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Bird communities in relation to the structure of urban habitats Lancaster, Richard K. 1976

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BIRD COMMUNITIES IN RELATION TO THE STRUCTURE OF URBAN HABITATS by RICHARD K. LANCASTER B . S c , U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1974 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n t h e Department o f Z o o l o g y We a c c e p t t h i s t h e s i s as 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 May, 1976 Q) Richard K. Lancaster 1976 In p r e s e n t i n g t h i s t h e s i s in p a r t j a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r ee t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r ag ree 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 pu rpo se s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f 2^n-rr^^-v The U n i v e r s i t y o f B r i t i s h Co lumb ia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 Date SsLsodu~Ms Zl /976 i Abstract This study i s an investigation of the hypothesis that b i r d species' abundances and other c h a r a c t e r i s t i c s of b i r d communities i n urban areas are a function of habitat struc-ture. To this end, eight study plots of approximately eight hectares each were selected in Vancouver, B.C., and described in terms of area covered by d i f f e r e n t classes of f o l i a g e , buildings, and other man-made features of the habitat. In addition, the amount of food intended for birds provided by people was estimated. The range of habitats represented by the plots depicted a gradient of urbanization; one extreme was a downtown commercial d i s t r i c t and the other was a wood-land. Birds were counted at regular intervals on these plots for one year. B i r d species d i v e r s i t y (H 1), the number of species, and the number of foraging guilds decreased with decreasing veg-etation cover, especially during spring migration and summer breeding seasons. The number and d i v e r s i t y of b i r d species i s not influenced by the d i v e r s i t y of man-made structures. In most plots, b i r d species d i v e r s i t y was lower in summer than in winter. Seasonal changes i n b i r d species d i v e r s i t y were not related to urbanization. However, changes in num-ber of species were greater in habitats with more vegetation. Evenness of species' abundances did not change greatly with s e a s o n i n most p l o t s , b u t d e c l i n e d n o t i c e a b l y w i t h u r b a n i z a -t i o n , i A few s p e c i e s o f b i r d s w e r e most a b u n d a n t t h r o u g h o u t t h e u r b a n e n v i r o n m e n t ; t h e s e w e re t h e Rock Dove ( D o m e s t i c P i g e o n ) , S t a r l i n g , House S p a r r o w , and A m e r i c a n R o b i n . The d e g r e e o f n u m e r i c a l d o m i n a n c e by t h e f i r s t t h r e e o f t h e s e s p e c i e s g e n e r a l l y i n c r e a s e d w i t h u r b a n i z a t i o n i n a l l s e a s o n s . O m n i v o r o u s s p e c i e s w e r e t h e most a b u n d a n t t y p e i n a l l u r b a n h a b i t a t s , i n a l l s e a s o n s . T h e r e was a d e c r e a s e i n t h e r e l -a t i v e a b u n d a n c e o f i n s e c t i v o r e s i n w i n t e r (many 0 f t h e s e were m i g r a t o r y ) . D i f f e r e n c e s among p l o t s i n t o t a l b i r d d e n s i t y i s n o t r e l a t e d t o t h e amount o f v e g e t a t i o n c o v e r . H o w e v e r , human r e s i d e n t s o f s u b u r b a n p l o t s p r o v i d e d s u b s t a n t i a l amounts o f f o o d f o r b i r d s , and t h i s i s t h o u g h t t o h a v e h a d a p r o -n o u n c e d e f f e c t on t o t a l b i r d d e n s i t y , e s p e c i a l l y i n t h e w i n t e r . B i r d d e n s i t i e s i n most h a b i t a t s were h i g h e s t i n t h e w i n t e r , when some s p e c i e s a p p e a r e d t o be d i s t r i b u t e d i n r e s p o n s e t o t h e a v a i l a b i l i t y o f f o o d p r o v i d e d by man, o t h e r s i n r e s p o n s e t o t h e amount o f n a t u r a l f o o d a v a i l a b l e . I t i s h y p o t h e s i z e d t h a t r e s i d e n t b i r d s p e c i e s r e s p o n d d i r e c t l y t o e s s e n t i a l f a c t o r s ( e . g . f o o d ) t o a g r e a t e r e x t e n t t h a n m i g r a n t s . M i g r a n t s a r e g e n e r a l l y b e l i e v e d t o be u s i n g hab-i t a t c h a r a c t e r i s t i c s t h a t a r e c u e s f o r t h e s e f a c t o r s , i n t h e i r s e l e c t i o n o f h a b i t a t . i i i TABLE OF CONTENTS SECTION PAGE INTRODUCTION 1 METHODS 4 P l o t S e l e c t i o n 4 Methods o f A n a l y s i s : H a b i t a t C h a r a c t e r i s t i c s . 