i n c l u d e t h e mean d i a m e t e r of a n e s t (47.3 cm, Bent 1922) r e s u l t s i n a s i m i l a r measurement t o t h o s e r e c o r d e d a t Stum L a k e . D i s t a n c e s between n e s t c e n t e r s a t t h e G r e a t S a l t Lake c o l o n y were 106.3 cm. I n t e r - n e s t d i s t a n c e s seem t o be r e l a t i v e l y c o n s t a n t f o r t h e s p e c i e s and do not a p p e a r t o be a f u n c t i o n o f 61 g r o u p s i z e . The b r e e d i n g d i s t r i b u t i o n o f w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a i s v e r y r e s t r i c t e d . By c r e a t i n g s e c o n d a r y b r e e d i n g h a b i t a t , we m ight be a b l e t o b u f f e r f u t u r e i m p a c t s o c c u r r i n g a t t h e Stum Lake c o l o n y . A d d i t i o n a l b r e e d i n g h a b i t a t c o u l d be c r e a t e d i n two ways. E x i s t i n g i s l a n d s c o u l d be m a n i p u l a t e d t o p r o d u c e n e s t i n g h a b i t a t f o r p e l i c a n s or a r t i f i c i a l i s l a n d s c o u l d be c o n s t r u c t e d . The most s u i t a b l e i s l a n d s a r e t h o s e t h a t would r e q u i r e o n l y t h e r e m o v a l of some v e g e t a t i o n . C r i t e r i a t o c e n s u s e x i s i t i n g i s l a n d s s u i t a b l e f o r a l t e r a t i o n i n c l u d e d : ( i ) m i n i m a l h a b i t a t improvement n e c e s s a r y ; t h a t i s , o n l y t h e r e m o v a l of some v e g e t a t i o n ; ( i i ) R e l a t i v e l y f l a t i s l a n d s t h a t have s u f f i c i e n t water b a r r i e r s ( d e p t h s and d i s t a n c e s t o t h e m a i n l a n d ) ; and, ( i i i ) Most i m p o r t a n t l y , i s l a n d s t h a t a r e i s o l a t e d from human a c t i v i t y . A t p r e s e n t , t h e b e s t p o t e n t i a l a l t e r n a t i v e n e s t i n g s i t e o c c u r s a t T a h a r t i L a k e , a p p r o x i m a t e l y 20 km n o r t h e a s t of Stum L a k e . However t h e l a k e ' s p o t e n t i a l may be l i m i t e d b e c a u s e of human a c t i v i t y . I t i s recommended t h a t f u r t h e r a e r i a l s u r v e y s be c o n d u c t e d t o l o c a t e a d d i t i o n a l s i t e s t h a t may be more s u i t a b l e as s e c o n d a r y n e s t i n g h a b i t a t . 62 CHAPTER 6. REPRODUCTIVE SUCCESS OF WHITE PELICANS AT STUM LAKE, BRITISH COLUMBIA 6.1 I n t r o d u c t i o n Many f a c t o r s a f f e c t t h e b r e e d i n g s u c c e s s of c o l o n i a l w a t e r b i r d s s u c h as p e l i c a n s . L i m i t i n g f a c t o r s i n c l u d e mammalian p r e d a t i o n ( S c o t t 1962, B l o k p o e l 1971, V e s t j e n s 1977), human d i s t u r b a n c e ( H a l l 1925, C a r s o n 1966, Vermeer 1970a, J o h n s o n and S l o a n 1976), f o o d a v a i l a b i l i t y (Brown and Urban 1969, W h i t f i e l d 1978), f l u c t u a t i n g water l e v e l s ( H o s f o r d 1965, Evans 1972, V e s t j e n s 1977), p a r a s i t e s and d i s e a s e ( G r e i c h u s and G r e i c h u s 1973, Wobeser e_t_ a l . 1974), and a d v e r s e w eather c o n d i t i o n s (Bartholomew e_t a_l. 1953, A d o l p h s o n and A d o l p h s o n 1968, Bremer 1977) . P r i o r t o my s t u d y , r e l a t i v e l y l i t t l e was known c o n c e r n i n g t h e l i m i t i n g f a c t o r s a f f e c t i n g w h i t e p e l i c a n s b r e e d i n g a t Stum L a k e . N e s t i n g s u r v e y s had been r e c o r d e d , but many of t h e s e a p p e a r e d t o be of a d e s t r u c t i v e n a t u r e . F o r example, W r i g h t and W r i g h t ( 1 9 7 0 ) , d e s c r i b i n g a s u r v e y t o d e t e r m i n e numbers o f n e s t s and eggs a t Stum Lake d u r i n g 1969, w r o t e : " I n t h e g a t h e r i n g dusk we s l o w l y and q u i e t l y s c u l l e d o u r canoe c l o s e r and c l o s e r t o P e l i c a n I s l a n d ( I s l a n d Two). As we were a b o u t t o b e a c h , a s l i g h t movement gave us away and w i t h a r u s h of a i r t h r o u g h f e a t h e r s , 300 w h i t e p e l i c a n s l a b o u r e d i n t o t h e a i r . Once, t w i c e , t h r e e t i m e s t h e b i g b i r d s p a s s e d o v e r our heads as t h e y c i r c l e d t h e i s l a n d , g r a d u a l l y g a i n i n g a l t i t u d e . " 63 C o y o t e p r e d a t i o n a l s o has been r e c o r d e d a t Stum L a k e . The d r a m a t i c d i f f e r e n c e s , however, i n t h e e f f e c t o f t i m i n g t h a t b o t h c o y o t e p r e d a t i o n and human d i s t u r b a n c e have on c o l o n y p r o d u c t i v i t y and s u r v i v o r s h i p of young have not been e s t a b l i s h e d . In a d d i t i o n , t h e o v e r a l l r e p r o d u c t i v e s u c c e s s and th e s u r v i v o r s h i p of young p r e v i o u s l y had not been r e c o r d e d d u r i n g n a t u r a l c o n d i t i o n s ( y e a r s w i t h no c o y o t e p r e d a t i o n o r human d i s t u r b a n c e ) . I n f o r m a t i o n r e g a r d i n g c o l o n y o c c u p a t i o n and e a r l y n e s t i n g p h e n o l o g y a t Stum Lake was n o n - e x i s t e n t p r i o r t o my s t u d y . O b j e c t i v e s a d d r e s s e d i n t h i s c h a p t e r were: 1. To document t h e s c h e d u l e of s p r i n g a r r i v a l s and t o d e s c r i b e t h e e a r l y n e s t i n g p h e n o l o g y ; 2. To o b t a i n a d i s t u r b a n c e - f r e e e s t i m a t e of t h e c l u t c h s i z e and o v e r a l l r e p r o d u c t i v e s u c c e s s of p e l i c a n s b r e e d i n g a t Stum L a k e ; and, 3. To d e t e r m i n e t h e e f f e c t of p r e d a t i o n and human d i s t u r b a n c e on c o l o n y p r o d u c t i v i t y and s u r v i v o r s h i p of young. 6.2 Methods 64 6.2.1 P o p u l a t i o n E s t i m a t e s I c o n d u c t e d p o p u l a t i o n s u r v e y s a t Stum Lake d u r i n g t h e summers of 1977 (29 May t o 28 A u g u s t ) , 1.978 (3 May t o 28 A u g u s t ) , and 1980 (11 A u g u s t t o 16 A u g u s t ) , as w e l l as d u r i n g t h e s p r i n g of 1979 (17 A p r i l t o 7 May) and 1980 (15 A p r i l t o 19 May). To m i n i m i z e d i s t u r b a n c e t o c o u r t i n g and n e s t i n g b i r d s , most o b s e r v a t i o n s of t h e c o l o n y were made from t h e m a i n l a n d w i t h t h e a i d of a 20 t o 45x s p o t t i n g s c o p e . N i n e d i f f e r e n t o b s e r v a t i o n s i t e s were e s t a b l i s h e d , r a n g i n g from 100 t o 800 m from t h e b i r d s . A t e n t h o b s e r v a t i o n s i t e from a canoe a t an a n c h o r e d marker buoy ( a p p r o x i m a t e l y 700 m) a l l o w e d me t o see t h e p o r t i o n of t h e i s l a n d not v i s i b l e from t h e m a i n l a n d . The p r o p o r t i o n of t h e c o l o n y v i s i b l e from t h e m a i n l a n d r a n g e d from 71% t o 100% and a v e r a g e d a b o u t 90%. Numbers of a d u l t p e l i c a n s and n e s t s were c e n s u s e d on a d a i l y b a s i s i n 1977 and 1978 e x c e p t when p r o h i b i t e d by a d v e r s e weather c o n d i t i o n s o r a l t e r n a t i v e a c t i v i t i e s . D u r i n g t h e s p r i n g s u r v e y s i n 1979 and 1980, I r e c o r d e d numbers of a d u l t s and n e s t s t h r e e t i m e s p e r day i n o r d e r t o document t h e s c h e d u l e of s p r i n g a r r i v a l s and t h e e s t a b l i s h m e n t of n e s t i n g s i t e s . C l u t c h s i z e and t h e number and f a t e of young were r e c o r d e d i n 1977, 1978, and 1980 t o d e t e r m i n e t h e s u r v i v o r s h i p of young ( s u c c e s s f u l l y f l e d g e d young p e r egg l a i d ) and t h e mean p r o d u c t i v i t y of t h e c o l o n y (young f l e d g e d p e r n e s t ) . C l u t c h s i z e s and s u r v i v a l of young were e s t i m a t e d by o b t a i n i n g more d e t a i l e d o b s e r v a t i o n s of s e l e c t e d n e s t s . I sampled 23 n e s t s ( t o t a l numbers o f n e s t s was 86) d u r i n g 1977 and 30 n e s t s ( t o t a l number of n e s t s was 105) durin.g 1978. N e s t s s e l e c t e d i n c l u d e d 65 o n l y t h o s e t h a t were c o m p l e t e l y v i s i b l e . To f a c i l i t a t e v i e w i n g i n 1978 and 1980, I o b s e r v e d n e s t s and t h e i r c o n t e n t s from a h a r n e s s s u s p e n d e d i n a t r e e 11 m above g r o u n d l e v e l . 6.3 R e s u l t s 6.3.1 C o l o n y O c c u p a t i o n P e l i c a n s f i r s t a r r i v e i n t h e C h i l c o t i n r e g i o n of B r i t i s h C o l u m b i a from t h e i r w i n t e r i n g g r o u n d s from e a r l y t o m i d - A p r i l . The t i m e of a r r i v a l u s u a l l y c o i n c i d e s a p p r o x i m a t e l y w i t h t h e s p r i n g m e l t . D u r i n g 1979 and 1980, p e l i c a n s f i r s t a r r i v e d a t Stum Lake on 19 A p r i l and 15 A p r i l , r e s p e c t i v e l y , w h i l e i c e s t i l l c o v e r e d t h e l a k e . In b o t h y e a r s , f l o c k s r a n g i n g i n s i z e from t h r e e t o 30 i n d i v i d u a l s a r r i v e d d u r i n g t h e n e x t two t o t h r e e weeks ( F i g . 18-A and 19-A). E s t i m a t e s of new i n d i v i d u a l s a r r i v i n g a t t h e l a k e were c o n f o u n d e d b e c a u s e some p e l i c a n s l e f t t h e l a k e d u r i n g t h e e v e n i n g and r e t u r n e d i n t h e m o r n i n g . The number of b i r d s p r e s e n t 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 end o f A p r i l , t h e n began t o l e v e l o f f . In b o t h y e a r s , t h e peak numbers of b i r d s o b s e r v e d a t Stum Lake o c c u r r e d on 4 May. The i n t e r v a l from t i m e of f i r s t a r r i v a l t o b r e a k - u p of t h e i c e was ab o u t two weeks. The mean d a t e of i c e b r e a k - u p a t Stum Lake f o r t h r e e b r e e d i n g s e a s o n s was 4 May. 66 T O T A L P O P U L A T I O N a m UJ 01 a E 3 Z 15 60 30 H 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 I S L A N D O N E i i p i | i 111 i | i • 11 i | H | i H 1 ' I ' ' l 1 ' l 1 1 1 1 1 1 ' 1 1 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 L A P R I L — T 1979 Figure 18. Colony occupation and nest site establishment during spring 1979 at Stum Lake, British Columbia. 67 Figure 19. Colony occupation and nest site establishment during spring 1980 at Stum Lake, British Columbia. 68 The e s t i m a t e d d a t e o f f i r s t a r r i v a l a t Stum Lake d u r i n g 1977 and 1978 was 27 A p r i l and 22 A p r i l , r e s p e c t i v e l y . T h e s e d a t e s were e s t i m a t e d by s u b t r a c t i n g t h e a v e r a g e p e r i o d o f c o u r t s h i p (3 d a y s ) , c o p u l a t i o n and e g g - l a y i n g (5 d a y s ) , and i n c u b a t i o n (30 d a y s ) f r o m t h e f i r s t o b s e r v e d h a t c h i n g d a t e . However, t h i s a p p r o a c h does not t a k e i n t o a c c o u n t any d e l a y s i n t h e c o u r t s h i p p e r i o d t h a t m ight r e s u l t from e x t e r n a l i n f l u e n c e s s u c h as c o y o t e a t t a c k s o r human d i s t u r b a n c e s . C o y o t e h a r a s s m e n t d u r i n g t h e c o u r t s h i p p e r i o d a p p e a r e d t o d e l a y c o l o n y o c c u p a t i o n . In 1980, c o y o t e s h a r a s s e d c o u r t i n g p e l i c a n s f o r f i v e c o n s e c u t i v e d a y s (20 t o 24 A p r i l ) . A n o t i c e a b l e r e d u c t i o n i n t h e numbers of p e l i c a n s p r e s e n t on t h e l a k e o c c u r r e d d u r i n g t h i s p e r i o d ( F i g . 19~A). C o u r t i n g b i r d s p r o b a b l y abandoned Stum Lake t e m p o r a r i l y f o r s a f e r f e e d i n g l a k e s , i n r e s p o n s e t o t h e c o n t i n u o u s c o y o t e h a r a s s m e n t . In 1979, however, c o y o t e h a r a s s m e n t was l e s s i n t e n s e (3 i n c i d e n t s from 22 A p r i l t o 27 A p r i l ) . C o l o n y o c c u p a t i o n a p p e a r e d t o have been d e l a y e d o n l y s l i g h t l y d u r i n g t h i s p e r i o d ( F i g . 18-A). 6.3.2 E a r l y N e s t i n g P h e n o l o g y P e l i c a n s began c o u r t i n g i m m e d i a t e l y upon t h e i r a r r i v a l a t Stum L a k e . H e r r i n g g u l l s , w hich were a l r e a d y p r e s e n t on I s l a n d One, c a l l e d b r i e f l y , but d i d not a p p e a r d i s t u r b e d by t h e c o u r t i n g p e l i c a n s . C o u r t s h i p a c t i v i t y c o n s i s t e d o f g r o u p s of m a les c h a s i n g one t o s e v e r a l f e m a l e s a r o u n d t h e b r e e d i n g i s l a n d . C h a s e s were o f t e n i n t e r s p e r s e d w i t h c o u r t s h i p f l i g h t s , i n w h i c h f l o c k s of p e l i c a n s would c i r c l e t h e i s l a n d s e v e r a l t i m e s . I m m e d i a t e l y a f t e r l a n d i n g , t h e m a l e s c o n t i n u e d t o p u r s u e the 69 f e m a l e s and would o c c a s i o n a l l y b i t e or j a b a t t h e back o f t h e i r n e c k s . C o u r t s h i p a c t i v i t y c o n t i n u e d f o r two o r t h r e e d a y s . A p a i r bond was e s t a b l i s h e d when a male c o u l d s u c c e s s f u l l y d e f e n d a f e m a l e from o t h e r m a l e s . D u r i n g t h e e a r l y p h a s e s o f c o u r t s h i p , t h e b i r d s were e x t r e m e l y e r r a t i c i n t h e i r b e h a v i o u r . C o u r t i n g f l o c k s would b u r s t i n t o t h e a i r u n p r e d i c t a b l y and would f l y t o g e t h e r t o a d i f f e r e n t i s l a n d where t h e y would b e g i n c o u r t i n g a g a i n . M u t u a l pouch d i s p l a y i n g ( e x p a n s i o n of g u l a r pouch) and bowing became much more common once t h e p a i r bond had been e s t a b l i s h e d . The p a i r e d b i r d s t h e n j o i n e d o t h e r c o u r t i n g b i r d s , or a t t e m p t e d t o o b t a i n a n e s t i n g s i t e on a n e s t i n g g r o u p ' s p e r i p h e r y . In a l l c a s e s , t h e n e s t i n g s i t e was s e l e c t e d by t h e f e m a l e w h i l e t h e male s t o o d b e s i d e and d e f e n d e d h e r . I f t h e p a i r c o u l d s u c c e s s f u l l y d e f e n d t h e n e s t s i t e , a s e r i e s of c o p u l a t i o n s took p l a c e o v e r th e f o l l o w i n g f o u r or f i v e d a y s . The f i r s t eggs were o b s e r v e d on t h e f i f t h day. In 1979 and 1980, n e s t i n g s i t e s were f i r s t i n i t i a t e d t h r e e and f o u r d a y s , r e s p e c t i v e l y , a f t e r p e l i c a n s f i r s t a r r i v e d a t Stum Lake ( F i g . 18-B and F i g . 19-B). In b o t h y e a r s , c o u r t s h i p a c t i v i t y and n e s t s i t e e s t a b l i s h m e n t f i r s t t o o k p l a c e on t h e low, open i s l a n d s (Scaup I s l a n d and I s l a n d One). T hese open s i t e s p r o b a b l y a l l o w p e l i c a n s t o o b s e r v e a p p r o a c h i n g p r e d a t o r s more e a s i l y . C o y o t e s were commonly o b s e r v e d on t h e i c e d u r i n g t h e s e e a r l y n e s t i n g p e r i o d s , but o n l y one a d u l t p e l i c a n (male) was k i l l e d by c o y o t e s . The a d u l t was m o r t a l l y wounded d u r i n g t h e e v e n i n g of 27 A p r i l 1979, o n l y 1 day a f t e r i t had e s t a b l i s h e d a n e s t i n g s i t e on I s l a n d Two. V e g e t a t i o n on t h e 70 i s l a n d e v i d e n t l y o b s c u r e d t h e a p p r o a c h i n g c o y o t e s . C o y o t e h a r a s s m e n t was t h e major c a u s e of n e s t abandonment d u r i n g t h e e a r l y n e s t i n g p e r i o d . The s h i f t s i n n e s t i n g s i t e s c a u s e d by c o y o t e h a r a s s m e n t ( F i g s . 18-B and 19-B) must i n c r e a s e e n e r g y c o s t s t o t h e b i r d s and c a u s e d s i g n i f i c a n t d e l a y s i n t h e b r e e d i n g s e a s o n . A l t h o u g h t h e more open i s l a n d h a b i t a t s were u s e d t o a g r e a t e r d e g r e e d u r i n g t h e e a r l y s t a g e s of c o u r t s h i p , p o s s i b l y t o a l l o w g r e a t e r v i s i b i l i t y w h i l e i c e r e m a i n e d on t h e l a k e , t h e r e was a s t r o n g t e n d e n c y f o r p e l i c a n s e v e n t u a l l y t o n e s t on I s l a n d Two. D u r i n g 13 s e a s o n s f o r w hich t h e r e a r e d a t a , p e l i c a n s have n e s t e d on I s l a n d Two d u r i n g a l l 13 b r e e d i n g s e a s o n s ; I s l a n d One, 4 b r e e d i n g s e a s o n s ; and Scaup I s l a n d , 3 b r e e d i n g s e a s o n s . D u r i n g 1979, 18 e s t a b l i s h e d n e s t s i t e s were abandoned on I s l a n d One and r e - e s t a b l i s h e d on I s l a n d Two f r o m 2-7 May ( F i g . 