13 B i r d C o u n t s 17 Methods o f A n a l y s i s : B i r d C ounts 20 Se a s o n s 20 D e n s i t y and D i v e r s i t y 20 S t a t i s t i c a l A n a l y s e s 21 Q u e s t i o n n a i r e S e n t t o P l o t R e s i d e n t s 23 RESULTS AND DISCUSSION 24 C h a r a c t e r i s t i c s o f S t u d y S i t e s 24 B i r d C e n s u s e s 36 D i s t r i b u t i o n and Abundance 53 M i g r a t o r y s p e c i e s 54 R e s i d e n t S p e c i e s 60 D o m e s t i c P i g e o n 61 S t a r l i n g 61 House Sparrow 64 G l a u c o u s - w i n g e d G u l l 64 House F i n c h 6 5 A m e r i c a n R o b i n 6 5 i v TABLE OF CONTENTS ( c o n t i n u e d ) SECTION PAGE N o r t h w e s t e r n Crow , . . , 66 B l a c k - c a p p e d C h i c k a d e e 67 W i n t e r r e s i d e n t s 67 Summary 68 C h a r a c t e r i s t i c s o f t h e B i r d Communities 69 D i v e r s i t y o f S p e c i e s 69 T o t a l B i r d D e n s i t y and T r o p h i c Groups 72 SUMMARY 86 LITERATURE CITED ,'. 89 APPENDICES 92 1. Sample o f B i r d Census Mapsheet 92 2. a) Q u e s t i o n n a i r e - L e t t e r 93 b) Q u e s t i o n n a i r e - Form 94 3. R e s u l t s o f B i r d C e n s u s e s : Mean D e n s i t y o f E a c h B i r d S p e c i e s 95 4. S i g n i f i c a n t C o r r e l a t i o n s between H a b i t a t F e a t u r e s 103 5. S t a t i s t i c a l A n a l y s e s - Methods and R e s u l t s a) R e s u l t s o f M u l t i p l e Range T e s t s 108 b) R e s u l t s o f M u l t i p l e R e g r e s s i o n s 113 V LIST OF TABLES TABLE PAGE 1. Abbreviations of Plot Names and Environ-mental Charac ter i s t i c s 15 2. Descr ipt ion of P lo t s : Cover by Habitat Features 25 3. Correlat ions among Plots with Respect to Habitat Features 26 4. Groups of Correlated Habitat Character-i s t i c s 27 5. Summary Descr ipt ion of Habitat 2 8 6. Measures of Habitat D ivers i ty 30 7. Questionnaire Results 32 8. Estimation of Food Biomass Requirements of B i rd Communities in Winter 35 9. L i s t of B i rd Species 39 10. Seasons: Dates of A r r i v a l and Departure of Some Species 42 11. Summary of B i rd Census Results 43 12. Numerically Dominant B i rd Species 45 13. Resident Status of B i rd Species in Van-couver 55 14. Comparison of B i rd Community Character-i s t i c s with those of Weber (1972) 76 15. Trophic Groups of B i rds: Proportion of Tota l Number of Individuals in each . Group 77. v i L I S T OF FIGURES FIGURE T I T L E PAGE 1. L o c a t i o n o f S t u d y P l o t s 6 2. A i r P h o t o s o f P l o t s 8 3. Mean T o t a l B i r d D e n s i t y v e r s u s T o t a l V e g e t a t i o n C o v e r 37 4. F l u c t u a t i o n o f T o t a l D e n s i t y and Number o f S p e c i e s between C e n s u s e s : Downtown .. 47 5. F l u c t u a t i o n o f T o t a l D e n s i t y and Number o f S p e c i e s between c e n s u s e s : F a l s e C r e e k 47 6. F l u c t u a t i o n o f T o t a l D e n s i t y and Number o f S p e c i e s between c e n s u s e s : M a c K e n z i e . 49 7. F l u c t u a t i o n o f T o t a l D e n s i t y and Number o f S p e c i e s between c e n s u s e s : Queen E l i z a b e t h 49 8. Number o f M i g r a n t S p e c i e s v e r s u s T o t a l V e g e t a t i o n C o v e r 56 9. E s t i m a t e s o f S t a r l i n g D e n s i t y v e r s u s T o t a l V e g e t a t i o n C o v e r 62 10. E s t i m a t e s o f B l a c k - c a p p e d C h i c k a d e e Den-s i t y v e r s u s T o t a l V e g e t a t i o n C o v e r 62 11. BSD v e r s u s FHD2 (Summer) 70 12. BSD v e r s u s Man-made Component o f H a b i t a t D i v e r s i t y (Summer) 73 13. Number o f F o r a g i n g G u i l d s p e r P l o t s (Sum-mer) v e r s u s T o t a l V e g e t a t i o n C o v e r 81 14. Number o f S p e c i e s p e r G u i l d (Summer) v e r s u s T o t a l V e g e t a t i o n C o v e r 81 v i i A c k n o w l e d g e m e n t T h i s s t u d y w o u l d n o t h a v e b e e n p o s s i b l e w i t h o u t t h e a s -s i s t a n c e o f a number o f p e r s o n s , o f whom I s h a l l m e n t i o n b u t a few. The c r i t i c i s m s , s u g g e s t i o n s , and a i d i n t h e c e n s u s o f b i r d s p r o v i d e d by my t h e s i s s u p e r v i s o r , Dr. W i l l i a m E. R e e s , m e r i t my d e e p e s t g r a t i t u d e . T h ose who a l s o h e l p e d i n c a r r y i n g o u t b i r d c e n s u s e s were L a r r y E v a n s and James H a r t . A d v i c e on s t a t i s t i c a l a n a l y s e s was p r o v i d e d by Dr. C h a r l e s J . K r e b s a n d Dr. C o n r a d Wehrhahn. I t h a n k Dr. J u d i t h M y e r s and Dr. Lee Gass f o r t h e s u g g e s t i o n s t h e y made as members o f my c o m m i t t e e . Thanks a l s o t o Thomas S u l l i v a n and Rudy B o o n s t r a : f o r t h e i r c o u n s e l t h r o u g h o u t t h i s s t u d y , and t o Wayne Weber and Dr. M u r r a y S p e i r s who p r o v i d e d t e c h n i c a l a d v i c e on t h e c e n s u s o f b i r d s . I am g r a t e f u l t o E l a i n e T a s a k a f o r h e r a s s i s -t a n c e i n p r e p a r i n g t h e q u e s t i o n n a i r e f o r m s . F i n a l l y , I t h a n k t h e Canada W i l d l i f e S e r v i c e whose s c h o l -a r s h i p h e l p e d f i n a n c e my e f f o r t s , a nd my s u p e r v i s o r f o r m e e t i n g some o f t h e e x p e n s e s t h a t a r o s e . INTRODUCTION T h i s s t u d y examines r e l a t i o n s h i p s between d i v e r s i t y , d e n s i t y , and t r o p h i c c h a r a c t e r i s t i c s o f c o m m u n i t i e s o f b i r d s , and t h e s t r u c t u r e o f t h e p h y s i c a l e n v i r o n m e n t w i t h i n a r a n g e o f u r b a n h a b i t a t t y p e s . The r e l a t i o n s h i p s between b i r d community c o m p l e x i t y and h a b i t a t s t r u c t u r a l c o m p l e x i t y have r e c e i v e d i n t e n s i v e e x a m i n a t i o n s i n c e M a c A r t h u r and M a c A r t h u r (1961) r e p o r t e d t h a t b i r d s p e c i e s d i v e r s i t y ( H 1 ) o f f o r e s t b i r d c o m m u n i t i e s c o u l d be p r e d i c t e d by t h e f o l i -age h e i g h t d i v e r s i t y Can i n d e x b a s e d on t h e r e l a t i v e amounts o f f o l i a g e i n gr o u n d , s h r u b , and t r e e s t r a t a ) . F o r example, r e l a t i o n s h i p s between b i r d s p e c i e s d i v e r s i t y , t o t a l b i r d d e n s i t y , and h a b i t a t t y p e s have been examined i n s t u d i e s i n u r b a n a r e a s o f N o r t h A m e r i c a (.Weber, 1972 ; Emlen, 1974). These s t u d i e s have shown t h a t b i r d s p e c i e s d i v e r s i t y , as i n d e x e d by t h e number o f s p e c i e s , t h e e v e n n e s s o f s p e c i e s ' a b u n d a n c e s , o r the i n f o r m a t i o n t h e o r y i n d e x H', i s l o w e r i n c i t i e s t h a n i n many o t h e r e n v i r o n m e n t s ; and have s u g g e s t e d t h a t d i v e r s i t y d e c r e a s e s w i t h u r b a n i z a t i o n w h i l e b i r d abund-ance and b i o m a s s may be g r e a t e r i n c i t i e s t h a n i n r u r a l o r " n a t u r a l " a r e a s . C i t y a v i f a u n a s a l s o a p p e a r t o d i f f e r f r o m o t h e r s by b e i n g composed l a r g e l y o f s p e c i e s t h a t a r e o n l y l o o s e l y t e r r i t o r i a l , t h a t a r e t r e e o r c a v i t y n e s t e r s , and t h a t a r e e i t h e r s e e d - e a t e r s o r o m h i v o r e s (Weber, 1972; Emlen, 1974). T h i s s t u d y i s d e s i g n e d t o examine some o f t h e f a c t o r s u n d e r l y i n g s u c h r e l a t i o n s h i p s w i t h i n an u r b a n a r e a . Spec-i f i c r e s e a r c h o b j e c t i v e s were as f o l l o w s . 1) To i d e n t i f y and d e s c r i b e q u a n t i t a t i v e l y and q u a l i t a t i v e l y a g r a d i e n t o f u r b a n h a b i t a t t y p e s , u s i n g s t r u c t u r a l f e a t u r e s o f t h e h a b i t a t . 2) To u n d e r t a k e a y e a r - l o n g c o u n t t o e s t i m a t e t h e number o f s p e c i e s , s p e c i e s ' a b u n d a n c e s , and s e a s o n a l f l u c t u a -t i o n i n t h e s e , w i t h i n s t u d y p l o t s . 3) To e s t i m a t e t h e amount o f f o o d p r o v i d e d f o r b i r d s by p e o p l e i n t h e s t u d y a r e a s . 4) To d e t e r m i n e t h e c o r r e l a t i o n s between d i s t r i b u t i o n o f s t r u c t u r a l f e a t u r e s o f t h e h a b i t a t , a r t i f i c i a l f o o d s u p p l y , c h a r a c t e r i s t i c s o f t h e b i r d c o m m u n i t i e s , and i n d i v i d u a l s p e c i e s ' d i s t r i b u t i o n s . T h i s t h e s i s examines t h e h y p o t h e s i s t h a t s p e c i e s d i v e r -s i t y , t o t a l d e n s i t y , and t r o p h i c s t r u c t u r e o f b i r d commun-i t i e s w i t h i n a r a n g e o f u r b a n h a b i t a t t y p e s a r e r e l a t e d t o r e a d i l y q u a n t i f i a b l e s t r u c t u r a l c h a r a c t e r i s t i c s o f t h e hab-i t a t s , as t h e y a r e i n n o n - u r b a n a r e a s . One r e a s o n f o r s t u d y i n g b i r d s i n c i t i e s i s t o o b t a i n i n f o r m a t i o n t h a t c o u l d be a p p l i e d t o e c o l o g i c a l management o f t h i s " w i l d l i f e " . The abundance o f c e r t a i n b i r d s p e c i e s i n c i t i e s o f t e n c a u s e s economic and a e s t h e t i c damage, and i n some s i t u a t i o n s h e a l t h h a z a r d s . B i r d s may a c t as v e c -3, t o r s o f s u c h d i s e a s e s as c o c c i d i o s i s and e n c e p h a l i t i s . M o r e o v e r l a r g