18-B). These b i r d s had been n e s t - r e l i e v i n g and c o p u l a t i n g a t t h e i r s i t e s f o r s e v e r a l d a y s , but had not y e t l a i d e g g s . The o n l y n e s t s not abandoned on I s l a n d One were t h o s e n e s t s w h i c h c o n t a i n e d eggs (27 n e s t s ) . A g a i n i n 1980, a l l 23 e s t a b l i s h e d n e s t s s i t e s on Scaup I s l a n d were d e s e r t e d on 29 A p r i l and r e -e s t a b l i s h e d on I s l a n d Two w i t h i n one day. I t seems p r o b a b l e t h a t most of t h e p r e s e n t b r e e d i n g a d u l t s were f l e d g e d on I s l a n d Two and now n e s t on t h e same i s l a n d t r a d i t i o n a l l y . 71 6.3.3 Commencement of Egg L a y i n g and H a t c h i n g Egg l a y i n g i n 1979 began on 4 and 6 May on I s l a n d s One and Two r e s p e c t i v e l y . D u r i n g 1980 egg l a y i n g was f i r s t r e c o r d e d on 5 May. On t h e s e d a t e s , o n l y one a d u l t of a n e s t i n g p a i r was l e f t on most o f t h e n e s t s i t e s . In t h e above t h r e e s u b c o l o n i e s a t Stum Lake, egg l a y i n g began an a v e r a g e of 5 ± 1 (x ± SD) days a f t e r u n d i s t u r b e d n e s t s were f i r s t e s t a b l i s h e d . D u r i n g 1977 and 1978 a t Stum L a k e , t h e f i r s t eggs h a t c h e d on 4 June and 30 May, r e s p e c t i v e l y . The d a t e s when 50% o f a l l n e s t s had one or more h a t c h l i n g s were 7 June d u r i n g 1977 and 1 June d u r i n g 1978 ( F i g . 2 0 ) . E s t i m a t e d d a t e s o f f i r s t h a t c h i n g d u r i n g t h e 1979 and 1980 b r e e d i n g , s e a s o n s , b a s e d on an i n c u b a t i o n p e r i o d of 30 d a y s , a r e 3 June and 4 J u n e , r e s p e c t i v e l y . The mean d a t e of f i r s t h a t c h i n g , u s i n g a l l 4 b r e e d i n g s e a s o n s , was 3 June ± 7 days ( S D ) . 6.3.4 C l u t c h S i z e s The mean c l u t c h s i z e a t Stum Lake d u r i n g y e a r s w i t h o u t d i s t u r b a n c e (1977, 1978) o r when d i s t u r b a n c e o c c u r r e d a f t e r t h e c o m p l e t i o n of c o u r t s h i p and egg l a y i n g (1971, 1972) was 1.95 ± 0.21 (n = 4 1 1 ) . C l u t c h s i z e s d u r i n g y e a r s when d i s t u r b a n c e s o c c u r r e d p r i o r t o or d u r i n g l a y i n g (1973, 1974, and 1980) were s i g n i f i c a n t l y s m a l l e r (1.69 e g g s / n e s t ) t h a n d u r i n g y e a r s w i t h o u t s u c h d i s t u r b a n c e ( t = 2.05, df = 755, P < 0.04). C l u t c h s i z e s and o t h e r p o p u l a t i o n d a t a a r e summarized i n T a b l e 2. 72 Figure 20. Hatching dates of white pelican eggs at Stum Lake, B.C. 73 TABLE 2. Number of adults, nests, clutch s i z e s , productivity, and survivorship of white pelicans at Stum Lake, B.C. Minimum Total Mean Year Number Number Clutch of Adults of NestB Size Fledged Productivity Survivorship Young (young/nest)(young/egg laid) 1953 - 140 - — — — 1959 (100-150)x - - - - -1960 - <239)2 - - - -1963 280 - - - - -1964 - 146 - - - -1967 - 153 1.79 - - -1968 - 85 - - - -1969 - 87 1.65 - - -1971 198 104 1.89 77 0.74 0.39 1972 202 116 2.21 10 0.09 0.04 1973 212 118 1.46 75 0.64 0.44 1974 234 108 1.84 24 0.22 0.12 1977 121 86 1.70 64 0.74 0.44 1978 130 105 1.93 89 0.85 0.44 1979 150 96 - - - -1980 215 120 1.78 62 0.52 0.29 Grand Mean - S.D. 187±53 113±23 1.81±0.21 57±29 0.54+0.29 0.31±0.1' n 10 13 9 7 7 7 Average number of adults used to calculate Grand Mean Abandoned nests (not used i n Grand Mean) 74 When a l l 9 y e a r s f o r w h i c h c l u t c h s i z e s a r e a v a i l a b l e f o r Stum Lake a r e c o n s i d e r e d ( i n c l u d i n g t h o s e y e a r s e x p e r i e n c i n g d i s t u r b a n c e ) , t h e o v e r a l l mean c l u t c h s i z e was 1.81 ± 0.01 (n = 997)., The c l u t c h s i z e f r e q u e n c y o f w h i t e p e l i c a n s a t Stum Lak e d u r i n g 1977 and 1978 i s summarized i n F i g u r e 21. In b o t h y e a r s t h e most f r e q u e n t l y o c c u r r i n g c l u t c h s i z e was two eggs p e r n e s t . 6.3.5 R e p r o d u c t i v e S u c c e s s D u r i n g two y e a r s w i t h o u t d i s t u r b a n c e of any k i n d a t Stum Lake (1977 and 1978), a v e r a g e egg m o r t a l i t y was 10% o f t h e eggs l a i d i n t h e sample n e s t s . I n f e r t i l e e g gs, ( o r eggs w i t h a r r e s t e d e m b r y o n i c d e v e l o p m e n t ) a c c o u n t e d f o r 5.1% (2 o f 39 e g g s ) and 1.7% (1 of 58 eggs) o f eggs l a i d i n 1977 and 1978, r e s p e c t i v e l y . N e s t abandonment a c c o u n t e d f o r a f u r t h e r egg l o s s o f 2.6% (1 of 39 eggs) i n 1977 and 6.9% egg l o s s (4 of 58 eggs) i n 1978. One o f t h e above eggs was e a t e n by a common crow ( C o r v u s b r a c h y r h y n c h o s ) w i t h i n 30 m i n u t e s a f t e r t h e n e s t had been abandoned. The r e m a i n i n g egg m o r t a l i t y r e s u l t e d from egg d i s p l a c e m e n t (eggs r o l l i n g out of n e s t s ) . Egg d i s p l a c e m e n t a c c o u n t e d f o r 2.6% (1 of 39 eggs) and 1.7% (1 of 58 eggs) of eggs i n 1977 and 1978, r e s p e c t i v e l y . B e c a u s e I d i d n o t go o n t o t h e n e s t i n g i s l a n d s but c o u n t e d eggs o p p o r t u n i s t i c a l l y t h r o u g h a s p o t t i n g s c o p e u n t i l a l l sample n e s t s were a c c o u n t e d f o r , some e a r l y egg m o r t a l i t y may have been m i s s e d . 75 100L 90 SO 70 m J2 60 Z 6 50 m O < 40 *— Z UJ £ 30 A. 20 10 0 26 1 EGG/NEST 2 EGGS/NEST CLUTCH SIZE • 1977 (23 NESTS) MEAN 1701 0.56 [l978 (30NESTS) MEAN 1.9310.36 3EGGS/NEST Figure 21. Clutch size frequencies of white pelicans at Stum Lake during 1977 and 1978. 76 Once eggs were h a t c h e d , n e s t l i n g m o r t a l i t y c l a i m e d a f u r t h e r 26% of t h e eggs l a i d i n t h e sample n e s t s ( a v e r a g e n e s t l i n g m o r t a l i t y was 28% i n 1977 and 24% i n 1978). M a j o r c a u s e s o f n e s t l i n g m o r t a l i t y a t Stum Lake a p p e a r t o be due p r i m a r i l y t o s i b l i n g r i v a l r y a n d / o r s t a r v a t i o n . In 17 of 22 n e s t s (77%) t h a t c o n t a i n e d two young, o n l y t h e s m a l l e r n e s t l i n g d i e d . In t h e f i v e o t h e r n e s t s , t h e s u r v i v i n g and dead n e s t l i n g s a p p e a r e d t o be o f s i m i l a r s i z e . O n l y one i n c i d e n t of h e r r i n g g u l l p r e d a t i o n upon a n e s t l i n g was o b s e r v e d d u r i n g t h e 1977 and 1978 b r e e d i n g s e a s o n s . A v i a n p r e d a t i o n d i d not r e p r e s e n t a major m o r t a l i t y f a c t o r among young p e l i c a n s a t Stum L a k e . F l e d g l i n g m o r t a l i t y r e p r e s e n t e d a f u r t h e r 20% l o s s of t h e eggs l a i d i n t h e sample n e s t s . A v e r a g e f l e d g l i n g m o r t a l i t y was 17% i n 1977 (7 dead f l e d g l i n g s o ut of 39 eggs l a i d ) and 22% i n 1978 (13 d e a d f l e d g l i n g s o u t of 58 eggs l a i d ) . M o r t a l i t y was g r e a t e s t i n t h e e a r l y f l e d g i n g s t a g e when young were s m a l l e r and b e g i n n i n g t o a g g r e g a t e i n s m a l l g r o u p s . S i b l i n g r i v a l r y a n d / o r s t a r v a t i o n a g a i n a p p e a r e d t o be t h e major m o r t a l i t y f a c t o r d u r i n g t h i s p e r i o d . V e r y few d e a t h s were o b s e r v e d d u r i n g t h e l a t e f l e d g i n g s t a g e . The t o t a l m o r t a l i t y f o r t h e 1977 and 1978 b r e e d i n g s e a s o n s was 56% of a l l eggs p r o d u c e d ( F i g . 22) or c o n v e r s e l y a s u r v i v o r s h i p of 44% (0.44 s u c c e s s f u l l y f l e d g e d young/egg l a i d ) . 77 Figure 22. Survivorship of white pelicans at Stum Lake, British Columbia during 1977 and 1978. 78 In summary, i n y e a r s w i t h no d i s t u r b a n c e d u r i n g or a f t e r i n c u b a t i o n (n = 309 n e s t s ) , t h e Stum Lake c o l o n y a v e r a g e d 0.74 f l e d g e d young p e r n e s t o r 0.44 young p e r egg l a i d ( T a b l e 2 ) . 6.3.6 P r e d a t i o n The e f f e c t s of p r e d a t i o n on c o l o n y p r o d u c t i v i t y r a n g e d from i n s i g n i f i c a n t t o c a t a s t r o p h i c . A v i a n p r e d a t i o n under n a t u r a l c o n d i t i o n s had v e r y l i t t l e e f f e c t on t h e b r e e d i n g p o p u l a t i o n a t Stum L a k e . I o b s e r v e d p r e d a t i o n by b i r d s on o n l y two o c c a s i o n s d u r i n g my s t u d y a t Stum L a k e . On one o c c a s i o n , a common crow was o b s e r v e d e a t i n g an egg a t an abandoned n e s t s i t e . The n e s t was 7.3 m from th e n e a r e s t n e s t i n g g r o u p . On a s e c o n d o c c a s i o n , a h e r r i n g g u l l a t t a c k e d and a t e a s m a l l n e s t l i n g . N e i t h e r of t h e n e s t l i n g ' s p a r e n t s was o b s e r v e d a t t h e c o l o n y d u r i n g t h e . a t t a c k s . G u l l s and crows d i d p a t r o l t h e p e r i p h e r y of s u b c o l o n i e s ; however, eggs and young were g e n e r a l l y w e l l p r o t e c t e d d u r i n g t h e i r v u l n e r a b l e p e r i o d s . D u r i n g a major d i s t u r b a n c e , however, g u l l s and c rows c o u l d p o t e n t i a l l y consume many of t h e eggs and n e s t l i n g s l e f t u n a t t e n d e d i n t h e i r n e s t s . B o t h a d u l t s c o u l d s a f e l y l e a v e t h e c o l o n y once t h e young f l e d g e d a t a b o u t 28 t o 30 days a f t e r h a t c h i n g . At t h i s s t a g e , t h e young were m o b i l e and l a r g e enough t o d e t e r a v i a n p r e d a t o r s on t h e i r own. 79 Mammalian p r e d a t i o n can have a much more s e r i o u s impact on p r o d u c t i v i t y and s u r v i v o r s h i p of young t h a n does a v i a n p r e d a t i o n . In 1979 and 1980, w h i l e i c e s t i l l c o v e r e d t h e l a k e , c o y o t e h a r a s s m e n t f o r c e d p e l i c a n s t o r e - n e s t on t h r e e and two s e p a r a t e o c c a s i o n s , r e s p e c t i v e l y . A s i d e from t h e u n d e s i r a b l e i n c r e a s e d e n e r g y c o s t s t o t h e b i r d s , egg l a y i n g , t h e i n c u b a t i o n p e r i o d , and t i m e of f l e d g i n g were d e l a y e d by 8 d a y s i n 1979 and 11 d a y s i n 1980". P r o d u c t i v i t y was n o t d e t e r m i n e d f o r 1979; however, i n 1980, p r o d u c t i v i t y was o n l y 0.52 y o u n g / n e s t . C o y o t e s a l s o a t t a c k e d t h e c o l o n y e a r l y i n t h e n e s t i n g s e a s o n d u r i n g 1973 (Ryder 1973). P r o d u c t i v i t y f o r t h a t y e a r was o n l y 0.64 young f l e d g e d / n e s t . C o m b i n i n g 1973 and 1980 d a t a , t h e mean p r o d u c t i v i t y was 0.58 ± 0.08 (SD) (n = 238 n e s t s ) , compared w i t h a mean p r o d u c t i v i t y of 0.80 ± 0.08 (SD) d u r i n g 1977 and 1978 when no d i s t u r b a n c e s o c c u r r e d (n = 191 n e s t s ) . C o y o t e p r e d a t i o n midway t h r o u g h a n e s t i n g s e a s o n can have even more d r a m a t i c r e s u l t s . In 1972, c o y o t e s swam the s h o r t d i s t a n c e (84 m) t o I s l a n d Two and c a u s e d a l m o s t t o t a l d e s t r u c t i o n o f t h e eggs and young (Ryder 1972). O n l y 10 young were s u c c e s s f u l l y f l e d g e d t h a t y e a r ( T a b l e 2 ) . The o v e r a l l p r o d u c t i v i t y of t h e c o l o n y f o r t h i s s e a s o n was d r a m a t i c a l l y r e d u c e d t o 0.09 young f l e d g e d / n e s t (n = 116 n e s t s ) compared w i t h t h e a v e r a g e p r o d u c t i v i t y i n y e a r s w i t h o u t d i s t u r b a n c e of 0.80 ± 0.08 (n = 191 n e s t s ) . 80 6.3.7 Human D i s t u r b a n c e Human d i s t u r b a n c e has o c c u r r e d f r e q u e n t l y a t Stum L a k e . A g a i n , t h e t i m i n g of t h e d i s t u r b a n c e i s c r i t i c a l . D i s t u r b a n c e d u r i n g t h e e a r l y s t a g e s , s u c h a s c o u r t s h i p and n e s t s i t e s e l e c t i o n , a p p e a r s t o have o n l y minor e f f e c t s . T w i c e d u r i n g t h e s p r i n g s u r v e y i n 1979 a h e l i c o p t e r f l e w low o v e r Stum Lake ( a l t i t u d e a p p r o x i m a t e l y 200 m) w h i l e p e l i c a n s were p r e s e n t . On b o t h o c c a s i o n s , c o u r t i n g b i r d s a n d t h o s e w i t h n e s t i n g s i t e s l e f t t h e i s l a n d s , b u t r e t u r n e d w i t h i n 30 m i n u t e s of t h e d i s t u r b a n c e . The d i s t u r b a n c e t o c o u r t i n g b i r d s , a l t h o u g h n o t p r o l o n g e d , may have d e l a y e d t h e b r e e d i n g s c h e d u l e s l i g h t l y t h r o u g h d i s r u p t i o n of t h e p a i r - b o n d i n g p r o c e s s . P r o d u c t i v i t y can be s e v e r e l y r e d u c e d , however, by human-i n d u c e d d i s t u r b a n c e d u r i n g t h e i n c u b a t i o n and e a r l y n e s t l i n g s t a g e s . At Stum Lake, human d i s t u r b a n c e (low f l y i n g a i r c r a f t ) d r a m a t i c a l l y r e d u c e d t h e p r o d u c t i v i t y of t h e c o l o n y d u r i n g t h e 1974 b r e e d i n g s e a s o n (Ryder 1974). A d u l t p e l i c a n s c r u s h e d eggs and young ( w h i t e p e l i c a n s i n c u b a t e t h e i r eggs w i t h t h e i r f e e t ) i n t h e i r a t t e m p t t o e s c a p e from a low f l y i n g a i r p l a n e . O n l y 24 young s u r v i v e d ( T a b l e 2 ) . The o v e r a l l p r o d u c t i v i t y f o r t h a t b r e e d i n g s e a s o n was 0.22 s u c c e s s f u l l y f l e d g e d y o u n g / n e s t (n = 108 n e s t s ) , w e l l below t h e a v e r a g e of y e a r s w i t h o u t d i s t u r b a n c e o r p r e d a t i o n (0.80 y o u n g / n e s t ) . 81 Human-induced d i s t u r b a n c e l a t e r i n t h e n e s t i n g s e a s o n , a f t e r most young have f l e d g e d , r e d u c e s p r o d u c t i v i t y o n l y s l i g h t l y . D u r i n g 1971, an a i r c r a f t o v e r f l i g h t c a u s e d m o r t a l i t y i n o n l y a few n e s t l i n g s and s m a l l e r f l e d g l i n g s (Ryder 1971) and r e s u l t e d i n an o v e r a l l p r o d u c t i v i t y o f 0.74 s u c c e s s f u l l y f l e d g e d y o u n g / n e s t (n = 104 n e s t s ) , o n l y s l i g h t l y below t h e a v e r a g e o f y e a r s w i t h o u t d i s t u r b a n c e or p r e d a t i o n (0.80 y o u n g / n e s t ) . 6.3.8 S u r v i v o r s h i p and P r o d u c t i v i t y i n r e l a t i o n t o C l u t c h S i z e The s u r v i v o r s h i p of young w h i t e p e l i c a n s and t h e p r o d u c t i v i t y o f i n d i v i d u a l n e s t s d i f f e r d r a m a t i c a l l y d e p e n d i n g on t h e i n i t i a l c l u t c h s i z e s of t h o s e n e s t s . When r e p r o d u c t i v e d a t a f o r 1977 and 1978 a r e combined, 11 n e s t s w i t h s i n g l e - e g g c l u t c h e s s u c c e s s f u l l y f l e d g e d 9 young. S u r v i v o r s h i p i n t h e s e n e s t s was h i g h e s t compared t o n e s t s w i t h two and t h r e e eggs (0.82 young f l e d g e d / e g g l a i d , F i g . 2 3 ) . However, t h e s e s i n g l e egg n e s t s were t h e l e a s t p r o d u c t i v e when measured as number o f young p r o d u c e d / n e s t . S u r v i v o r s h i p of young i n n e s t s w i t h a c l u t c h s i z e of two e g g s / n e s t (n = 43 n e s t s ) was l o w e r (0.65 young f l e d g e d / e g g l a i d ) ; however, n e s t p r o d u c t i v i t y was g r e a t e r (1.30 young f l e d g e d / n e s t ) compared w i t h s i n g l e egg n e s t s ( F i g . 2 3 ) . The s u r v i v o r s h i p o f n e s t s w i t h a c l u t c h s i z e of t h r e e (n = 2 n e s t s ) was even l o w e r (0.33 young f l e d g e d / e g g l a i d ) compared w i t h n e s t s w i t h one and two egg c l u t c h e s ; however, t h e a v e r a g e p r o d u c t i v i t y f o r t h e s e n e s t s was s t i l l g r e a t e r (1.0 young f l e d g e d / n e s t ) t h a n n e s t s w i t h a c l u t c h of o n l y one egg ( F i g . 2 3 ) . 82 1 1 1 1 2 3 (11 n e s t s ) (43 nests ) (2 n e s t s ) C l u t c h S i z e ( E g g s / N e s t ) Figure 23. Clutch size in relation to productivity and survivorship of young at Stum Lake, during 1977 and 1978. 83 6.4 D i s c u s s i o n 6.4.1 C o m p a r i s o n of R e p r o d u c t i v e S u c c e s s w i t h o t h e r W h i t e P e l i c a n C o l o n i e s i n N o r t h A m e r i c a Mean c l u t c h s i z e of w h i t e p e l i c a n s a t Stum Lake d u r i n g y e a r s w i t h o u t d i s t u r b a n c e (1.95 ± 0.21) does n o t d i f f e r m a r k e d l y from o b s e r v a t i o n s r e p o r t e d f o r o t h e r w h i t e p e l i c a n c o l o n i e s i n N o r t h A m e r i c a and l i e s i n t h e m i d d l e of t h e r e p o r t e d r a n g e . M a n s e l l (1965) r e p o r t e d a mean c l u t c h s i z e o f 1.81 ± 0.10 f o r w h i t e p e l i c a n s a t Lake of t h e Woods, O n t a r i o , and J o h n s o n (1976) o b t a i n e d s i m i l a r o b s e r v a t i o n s d u r i n g h i s 4-year s t u d y a t Chase L a k e , N o r t h D a k o t a (1.86 ± 0.18 eggs p e r n e s t ) . At a s m a l l c o l o n y i n S o u t h D a k o t a t h e a v e r a g e c l u t c h s i z e of 29 n e s t s was 1.97 eggs p e r n e s t (McCrow 1974). Knopf (1975) f o u n d t h e mean c l u t c h s i z e s a t G r e a t S a l t L a k e , U t a h , were 2.02 eggs p e r n e s t , w h i l e S c h a l l e r (1964) r e p o r t e d mean c l u t c h s i z e s of o n l y 1.69 eggs p e r n e s t a t Y e l l o w s t o n e L a k e , Wyoming. Mean egg m o r t a l i t y d u r i n g y e a r s w i t h o u t any d i s t u r b a n c e s a t Stum Lake was about 10% of t h e eggs l a i d i n t h e sample n e s t s . N e s t abandonment was t h e major m o r t a l i t y f a c t o r d u r i n g 1977 and 1978, r e s u l t i n g i n h a l f of t h e egg l o s s e s . I n f e r t i l e eggs ( o r eggs w i t h a r r e s t e d e m b r y o n i c d e v e l o p m e n t ) and egg d i s p l a c e m e n t were t h e c a u s e o f t h e r e m a i n i n g egg m o r t a l i t y . In o t h e r w h i t e p e l i c a n c o l o n i e s i n N o r t h A m e r i c a , n e s t abandonment has had much g r e a t e r e f f e c t s on egg l o s s e s compared t o t h o s e a t Stum L a k e . Human d i s t u r b a n c e however, a p p e a r s t o have been a major i n f l u e n c e i n t h o s e c o l o n i e s r e c o r d i n g h i g h r a t e s of n e s t 84 abandonment. At Chase L a k e , N o r t h D a k o t a , a r e s e a r c h e r s t u d i e d t h e c o l o n y f r o m a b l i n d s i t u a t e d o n l y 30 m f r o m t h e c o l o n y , c h e c k e d n e s t c o n t e n t s w e e k l y , and t a g g e d newly f l e d g e d young. D u r i n g t h e two y e a r s t u d y , n e s t abandonment a c c o u n t e d f o r an a v e r a g e of 53% o f a l l n e s t s . L o s s e s of between 60 and 80% of a l l eggs l a i d were r e c o r d e d . Knopf (1975) i n d i c a t e d t h a t n e s t abandonment (26% of n e s t s d u r i n g i n c u b a t i o n ) was t h e l a r g e s t s o u r c e o f egg m o r t a l i t y a t G r e a t S a l t L a k e , U t a h . Egg l o s s e s t h r o u g h d i s p l a c e m e n t from n e s t s was t h e s e c o n d h i g h e s t s o u r c e of m o r t a l i t y a t G r e a t S a l t L a k e , a c c o u n t i n g f o r 9% of a l l e g g s . N e s t l i n g m o r t a l i t y c l a i m e d a f u r t h e r 26% of t h e eggs l a i d i n t h e sample n e s t s d u r i n g 1977 and 1978 a t Stum L a k e . The major c a u s e o f m o r t a l i t y a p p e a r e d t o r e s u l t from s i b l i n g r i v a l r y a n d / o r s t a r v a t i o n . When c h i c k m o r t a l i t y was o b s e r v e d i n n e s t s o c c u p i e d by two n e s t l i n g s , t h e s m a l l e r c h i c k d i e d much more f r e q u e n t l y t h a n t h e l a r g e r n e s t l i n g (77% of t h o s e n e s t s ) . Knopf (1975) f o u n d t h a t 29% of t h e eggs l a i d were l o s t d u r i n g t h e n e s t l i n g s t a g e a t G r e a t S a l t L a k e , U t a h . Knopf n o t e d t h a t , o f t h e n e s t s i n w h i c h two eggs h a t c h e d , t h e s e c o n d c h i c k t o h a t c h u s u a l l y d i e d d u r i n g t h e n e s t l i n g p e r i o d . He f r e q u e n t l y o b s e r v e d a g g r e s s i o n between t h e n e s t l i n g s and f e l t t h a t t h e m ajor m o r t a l i t y f a c t o r d u r i n g t h e n e s t l i n g s t a g e was a c o n s e q u e n c e of s i b l i n g r i v a l r y a n d/or s t a r v a t i o n . J o h n s o n (1976) a t Chase Lake, N o r t h D a k o t a , a l s o f e l t t h a t t h e major m o r t a l i t y f a c t o r f o r n e s t l i n g s was e i t h e r s t a r v a t i o n or p h y s i c a l a b u s e by a l a r g e r n e s t l i n g . He n o t e d t h a t t h e . s m a l l e r young i n a n o r m a l two egg n e s t d i e d a t a r a t e a p p r o a c h i n g 100 p e r c e n t . 85 At Stum L a k e , t h e mean f l e d g l i n g m o r t a l i t y a c c o u n t e d f o r an a d d i t i o n a l 20% l o s s of eggs l a i d . S i b l i n g r i v a l r y a n d / o r s t a r v a t i o n a g a i n a p p e a r e d t o be t h e major m o r t a l i t y f a c t o r . The t o t a l m o r t a l i t y o f young f o r t h e 1977 and 1978 b r e e d i n g s e a s o n s a t Stum Lake was 56% o f t h e eggs p r o d u c e d . O v e r a l l p r o d u c t i v i t y and s u r v i v o r s h i p of young a t Stum L a k e , i n y e a r s w i t h o u t d i s t u r b a n c e , (0.80 y o u n g / n e s t and 0.44 young/egg l a i d r e s p e c t i v e l y ) does not d i f f e r g r e a t l y from o t h e r w h i t e p e l i c a n c o l o n i e s i n N o r t h A m e r i c a . Palmer (1962) s t a t e d t h a t a 50% m o r t a l i t y r a t e o f young i s common f o r w h i t e p e l i c a n s . Based on 1323 n e s t s a t G r e a t S a l t Lake, U t a h , w h i t e p e l i c a n s p r o d u c e d 0.85 y o u n g / n e s t and f l e d g e d 0.42 young f o r e a c h egg l a i d (Knopf 1975). W h i t e p e l i c a n s a t M e d i c i n e L a k e , Montana, p r o d u c e d 0.77 y o u n g / n e s t (n = 1140 n e s t s ) d u r i n g 1963, and a n o t h e r c o l o n y of about 500 n e s t s on S o u t h B i r d I s l a n d , T e x a s , p r o d u c e d a p p r o x i m a t e l y 0.9 y o u n g / n e s t ( L i e s and B e h l e 1966). A c o l o n y of 105 n e s t s a t R i v e r s i d e R e s e r v o i r , C o l o r a d o , f l e d g e d a mean o f 0.75 y o u n g / n e s t d u r i n g 1963 (Ryder and G r i e b 1963). D u r i n g 1976, however, t h e same c o l o n y p r o d u c e d 1.17 y o u n g / n e s t , t h e h i g h e s t e v e r r e c o r d e d f o r t h e s p e c i e s ( M i l l e r and Ryder 1977). They n o t e d t h a t t h e s u c c e s s r e s u l t e d from h i g h h a t c h l i n g s u r v i v a l r a t h e r t h a n h a t c h i n g s u c c e s s . 86 6.4.2 E f f e c t s of P r e d a t i o n and D i s t u r b a n c e a t White P e l i c a n N e s t i n g C o l o n i e s The e f f e c t s of p r e d a t i o n and d i s t u r b a n c e a t w h i t e p e l i c a n n e s t i n g c o l o n i e s a r e e x t r e m e l y v a r i a b l e . Under n o r m a l c o n d i t i o n s a t Stum L a k e , a v i a n p r e d a t i o n has v e r y l i t t l e e f f e c t on t h e s u r v i v a l o f young. Combined w i t h human d i s t u r b a n c e however, a v i a n p r e d a t i o n can be a major p r o b l e m . D u r i n g 1971 and 1974 a low f l y i n g a i r c r a f t c a u s e d p e l i c a n s t o t e m p o r a r i l y abandon t h e i r n e s t s a t Stum L a k e . D u r i n g t h e a d u l t ' s a b s e n c e , eggs and s m a l l n e s t l i n g s were consumed by g u l l s and c r o w s (Ryder 1971, 1974). J o h n s o n and S l o a n (1976) o b s e r v e d s i m i l a r phenomena d u r i n g t h e i r r e s e a r c h a c t i v i t i e s a t Chase L a k e . They f o u n d t h a t C a l i f o r n i a and r i n g - b i l l e d g u l l s ( L a r u s d e l a w a r e n s i s ) were more t o l e r a n t of human a c t i v i t y t h a n p e l i c a n s and moved f r e e l y i n t h e c o l o n y consuming p e l i c a n eggs and young w h i l e t h e r e s e a r c h e r s were p r e s e n t . Houston (1962) and S a n d e r s o n (1966) a l s o o b s e r v e d egg p r e d a t i o n by g u l l s when p e l i c a n s were d i s t u r b e d o f f t h e i r n e s t s i n S a s k a t c h e w a n . In g e n e r a l , w h i t e p e l i c a n young a r e most v u l n e r a b l e t o a v i a n p r e d a t i o n t h r o u g h o u t t h e i n c u b a t i o n p e r i o d (30 d a y s ) and d u r i n g t h e e a r l y b r o o d i n g p e r i o d ( f i r s t 10 t o 15 d a y s ) . The e f f e c t s o f mammalian p r e d a t i o n a r e u s u a l l y much more s e v e r e t h a n a v i a n p r e d a t i o n a t b r e e d i n g c o l o n i e s of w h i t e p e l i c a n s . A t Stum L a k e , w h i l e i c e s t i l l c o v e r e d t h e l a k e , c o y o t e s h a r a s s e d n e s t i n g p e l i c a n s on s e v e r a l o c c a s i o n s , c a u s i n g i n c r e a s e d e n e r g y e x p e n d i t u r e s f o r t h e n e s t i n g b i r d s , as w e l l as d e l a y s i n b r e e d i n g r a n g i n g from e i g h t t o e l e v e n d a y s . T h e s e d e l a y s p o t e n t i a l l y c o u l d a f f e c t t h e r e p r o d u c t i v e s u c c e s s o f t h e 87 c o l o n y . At G r e a t S a l t L a k e , Knopf (1975) f o u n d t h a t t h e r e p r o d u c t i v e s u c c e s s of w h i t e p e l i c a n s d e c l i n e d a s t h e b r e e d i n g s e a s o n p r o g r e s s e d . D e c r e a s e d p r o d u c t i o n r e f l e c t e d g r e a t e r l o s s e s of eggs and c h i c k s r e s u l t i n g from eggs r o l l i n g from n e s t s , n e s t abandonment, and i n c r e a s e d c h i c k m o r t a l i t y . G. M i l l e r ( p e r s . comm. 1980) a l s o i n d i c a t e d t h a t d e l a y s i n t h e b r e e d i n g s e a s o n r e d u c e d r e p r o d u c t i v e s u c c e s s of p e l i c a n s a t R i v e r s i d e R e s e r v o i r i n C o l o r a d o . Lower p r o d u c t i v i t y a t R i v e r s i d e R e s e r v o i r a p p e a r e d t o r e s u l t from s m a l l e r c l u t c h e s b e i n g l a i d as t h e s e a s o n p r o g r e s s e d . In a c o l o n y of C a s s i n ' s a u k l e t s ( P t y c h o r a m p h u s a l e u t i c u s ) , Manuwal (1979) f o u n d t h a t t h e r e p r o d u c t i v e s u c c e s s was l o w e r i n a u k l e t s t h a t l a i d eggs l a t e r i n t h e b r e e d i n g s e a s o n . F u r t h e r m o r e , growth r a t e s a n d ' f l e d g l i n g s w e i g h t s were l o w e r , and n e s t l i n g p e r i o d s l o n g e r among young h a t c h e d l a t e r i n t h e s e a s o n . Mammalian p r e d a t i o n midway t h r o u g h a n e s t i n g s e a s o n can c a u s e even g r e a t e r damage t o a c o l o n y . At Stum Lake i n 1972, c o y o t e s c a u s e d a l m o s t t o t a l d e s t r u c t i o n of eggs and young (Ryder 1972). Mammalian p r e d a t i o n a l s o has been a major f a c t o r l i m i t i n g t h e p r o d u c t i v i t y o f o t h e r w h i t e p e l i c a n c o l o n i e s i n N o r t h A m e r i c a . B l o k p o e l (1971) r e p o r t e d l i t t l e t o no p r o d u c t i o n of young p r i m a r i l y b e c a u s e of fox p r e d a t i o n a t Canada's l a r g e s t p e l i c a n b r e e d i n g c o l o n y a t P r i m r o s e L a ke, S a s k a t c h e w a n (2,459 n e s t s i n 1970). C o y o t e p r e d a t i o n a l s o r e s u l t e d i n t h e c o m p l e t e n e s t i n g f a i l u r e a t M a l h e u r Lake i n e a s t e r n Oregon d u r i n g 1960 ( S c o t t 1960). Young p e l i c a n s a r e v u l n e r a b l e t o c o y o t e p r e d a t i o n f r o m t h e b e g i n n i n g o f egg l a y i n g u n t i l t h e y a r e a b l e t o swim. S c h a l l e r (1964) r e p o r t e d t h a t young n o r m a l l y e n t e r t h e water a t 88 one month of age. However, a t Chase L a k e , one month o l d young were o b s e r v e d t o e n t e r t h e water o n l y when d i s t u r b e d ( J o h n s o n and S l o a n 1976). They n o t e d t h a t t h e s e young became r a p i d l y w a t e r l o g g e d and c h i l l e d . At Stum L a k e , young f i r s t e n t e r e d t h e water a t ab o u t 60 days of age. W h i t e p e l i c a n s a r e e x t r e m e l y i n t o l e r a n t of human a c t i v i t y d u r i n g t h e b r e e d i n g s e a s o n . When d i s t u r b e d , t h e y r e a d i l y abandon t h e i r n e s t s , e x p o s i n g eggs and young t o p h y s i c a l s t r e s s and p r e d a t i o n by g u l l s and c r o w s . E n t i r e c o l o n i e s may be d e s t r o y e d as a r e s u l t o f human d i s t u r b a n c e (Houston 1962, C a r s o n 1966, Vermeer 1970a). In t h e l a s t two d e c a d e s , a t l e a s t 10 c o l o n i e s have d i s a p p e a r e d from Canada b e c a u s e o f d i r e c t human i n t e r f e r e n c e o r b e c a u s e of h a b i t a t c h a n g e s made by man (Vermeer 1971). At Stum L a k e , d i s t u r b a n c e d u r i n g t h e e a r l y s t a g e s , s u c h as c o u r t s h i p and n e s t s i t e s e l e c t i o n , a p p e a r s t o have had o n l y minor e f f e c t s . However, r e p e a t e d d i s t u r b a n c e d u r i n g t h e i n i t i a l s t a g e s o f r e p r o d u c t i o n c o u l d c a u s e t h e b i r d s t o t o t a l l y abandon th e c o l o n y f o r t h e y e a r (Committee on t h e S t a t u s o f E n d a n g e r e d W i l d l i f e i n Canada 1979). Human d i s t u r b a n c e d u r i n g i n c u b a t i o n and e a r l y n e s t l i n g s t a g e s c a n s e v e r e l y l i m i t t h e p r o d u c t i v i t y of a c o l o n y . D u r i n g 1974 a t Stum L a k e , a low f l y i n g a i r c r a f t c a u s e d p e l i c a n s t o c r u s h many eggs and young as t h e y a t t e m p t e d t o e s c a p e . In a d d i t i o n t o t h e d i r e c t m o r t a l i t y c a u s e d by t h e a d u l t s , abandoned eggs and young were p r e y e d on by g u l l s and were s u b j e c t t o t e m p e r a t u r e s t r e s s . U n p r o t e c t e d eggs and naked n e s t l i n g s can q u i c k l y succumb t o d i r e c t s u n l i g h t (Bartholomew e_t a_l. 1953). At Chase L a k e , naked young d i e d w i t h i n f i v e m i n u t e s when e x p o s e d 89 t o h i g h t e m p e r a t u r e s ( J o h n s o n and S l o a n 1976). The p e r i o d when young p e l i c a n s a r e most v u l n e r a b l e t o human d i s t u r b a n c e o c c u r s t h r o u g h o u t t h e i n c u b a t i o n p e r i o d u n t i l t h e y have f l e d g e d ( a b o u t 28 t o 30 d a y s ) . Human d i s t u r b a n c e a f t e r young have f l e d g e d c a u s e d o n l y a m i n i m a l r e d u c t i o n i n p r o d u c t i v i t y a t Stum Lake d u r i n g 1971 (Ryder 1971). 6.4.3 I m p l i c a t i o n s of C l u t c h S i z e D a t a c o l l e c t e d a t Stum Lake s u p p o r t L a c k ' s (1966) h y p o t h e s i s t h a t i n n i d i c o l o u s b i r d s t h e n o r m a l c l u t c h s i z e i s t h a t w h i c h , on a v e r a g e , r e s u l t s i n t h e l a r g e s t number of s u r v i v i n g young. The mean c l u t c h s i z e a t Stum Lake d u r i n g y e a r s w i t h o u t d i s t u r b a n c e (1977, 1978) o r when d i s t u r b a n c e o c c u r r e d a f t e r t h e c o m p l e t i o n of c o u r t s h i p and egg l a y i n g (1971, 1972) was 1.95 ± 0.21 (n = 4 1 1 ) . In b o t h 1977 and 1978, t h e most f r e q u e n t l y o c c u r r i n g c l u t c h s i z e was two eggs p e r n e s t ( 7 5 % of t h e c l u t c h e s had two e g g s ) . N e s t s w i t h two egg c l u t c h e s a t Stum Lake p r o d u c e d , on a v e r a g e , more s u c c e s s f u l young (1.3 y o u n g / n e s t ) t h a n s i n g l e egg c l u t c h e s (0.82 y o u n g / n e s t ) . L a c k (1966) a l s o s t a t e d t h a t t h e a d d i t i o n of eggs t o make l a r g e r t h a n normal b r o o d s s h o u l d r e s u l t i n f e w e r , not more, young s u r v i v i n g p e r b r o o d . At Stum L a k e , n e s t s w i t h t h r e e egg c l u t c h e s p r o d u c e d fewer s u c c e s s f u l young (1.0 y o u n g / n e s t ) t h a n more common c l u t c h e s w i t h two eggs (1.3 y o u n g / n e s t ) . 