e u r b a n p o p u l a t i o n s o f S t a r l i n g s ( S t u r n u s  v u l g a r i s ) , D o m e s t i c P i g e o n s o r Rock Doves C£olumb<i l i v i a ) , and House S p a r r o w s C P a s s e ^ d o m e s t i c u s ) c a n damage n e a r b y c r o p s , s t o r e d f o o d , and t h e b u i l d i n g s i n w h i c h t h e y r o o s t ( P r i n c . o f p l a n t and anim. p e s t c o n t . , 1970). Many methods o f a v i a n p e s t c o n t r o l have been a t t e m p t e d , most o f w h i c h i n v o l v e d t r a p p i n g o r p o i s o n i n g ( E l l i o t t , 1964; M u r ton e t a l . , 1972). S u c c e s s e s have been l i m i t e d , however, and may i n v o l v e c o n s i d e r a b l e c o s t s . C l e a r l y t h e r e f o r e , an e c o l o g i c a l management t e c h n i q u e t h a t w o u l d f a v o u r d e s i r a b l e s p e c i e s b u t a t t h e same t i m e d i s c o u r a g e p e s t s , w o u l d improve t h e u r b a n e n v i r o n m e n t f o r man. T h i s s t u d y f o c u s e s on t h e r e l a t i o n s h i p s between b i r d s i n c i t i e s and h a b i t a t s t r u c t u r e , s i n c e m a n i p u l a t i o n o f h a b i t a t s t r u c t u r e may be a u s e f u l t e c h n i q u e i n t h i s r e g a r d . METHODS P l o t S e l e c t i o n P l o t s r e p r e s e n t i n g h a b i t a t s w i t h d i f f e r e n t p h y s i c a l s t r u c t u r e and r e p r e s e n t a t i v e o f d i f f e r e n t l e v e l s o f u r b a n -i z a t i o n were u s e d i n t h i s s t u d y . The " l e v e l o f u r b a n i z a t i o n " r e f e r s t o t h e r e l a t i v e amounts o f a r e a c o v e r e d by v e g e t a t i o n and by man-made s t r u c t u r e s . H a b i t a t s w i t h much b u i l d i n g and pavement c o v e r a r e c o n s i d e r e d t o be more " u r b a n " i n c h a r a c t e r t h a n t h o s e w i t h r e l a t i v e l y more v e g e t a t i o n . I e x p e c t e d t h a t t h e s p e c i e s and n u m e r i c a l c o m p o s i t i o n o f b i r d c o m m u n i t i e s w o u l d r e f l e c t t h e e n v i r o n m e n t a l g r a d i e n t s a s s o c -i a t e d w i t h u r b a n i z a t i o n , and t h a t t h e f o r m e r c o u l d be c o r -r e l a t e d w i t h q u a n t i f i a b l e changes i n 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 a r e a s sampled. P l o t s were s e l e c t e d u s i n g 1972 a i r p h o t o s o f V a n c o u v e r , o b t a i n e d from t h e C i t y P l a n n i n g Department, i n c o n j u n c t i o n w i t h a f i e l d s u r v e y . C h o i c e o f p l o t s was p r i m a r i l y b a s e d on t h e a p p a r e n t amount o f t r e e c o v e r . I n a d d i t i o n , t h e l o c a t i o n o f p l o t s was c o n s i d e r e d i n r e l a t i o n t o time w h i c h w o u l d have t o be s p e n t t r a v e l l i n g t o t h e s e , and t h e p r o x -i m i t y o f m a j o r e n v i r o n m e n t a l d i s c o n t i n u i t i e s , s u c h as p a r k s and t h e o c e a n . I p r e f e r r e d a r e a s t h a t were homogeneous w i t h i n , and t h a t were s u r r o u n d e d by s i m i l a r h a b i t a t . Edge e f f e c t s and t h e e f f e c t s o f i n t e r n a l v a r i a t i o n o f h a b i t a t 5. were t h e r e b y m i n i m i z e d . P l o t s were a l l l o c a t e d on f a i r l y l e v e l t e r r a i n . A r e a s w i t h o u t b a c k l a n e s , w i t h c u r v i n g s t r e e t s , o r n e a r the edge o f t h e a i r p h o t o s were n o t s e l -e c t e d . E i g h t p l o t s were c h o s e n (.Figures 1, 2). t o r e p r e s e n t m a j o r h a b i t a t t y p e s w i t h i n V a n c o u v e r . These were "commer-c i a l " (Downtown, DT), " l i g h t i n d u s t r i a l " ( F a l s e C r e e k , F C ) , " d e n s e l y p o p u l a t e d a p a r t m e n t " (West End, WE), " s i n g l e - d w e l l i n g r e s i d e n t i a l " (.Queen E l i z a b e t h , QE; M a c K e n z i e , MK; C o l l i n g w o o d , CW; S h a u g h n e s s y , SH), and " s e c o n d - g r o w t h m i x e d - f o r e s t " ( U . B . C , UB) h a b i t a t s . A l l p l o t s were r e c t a n g u l a r and a p p r o x i m a t e l y 8 h e c t a r e s (2 0 a c r e s ) i n a r e a . F o r u r b a n s t u d -i e s t h i s s i z e p r o v i d e s a compromise between l a r g e p l o t s w h i c h have p r o p o r t i o n a t e l y r e d u c e d edge e f f e c t and p r o b a b l y l e s s d a i l y f l u c t u a t i o n i n t h e a v i f a u n a ( e s p e c i a l l y i n non-b r e e d i n g s e a s o n s ) and s m a l l e r p l o t s w h i c h m i g h t be more homogeneous. P l o t s o f a b o u t t h e same s i z e have been u s e d by S p e i r s e t a l . (.1970) i n u r b a n b i r d s t u d i e s . However some a u t h o r i t i e s a d v i s e a r e a s 2 o r 3 t i m e s l a r g e r t h a n t h o s e u s e d ( e g . A. E r s k i n e , CWS, p e r s o n a l c o m m u n i c a t i o n ) , w h i l e u r b a n p l o t s o f l e s s t h a n 0. 