90 A p p a r e n t l y t h e b e s t s t r a t e g y f o r w h i t e p e l i c a n s t o maximize t h e i r r e p r o d u c t i v e o u t p u t i s t o l a y a c l u t c h o f two e g g s / n e s t . In an u n d i s t u r b e d c o n d i t i o n , a c l u t c h o f two e g g s / n e s t w i l l r e s u l t i n an i n t e r m e d i a t e amount o f m o r t a l i t y ( i n c r e a s e d s i b l i n g r i v a l r y w i t h l a r g e r c l u t c h e s ) compared w i t h one and t h r e e egg c l u t c h e s , and, on a v e r a g e , w i l l r e s u l t i n t h e maximum number of o f f s p r i n g / n e s t . 91 CHAPTER 7. BEHAVIOUR OF WHITE PELICANS AT STUM LAKE 7. 1 I n t r o d u c t i o n I n t r a s p e c i f i c and i n t e r s p e c i f i c b e h a v i o u r were m o n i t o r e d a t Stum Lake t o d e t e r m i n e t h e i r e f f e c t s on t h e c o l o n y ' s n e s t i n g s u c c e s s . I n t r a s p e c i f i c b e h a v i o u r was examined t o a s s e s s t h e p o s s i b i l i t y t h a t upper l i m i t s t o t h e c o l o n y were b e i n g e s t a b l i s h e d by t h e p e l i c a n s t h e m s e l v e s . I r e c o r d e d a g g r e s s i v e i n t e r a c t i o n s betweem a d u l t s , a d u l t a g g r e s s i o n d i r e c t e d a t young, and s i b l i n g a g g r e s s i o n . O b s e r v a t i o n s a l s o were made of i n t e r s p e c i f i c r e l a t i o n s and p o t e n t i a l p r e d a t i o n by C o r v i d s and h e r r i n g g u l l s . I a l s o t r i e d t o d e t e r m i n e whether t h e r e was any c o m p e t i t i o n f o r n e s t i n g s i t e s between h e r r i n g g u l l s and w h i t e p e l i c a n s . S p e c i f i c o b j e c t i v e s were: 1) To document a d u l t w h i t e p e l i c a n a g g r e s s i o n a t Stum Lake d u r i n g t h e b r e e d i n g s e a s o n ; 2) To document s i b l i n g a g g r e s s i o n a t Stum L a k e ; and, 3) To d e s c r i b e t h e b e h a v i o u r a l i n t e r a c t i o n s of w h i t e p e l i c a n s w i t h o t h e r s p e c i e s , s u c h as c r o w s , g u l l s , c o y o t e s , and humans. 92 7.2 Methods Due t o t h e s e n s i t i v i t y of w h i t e p e l i c a n s t o human d i s t u r b a n c e , a l l b e h a v i o u r a l o b s e r v a t i o n s were r e c o r d e d f r o m t h e m a i n l a n d w i t h t h e a i d of a 20 t o 45X s p o t t i n g s c o p e . A l t h o u g h a d u l t b i r d s c o u l d n ot be marked, b o t h p h y s i c a l and b e h a v i o u r a l f e a t u r e s o f t h e b i r d s made i t p o s s i b l e t o i d e n t i f y many i n d i v i d u a l s . F o r example, males a r e g e n e r a l l y l a r g e r t h a n f e m a l e s (Palmer 1962) and d u r i n g c o u r t s h i p e x h i b i t many b e h a v i o u r a l d i f f e n c e s . In a d d i t i o n , t h e f i b r o u s p l a t e on t h e upper m a n d i b l e of b o t h s e x e s d u r i n g t h e e a r l y p h a s e s of t h e b r e e d i n g s e a s o n , and t h e plumage c h a r a c t e r i s t i c s of t h e crown ( p o s t - n u p t i a l m o l t ) d u r i n g i n c u b a t i o n and l a t e r p h a s e s of t h e b r e e d i n g s e a s o n were h i g h l y v a r i a b l e between i n d i v i d u a l s . I m o n i t o r e d i n t r a s p e c i f i c b e h a v i o u r a t t h e c o l o n y d u r i n g a l l f o u r b r e e d i n g s e a s o n s . D u r i n g t h e 1979 and 1980 b r e e d i n g s e a s o n s , e m p h a s i s was p l a c e d on c o u r t s h i p and e a r l y n e s t i n g b e h a v i o u r , and d u r i n g 1977 and 1978, on i n c u b a t i o n and b r o o d i n g b e h a v i o u r . I u s e d f o c a l - a n i m a l s a m p l i n g t o s t u d y i n t r a s p e c i f i c b e h a v i o u r . U s i n g t h i s s a m p l i n g method, a l l o c c u r r e n c e s of s p e c i f i e d ( i n t e r ) a c t i o n s of an i n d i v i d u a l a r e r e c o r d e d d u r i n g a sample p e r i o d (Altmann 1974). A t o t a l of 387.2 h o u r s of i n t r a s p e c i f i c b e h a v i o u r was r e c o r d e d . Sample s e s s i o n s began a t p r e - d e t e r m i n e d t i m e s d u r i n g t h e day ( g e n e r a l l y on t h e h o u r ) and were t e r m i n a t e d a f t e r one, two, or t h r e e h o u r s . S e s s i o n s a l s o were t e r m i n a t e d when t h e f o c a l i n d i v i d u a l was no l o n g e r i n v i e w . F o c a l i n d i v i d u a l s were s e l e c t e d e i t h e r r andomly or on t h e b a s i s of some b e h a v i o u r a l c r i t e r i o n ; f o r example, t h e f i r s t b i r d t o 93 ' s t r e t c h ' . O n l y r e a d i l y - v i s i b l e i n d i v i d u a l s were c h o s e n f o r b e h a v i o u r a l s t u d i e s . D u r a t i o n s o f a c t i v i t i e s were t i m e d u s i n g an ' a c t i v i t y b o a r d ' w h i c h c o n t a i n e d t h r e e s t o p w a t c h e s m e a s u r i n g 0.01-min i n t e r v a l s . I n t e r s p e c i f i c i n t e r a c t i o n s of w h i t e p e l i c a n s w i t h p o t e n t i a l a v i a n p r e d a t o r s were r e c o r d e d o p p o r t u n i s t i c a l l y t h r o u g h o u t t h e p e l i c a n i n c u b a t i o n and b r o o d i n g p e r i o d s i n 1978. O b s e r v a t i o n p e r i o d s began when an a v i a n p r e d a t o r l a n d e d on t h e n e s t i n g i s l a n d and t e r m i n a t e d when t h e b i r d d e p a r t e d . T h e s e o b s e r v a t i o n p e r i o d s r a n g e d from 0.5 t o 4.4 min i n d u r a t i o n . The t o t a l sample s i z e of a v i a n i n t e r s p e c i f i c i n t e r a c t i o n s was 34 min c o n t a i n i n g 270 crow- or g u l l - p e l i c a n i n t e r a c t i o n s . 7.3 R e s u l t s 7.3.1 I n t r a s p e c i f i c I n t e r a c t i o n s A g g r e s s i v e a c t i v i t y among a d u l t w h i t e p e l i c a n s a t Stum Lake was g r e a t e s t w h i l e t h e b i r d s were c o u r t i n g and s e l e c t i n g n e s t s i t e s ( F i g . 2 4 ) . The mean number o f a g o n i s t i c e n c o u n t e r s f o r mal e s and f e m a l e s combined d u r i n g t h i s p e r i o d was 11.5 a g g r e s s i v e i n t e r a c t i o n s / h o u r . T h i s r a t e d e c l i n e d d r a m a t i c a l l y once i n c u b a t i o n began (6.2 a g g r e s s i v e i n t e r a c t i o n s / h o u r ) , and once a g a i n when t h e young h a t c h e d (1.3 a g g r e s s i v e i n t e r a c t i o n s / h o u r ) . T h e r e was no change i n t h e mean a g o n i s t i c r a t e f r o m t h e b r o o d i n g p e r i o d t o t h e p o s t - b r o o d i n g p e r i o d . T h r o u g h o u t t h e e n t i r e b r e e d i n g s e a s o n , m a l e s had more a g g r e s s i v e e n c o u n t e r s / h o u r t h a n f e m a l e s . T h i s was e s p e c i a l l y 94 Courtship Incubation Brooding Post-brooding and Nest ,_„. Establishment ( 9 7 8 h,) <93 7 hr> <20-» "0 (174.8 hr) Figure 24. Aggressive i n t e r a c t i o n rate among adult white pelicans at Stum Lake, B r i t i s h Columbia. 95 e v i d e n t d u r i n g c o u r t s h i p and n e s t s e l e c t i o n ( F i g . 2 4 ) . The mean number of a g o n i s t i c e n c o u n t e r s f o r m a l e s and f e m a l e s d u r i n g t h i s p e r i o d was 16.1 and 6.5 a g g r e s s i v e i n t e r a c t i o n s / h o u r , r e s p e c t i v e l y . D u r i n g t h e i n c u b a t i o n and b r o o d i n g p e r i o d s , d i f f e r e n c e s between male and f e m a l e a g o n i s t i c e n c o u n t e r r a t e s were o n l y s l i g h t . A g o n i s t i c e n c o u n t e r s f o r m ales and f e m a l e s were 7.5 and 7.1 i n t e r a c t i o n s / h o u r , r e s p e c t i v e l y d u r i n g i n c u b a t i o n and 1.6 and 1.1 i n t e r a c t i o n s / h o u r , r e s p e c t i v e l y d u r i n g b r o o d i n g . The d i f f e r e n c e s o b s e r v e d between males and f e m a l e s d u r i n g t h e p o s t - b r o o d i n g p e r i o d may not g i v e an a c c u r a t e r e p r e s e n t a t i o n of a g g r e s s i v e a c t i v i t y f o r two r e a s o n s . The t o t a l o b s e r v a t i o n p e r i o d f o r m a l e s was s m a l l ( t h r e e h o u r s ) and one male a c c o u n t e d f o r more t h a n h a l f of a l l a g o n i s t i c e n c o u n t e r s o b s e r v e d ( s e v e n of t h e t w e l v e a g g r e s s i v e i n t e r a c t i o n s ) . A d u l t a g g r e s s i v e b e h a v i o u r d i r e c t e d a t young was o b s e r v e d i n f r e q u e n t l y a t Stum L a k e . D u r i n g one i n s t a n c e , an a d u l t on t h e p e r i p h e r y o f a n e s t i n g g r o u p t o s s e d a n e s t l i n g i n t o t h e s u r r o u n d i n g v e g e t a t i o n . I c o u l d n o t d e t e r m i n e i f t h i s young b e l o n g e d t o t h e a d u l t , or i f i t came from a n o t h e r n e s t . D u r i n g t h e p o s t - b r o o d i n g s t a g e , when f l e d g l i n g s were l e f t u n a t t e n d e d , I o b s e r v e d s e v e r a l a t t e m p t s by a d u l t s t o mount young. D u r i n g t h e s e c o p u l a t i o n a t t e m p t s th e young were r e p e a t e d l y b i t t e n and p e c k e d by t h e a d u l t . The c o p u l a t i o n a t t e m p t s g e n e r a l l y were of s h o r t d u r a t i o n (10 t o 30 s e c o n d s ) and d i d not a p p e a r t o r e s u l t i n s e r i o u s i n j u r y t o t h e f l e d g l i n g s . I n t r a s p e c i f i c a g g r e s s i o n between young o c c u r r e d f r e q u e n t l y t h r o u g h o u t t h e b r o o d i n g p e r i o d . A g o n i s t i c b e h a v i o u r was 96 e s p e c i a l l y common i n n e s t s o c c u p i e d by two young. In n e s t s where one s i b l i n g was l a r g e r t h a n a n o t h e r , n e a r l y a l l o f t h e a g g r e s s i v e i n t e r a c t i o n s were i n i t i a t e d by t h e l a r g e r n e s t l i n g . A t t a c k s were n e a r l y a l w a y s d i r e c t e d a t t h e h e a d an d neck r e g i o n . F o r example, i n a n e s t s t u d i e d i n t e n s i v e l y d u r i n g 1977, one egg h a t c h e d a t l e a s t 24 h o u r s p r i o r t o t h e s e c o n d eg g . At f o u r d a y s of age, t h e l a r g e r n e s t l i n g ( a b o u t t w i c e t h e s i z e of t h e s m a l l e r ) c o n t i n u a l l y h a r a s s e d t h e s m a l l e r c h i c k . N e a r l y a l l o f t h e p e c k i n g was d i r e c t e d a t t h e head and e y e s o f t h e s m a l l e r n e s t l i n g . By s e v e n d ays of age ( l a r g e r y o u n g ) , t h e s m a l l e r c h i c k was f r e q u e n t l y f o r c e d t o r e t r e a t o u t s i d e t h e n e s t . In a d d i t i o n , t h e two c h i c k s were n o t f e d e q u a l l y . The l a r g e r young u s u a l l y f e d d i r e c t l y from th e a d u l t s pouch, w h i l e t h e s m a l l e r c h i c k f e d o n l y on what d r o p p e d t o t h e g r o u n d . O c c a s i o n a l l y t h e a d u l t r e g u r g i t a t e d f o o d i n t o t h e n e s t , but t h e l a r g e r n e s t l i n g was f a s t e r and p i c k e d up f o o d more q u i c k l y . At 14 d a y s of age (age of l a r g e r c h i c k ) , o n l y t h e l a r g e r n e s t l i n g was o b s e r v e d i n t h e n e s t . In n e s t s w i t h s i b l i n g s o f e q u a l s i z e , i n t r a s p e c i f i c a g g r e s s i o n was a l s o i n t e n s e ; however, b o t h young u s u a l l y o b t a i n e d some f o o d . D u r i n g mid A u g u s t , I f r e q u e n t l y o b s e r v e d a d u l t s a r r i v e a t t h e l a k e , f e e d two young of e q u a l s i z e , and t h e n d e p a r t . 97 7.3.2 I n t e r s p e c i f i c R e l a t i o n s E f f e c t s of i n t e r s p e c i f i c i n t e r a c t i o n s on t h e p r o d u c t i v i t y of w h i t e p e l i c a n s a t Stum Lake have been d i s c u s s e d ( C h a p t e r 6 ) . The few o b s e r v a t i o n s of b e h a v i o u r a l i n t e r a c t i o n s o f w h i t e p e l i c a n s w i t h o t h e r s p e c i e s a r e d e s c r i b e d b r i e f l y . I r e c o r d e d i n t e r a c t i o n s w i t h o t h e r b i r d s , p a r t i c u l a r l y p o t e n t i a l p r e d a t o r s on eggs and young, s u c h as h e r r i n g g u l l s and common c r o w s . I n t e r a c t i o n s f r e q u e n t l y o c c u r r e d whenever a g u l l o r crow l a n d e d n e a r t h e n e s t i n g b i r d s . A n t i - p r e d a t o r d e f e n c e b e h a v i o u r by n e s t i n g p e l i c a n s , s u c h as a ' b i l l l u n g e ' , u s u a l l y o c c u r r e d when t h e p r e d a t o r a p p r o a c h e d t o w i t h i n a c e r t a i n d i s t a n c e . I f o u n d t h a t g u l l s and crows v i s i t e d p e r i p h e r a l n e s t s much more f r e q u e n t l y t h a n would be e x p e c t e d i n terms of t h e i r a v a i l a b i l i t y r e l a t i v e t o c e n t r a l n e s t s ( C h i - S q u a r e d One Sample T e s t , P < 0.001). N e a r l y a l l o f t h e i n t e r a c t i o n s r e c o r d e d (264 of 270) i n v o l v e d p e l i c a n s n e s t i n g on g r o u p p e r i p h e r i e s (84 of the 105 n e s t s were c o n s i d e r e d a s p e r i p h e r a l n e s t s ) . The i n t e r a c t i o n r a t e of p e r i p h e r a l n e s t i n g p e l i c a n s w i t h a v i a n p r e d a t o r s was 7.8 i n t e r a c t i o n s / m i n o f o b s e r v a t i o n , w h i l e t h a t o f th e c e n t r a l n e s t i n g p e l i c a n s , was 0.2 i n t e r a c t i o n s / m i n of o b s e r v a t i o n . F i v e of t h e s i x c e n t r a l b i r d s t h a t i n t e r a c t e d w i t h a p r e d a t o r were a d j a c e n t t o a p e r i p h e r a l n e s t and were a s s i s t i n g a p e r i p h e r a l b i r d . The o t h e r c e n t e r - n e s t i n g b i r d t h a t r e a c t e d t o a p r e d a t o r snapped i t s b i l l a t a crow f l y i n g o v e r h e a d . A l l of t h e 270 i n t e r a c t i o n s i n v o l v e d t h r e a t e n i n g b e h a v i o u r by n e s t i n g p e l i c a n s . 98 I d i d not o b s e r v e any i n t e r s p e c i f i c c o m p e t i t i o n f o r n e s t i n g s i t e s between p e l i c a n s and h e r r i n g g u l l s a t Stum L a k e . When p e l i c a n s f i r s t a r r i v e d d u r i n g t h e s p r i n g , h e r r i n g g u l l s had a l r e a d y e s t a b l i s h e d n e s t i n g s i t e s on I s l a n d One and Sc a u p I s l a n d . The g u l l s d i d not a p p e a r d i s t u r b e d by t h e c o u r t i n g p e l i c a n s . P e l i c a n s u t i l i z e d a l l t h r e e i s l a n d s d u r i n g t h e i r c o u r t s h i p , and t h e p r e s e n c e or a b s e n c e of g u l l s d i d not seem t o c a u s e any d e v i a t i o n s from t h e i r n o r m a l b e h a v i o u r . I n t e r a c t i o n s between t h e two s p e c i e s were not common. Those i n t e r a c t i o n s o b s e r v e d u s u a l l y i n v o l v e d p e l i c a n s w h i c h had e i t h e r d i s p l a c e d o r t h r e a t e n e d a p a s s i n g g u l l . O n l y on one o c c a s i o n was a g u l l o b s e r v e d t h r e a t e n i n g a p e l i c a n . Mammalian i n t e r a c t i o n s w i t h n e s t i n g p e l i c a n s g e n e r a l l y had more d r a m a t i c c o n s e q u e n c e s t h a n d i d a v i a n i n t e r a c t i o n s . I o b s e r v e d f i v e c o y o t e d i s t u r b a n c e s d u r i n g t h e c o u r t s h i p and e a r l y n e s t i n g p e r i o d s w h i l e i c e s t i l l c o v e r e d Stum L a k e . D i s t u r b a n c e s d u r i n g t h e s e p e r i o d s c a u s e d p e l i c a n s t o abandon t h e l a k e f o r one or two d a y s . P e l i c a n s t y p i c a l l y f l e w from t h e i r i s l a n d s when c o y o t e s came w i t h i n 150 m. H e r r i n g g u l l s a l w a y s l e f t t h e i s l a n d s s e v e r a l m i n u t e s b e f o r e p e l i c a n s d i d . B o t h s p e c i e s c i r c l e d t h e i s l a n d f o r p e r i o d s r a n g i n g from f i v e t o t e n m i n u t e s , w h i l e c o y o t e s s e a r c h e d t h e n e s t i n g s i t e s . G e n e r a l l y , t h e b i r d s l a n d e d on t h e i c e near t h e i s l a n d , o n l y a f t e r t h e c o y o t e s had l e f t . S m a l l f l o c k s of p e l i c a n s t h e n began t o l e a v e t h e l a k e , and by s u n s e t , most had d e p a r t e d . I t was d i f f i c u l t t o d e t e r m i n e i f d i s t u r b e d b i r d s r e t u r n e d t h e n e x t day, as m i g r a t i n g f l o c k s a r r i v e d e a c h day d u r i n g t h e s p r i n g . 