5h have a l s o been c e n s u s e d (.Thomas, 1973). I t was n o t p o s s i b l e i n t h i s s t u d y t o c o u n t b i r d s i n more t h a n e i g h t 20h p l o t s r e g u l a r l y b e c a u s e o f l i m i t a t i o n s i n manpower. 6. F i g u r e 1: L o c a t i o n o f s t u d y p l o t s w i t h i n V a n c o u v e r , B.C. 8. Figure 2: A i r photos of- study plo t s . Scale approximately lcm = 50 m. These photos are smaller scale copies of 19 72 a i r photo enlargements, obtained from the City Planning Department. 9 . F i g u r e 2: A i r P h o t o s o f P l o t s F a l s e C r e e k Queen E l i z a b e t h F i g u r e 2: A i r P h o t o s o f P l o t s C o l 1 i n g w o o d U.B.C. 13. Methods o f A n a l y s i s : H a b i t a t C h a r a c t e r i s t i c s I t was n e c e s s a r y t o i n v e n t o r y and c h a r a c t e r i z e t h e p h y s i c a l p r o p e r t i e s o f e a c h p l o t . T h e r e f o r e c o v e r p r o -v i d e d by m a j o r t y p e s o f v e g e t a t i o n and man-made s t r u c t u r e s was m e a s u r e d i n c l u d i n g t h a t o f f l a t - r o o f e d b u i l d i n g s (^apart-ments, c o m m e r c i a l , i n d u s t r i a l ) , s l a n t - r o o f e d b u i l d i n g s ( m a i n l y r e s i d e n t i a l ) , r o a d s , l a n e s , s i d e w a l k s and m i s c e l -l a n e o u s p a v e d and g r a v e l s u r f a c e s , lawns, g a r d e n s , t r e e s , s h r u b s , and weedy p a t c h e s ( e . g . t a l l g r a s s , n a t u r a l h e r b -aceous v e g e t a t i o n ) ( s e e T a b l e 1 ) . The woody c a t e g o r i e s were f u r t h e r d e s c r i b e d as b e i n g d e c i d u o u s , c o n i f e r o u s , o r b r o a d l e a v e d e v e r g r e e n , and were a s s i g n e d t o one o f f o u r h e i g h t c l a s s e s : 0 t o 1.5m ( 5 ' ) , 1.5 t o 4.5m ( 1 5 ' ) , 4.5 t o 7.5m ( 2 5 ' ) , and o v e r 7.5m. T r e e s were d e f i n e d as woody v e g e t a t i o n o v e r 4.5m i n h e i g h t . The c h o i c e o f t h e s e v e g -e t a t i o n s t r a t a and h a b i t a t f e a t u r e s p a r t i a l l y r e f l e c t s t h e c h o i c e s made i n r e l a t e d s t u d i e s ( M a c A r t h u r and M a c A r t h u r , 1961; Weber, 1972; Emlen, 1 9 7 4 ) , b u t was a l s o b a s e d on o b s e r v a t i o n s o f l a y e r i n g o f v e g e t a t i o n i n u r b a n a r e a s o f V a n c o u v e r . An a i r p h o t o e n l a r g e m e n t was o b t a i n e d f o r e a c h o f t h e p l o t s ; t h e s e were o f t h e s c a l e 1cm = 24m so t h a t c o n s i d -e r a b l e d e t a i l was d i s c e r n a b l e . These were u s e d t o d e t e r m i n e , f o r e a c h o f t h e u r b a n p l o t s , t h e p e r c e n t o f a r e a c o v e r e d by e a c h o f t h e f e a t u r e s m e n t i o n e d above, w i t h t h e e x c l u s i o n o f shrubs, gardens, and weedy patches. The l a t t e r were often indistinguishable from and grouped with "lawn". A transparent grid of transect lines spaced 1cm apart was placed over the plot area on each photograph, and the length of these lines intersected by each habitat feature was measured. The percent of plot area covered by each fea-ture was then calculated. This method was subject to errors p a r t i c u l a r l y when estimating the amount of area covered by features which were regularly d i s t r i b u t e d such as roads, lanes, and sidewalks. Therefore the amount of these fea-tures was estimated d i r e c t l y from the a i r photos. This more accurate measurement of the amount of area covered by road, lane, and sidewalk i n each plot was then substituted for the estimates derived from the transect sampling. I v i s i t e d each of the plots i n order to estimate densit of trees, proportion of trees and shrubs i n each height and foliage class, and area covered by shrubs and garden. This 'on-site' survey covered at least 1/4 of each of the urban plots (Table 2). Since I had chosen the plots to be as i n -te r n a l l y homogeneous as possible, the areas sampled 'on-site were selected subjectively. During these surveys, I paced along streets and lanes to measure one dimension of features such as hedges, and estimated the other dimensions by eye. Heights of trees and shrubs were i n i t i a l l y measured using a Suunto Clinometer, but I gained confidence in estimating 15. T a b l e 1: A b b r e v i a t i o n s o f P l o t Names and E n v i r o n m e n t a l C h a r a c t e r i s t i c s P l o t Names H a b i t a t Type DT - Downtown C o m m e r c i a l , R e t a i l FC - F a l s e C r e e k I n d u s t r i a l , W h o l e s a l e WE - West End R e s i d e n t i a l - A p a r t m e n t QE - Queen E l i z a b e t h R e s i d e n t i a l MK - M a c K e n z i e R e s i d e n t i a l CW - C o l l i n g w o o d R e s i d e n t i a l SH - S h a u n g h e s s y R e s i d e n t i a l UB - U.B.C. M i x e d Woodland Table 1 ( c o n t i n u e d ) 16. E n v i r o n m e n t a l C h a r a c t e r i s t i c s D Deciduous shrubs or t r e e s C C o n i f e r o u s shrubs o r t r e e s BDEVG B r o a d l e a v e d e v e r g r e e n t r e e s E B r o a d l e a v e d e v e r g r e e n shrubs <7.5. Less than 7.5m (25') but g r e a t e r than 4.5m (1 5 1 ) i n h e i g h t >7.5 G r e a t e r than 7.5m <1.5 Less than 1.5m (5') >1.5 G r e a t e r than 1.5m but l e s s than 4.5m i n h e i g h t SLANT S l a n t - r o o f e d b u i l d i n g s (houses, churches) FLAT F l a t - r o o f e d b u i l d i n g s ( a p a r t m e n t s , o f f i c e s , warehouses) ROAD Paved r o a d s u r f a c e LANE Paved o r g r a v e l back l a n e s u r f a c e PVT+S M i s c e l l a n e o u s pavement p l u s s i d e w a l k LAWN Ground c o v e r e d by s h o r t (<30cm) gras s p r i m a r i l y HERB Gardens (herbaceous p l a n t s p l u s bare e a r t h ) WEED Untended herbaceous v e g e t a t i o n SHRUB Woody p l a n t l e s s t h a n 4.5m TREE Woody p l a n t over 4.5m FHD F o l i a g e h e i g h t s l i v e r s i t y - i n f o r m a t i o n t h e o r y measure HFD H a b i t a t f e a t u r e d i v e r s i t y - " " " TD Tree d e n s i t y (#/40h) FOOD Amount o f f o o d p r o v i d e d i n t e n t i o n a l l y by r e s i d e n t s (kg/month/40h) TOTVEG T o t a l cover by v e g e t a t i o n 17. h e i g h t s by eye and t h e r e f o r e u s e d t h i s method. The ' o n - s i t e ' s u r v e y r e s u l t s were u s e d t o a d j u s t t h e c o v e r v a l u e s d e r i v e d f r o m t h e a i r p h o t o t r a n s e c t s , i . e . t h e a r e a f o u n d t o be c o v e r e d by g a r d e n s , s h r u b s , and weeds, i n t h e s i t e v i s i t s was s u b t r a c t e d f r o m t h a t o f " l a w n " e s t -i m a t e d by t h e t r a n s e c t method. In t h e w o o d l a n d p l o t , l o c a t e d i n t h e U.B.C. Endowment Lands f o r e s t , a p l o t was l a i d o u t u s i n g compass and measur-i n g t a p e , w i t h l i n e s c u t and f l a g g e d e v e r y 30m. A b u f f e r s t r i p o f v e g e t a t i o n a t l e a s t 60m wide s e p a r a t e d t h e p l o t f r o m n e a r b y r o a d s and r e s i d e n t i a l a r e a s . A l l e s t i m a t e s o f v e g e t a t i o n c o v e r were made s u b j e c t i v e l y ' o n - s i t e ' . F i f t e e n q u a d r a t s , e a c h 12m x 12m s q u a r e were l o c a t e d a p p r o x i m a t e l y t h r o u g h o u t t h e census p l o t . I n t h e s e , I e s t i m a t e d t h e c o v e r o f v e g e t a t i o n i n e a c h s t r a t u m by e y e , and c o u n t e d t h e number o f t r e e s p e r q u a d r a t . B i r d C o unts The t e c h n i q u e u s e d to c o u n t b i r d s i n t h i s s t u d y was s i m i l a r t o t h e " d i r e c t s t r i p c o u n t " method f a v o u r e d by Emlen (1974) f o r c e n s u s i n g i n an u r b a n s i t u a t i o n . Emlen a l s o u s e d " c o n v e r t e d t r a n s e c t c o u n t " and "home r a n g e map-p i n g " t e c h n i q u e s . A f t e r a d j u s t i n g t h e r e s u l t s o f t h e s e t h r e e a p p r o a c h e s t o a c c o u n t f o r known b i a s e s , he a r r i v e d a t a " b e s t e s t i m a t e " o f t h e d e n s i t y o f ea c h s p e c i e s . How-18. e v e r t h e r e s u l t s o f t h e d i r e c t s t r i p c o u n t c l o s e l y a p p r o x i -mated h i s b e s t e s t i m a t e s . The d i r e c t s t r i p c o u n t t h e r e f o r e a p p e a r s t o be t h e b e s t method a v a i l a b l e f o r c e n s u s i n g u r b a n b i r d c o m m u n i t i e s p a r t i c u l a r l y when o f t - r e p e a t e d c o u n t s and many p l o t s a r e i n v o l v e d . Methods s i m i l a r t o t h e one u s e d h e r e have a l s o been u s e d by G r a b e r and G r a b e r (JL963) , and Weber (19 72) . A s u r v e y r o u t e was d e f i n e d f o r e a c h p l o t , i n w h i c h l a n e s and r o a d s were t r a v e r s e d , o r i n t h e c a s e o f t h e w o o d l a n d p l o t s , i n w h i c h t r a n s e c t l i n e s s p a c e d 60m a p a r t were t r a v -e r s e d ( A p p e n d i x 1 ) . The l a n e s and r o a d s were s u f f i c i e n t l y c l o s e t o g e t h e r t o e n s u r e t h a t c o m p l e t e v i s u a l c o v e r a g e o f the p l o t s was o b t a i n e d . The d i r e c t i o n o f p a s s a g e t h r o u g h a p l o t was r e v e r s e d on a l t e r n a t e c