99 C o y o t e d i s t u r b a n c e d u r i n g t h e i n c u b a t i o n and b r o o d i n g p e r i o d s c a u s e d p e l i c a n s t o abandon Stum Lake f o r t h r e e or f o u r d a y s (Ryder 1972). A d u l t s b u r s t i n t o t h e a i r from t h e i r n e s t s and i m m e d i a t e l y began l e a v i n g t h e l a k e i n s m a l l f l o c k s . The young s c a t t e r e d i n many d i r e c t i o n s and some o f t h e s e became e n t a n g l e d i n t h e v e g e t a t i o n . Many of t h e young n o t k i l l e d i m m e d i a t e l y by t h e c o y o t e s , e v e n t u a l l y d i e d o f e i t h e r s t a r v a t i o n or p h y s i c a l s t r e s s ( e x p o s u r e ) . When a d u l t p e l i c a n s r e t u r n e d t o th e l a k e , most l a n d e d on a n o t h e r i s l a n d and o n l y f l e w b r i e f l y o v e r t h e n e s t i n g i s l a n d . Human-induced d i s t u r b a n c e a p p e a r e d t o c a u s e s i m i l a r r e s u l t s t o t h a t of c o y o t e d i s t u r b a n c e . D u r i n g a n e s t s u r v e y i n 1969, i n c u b a t i n g p e l i c a n s i m m e d i a t e l y abandoned t h e i r n e s t s when a boat was b e a c h e d on t h e b r e e d i n g i s l a n d ( W r i g h t and W r i g h t 1970). The p e l i c a n s c i r c l e d t h e i s l a n d s e v e r a l t i m e s , t h e n l e f t t h e l a k e . The outcome of d i s t u r b a n c e by l o w - f l y i n g a i r c r a f t d u r i n g 1974 a p p e a r e d s i m i l a r . In l a t e J u n e , a l o w - f l y i n g a i r c r a f t f l e w o v e r Stum Lake and c a u s e d a l l i n c u b a t i n g and b r o o d i n g a d u l t s on I s l a n d Two t o abandon t h e i r n e s t s . Eggs and young were c r u s h e d by s t a m p e d i n g a d u l t s d u r i n g t h e i n c i d e n t . A d u l t s d i d not r e t u r n t o t h e n e s t i n g i s l a n d f o r s i x or sev e n d ays (G.R. Ryder P e r s . Comm.). As a r e s u l t , many of t h e young t h a t s u r v i v e d t h e i n i t i a l e f f e c t of t h e d i s t u r b a n c e , s t a r v e d d u r i n g t h e a d u l t s a b s e n c e . 100 7.4 D i s c u s s i o n A d u l t i n t r a s p e c i f i c a g g r e s s i o n was o b s e r v e d a t Stum Lake t h r o u g h o u t t h e b r e e d i n g s e a s o n . The mean number of a d u l t a g o n i s t i c e n c o u n t e r s (males and f e m a l e s combined) was g r e a t e s t d u r i n g t h e c o u r t s h i p p e r i o d (11.5 i n t e r a c t i o n s / h o u r ) and d e c l i n e d r a p i d l y once i n c u b a t i o n began (6.2 i n t e r a c t i o n s / h o u r ) . T h i s r e d u c t i o n i n a g g r e s s i v e a c t i v i t y may be a f u n c t i o n of t h e d e c r e a s e i n p e l i c a n d e n s i t y a s s o c i a t e d w i t h t h e o n s e t of i n c u b a t i o n . Once t h e f e m a l e of a p a i r l a y s an egg, t h e male l e a v e s t h e c o l o n y f o r s e v e r a l d a y s t o f o r a g e . T h i s e f f e c t i v e l y r e d u c e s t h e p e l i c a n p o p u l a t i o n on t h e b r e e d i n g i s l a n d by a b o u t h a l f . P r i o r t o l a y i n g , b o t h t h e male and f e m a l e o c c u p y e d t h e n e s t s i t e . The d e c l i n e i n t h e a g o n i s t i c r a t e from t h e i n c u b a t i o n p e r i o d (6.2 i n t e r a c t i o n s / h r ) t o t h e b r o o d i n g p e r i o d (1.3 i n t e r a c t i o n s / h r ) may have r e s u l t e d from an i n c r e a s e i n t h e amount of t i m e t h e a d u l t s s p e n t c a r i n g f o r ( f e e d i n g ) t h e i r young. Newly h a t c h e d young were f e d f i v e or s i x t i m e s p e r hour w i t h f e e d i n g b o u t s r a n g i n g between 0.5 and 5.0 m i n u t e s . A g o n i s t i c a c t i v i t y d i d n o t change between t h e b r o o d i n g and p o s t -b r o o d i n g p e r i o d . In g e n e r a l , a d u l t i n t r a s p e c i f i c a g g r e s s i o n d i d not a p p e a r t o a d v e r s e l y a f f e c t t h e b r e e d i n g s u c c e s s of w h i t e p e l i c a n s a t Stum L a k e . In f a c t , a l l of t h e n e s t s i t e s abandoned a t Stum Lake d u r i n g 1977 and 1978 (8 of 191 n e s t s ) were s i t u a t e d i n a r e a s of low d e n s i t y where a g g r e s s i v e i n t e r a c t i o n s were few; t h a t i s t h e n e s t s were e i t h e r s o l i t a r y or on g r o u p p e r i p h e r i e s . 101 I t i s p o s s i b l e t h a t i n t r a s p e c i f i c a g g r e s s i o n among a d u l t w h i t e p e l i c a n s d u r i n g i n c u b a t i o n may s t i m u l a t e n e s t - a t t e n t i v e n e s s and r e d u c e t h e p o t e n t i a l f o r n e s t abandonment. Pomeroy (1978) s u g g e s t e d t h a t , i n marabou s t o r k s ( L e p t o p t i l o s c r u m e n i f e r u s ) , t h e c l o s e r n e s t s a r e t o e a c h o t h e r , t h e more f r e q u e n t l y t h e p a r e n t s a r e r e m i n d e d of l e a v i n g them u n g u a r d e d . T e n a z a ( 1 9 7 1 ) , s t u d y i n g A d e l i e p e n g u i n s ( P y g o s c e l i s a d e l i a e ) , f o u n d t h a t c e n t r a l n e s t s were l e s s l i k e l y t o be l e f t e x p o s e d t h a n were p e r i p h e r a l o n e s . He s u g g e s t e d t h a t one a d v a n t a g e of c e n t r a l n e s t i n g i s t h a t t h e t e n d a n c y t o r e m a i n on t h e n e s t i s i n c r e a s e d by n e i g h b o u r s ' h o s t i l i t y . A d u l t a g g r e s s i v e b e h a v i o u r d i r e c t e d a t young was r a r e l y o b s e r v e d a t Stum Lake and a p p e a r e d t o r e p r e s e n t o n l y a v e r y m i n o r s o u r c e of m o r t a l i t y . I n t r a s p e c i f i c a g g r e s s i o n between young i n t h e same n e s t however, was f r e q u e n t and a p p e a r e d t o a c c o u n t f o r a h i g h p e r c e n t a g e of m o r t a l i t y i n b o t h n e s t l i n g s and f l e d g l i n g s . In n e s t s where the s i z e of t h e s i b l i n g s d i f f e r e d , t h e s m a l l e r n e s t l i n g r e c e i v e d t h e m a j o r i t y of t h e a g g r e s s i v e a t t a c k s . 1 In 17 of 22 n e s t s t h a t c o n t a i n e d two young, o n l y t h e s m a l l e r n e s t l i n g d i e d . In t h e f i v e o t h e r n e s t s , t h e s u r v i v i n g and dead n e s t l i n g s a p p e a r e d t o be of s i m i l a r s i z e . O b s e r v a t i o n s a t Chase Lake, N o r t h D a k o t a , a l s o r e v e a l p o o r s u r v i v a l o f s e c o n d b o r n young. No n e s t s were o b s e r v e d t h a t c o n t a i n e d two young o v e r t h r e e weeks of age ( J o h n s o n 1976). The m a j o r i t y o f t h e m o r t a l i t y a t Chase Lake r e s u l t e d from e i t h e r s t a r v a t i o n o r p h y s i c a l abuse by t h e l a r g e r n e s t l i n g . Knopf (1975) a l s o n o t e d t h a t t h e major s o u r c e of m o r t a l i t y was d e a t h of t h e s m a l l e r c h i c k i n n e s t s where two c h i c k s h a t c h e d . Knopf 1 02 (1980) f o u n d t h a t t h e i n c i d e n c e of b o t h c h i c k s s u r v i v i n g i n t h e same n e s t d e c l i n e d w i t h an i n c r e a s e i n t h e i n t e r v a l between h a t c h i n g of t h e e g g s . I n t e r s p e c i f i c i n t e r a c t i o n s of w h i t e p e l i c a n s w i t h p o t e n t i a l p r e d a t o r s on eggs and young were examined. G u l l s and crows v i s i t e d p e r i p h e r a l n e s t s much more f r e q u e n t l y t h a n would be e x p e c t e d i n terms of t h e i r a v a i l a b i l i t y r e l a t i v e t o c e n t r a l n e s t s . C o u l s o n (1968) and V i n e (1971) h y p o t h e s i z e d t h a t i n d i v i d u a l s a t t h e c e n t e r s of n e s t i n g g r o u p s would be a t a l e s s e r r i s k t h a n t h o s e a t t h e e d g e s . In a d d i t i o n , p e r i p h e r a l n e s t e r s s h o u l d a l s o e x p e r i e n c e g r e a t e r , s t r e s s from th e h i g h e r number of p r e d a t o r c o n t a c t s ( B a r n e t t 1964). D a t a c o l l e c t e d a t Stum La k e a p p e a r t o s u p p o r t t h e s e h y p o t h e s e s . At Stum Lake, th e h i g h e r i n t e r a c t i o n r a t e of a v i a n p r e d a t o r s w i t h p e l i c a n s n e s t i n g on p e r i p h e r i e s (7.8 i n t e r a c t i o n s / m i n o f o b s e r v a t i o n ) compared w i t h t h o s e i n g r o u p c e n t e r s (0.2 i n t e r a c t i o n s / m i n of o b s e r v a t i o n ) i n d i c a t e t h a t t h e r i s k of p r e d a t i o n and t h e p o s s i b l i t y of g r e a t e r s t r e s s was g r e a t e r i n p e r i p h e r a l n e s t s . B i r d p r e d a t i o n a t Stum L a k e , however, was o n l y a minor m o r t a l i t y f a c t o r , u n l e s s combined w i t h human d i s t u r b a n c e . Combined w i t h human d i s t u r b a n c e c e n t r a l n e s t s were as v u l n e r a b l e as p e r i p h e r a l n e s t s . Abandonment of eggs and young a p p e a r e d t o be t h e p r i m a r y s t r a t e g y of w h i t e p e l i c a n s i n t h e e v e n t of e i t h e r mammalian p r e d a t i o n or human d i s t u r b a n c e . In r e l a t i v e l y l o n g - l i v e d s p e c i e s , s u c h as w h i t e p e l i c a n s (17 y e a r s ) , t h e s u r v i v a l of t h e a d u l t s i s a l m o s t as i m p o r t a n t as t h e s u r v i v a l o f t h e young (Klomp 1970, C harnov and K r e b s 1974). I f by a b a n d o n i n g eggs or 1 03 young d u r i n g a d i s t u r b a n c e , t h e a d u l t ' s c h a n c e s o f s u r v i v a l a r e i n c r e a s e d , t h e n i t becomes b e n e f i c i a l f o r t h e s p e c i e s t o do so (Goodman 1974). Goodman (1974) d e s c r i b e d t h i s a s t h e a d v a n t a g e s of f u t u r e f i t n e s s o u t w e i g h i n g t h o s e of p r e s e n t f i t n e s s . 104 CHAPTER 8. MANAGEMENT RECOMMENDATIONS AND RECOVERY PLAN FOR WHITE PELICANS IN BRITISH COLUMBIA 8.1 I n t r o d u c t i o n 8.1.1 B a c k g r o u n d The w h i t e p e l i c a n i s c o n s i d e r e d a ' t h r e a t e n e d ' s p e c i e s i n Canada l a r g e l y b e c a u s e of i t s v u l n e r a b l i t y as a c o l o n i a l n e s t e r . A v a i l a b l e d a t a s u g g e s t t h a t t h e p o p u l a t i o n of w h i t e p e l i c a n s i n Canada has s l o w l y d e c l i n e d o v e r many y e a r s , but has been r e l a t i v e l y s t a b l e d u r i n g t h e l a s t d ecade (Committee on t h e S t a t u s of E n d a n g e r e d W i l d l i f e i n Canada 1979). Human d i s t u r b a n c e a t t h e b r e e d i n g c o l o n i e s a p p e a r s t o have been t h e major c a u s e of t h e p o p u l a t i o n d e c l i n e . The p o p u l a t i o n of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a i s a l s o h i g h l y v u l n e r a b l e . T h e r e i s o n l y one n e s t i n g l o c a t i o n . At p r e s e n t l e s s t h a n 300 p e l i c a n s n e s t a t t h e c o l o n y . T h r e e e a r l y n e s t r e c o r d s a t Stum Lake (1953, 1964, and 1967) i n d i c a t e t h a t t h e b r e e d i n g p o p u l a t i o n was h i s t o r i c a l l y l a r g e r t h a n p r e s e n t l e v e l s . Under t h e c r i t e r i a t o d e s i g n a t e t h r e a t e n e d and e n d a n g e r e d s p e c i e s f o r B r i t i s h C o l u m b i a , t h e w h i t e p e l i c a n r a n k s n e a r t h e t o p i n d e g r e e of 'endangerment'. In March, 1980, t h e w h i t e p e l i c a n was o f f i c i a l l y d e s i g n a t e d as an e n d a n g e r e d s p e c i e s i n B.C. by t h e L i e u t e n a n t G o v e r n o r i n C o u n c i l . 105 8.1.2 Need and J u s t i f i c a t i o n F o r P r o t e c t i o n T h e r e a r e many r e a s o n s f o r p r o t e c t i n g t h e c o l o n y of w h i t e p e l i c a n s a t Stum L a k e . I l i s t s i x . (1) P r o t e c t i o n o f P e l e c a n i f o r m e s , i n c l u d i n g w h i t e p e l i c a n s i s now mandated by t h e B r i t i s h C o l u m b i a W i l d l i f e A c t . (2) We have a m o r a l o b l i g a t i o n t o c o u n t e r human-induced p o p u l a t i o n d e c l i n e s . (3) The g e n e r a l p u b l i c d e s i r e s t o p r e v e n t e n d a n g e r e d s p e c i e s f r o m d i s a p p e a r i n g . S o c i e t y v a l u e s t h e d i v e r s i f i e d w i l d l i f e h e r i t a g e of B r i t i s h C o l u m b i a . (4) P r e s e r v a t i o n of a l l s p e c i e s i s i m p o r t a n t , e s p e c i a l l y p r e v e n t i o n of t h e l o s s of g e n e t i c d i v e r s i t y . (5) B e c a u s e t h e y a r e a t t h e t o p o f t h e f o o d c h a i n , w h i t e p e l i c a n s a r e e s p e c i a l l y v u l n e r a b l e t o p e s t i c i d e s and t h e r e f o r e a r e b i o l o g i c a l i n d i c a t o r s of e n v i r o n m e n t a l c o n t a m i n a t i o n . (6) W h i t e p e l i c a n s a r e of r e c r e a t i o n a l i m p o r t a n c e t o t h e g e n e r a l p u b l i c and b i r d w a t c h e r s . P e l i c a n s r e p r e s e n t a r a r e and ' f u l f i l l i n g ' s i g h t i n g . 106 8.2 S u s p e c t e d Or P r o v e n Reasons F o r Changes In S t a t u s The two most i m p o r t a n t f a c t o r s t h a t a r e l i m i t i n g t h e g r o w t h of t h e w h i t e p e l i c a n p o p u l a t i o n i n B r i t i s h C o l u m b i a , and t h a t c o n t i n u e t o t h r e a t e n t h e c o l o n y , a p p e a r t o be human-induced d i s t u r b a n c e and c o y o t e p r e d a t i o n . T a b l e 3 summarizes t h e y e a r s d u r i n g w h i c h c o y o t e p r e d a t i o n and forms of human d i s t u r b a n c e have o c c u r r e d a t t h e Stum Lake c o l o n y . A v a i l a b l e d a t a s u g g e s t t h a t human-induced d i s t u r b a n c e s have been much more f r e q u e n t t h a n c o y o t e - r e l a t e d d i s t u r b a n c e s . The c o l o n y has been d i s t u r b e d by humans d u r i n g a t l e a s t n i n e b r e e d i n g s e a s o n s s i n c e i t s d i s c o v e r y . T h e s e i n c l u d e o c c a s i o n s where eggs were c o l l e c t e d , eggs and young p h o t o g r a p h e d , n e s t s s u r v e y e d , and young banded, as w e l l as i n c i d e n t s of l o w - f l y i n g a i r c r a f t ( T a b l e 3*). C o y o t e p r e d a t i o n and h a r a s s m e n t d u r i n g t h e e a r l y n e s t i n g p e r i o d o c c u r r e d d u r i n g a t l e a s t f o u r b r e e d i n g s e a s o n s . U n d o u b t e d l y , t h e many documented d i s t u r b a n c e s ( T a b l e 3) and o t h e r unknown i n c i d e n t s have l i m i t e d t h e p e l i c a n p o p u l a t i o n ' s g r o w t h i n B r i t i s h C o l u m b i a . B o t h k i n d s o f d i s t u r b a n c e (humans and. c o y o t e s ) can d r a m a t i c a l l y r e d u c e t h e s u r v i v o r s h i p of young and t h e o v e r a l l p r o d u c t i v i t y of t h e c o l o n y . A v a i l a b l e d a t a s u g g e s t e d we c o u l d c h a r a c t e r i z e a t l e a s t f o u r k i n d s o f d i s t u r b a n c e . They were: a i r c r a f t e a r l y i n t h e n e s t i n g s i t e ( b e f o r e o r d u r i n g i n c u b a t i o n ) ; a i r c r a f t - l a t e i n t h e n e s t i n g s e a s o n ( a f t e r i n c u b a t i o n ) ; c o y o t e - e a r l y ; and c o y o t e - l a t e . A s i m u l a t i o n model was d e s i g n e d ( u s i n g a m o d i f i e d L e s l i e M a t r i x ) t o e x p l o r e t h e r a t e s of change i n t h e s i m u l a t e d p o p u l a t i o n under t h e f o u r d i f f e r e n t k i n d s of d i s t u r b a n c e s a t v a r i o u s f r e q u e n c i e s . A more d e t a i l e d d i s c u s s i o n of t h e model and t h e m a t h e m a t i c a l 107 TABLE 3. Chronology of disturbances to the white pelican colony at Stum Lake, B r i t i s h Columbia. Year Date Nesting stage Factor, o Incident 1939 July 1 In, Br BD Islands v i s i t e d , eggs and young photographed 1950 May 21,28 In HD Eggs collected on two occasions 1959 June/July In, Br HD Eggs, nests, and young counted 1960 May 25 In ? 