e n s u s d a y s , and t h e t i m e o f c e n s u s r e l a t i v e t o s u n r i s e , w i t h i n t h e f i r s t 1/2 h o u r t o 2 1/2 h o u r s a f t e r s u n r i s e , was v a r i e d . T h i s was done t o ra n d o m i z e t h e c o u n t s w i t h i n t h i s p e r i o d . The o b s e r v e r w a l k e d th e c e n s u s l i n e s a t a l e i s u r e l y p a c e w i t h o c c a s i o n a l p a u s e s . The s p e c i e s and l o c a t i o n o f a l l p e r c h e d o r f o r a g i n g f l e d g e d o r a d u l t b i r d s o b s e r v e d i n t h e p l o t were r e c o r d e d on c e n s u s m a p s h e e t s . C e r t a i n a c t i v i t i e s o f b i r d s , p a r t i c u l a r l y f o r -a g i n g and n e s t i n g , were n o t e d as i n d i c a t o r s o f t h e use made o f p l o t s by b i r d s p e c i e s . I d i d n o t c e n s u s b i r d s when i t was r a i n i n g o r windy b e c a u s e o f i m p a i r e d o b s e r v a b i l i t y and r e d u c e d a c t i v i t y o f b i r d s . The " d i r e c t s t r i p c o u n t " method i s r e a s o n a b l y q u i c k , a p p l i c a b l e y e a r - r o u n d , and s u i t e d f o r s t u d y i n a r e a s where many s p e c i e s a r e l o o s e l y f l o c k i n g , and n o t h i g h l y t e r r i t o r i a l . F o u r p e r s o n s h e l p e d w i t h t h e b i r d s u r v e y s , b u t I d i d a p p r o x i m a t e l y 80% o f t h e t o t a l c e n s u s e s . S i n c e o b s e r v e r s may be b i a s e d i n d i f f e r e n t d i r e c t i o n s , I c e n s u s e d a l l p l o t s t h r o u g h o u t t h e s t u d y i n o r d e r t o p r o v i d e o v e r l a p between o b s e r v e r s . The e s t i m a t e s o f t o t a l d e n s i t y by s e p a r a t e ob-s e r v e r s d i f f e r e d by an a v e r a g e o f 20%, when t h e r e s u l t s f r o m s u c c e s s i v e c o u n t s i n t h e same a r e a were compared. I t was p o s s i b l e f o r one o b s e r v e r t o s u r v e y two p l o t s i n one m o r n i n g , and t h i s was o f t e n done. G e n e r a l l y , t h e more woody t h e p l o t ( i . e . t h e l e s s urban) t h e more t i m e was r e -q u i r e d f o r c o u n t s . Time t o c o u n t b i r d s i n a p l o t v a r i e d w i t h s e a s o n b u t a v e r a g e d about 45 m i n u t e s i n t h e u r b a n p l o t s . I t i s my o p i n i o n t h a t t h e methods u s e d t o c o u n t b i r d s i n t h i s s t u d y gave a r e a s o n a b l e e s t i m a t e o f t h e b i r d s p e c i e s p o p u l a t i o n s i n u r b a n p l o t s , e x c e p t f o r t h o s e s p e c i e s w h i c h were v e r y r a r e . T h e r e i s no way o f c o n f i r m i n g t h i s . C o unts i n t h e w o o d l a n d p l o t may h a v e been u n d e r e s t i m a t e d t o a g r e a t -e r d e g r e e t h e number o f i n d i v i d u a l s and s p e c i e s p r e s e n t , owing t o t h e d i f f i c u l t y o f d e t e c t i n g b i r d s i n dense v e g e t a -t i o n . B e c a u s e o f t h e low l e v e l s o f v e g e t a t i o n i n u r b a n a r e a s , v i s i b i l i t y was g e n e r a l l y e x c e l l e n t . 20. Methods o f A n a l y s i s : B i r d C e n suses S e v e r a l a n a l y s e s were employed t o compare b i r d communi-t i e s and h a b i t a t s . These a r e b r i e f l y d e s c r i b e d b elow. SEASONS The c e n s u s r e s u l t s were c a t e g o r i z e d i n t o f o u r " s e a s o n s " b a s e d on b e h a v i o u r a l c r i t e r i a i n o r d e r t o d e t e c t s e a s o n a l t r e n d s i n c l u d i n g t h o s e t h a t m i g h t be a t t r i b u t e d t o u r b a n i z a -t i o n , and t o r e d u c e p o s s i b l e v a r i a n c e i n t h e c e n s u s r e s u l t s . W h i l e I r e f e r t o t h e s e " s e a s o n s " as S p r i n g , Summer, F a l l , and W i n t e r , t h e y do n o t c o i n c i d e p r e c i s e l y w i t h c a l e n d a r s e a s o n s . S p r i n g and F a l l were peak t i m e s o f b i r d m i g r a -t i o n w h i l e Summer and W i n t e r were t h e t i m e s between t h e s e . The d a t e s o f a r r i v a l and d e p a r t u r e o f a number o f t r a n s i e n t s p e c i e s were d e t e r m i n e d f rom c e n s u s r e s u l t s and u s e d t o s e t s e a s o n l e n g t h s . DENSITY AND DIVERSITY B i r d d e n s i t i e s a r e g e n e r a l l y r e p o r t e d i n t h e l i t e r a t u r e as number p e r 40 h e c t a r e s (100 a c r e s ) ; t h i s c o n v e n t i o n w i l l be f o l l o w e d h e r e . The mean d e n s i t y o f e a c h s p e c i e s and o f th e t o t a l b i r d community w i t h i n e a c h p l o t (.for e a c h s e a s o n ) were c a l c u l a t e d . T o t a l s p e c i e s d i v e r s i t y i s a n o t h e r community a t t r i b