239 nests found abandoned 1964 June 22 In, Br HD, AW Eggs collected, waves washing eggs from nests 1967 June 19 In, Br HD Eggs, nests, and young counted 1968 July 20 In, Br HD Nests counted, young banded 1969 June 22 In, Br HD Eggs, nests, and young counted 1971 July 3 In, Br HD Ai r c r a f t overflight 1972 July 2 In, Br PD Coyote predation 1973 late May In PD Coyote predation 1974 June 9 In, Br HD Ai r c r a f t overflight 1979 late A p r i l Ct PD Coyote harassment 1980 late A p r i l Ct PD Coyote harassment a Ct - courtship, In - incubation, Br - brooding (young in nest) HD « human disturbance, PD • predation, AW • adverse weather 108 f o r m u l a t i o n s employed a r e g i v e n i n B u n n e l l e_t a l . (1981) and i n t h e a p p e n d i x o f B u n n e l l and T a i t ( 1 9 8 0 ) , r e s p e c t i v e l y . Most v a r i a b l e s u s e d t o s i m u l a t e t h e c o n s e q u e n c e s a t s p e c i f i c f r e q u e n c i e s o f e m p i r i c a l l y d e r i v e d e f f e c t s a r e summarized i n T a b l e 4. The model assumes no b i r d s l i v e l o n g e r t h a n 15 y e a r s . O b s e r v e d m o r t a l i t y r a t e s ( S t r a i t and S l o a n 1974) y i e l d fewer t h a n 2 b i r d s / 1 0 0 a f t e r age 15 y e a r s . S i x t e e n age c l a s s e s were emplo y e d . The f i r s t age c l a s s r e p r e s e n t e d s u r v i v o r s h i p from egg t o i m m e d i a t e l y p r i o r t o f a l l m i g r a t i o n (44% d u r i n g u n d i s t u r b e d c o n d i t i o n s , t h i s s t u d y ) ; t h e s e c o n d , from t h a t l a t t e r age u n t i l t h e f i r s t b i r t h d a y ( t o a l l o w i n c o r p o r a t i o n of d a t a of S t r a i t and S l o a n 1974); a l l o t h e r age c l a s s e s were a t y e a r l y i n c r e m e n t s f o r a t o t a l of 15 y e a r s . A l l a d u l t s were assumed t o b r e e d a t t h r e e y e a r s of age. The c l u t c h s i z e f o r t h e c o n t r o l p o p u l a t i o n was t h a t d e r i v e d from t h o s e y e a r s i n w h i c h d i s t u r b a n c e , i f i t o c c u r r e d , o c c u r r e d a f t e r t h e c o m p l e t i o n of c o u r t s h i p and egg l a y i n g (1.95 eggs p e r c l u t c h , t h i s s t u d y ) . U s i n g band r e t u r n s , f r o m th e Chase Lake p o p u l a t i o n of N o r t h D a k o t a , S t r a i t and S l o a n (1974) e s t i m a t e d s u r v i v o r s h i p from p o s t - f l e d g i n g u n t i l t h e f i r s t b i r t h d a y (age c l a s s 2 or ' s u b a d u l t ' o f T a b l e 4) a t 59%. F o r t h e r e m a i n i n g s u b a d u l t s and a d u l t s ( ' a d u l t s ' of T a b l e 4) t h e y e s t i m a t e d 78.7% s u r v i v o r s h i p , but a r g u e d t h a t t h e s e v a l u e s were t o o low as t h e y d i d not i n c o r p o r a t e known band l o s s e s . The model u t i l i z e d ' s u b a d u l t ' s u r v i v o r s h i p of 60%, i n c o r p o r a t e d t h e maximum young p e r egg s u r v i v o r s h i p (44%, T a b l e 4 ) , and examined t h e s e n s i t i v i t y of t h e p o p u l a t i o n t o c h a n g e s i n ' a d u l t ' s u r v i v o r s h i p . F o r t h e s i m u l a t i o n s i l l u s t r a t e d , an ' a d u l t ' s u r v i v o r s h i p r a t e of 82.5%, TABLE 4. Parameter values employed i n the simulation model and associated rates of change i n the simulated population. Survivorship Rates of change/year 3 Disturbance Clutch Young/ Sub-type size egg adult Adult Frequency of disturbance/20 yr None 1.95 0.44 0.60 0.80 -0.005 1.95b 0.44 0.60 0.825 0.017 1.95 0.44 0.60 0.85 0.037 1.90 0.44 0.60 0.825 0.012 1.90 0.44 0.60 0.85 0.033 A i r c r a f t - e a r l y 1.84 0.12 0.60 0.825 0.003 -0.003 -0.016 -0. 023 A i r c r a f t - l a t e 1.95 0.39 0.60 0.825 0.015 0.014 0.012 0. 011 Coyote-early 1.62 0.29 0.60 0.825 0.008 0.004 -0.004 -0. 008 Coyote-late 1.95 0.04 0.60 0.825 0.0003 -0.007 -0.022 -0. 03 a Computed solution to Nfc = N Qe r t, value tabulated i s r. b Values i n th i s row used for undisturbed population of Figures 25 and 26. 1 10 w h i c h p r o d u c e d an a n n u a l growth r a t e o f about 1.7% ( T a b l e 4 ) , was u s e d . R e s u l t s of t h e s i m u l a t i o n r u n s a r e summarized i n F i g u r e s 25 and 26. The f r e q u e n c i e s s e l e c t e d r a n g e d from 1 t o 5 t i m e s p e r 20 y e a r s . Under t h e c o n d i t i o n s s t a t e d , an u n d i s t u r b e d p o p u l a t i o n a t Stum Lake would s l o w l y i n c r e a s e a t a b o u t 1% p e r y e a r ( T a b l e 4 ) . D i s t u r b a n c e by l o w - f l y i n g a i r c r a f t a f t e r i n c u b a t i o n ( l a t e ) had l i t t l e e f f e c t on t h e p o p u l a t i o n growth ( F i g . 2 5 - B ) . D i s t u r b a n c e by a i r c r a f t d u r i n g i n c u b a t i o n had more p r o n o u n c e d e f f e c t s ( F i g . 2 5 -A). D i s t u r b a n c e more f r e q u e n t t h a n once i n 20 y e a r s would c a u s e a d e c l i n e i n t h e p o p u l a t i o n ( T a b l e 4 ) . The e f f e c t s o f ' c o y o t e d i s t u r b a n c e were i m p o r t a n t whether t h e y o c c u r r e d e a r l y o r l a t e i n t h e b r e e d i n g s e a s o n ( F i g . 2 6 ) . E a r l y d i s t u r b a n c e o c c u r r i n g more t h a n once i n 7 y e a r s f o r c e d t h e p o p u l a t i o n t o d e c l i n e ( F i g . 26-A). I f s u c h a d i s t u r b a n c e o c c u r r e d as f r e q u e n t l y as once i n 4 y e a r s , t h e p o p u l a t i o n would d e c l i n e a t an a n n u a l r a t e of about 1% ( T a b l e 4 ) . The impact of l a t e c o y o t e d i s t u r b a n c e was more d r a m a t i c ( F i g . 2 6 - B ) . A v a i l a b l e d a t a s u g g e s t t h a t i f t h e c o l o n y i s d i s t u r b e d by l a t e c o y o t e p r e d a t i o n o n l y once e v e r y 20 y e a r s , i t would j u s t r e m a i n s t a b l e . Two s u c h d i s t u r b a n c e s e v e r y 20 y e a r s i n d u c e d an a n n u a l r a t e of d e c l i n e of about 0.7% ( T a b l e 4 ) . A l l s i m u l a t i o n r e s u l t s a r e a c c u r a t e o n l y t o t h e d e g r e e t h a t e m p i r i c a l l y d e r i v e d v a l u e s o f r e p r o d u c t i o n and s u r v i v o r s h i p r e p r e s e n t a c t u a l c o n d i t i o n s . I l l (a) 400 r co or I d CD 300 200 z § 100 U J C L I X 2x 4x 5x J. 10 YEARS 15 20 (b) 400 r co or m 300 z 200 z § 100 U J Q . c — Ix2x 4x5x 10 YEARS 15 20 Figure 25. Simulated changes in pelican numbers resulting from aircraft disturbance at different frequencies. A) Represents disturbances during incubation; B) disturbances after completion of incubation. Numbers indicate the frequency of disturbance during a 20-year period; C) indicates control or undisturbed population. 112 ( 0 ) CO cc hi CD 2 < o - J UJ 0 . 400 300 200 -100 -0 10 YEARS 15 20 (b) 400 r to cc UJ m 300 200 h z < 3 1 0 0 I-UJ Q . i « 2 x • 4x V " 5* J_ 10 YEARS 15 20 Figure 26. Simulated changes in pelican nunbers resulting from coyote predation at different frequencies. A) Represents disturbances during incubation; B) disturbances after completion of incubation. Numbers indicate the frequency of disturbance during a 20-year period; C) indicates control or undisturbed population. 1 13 In t h e a b s e n c e of management o t h e r t h a n t h e p r e s e n t p a r k r e s t r i c t i o n s , t h e f u t u r e of t h e w h i t e p e l i c a n p o p u l a t i o n i n B.C. does not a p p e a r o p t i m i s t i c . A t p r e s e n t , t h e l a k e i s c l o s e d t o b o a t i n g , f i s h i n g , and t o t h e d i s c h a r g e of f i r e a r m s d u r i n g t h e c r i t i c a l b r e e d i n g s e a s o n from 1st March t o 3 1 s t A u g u s t . A i r c r a f t a r e d i s c o u r a g e d from f l y i n g o v e r t h e p a r k below 610 m d u r i n g t h e same p e r i o d . D e s p i t e t h e s e r e s t r i c t i o n s , v i o l a t i o n s o c c u r f r e q u e n t l y . As human s e t t l e m e n t s and d e v e l o p m e n t c o n t i n u e t o expand o u t w a r d i n t o more remote a r e a s of t h e C a r i b o o , t h e l i k e l i h o o d o f human d i s t u r b a n c e a t t h e c o l o n y w i l l a l s o i n c r e a s e . Between 1971 and 1974, Ryder (1974) n o t e d t h a t t h e number of v i s i t o r s t o t h e p a r k n e a r l y d o u b l e d (34 v i s i t o r s i n 1971 and 63 v i s i t o r s i n 1974). A c c e s s t o Stum Lake i s c o n t i n u a l l y b e i n g i m p r o v e d . S i n c e 1976, two a l l - w e a t h e r , l o g g i n g r o a d s have been c o n s t r u c t e d t h a t p a s s w i t h i n 12 km of t h e l a k e . A i r c r a f t d i s t u r b a n c e a l s o c o n t i n u e s t o be a p r o b l e m . D u r i n g t h e c o u r t i n g and egg l a y i n g p e r i o d s of 1980, a t w i n e n g i n e a i r c r a f t ( B e l l a C o o l a A i r l i n e s ) p a s s e d r e g u l a r l y o v e r t h e l a k e below t h e l e g a l a l t i t u d e of 610 m. D u r i n g t h e f o l l o w i n g b r e e d i n g s e a s o n , a s m a l l f l o a t p l a n e l a n d e d on t h e l a k e w h i l e p e l i c a n s were p r e s e n t (Tony P e t a l p e r s . comm.). G r e a t e r p r o t e c t i o n and e n f o r c e m e n t of t h e p r e s e n t r e s t r i c t i o n s a r e n e c e s s a r y t o p r e v e n t f u t u r e p o p u l a t i o n d e c l i n e s of w h i t e p e l i c a n s a t Stum L a k e . I n c r e a s e d e n f o r c e m e n t c o u l d a l s o p r o v i d e us w i t h b e t t e r i n f o r m a t i o n c o n c e r n i n g t h e p o p u l a t i o n d y n a m i c s of t h e c o l o n y . 1 14 P r e d a t i o n by c o y o t e s , a l t h o u g h n o t a new i n f l u e n c e , has been a major f a c t o r l i m i t i n g t h e r e p r o d u c t i v e s u c c e s s of p e l i c a n s i n B r i t i s h C o l u m b i a . C o y o t e h a r a s s m e n t d u r i n g t h e c o u r t s h i p p e r i o d and p r e d a t i o n d u r i n g t h e i n c u b a t i o n and n e s t l i n g p e r i o d s w i l l c o n t i n u e t o o c c u r i f c o n t r o l s a r e n o t i n i t i a t e d . W i t h o u t f u r t h e r management, t h e c o l o n y w i l l , a t b e s t , f l u c t u a t e a r o u n d 100 n e s t i n g p a i r s . U n f o r t u n a t e l y , i t i s more p r o b a b l e t h a t t h e p o p u l a t i o n w i l l d e c l i n e as human p o p u l a t i o n s grow i n t h e C a r i b o o . 8.3 R e c o v e r y P l a n Of W h i t e P e l i c a n s I n B r i t i s h C o l u m b i a W h i t e p e l i c a n s a r e c o n s i d e r e d e n d a n g e r e d i n B r i t i s h C o l u m b i a . The p o p u l a t i o n r e q u i r e s s p e c i a l p r o t e c t i v e and enhancement measures t o c o u n t e r a c t t h e poor r e p r o d u c t i v e s u c c e s s t h e c o l o n y has e x p e r i e n c e d r e c e n t l y as a r e s u l t o f human d i s t u r b a n c e and c o y o t e p r e d a t i o n . Enhancement measures a l s o s h o u l d be i n i t i a t e d t o b u f f e r f u t u r e impact a t t h e p r e s e n t b r e e d i n g l o c a t i o n . The o v e r a l l o b j e c t i v e o f t h i s r e c o v e r y p l a n i s t o remove t h e w h i t e p e l i c a n i n B r i t i s h C o l u m b i a from th e ' e n d a n g e r e d ' c a t e g o r y t o e i t h e r ' t h r e a t e n e d ' o r ' r a r e ' . The r e c o v e r y p l a n i s t r e a t e d i n t h r e e i n t e r - r e l a t e d s e c t i o n s . S e c t i o n 8.3.1 d i s c u s s e s t h e b a s i c r e s t r i c t i o n s and r e q u i r e m e n t s n e c e s s a r y t o e n s u r e c o n d i t i o n s t h a t a l l o w s u c c e s s f u l b r e e d i n g of the p e l i c a n p o p u l a t i o n . I t forms t h e b a s i s f o r a l l f u r t h e r m a n i p u l a t i v e and m a n a g e m e n t - o r i e n t e d a c t i v i t i e s a t t h e c o l o n y . S e c t i o n 8.3.2 d e a l s w i t h v a r i o u s enhancement t e c h n i q u e s b o t h a t t h e b r e e d i n g c o l o n y and o u t s i d e t h e p a r k . S e c t i o n 8.3.3 d e s c r i b e s t e c h n i q u e s t o i n c r e a s e t h e p o p u l a t i o n and number of 115 b r e e d i n g c o l o n i e s i n B r i t i s h C o l u m b i a t h r o u g h i n t r o d u c t i o n s from a r e a s o u t s i d e of t h e p r o v i n c e . 8.3.1 P r o t e c t i o n And M a i n t e n a n c e Of The Stum Lak e P e l i c a n C o l o n y In May 1970, Stum Lake and t h e i s l a n d s w i t h i n Stum Lake were d e c l a r e d a ' w i l d l i f e s a n c t u a r y ' under a u t h o r i t y o f S e c t i o n 78 c o n t a i n e d i n t h e W i l d l i f e A c t , 1966. The p u r p o s e was t o p r o t e c t t h e p e l i c a n s f r o m d i s t u r b a n c e t h r o u g h t r e s p a s s on w a t e r , i n t h e a i r , o r by d i s c h a r g e of f i r e a r m s , f o r a p e r i o d from 1 M a r c h t o 31 A u g u s t e a c h y e a r . In 1971 t h e e s t a b l i s h m e n t of t h e W h i t e P e l i c a n P r o v i n c i a l P a r k p r o v i d e d t h e means f o r e n f o r c i n g r e s t r i c t i o n s t o l i m i t human a c t i v i t y d u r i n g t h e b r e e d i n g s e a s o n . However, p r o t e c t i o n of t h e c o l o n y and e n f o r c e m e n t of p r e s e n t r e s t r i c t i o n s have been n e g l i g i b l e . D e s p i t e t h e many v i o l a t i o n s t h a t have o c c u r r e d , t h e r e have been no c o n v i c t i o n s o r f i n e s l e v i e d t o d a t e . U n d e r s t a n d a b l y , many of t h e v i o l a t i o n s have o c c u r r e d t h r o u g h i g n o r a n c e r a t h e r t h a n m a l i c i o u s i n t e n t ; however, m o t i v e s make no d i f f e r e n c e t o t h e p e l i c a n p o p u l a t i o n . In o r d e r t o p r o v i d e f u l l p r o t e c t i o n f o r t h e Stum Lak e p e l i c a n c o l o n y s e v e r a l recommendations have been f o r m u l a t e d : 1. The p a r k r e s t r i c t i o n s c l o s i n g Stum La k e t o b o a t i n g , a n g l i n g , and t o t h e d i s c h a r g e o f f i r e a r m s f r o m 1 M a r c h t o 31 Au g u s t a r e c o m p l e t e l y a c c e p t a b l e . However, e x i s t i n g r e s t r i c t i o n s on a i r c r a f t a r e not c o m p u l s o r y and must be s t r e n g t h e n e d . A l l a i r c r a f t , e x c e p t i n g i n e m e r g e n c i e s , s h o u l d be p r o h i b i t e d f r o m f l y i n g o v e r t h e p a r k below 610 m (2000 f e e t ) from 1 March t o 31 A u g u s t . A i r c r a f t r e s t r i c t i o n s a r e e s p e c i a l l y 116 c r i t i c a l d u r i n g t h e e a r l y b r e e d i n g s e a s o n , f r o m m i d - A p r i l t o l a t e J u n e . 2. E n f o r c e m e n t of t h e f o u r r e s t r i c t i o n s ( b o a t i n g , a n g l i n g , f i r e a r m s , and o v e r f l i g h t s ) i s e s s e n t i a l . The v a l u e o f a l l r e s t r i c t i o n s c a n be i n c r e a s e d by an a c t i v e , w e l l r o u n d e d p r ogram of e d u c a t i o n , p a t r o l , and law e n f o r c e m e n t ( W i l b u r 1975). E d u c a t i o n a l emphasis s h o u l d c e n t e r on our u n d e r s t a n d i n g or our l a c k of u n d e r s t a n d i n g of t h e c o l o n y and t h e j u s t i f i c a t i o n f o r r e s t r i c t e d use of t h e i r n e s t i n g a r e a . A p r o g r a m t o i n c r e a s e p u b l i c a w a r e n e s s of t h e s e n s i t i v i t y of t h e p e l i c a n c o l o n y d u r i n g t h e b r e e d i n g s e a s o n and of t h e 'endangered' s t a t u s of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a s h o u l d be i n i t i a t e d . P a m p h l e t s , p o s t e r s , and a n n u a l s t a t u s r e p o r t s s h o u l d be p u b l i s h e d and d i s p l a y e d i n B.C. F i s h and W i l d l i f e B r a n c h o f f i c e s and a t l o c a l n a t u r a l i s t c l u b s . A l l p u b l i c a t i o n s s h o u l d s t r e s s how e a s i l y w h i t e p e l i c a n s a r e d i s t u r b e d d u r i n g t h e b r e e d i n g s e a s o n . L a r g e v i s i b l e p o s t e r s p l a c e d i n l o c a l a i r p o r t s m i ght h e l p t o p r e v e n t f u r t h e r a i r c r a f t d i s t u r b a n c e s a t t h e c o l o n y s i t e . The Notam ( N o t i c e t o A i r m e n ) s h o u l d a l s o be r e - i s s u e d w i t h somewhat more d e t a i l and t h e c o r r e c t l o c a t i o n . I n f o r m a t i o n s i g n s a t t h e b r e e d i n g l a k e a r e i n a d e q u a t e a t p r e s e n t . C l e a r l y v i s i b l e s i g n s s h o u l d be p o s t e d a t t h e p a r k e n t r a n c e . These s h o u l d s t r e s s t h e s e n s i t i v i t y of t h e c o l o n y and l i s t t h e p r e s e n t r e s t r i c t i o n s a t t h e l a k e . I f p o s s i b l e , t h e Anahim I n d i a n Band s h o u l d be c o n s u l t e d t o p r o v i d e i n p u t r e g a r d i n g w o r d i n g . 1 17 P a t r o l s s h o u l d be c o n d u c t e d t o r e d u c e t h e p o t e n t i a l f o r v i o l a t i o n s o f r e s t r i c t i o n s . T h e s e c o u l d be c o n d u c t e d on a r e g u l a r b a s i s o r o p p o r t u n i s t i c a l l y . L o c a l c o n s e r v a t i o n o f f i c e r s m i g h t p r o v i d e t h i s s e r v i c e . D i l i g e n t law e n f o r c e m e n t w i l l a c t t o d e t e r f u r t h e r v i o l a t i o n s . I n c r e a s e d p e n a l t i e s and f i n e s must be l e v i e d t o d e t e r human a c t i v i t y w i t h i n t h e p a r k d u r i n g t h e c r i t i c a l b r e e d i n g s e a s o n . 3 . A s y s t e m a t i c i n v e n t o r y p l a n i s n e c e s s a r y t o m o n i t o r and e v a l u a t e t h e p r o d u c t i v i t y and v i a b i l i t y of t h e c o l o n y . Census d a t a s h o u l d i n c l u d e a n o n - d e s t r u c t i v e s u r v e y of n e s t s i n mid-May and a s u r v e y o f young t o o b t a i n t h e c o l o n y ' s o v e r a l l p r o d u c t i v i t y c o n d u c t e d i n m i d - A u g u s t . S u r v e y s s h o u l d be c o n d u c t e d a n n u a l l y d u r i n g i n i t i a l management p h a s e s of t h e p r o j e c t and e v e r y two y e a r s once t h e c o l o n y a p p e a r s more s t a b l e . I t s h o u l d be n e c e s s a r y t o d e t e r m i n e c l u t c h s i z e s and s u r v i v o r s h i p of young o n l y i f t h e c o l o n y b e g i n s t o d e c l i n e . Two methods c o u l d be employed t o d e t e r m i n e t h e number of n e s t s . A e r i a l s u r v e y s a r e e f f i c i e n t i n terms of c o s t and t i m e c o n s t r a i n t s , however t h e y may b i a s c o u n t s s l i g h t l y upwards and c o u l d p r e s e n t a r i s k of d i s t u r b a n c e t o n e s t i n g b i r d s . Ground c e n s u s i n g , u s i n g a s p o t t i n g s c o p e s i t u a t e d on t h e m a i n l a n d i s more t i m e - c o n s u m i n g and c o s t l y , b ut t h e r i s k o f d i s t u r b a n c e i s g r e a t l y r e d u c e d and n e s t c o u n t s a r e more a c c u r a t e . F o r t h i s r e a s o n , I recommend t h a t , o n l y t h e g r o u n d - c e n s u s method be u s e d a t p r e s e n t . 1 18 S u r v e y s u s u a l l y s h o u l d be c o n d u c t e d between 10th May and 3 0 t h May, r e g a r d l e s s o f t h e method u s e d t o c o u n t n e s t s . The a c t u a l d a t e s o f t h e n e s t s u r v e y s h o u l d commence a p p r o x i m a t e l y two weeks a f t e r i c e b r e a k - u p a t Stum L a k e . T h i s s h o u l d a l l o w b r e e d i n g b i r d s t i m e t o e s t a b l i s h t h e i r n e s t s , and a l s o w i l l m i n i m i z e t h e number of c o u r t i n g b i r d s p r e s e n t a t t h e c o l o n y d u r i n g t h e s u r v e y . To i n c r e a s e a c c u r a c y of a e r i a l s u r v e y s , n e s t c o u n t s s h o u l d be c o n d u c t e d when c o l o n y a c t i v i t i e s s u c h as n e s t r e l i e v i n g and t h e number of l o a f i n g b i r d s a r e m i n i m a l . In A l b e r t a , B e a v e r and L e w i n (1981) f o u n d t h a t c o l o n y a c t i v i t y and t h e number of l o a f i n g b i r d s were a t a minimum between 16:00 and 22:00 h o u r s . Roney (1979) f o u n d t h a t a e r i a l s u r v e y s c o n d u c t e d from a s m a l l f i x e d - w i n g a i r c r a f t , s u c h as a S u p e r c u b or C e s s n a 172, f l y i n g 230 m (750 f t ) above g r o u n d l e v e l , p r o d u c e d no v i s i b l e s i g n s o f d i s t u r b a n c e t o n e s t i n g w h i t e p e l i c a n c o l o n i e s i n S a s k a t c h e w a n . A e r i a l p h o t o g r a p h s were t a k e n u s i n g a hand-h e l d camera ( w i t h 200 mm l e n s ) out t h e window o f t h e a i r c r a f t . C o u n t s were t a k e n d i r e c t l y from s l i d e s when v i e w e d under a m i c r o s c o p e . B e a v e r and Lewin (1981) f o u n d t h a t p r o j e c t i o n s of c o l o u r t r a n s p a r e n c i e s (Kodak E k t a c h r o m e 160), t a k e n a t 300 m (1,000 f t ) above g r o u n d l e v e l w i t h a 200 mm l e n s , p r o v i d e d e x c e l l e n t r e s o l u t i o n . In o r d e r t o e l i m i n a t e p o t e n t i a l b i a s d u r i n g a e r i a l s u r v e y s of n e s t s , t h e y s u g g e s t e d t h a t a c o n c u r r e n t g r o u n d c o u n t be c o n d u c t e d . 119 Ground c e n s u s i n g would i n v o l v e s e v e r a l d a y s of o b s e r v i n g t h e c o l o n y w i t h a 20-45x s p o t t i n g s c o p e . To m i n i m i z e d i s t u r b a n c e , a l l g r o u n d o b s e r v a t i o n s must be c o n d u c t e d from v a n t a g e p o i n t s on t h e a d j a c e n t m a i n l a n d . An a c c u r a t e c o u n t o f n e s t s can be r e c o r d e d i n two o r t h r e e d a y s , b u t s e v e r a l weeks o f o b s e r v a t i o n s may be n e c e s s a r y t o d e t e r m i n e an a c c u r a t e sample of eggs p e r n e s t . C l u t c h s i z e s can b e s t be o b t a i n e d d u r i n g n e s t r e l i e f and g e n e r a l l y between 10:00 and 14:00 when c o l o n y a c t i v i t y , s u c h as p r e e n i n g and s h i f t i n g , i s g r e a t e s t . In t h e e v e n t t h a t no n e s t s a r e f o u n d a t t h e b r e e d i n g c o l o n y , I recommend t h a t an i n t e n s i v e a e r i a l s u r v e y of t h e l a k e s on t h e F r a s e r P l a t e a u be i n i t i a t e d . L o c a t i o n s of p e l i c a n s a n d / o r new n e s t i n g s i t e s s h o u l d be m o n i t o r e d . I n v e s t i g a t i o n s s h o u l d a l s o be c o n d u c t e d a t Stum Lake t o d e t e r m i n e why t h e s i t e was abandoned. O v e r a l l p r o d u c t i v i t y s h o u l d be o b t a i n e d a p p r o x i m a t e l y t h r e e months a f t e r t h e n e s t s u r v e y , u s u a l l y between 10th A u g ust and 3 0 t h A u g u s t . The number of s u c c e s s f u l l y f l e d g e d young can e a s i l y be d e t e r m i n e d by b o a t d u r i n g t h i s p e r i o d . The young a r e a d u l t - s i z e a t t h i s s t a g e , however t h e i r plumage i s g r e y i s h -w h i t e , t h e y l a c k t h e o r a n g e c o l o r a t i o n on t h e i r b i l l s and l e g s , and most a r e s t i l l u n a b l e t o f l y . D u r i n g t h e m i d-August s u r v e y of young, t h e n a t a l i s l a n d s h o u l d be e x a m i n e d f o r whole eggs and p a r t i a l egg s h e l l s . S h e l l t h i c k n e s s e s s h o u l d be c a l c u l a t e d and p e s t i c i d e r e s i d u e a n a l y s e s c o n d u c t e d on whole eggs. T h e s e c o u l d be compared w i t h d a t a c o l l e c t e d by K.Vermeer d u r i n g 1968. Ten eggs t a k e n from t e n n e s t s a t Stum Lake i n 1968 y i e l d e d p e s t i c i d e r e s i d u e s of 1.46 1 ppm DDE, 0.184 ppm d i e l d r e n , 0.314 ppm DDD, and 0.121 ppm DDT. These l e v e l s a r e low f o r f i s h - e a t i n g a q u a t i c b i r d s s u c h as p e l i c a n s (K. Vermeer P e r s . Comm.). 4. A d d i t i o n a l a e r i a l s u r v e y s s h o u l d be c o n d u c t e d on t h e F r a s e r P l a t e a u t o i d e n t i f y p o t e n t i a l l a k e s t h a t c o u l d be en h a n c e d t o s u p p o r t a s e c o n d p e l i c a n c o l o n y . A s e c o n d n e s t i n g a r e a n e a r Stum Lak e c o u l d a l s o be u s e d by p e l i c a n s i f f a c t o r s p r e v e n t e d n e s t i n g a t t h e o r i g i n a l b r e e d i n g c o l o n y . 8.3.2 Enhancement T e c h n i q u e s 8.3.2.1 M a i n t e n a n c e And Enhancement Of P r e s e n t F e e d i n g L a k e s D u r i n g t h e b r e e d i n g s e a s o n , w h i t e p e l i c a n s from Stum Lake a r e e n t i r e l y d e p e n d e n t upon a few l a k e s s u r r o u n d i n g t h e c o l o n y s i n c e no p r e y s p e c i e s o c c u r i n Stum L a k e . T h e s e few f e e d i n g l a k e s u s e d by t h e b i r d s d u r i n g t h e s p r i n g and summer a r e e s s e n t i a l f o r t h e p r o d u c t i o n of eggs and t h e s u r v i v a l of young As human p o p u l a t i o n s c o n t i n u e t o grow i n t h e C a r i b o o , an i n c r e a s i n g number of c o n f l i c t s c a n be e x p e c t e d . T h e s e might i n c l u d e l a n d - u s e d e c i s i o n s t h a t a f f e c t p e l i c a n f e e d i n g l a k e s , i n c r e a s e d c o m p e t i t i o n between f i s h e r m e n and p e l i c a n s f o r f i s h , or s i m p l y t h e d i s r u p t i o n of f o r a g i n g p a t t e r n s o f p e l i c a n s by b a c k - c o u n t r y r e c r e a t i o n a l i s t s . 121 To c o u n t e r a c t t h e s e a n t i c i p a t e d p r o b l e m s , I have s u g g e s t e d s e v e r a l management p r e s c r i p t i o n s : 1. Summer f o r a g i n g l a k e s s h o u l d be i d e n t i f i e d d u r i n g a e r i a l s u r v e y s and s h o u l d be c l a s s i f i e d by p e l i c a n - u s e ( l i g h t , m o d e r a t e , h e a v y ) . I f p o s s i b l e , ' h e a v i l y - u s e d ' l a k e s s h o u l d be a c q u i r e d and p r o t e c t e d . A e r i a l s u r v e y s s h o u l d a l s o be c o n d u c t e d d u r i n g t h e s p r i n g t o d e t e r m i n e i m p o r t a n t s p r i n g f o r a g i n g l a k e s , p r e s e n t l y unknown. 2. Water l e v e l s a t h e a v i l y u s e d l a k e s s h o u l d be m a i n t a i n e d t o p r o v i d e p r o p e r water d e p t h s f o r f o r a g i n g p e l i c a n s and f o r t h e p r e s e r v a t i o n of i m p o r t a n t s p e c i e s o f p r e y f i s h . S p e c i a l management c o n s i d e r a t i o n s s h o u l d i n c l u d e t h e p r o t e c t i o n and enhancement of C h i l c o t i n Lake (52°19'N, 1 2 4 ° 3 ' W ) . At p r e s e n t , u n a u t h o r i z e d c h a n n e l i z a t i o n of t h i s l a k e i s c a u s i n g i m p r o p e r water d e p t h s f o r i m p o r t a n t s p e c i e s of p r e y f i s h i n t h e w e s t e r n h a l f of t h e l a k e (Ed Hennan P e r s . Comm.). N a t u r a l w ater l e v e l s s h o u l d be r e s t o r e d a t t h i s i m p o r t a n t f e e d i n g l a k e . 3. Human-caused d i s t u r b a n c e s h o u l d be m i n i m i z e d a t i m p o r t a n t f e e d i n g l a k e s . S i g n s s h o u l d be p o s t e d i n f o r m i n g t h e p u b l i c t o a v o i d d i s t u r b i n g g r o u p s of f o r a g i n g p e l i c a n s . The use of o u t b o a r d m otors on i m p o r t a n t f e e d i n g l a k e s s h o u l d a l s o be c u r t a i l e d . 122 8.3.2.2 S t o c k i n g Stum Lake W i t h S u i t a b l e C o a r s e F i s h Stum Lake c o n t a i n s no i m p o r t a n t p r e y s p e c i e s o f f i s h f o r p e l i c a n s . P e l i c a n s t r a v e l as f a r as 142 km (Towdystan Lake) from t h e b r e e d i n g c o l o n y t o f o r a g e , a l t h o u g h t h e m a j o r i t y f o r a g e a t C h i l c o t i n Lake ( a p p r o x i m a t e l y 70 km from t h e c o l o n y ) . I t i s p o s s i b l e t h a t t h e c o l o n y ' s p r o d u c t i v i t y i s b e i n g l i m i t e d by e n e r g y c o n s t r a i n t s . A t p r e s e n t , t h e h a t c h l i n g s u r v i v a l o f young and t h e o v e r a l l p r o d u c t i v i t y of n e s t s a t Stum L a k e , even i n t h e a b s e n c e of c o y o t e or human-induced d i s t u r b a n c e s , i s o n l y 44% and 0.80 y o u n g / n e s t , r e s p e c t i v e l y . M i l l e r and Ryder (1977) n o t e d a p r o d u c t i v i t y o f 1.17 f l e d g e d y o u n g / n e s t a t R i v e r s i d e R e s e r v o i r , C o l o r a d o - t h e h i g h e s t e v e r r e c o r d e d f o r t h e s p e c i e s . They o b s e r v e d t h a t t h i s s u c c e s s r e s u l t e d from h i g h h a t c h l i n g s u r v i v a l (89%) r a t h e r t h a n h a t c h i n g s u c c e s s . M o r t a l i t y f a c t o r s , s u c h a s s t a r v a t i o n , f l u c t u a t i n g water l e v e l s , p r e d a t i o n , and human d i s t u r b a n c e , were m i n i m a l ( M i l l e r a n d Ryder 1977). They a t t r i b u t e d t h i s h i g h h a t c h l i n g s u r v i v a l t o t h e abundant s u p p l y and c l o s e p r o x i m i t y of f o o d . The r e s e r v o i r was w e l l s t o c k e d w i t h s p e c i e s on w h i c h p e l i c a n s f e e d , and n e s t i n g b i r d s d i d n o t have t o l e a v e t h e b r e e d i n g l a k e t o f o r a g e e l s e w h e r e . Not o n l y would an abundant s u p p l y o f f o o d be i m p o r t a n t t o t h e p r o d u c t i o n o f eggs and s u r v i v a l of de p e n d e n t young, but j u v e n i l e s p r o b a b l y would l e a r n t o f o r a g e i n d e p e n d e n t l y much e a r l i e r t h a n young would i n c o l o n i e s l a c k i n g a f o o d s u p p l y a t t h e b r e e d i n g l a k e . 123 I recommend t h a t a p r o g r a m of s t o c k i n g s u i t a b l e c o a r s e f i s h , s u c h a s s q u a w f i s h , be c a r r i e d o ut a t Stum L a k e . I t seems l i k e l y t h a t t h e o v e r a l l p r o d u c t i v i t y of t h e c o l o n y and t h e s u r v i v a l of young c o u l d be i n c r e a s e d by s u c h an i n t r o d u c t i o n . D r . T a u t z of t h e B r i t i s h C o l u m b i a F i s h and W i l d l i f e B r a n c h ( P e r s . Comm.) f e l t t h a t t h e l a k e c h a r a c t e r i s t i c s c o u l d s u p p o r t a v i a b l e p o p u l a t i o n o f c o a r s e f i s h . However, he n o t e d t h a t i t i s n o t t h e p o l i c y of th e B r i t i s h C o l u m b i a F i s h and W i l d l i f e B r a n c h t o i n t r o d u c e c o a r s e f i s h i n t o l a k e s . U n f o r t u n a t e l y , t h e i n t r o d u c t i o n of game f i s h w ould not be d e s i r a b l e a t Stum Lake as i t p r o b a b l y would a t t r a c t f i s h e r m e n t o t h e l a k e , r e s u l t i n g i n d i s t u r b a n c e t o n e s t i n g b i r d s . Nor would game f i s h be as a c c e s s i b l e t o p e l i c a n s b e c a u s e o f t h e g r e a t e r d e p t h s a t w h i c h s u c h f i s h a r e f o u n d . A n o t h e r p o s s i b l e p r o b l e m of i n t r o d u c i n g f i s h i n t o Stum Lake i s t h a t i t may a t t r a c t f i s h - e a t i n g p r e d a t o r s , s u c h as r i v e r o t t e r ( L o n t r a c a n a d e n s i s ) and mink ( M u s t e l a v i s o n ) , t h a t may i n t u r n p r e y on t h e eggs and young of p e l i c a n s . However i t i s u n l i k e l y t h a t t h e s e s p e c i e s would become a s e r i o u s p r o b l e m t o p e l i c a n s , s i n c e f u r - b e a r e r s a r e h e a v i l y t r a p p e d i n t h e p a r k . 8.3.2.3 Improvement Of P r e s e n t B r e e d i n g H a b i t a t At Stum Lake P r e s e n t b r e e d i n g h a b i t a t a t Stum Lake c an be i m p r o v e d i n a t l e a s t two ways: h a b i t a t m a n i p u l a t i o n s t o t h e i s l a n d s and c o n t r o l of water l e v e l s . 124 M a n i p u l a t i o n of v e g e t a t i v e and p h y s i c a l f e a t u r e s o f e x i s t i n g i s l a n d h a b i t a t c o u l d i n c r e a s e n e s t i n g s i t e a v a i l a b i l i t y . W h i t e p e l i c a n s g e n e r a l l y a v o i d a r e a s o f dense v e g e t a t i o n d u r i n g n e s t i n g , and s e l e c t i n s t e a d more open, b a r r e n a r e a s . The v e g e t a t e d a r e a s on I s l a n d 2 c o u l d be c l e a r e d t o i n c r e a s e t h e number o f p o t e n t i a l n e s t i n g a r e a s . A l t h o u g h w h i t e p e l i c a n s do not a p p e a r t o be l i m i t e d by t h e number of n e s t i n g s i t e s a t p r e s e n t , t h i s may be an i m p o r t a n t t o o l i n ' t h e f u t u r e i f t h e p o p u l a t i o n i n c r e a s e s i n s i z e . Removal o f p h y s i c a l o b s t a c l e s s h o u l d p r o v i d e a u s e f u l s e r v i c e f o r t h e b i r d s . S e v e r a l f a l l e n snags on I s l a n d 2 a p p e a r t o i n t e r f e r e w i t h c o u r t s h i p a c t i v i t i e s and g e n e r a l l y r e s t r i c t movement a t t h e c o l o n y . Removal o f t h e s e snags would f a c i l i t a t e movement w i t h i n t h e crowded s u b - c o l o n i e s and p r o v i d e s e v e r a l new b r e e d i n g s i t e s . I recommend t h a t o n l y l i m i t e d h a b i t a t m a n i p u l a t i o n s t a k e p l a c e a t p r e s e n t , c o n c e n t r a t i n g on f a l l e n -snag r e m o v a l . Water l e v e l s c an i n f l u e n c e t h e a v a i l a b i l i t y of n e s t i n g h a b i t a t f o r i s l a n d - n e s t i n g b r e e d i n g b i r d s s u c h as w h i t e p e l i c a n s . When water l e v e l s a r e t o o h i g h , n e s t i n g h a b i t a t c an become p a r t i a l l y o r c o m p l e t e l y submerged. T h a t o c c u r r e d a t Stum Lake i n 1964 when waves washed eggs from n e s t s on I s l a n d One. I f w a t e r l e v e l s a r e t o o low, i s l a n d s c a n become c o n t i g u o u s w i t h t h e m a i n l a n d , t h e r e b y e x p o s i n g b r e e d i n g b i r d s t o mammalian p r e d a t i o n . Water l e v e l s a t Stum Lak e must be more s t r i c t l y r e g u l a t e d . 125 R e c e n t l y a c o n f l i c t of i n t e r e s t s o c c u r r e d between t h e Anahim I n d i a n Band (who c o n t r o l t h e water r i g h t s f o r Stum La k e ) and t h e B r i t i s h C o l u m b i a F i s h and W i l d l i f e B r a n c h . The Anahim Band wanted t o l o w e r water l e v e l s a t Stum Lak e f o r i r r i g a t i o n a l p u r p o s e s downstream. The B r i t i s h C o l u m b i a F i s h and W i l d l i f e B r a n c h f e l t t h a t water l e v e l s a t Stum Lake s h o u l d be m a i n t a i n e d a t e x i s t i n g l e v e l s . F o r t u n a t e l y , o u t s i d e water i n t e r e s t s a p p e a r t o c o i n c i d e r e l a t i v e l y w e l l w i t h t h e b i o l o g i c a l needs o f t h e n e s t i n g w h i t e p e l i c a n s . N e s t i n g w h i t e p e l i c a n s r e q u i r e t h a t w a t e r l e v e l s r e m a i n r e l a t i v e l y h i g h u n t i l l a t e J u l y . A f t e r t h i s t i m e , young a r e no l o n g e r v u l n e r a b l e t o mammalian p r e d a t i o n . Water can t h e n be drawn o f f t o i r r i g a t e a r e a s downstream and t o d r y t h e meadows a t Stum Lak e f o r h a y i n g . I t i s recommended, however, t h a t a c o n t r o l s t r u c t u r e be b u i l t on t h e o u t l e t a t t h e s o u t h - e a s t c o r n e r o f t h e l a k e . 8.3.2.4 P r e d a t o r C o n t r o l C o n t r o l s s h o u l d be u n d e r t a k e n on t h e c o y o t e p o p u l a t i o n w i t h i n t h e p a r k t o p r e v e n t f u r t h e r l o s s e s of eggs and young, s u c h as have o c c u r r e d i n t h e p a s t . S e l e c t i v e l e t h a l and non-l e t h a l methods s h o u l d be c o n s i d e r e d . An e f f e c t i v e and s e l e c t i v e t e c h n i q u e f o r r e m o v i n g c o y o t e s from l o c a l d e p r e d a t i o n a r e a s i s t h e 3N V i c t o r T r a p u s e d i n t h e F e d e r a l A n i m a l Damage C o n t r o l Program of t h e U n i t e d S t a t e s ( C o n n o l l y 1978). O t h e r l e t h a l methods i n c l u d e t h e use o f p o i s o n s , s u c h as sodium f l u o r a c e t a t e ( 1 0 8 0 ) , p l a c e d i n b a i t e d meat. 126 A l t e r n a t i v e n o n - l e t h a l methods f o r p r e v e n t i n g c o y o t e p r e d a t i o n a r e f e n c i n g and ' c h a r c o a l i n g ' . Thompson (1979) e v a l u a t e d 34 f e n c e p a t t e r n s t o d e t e r m i n e t h e most e f f e c t i v e d e t e r r e n t t o c o y o t e s . D e C a l e s t a and C r o p s e y (1978) f i e l d t e s t e d t h e s e l e c t e d f e n c e and f o u n d i t h i g h l y s u c c e s s f u l . Such a f e n c e c o u l d be c o n s t r u c t e d on t h e m a i n l a n d a d j a c e n t t o t h e n e s t i n g c o l o n y a t Stum Lake t o p r e v e n t c o y o t e s from r e a c h i n g t h e n e s t i n g c o l o n y d u r i n g m i d - s e a s o n . The c o s t ( n o t i n c l u d i n g l a b o u r ) f o r a f e n c e 350 m l o n g would be a b o u t $500.00 (1978 p r i c e s ) . However, d u r i n g t h e s p r i n g , w h i l e i c e s t i l l c o v e r s t h e l a k e , f e n c i n g would o f f e r no p r o t e c t i o n . At t h i s t i m e , t h e i c e a r o u n d t h e c o l o n y c o u l d be s p r i n k l e d w i t h c h a r c o a l t o i n d u c e m e l t i n g . T h i s c o u l d be done m a n u a l l y or from a l i g h t a i r c r a f t b e f o r e p e l i c a n s a r r i v e i n t h e s p r i n g . C o y o t e c o n t r o l s a t Stum Lake t h e r e f o r e c o u l d i n v o l v e b o t h l e t h a l a n d / o r n o n - l e t h a l methods. 8.3.3 R e c o v e r y T e c h n i q u e s f o r W hite P e l i c a n s In t h e e v e n t of e i t h e r s e v e r e p o p u l a t i o n d e c l i n e s s u g g e s t i n g p o s s i b l e e x t i n c t i o n or a d e s i r e t o i n c r e a s e our p r e s e n t w h i t e p e l i c a n p o p u l a t i o n , i t may be n e c e s s a r y t o i n i t i a t e a l o n g - t e r m r e s t o c k i n g p r ogram. A r e s t o c k i n g e f f o r t would r e q u i r e t h e c o o p e r a t i o n of s e v e r a l p r o v i n c i a l a g e n c i e s and would i n v o l v e t r a n s p l a n t i n g young from o t h e r more p r o d u c t i v e and s t a b l e s i t e s t o l o c a t i o n s i n B r i t i s h C o l u m b i a . C o l o n i e s s u c h as P r i m r o s e L a k e , S a s k . (4,007 n e s t s ) , O l d Wives Lake, Sask. (3,084 n e s t s ) , and L a v a l l e e L a k e , S a s k . (3,019 n e s t s ) would make i d e a l c a p t u r e s i t e s . Young b i r d s between 8 and 11 weeks o l d c a n e a s i l y be h e r d e d by canoe i n t o f u n n e l s haped w i r e t r a p s ( S t e v e E l a f a n t 1 27 P e r s . Comm). At t h i s age t h e young b i r d s a r e o l d enough t o swim but s t i l l t o o young t o f l y . I t i s recommended t h a t c a p t u r e d b i r d s be banded and marked w i t h p a t a g i a l wing t a g s t o e n a b l e o b s e r v e r s t o i d e n t i f y them from a d i s t a n c e . E f f o r t s t o i n t r o d u c e p e l i c a n s can be e n h a n c e d by s e l e c t i n g b i r d s w i t h t h e l e a s t number o f p a r a s i t e i n f e c t i o n s (Humphrey et_ a_l. 1978). I d e a l l y , r e l e a s e s i t e s s h o u l d have s e v e r a l p r e d a t o r - f r e e i s l a n d s s u i t a b l e f o r r o o s t i n g a n d / o r b r e e d i n g . Such i s l a n d s c o u l d be e i t h e r man-made s t r u c t u r e s o r m o d i f i e d n a t u r a l l y o c c u r r i n g i s l a n d s . The l a k e s must be i s o l a t e d f r o m human d i s t u r b a n c e ( p r o b a b l y t h e p r i m a r y n e s t i n g h a b i t a t r e q u i r e m e n t f o r w h i t e p e l i c a n s ) and c o n t a i n an abundant f o o d s u p p l y . The c a p t u r e - r e l e a s e p r o g ram s h o u l d be c a r r i e d out f o r a minimum of f i v e y e a r s and p r e f e r a b l y f o r a b o u t 10 y e a r s . In a r e s t o c k i n g p r o g r a m i n L o u i s i a n a (young t r a n s p o r t e d from F l o r i d a t o L o u i s i a n a ) , d i r e c t r e l e a s e w i t h two d a i l y f e e d i n g s was f o u n d t o be t h e most e f f e c t i v e method f o r e s t a b l i s h i n g brown p e l i c a n s ( N e s b i t t e t a l . 1978). • A t t e m p t s t o c r e a t e a s e c o n d w h i t e p e l i c a n b r e e d i n g c o l o n y i n C o l o r a d o were u n s u c c e s s f u l (Gary M i l l e r p e r s . comm.). Young were c a p t u r e d a t t h e n a t a l c o l o n y ( R i v e r s i d e R e s e r v o i r ) and t r a n s p l a n t e d t o a n o t h e r l a k e a p p r o x i m a t e l y 30 km away. N e a r l y a l l young s u r v i v e d w i t h o u t s u p p l e m e n t a l f e e d i n g s as t h e l a k e had an a b u n d a n t s u p p l y o f f i s h . D u r i n g t h e f o l l o w i n g b r e e d i n g s e a s o n s , however, t h e t r a n s p l a n t e d young r e t u r n e d t o t h e i r o r i g i n a l n a t a l c o l o n y . An a t t e m p t t o r e s t o c k young p e l i c a n s from S a s k a t c h e w a n t o a new s i t e i n B r i t i s h C o l u m b i a would not n e c e s s a r i l y e n s u r e a s e c o n d b r e e d i n g c o l o n y , a l t h o u g h s u r v i v i n g 1 28 b i r d s w o u l d enhance t h e t o t a l p o p u l a t i o n of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a . The c h a n c e of p e l i c a n s c o l o n i z i n g a s e c o n d b r e e d i n g l o c a t i o n p r o b a b l y would be much g r e a t e r a f t e r s e v e r a l y e a r s o f i n t r o d u c i n g w h i t e p e l i c a n s . The c r e a t i o n of new n e s t i n g h a b i t a t a t o t h e r l o c a t i o n s on t h e F r a s e r P l a t e a u c o u l d p o t e n t i a l l y i n c r e a s e t h e b r e e d i n g p o p u l a t i o n and r e d u c e t h e v u l n e r a b i l i t y of t h e p e l i c a n p o p u l a t i o n i n B r i t i s h C o l u m b i a . A l t h o u g h w h i t e p e l i c a n s a p p e a r t r a d i t i o n a l i n t h e i r s e l e c t i o n o f n e s t i n g c o l o n i e s , s e v e r a l s t u d i e s ( M a n s e l l 1965, L i e s and B e h l e 1966, Lapp 1976, Thompson and L i t t l e f i e l d 1979) have d e m o n s t r a t e d t h e p e l i c a n ' s a b i l i t y t o e s t a b l i s h new c o l o n i e s when h a b i t a t becomes a v a i l a b l e . P o t e n t i a l b r e e d i n g i s l a n d s s h o u l d be r e l a t i v e l y b a r r e n , g e n t l y s l o p e d , and a t l e a s t 350 m from any a d j a c e n t m a i n l a n d . The abundance of f o o d i n t h e l a k e i s p r o b a b l y not a major f a c t o r . I s l a n d s a l r e a d y p r e s e n t a t s u c h u n d i s t u r b e d s i t e s c o u l d be m a n i p u l a t e d i f t h e y s u p p o r t a d ense v e g e t a t i o n c o v e r . In l a k e s l a c k i n g n a t u r a l i s l a n d s , man-made i s l a n d s c o u l d be c o n s t r u c t e d . McCrow (1974) d e s c r i b e d an i s l a n d c o n s t r u c t e d i n S o u t h D a k o t a w h i c h was c o l o n i z e d and u s e d f o r b r e e d i n g by w h i t e p e l i c a n s . The i s l a n d (47 x 26 m) was s i t u a t e d i n s h a l l o w w a t e r , c o v e r e d 0.12 ha (0.3 a c r e s ) and had an open s u r f a c e of s i l t c l a y s o i l w i t h a r o c k y p e r i p h e r y . A p p a r e n t l y t h i s s i t e may have been e i t h e r t o o s h a l l o w o r l o c a t e d t o o c l o s e t o a d j a c e n t m a i n l a n d . D u r i n g one b r e e d i n g s e a s o n , a l l n e s t s were abandoned when a w h i t e - t a i l e d d e e r ( O d o c o i l e u s v i r g i n i a n u s ) wandered o n t o t h e i s l a n d . 1 29 O t h e r t y p e s o f i s l a n d s o c c a s i o n a l l y u s e d by w h i t e p e l i c a n s f o r b r e e d i n g a r e i s l a n d s of d r e d g e d m a t e r i a l . W hite and brown p e l i c a n s have been known t o use t h e s e i n T e x a s ( L a n d i n and S o o t s 197.7). S u i t a b i l i t y of s u c h i s l a n d s as n e s t i n g s i t e s were d e t e r m i n e d by f a c t o r s s u c h as i s l a n d c o n f i g u r a t i o n , e l e v a t i o n , l o c a t i o n , p r e s e n c e or a b s e n c e of v e g e t a t i o n , and p o t e n t i a l f o r human d i s t u r b a n c e and mammalian p r e d a t i o n . In B r i t i s h C o l u m b i a , s e v e r a l l a k e s c o n t a i n i n g i s l a n d s s u r v e y e d d u r i n g 1977 c o u l d p r o v i d e p o t e n t i a l n e s t i n g h a b i t a t . T h ese i n c l u d e T a h a r t i , T z a z a t i , Temapho, D e e r p e l t , Nasko, and T z e n z a i c u t L a k e s . However, f u r t h e r a e r i a l s u r v e y s must be c o n d u c t e d t o l o c a t e an i d e a l b r e e d i n g s i t e . The use o f s e v e r a l p e l i c a n d e c o y s on t h e s e l e c t e d i s l a n d would p r o b a b l y i n c r e a s e c h a n c e s of a t t r a c t i n g p e l i c a n s . Wooden p u f f i n d e c o y s a i d e d i n t h e r e c o l o n i z a t i o n of an abandoned p u f f i n c o l o n y on E a s t e r n Egg Rock o f f t h e c o a s t of Maine ( K r e s s 1978). A n o t h e r p o t e n t i a l method t o i n c r e a s e t h e p o p u l a t i o n of w h i t e p e l i c a n s i n B r i t i s h C o l u m b i a would be t h e e s t a b l i s h m e n t of a c a p t i v e b r e e d i n g p r o gram. The T ynehead Z o o l o g i c a l S o c i e t y n e a r V a n c o u v e r has e x p r e s s e d a g r e a t d e a l of i n t e r e s t r e g a r d i n g t h i s p o s s i b i l i t y ( P a u l J o s l i n p e r s . comm.). Such a p r o g r a m c o u l d i n c o r p o r a t e methods from o t h e r c u r r e n t c a p t i v e b r e e d i n g p rograms s u c h as t h o s e b e i n g c o n d u c t e d w i t h t h e whooping c r a n e ( G r u s a m e r i c a n a ) and p e r e g r i n e f a l c o n ( F a l c o p e r e g r i n u s ) . T hese c a p t i v e b r e e d i n g p r o g r a m s , however, do have s e v e r e l i m i t a t i o n s , one of w h i c h i s s u c c e s s f u l l y i n t r o d u c i n g c a p t i v e - b r e d b i r d s back i n t o w i l d p o p u l a t i o n s . 130 As more i n f o r m a t i o n on w h i t e p e l i c a n s becomes a v a i l a b l e , i t may be n e c e s s a r y t o m o d i f y o r change e n t i r e l y c e r t a i n management r e c o m m e n d a t i o n s . I s u g g e s t t h a t t h e e n t i r e p l a n be r e v i e w e d a t f o u r or f i v e y e a r i n t e r v a l s . 131 LITERATURE CITED A d o l p h s o n , D.G. and M. A d o l p h s o n . 1968. S i z e , d i s t r i b u t i o n , a nd p o p u l a t i o n of t h r e e c o l o n y n e s t i n g s p e c i e s i n S o u t h D a k o t a . S o u t h D a k o t a B i r d N o t e s 20: 4-10. A l t m a n n , J . 1974. O b s e r v a t i o n a l s t u d y of b e h a v i o r : S a m p l i n g M e t h o d s . 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J o u r n a l of W i l d l i f e D i s e a s e s 10: 135-138. W r i g h t , R. and R. W r i g h t . 1970. The p e l i c a n s o f Stum L a k e , B r i t i s h C o l u m b i a . B.C. O u t d o o r s 26: 16-20. 138 APPENDIX I. Foraging sightings of white pelicans recorded during three a e r i a l surveys conducted i n 1977. Survey Date Lake Total 27/6/77 5/8/77 25/8/77 Pelicans Observed Alex Graham 0 0 3 3 Alexis 0 NS 0 0 Beaver 1 0 0 1 Charlotte NS NS 0 0 C h i l c o t i n 10 14 16 40 Deerpelt 0 NS 0 0 Loomis 0 NS 0 0 Maxwell 1 NS 1 2 Nasko 2 NS 1 3 Nimpo NS NS 0 0 One 0 NS 0 0 Palmer 2 0 1 3 Plover 0 NS 0 0 Punti 0 0 0 0 Puntzi 0 0 0 0 Rosita 2 NS 18 20 Siwash 0 0 0 0 Skinny 0 0 0 0 Summit 0 NS 0 0 Taharti 1 NS NS 1 Tau t r i 1 NS 0 1 Temapho 0 NS 0 0 Tunilkul 2 NS 0 2 Two 0 NS 0 0 Tzazati 0 NS 0 0 Unnamed 1 NS 0 1 (52°25 ,N f 123°15 ,W) NS - Not surveyed 139 APPENDIX 2. Foraging sightings of white pelicans obtained from the B r i t i s h Columbia P r o v i n c i a l Museum. Lake Distance from Stum Lake (Km) Year Comment A l k a l i 78 1976 frequent i n spring Anahim 167 1961 10 feeding Chezacut 71 1941 12 feeding - common Chilanko Forks 71 1973 2 feeding - common Comox (beach) 330 1930 5 f l y i n g - occasion Courtney (beach) 326 1940 2 f l y i n g - occasion Crescent Beach 362 1954 4 lo a f i n g - rare Deerpelt 40 1973 2 feeding Kalkamalka 354 1970 1 f l y i n g - rare Kleena Kleen 132 1957 2 feeding - occasion Klusquoil 127 1977 13 f l y i n g - rare Nimpo 151 1975 1 feeding Nulki 190 1947 1 f l y i n g - rare Pantage 106 1968 3 swimming Pelican (north) 125 1947 feeding - common Pelican (west) 168 1961 1 lo a f i n g Puntataenkut 74 . 1940 once common Rush 312 ' 1959 25 feeding - rare Skaha . 402 1963 65 f l y i n g south - rare Towdystan 142 1977 feeding - occasion Tzenaicut 45 1947 breeding on island? Vaseaux 426 1966 1 feeding - rare Williams 68 1963 15 swimming 

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