u t e o f i n t e r e s t . The i n f o r m a t i o n t h e o r y measure H' (j=" 2 P j ^ ° § e P i > t h where p i i s t h e p r o p o r t i o n o f .the i s p e c i e s ) has been most f r e q u e n t l y u s e d f o r t h i s so w i l l be u s e d h e r e f o r p u r p o s e s o f c o m p a r i s o n . H' may be i n t e r p r e t e d as t h e amount o f un-c e r t a i n t y s u r r o u n d i n g t h e i d e n t i f i c a t i o n as t o s p e c i e s o f an i n d i v i d u a l r a n d o m l y s e l e c t e d f r o m a community ( M a c A r t h u r , 1965) . The terms b i r d s p e c i e s d i v e r s i t y (BSD) and H' a r e synonymous t h r o u g h o u t t h i s p a p e r . T h e r e a r e two components t o b i r d s p e c i e s d i v e r s i t y . One i s t h e s p e c i e s r i c h n e s s o r number o f s p e c i e s CS)• The o t h e r i s t h e e v e n n e s s ( J 1 , r a n g e 0 t o 1 ) , w h i c h i s a measure o f t h e r e l a t i v e p r o p o r t i o n s o f e a c h s p e c i e s , and a p p r o a c h e s 1 as t h e p r o p o r t i o n s o f a l l s p e c i e s become e q u a l . I t i s c a l c u l a t e d a s : J ' = _H1 ; H ' m a x = l o g e S ( P i e l o u , 1969). ^ max F o u r b i r d community d i v e r s i t y i n d i c e s i n a l l w i l l be r e f e r r e d t o : H 1 , S, J ' , and SAV ( t h e a v e r a g e number o f s p e c i e s i n a p l o t ) . H a b i t a t d i v e r s i t y i n d i c e s have a l s o b e e n c a l c u l a t e d ; FHD o r f o l i a g e h e i g h t d i v e r s i t y ( M a c A r t h u r and M a c A r t h u r , 1961), and HFD o r h a b i t a t f e a t u r e d i v e r s i t y ( T o m o f f , 1974). These were c a l c u l a t e d i n t h e same manner as H*, and r e f e r t o t h e f o l i a g e s t r a t a and h a b i t a t f e a t u r e s r e s p e c t i v e l y , t h a t have been r e c o g n i z e d by t h e o b s e r v e r . S TATISTICAL ANALYSES A number o f r e l a t i o n s h i p s b e t w e e n * h a b i t a t s t r u c t u r e and c h a r a c t e r i s t i c s of b i r d communities were examined s t a t i s -t i c a l l y . Analysis of variance and multiple range tech-niques were used to examine va r i a t i o n between plots and between seasons with respect to the t o t a l b i r d density, the species d i v e r s i t y (H'), number of species, and the evenness of species' abundances. Multiple regression was used to derive " p r e d i c t i v e " equations for the abundance of each species as well as d i v e r s i t y , density, and evenness c h a r a c -t e r i s t i c s of b i r d communities, using area covered by habitat features and d i v e r s i t y measures of habitat s t r u c t u r a l com-pl e x i t y (see Table 1 ) . The assumptions i m p l i c i t in these techniques, that variances are homogeneous and that the abundance data (dep-? endent variables) have a normal d i s t r i b u t i o n , were vio l a t e d in many instances by my data. Since i t i s not known how robust these tests are in the face of these v i o l a t i o n s , the methods used in carrying out the tests, and the results obtained from them, w i l l be described in the Appendix rather than i n the text of this thesis. Multiple range test re-sults are presented in Appendix 5a and multiple regression results are presented in Appendix 5b. A n o n s t a t i s t i c a l approach has been used in the interpretation of the r e s u l t s , with but a few references to the s t a t i s t i c a l results pre-sented in the Appendix. 23. Questionnaire Sent to Plot Residents A mail-back questionnaire (Appendix 2) was delivered to residents of the urban plots to gather information on the amount and types of food provided by people for birds. This questionnaire was also used to determine the species of birds which residents noticed using this food most fre-quently, the frequency of birds nesting in buildings, and the general attitudes of residents towards urban avifauna. A questionnaire was delivered to every household in the suburban plots (Queen Elizabeth, MacKenzie, Collingwood, Shaughnessy). One hundred more were di s t r i b u t e d in the West End pl o t , primarily to residents of old houses and small apartments. The high population density and limited access to new apartment buildings made i t impossible to send a questionnaire to every household in the West End. RESULTS AND DISCUSSION C h a r a c t e r i s t i c s o f S t u d y S i t e s E a c h p l o t has been d e s c r i b e d i n terms o f t h e a r e a cov-e r e d by v a r i o u s h a b i t a t f e a t u r e s ( T a b l e 2 ) . I t c a n be s e e n f r o m T a b l e 2 t h a t t h e r e was a g r a d i e n t w i t h r e s p e c t t o t o t a l v e g e t a t i o n c o v e r v a r y i n g f r o m l e s s t h a n 5% t o o v e r 175%, The t h e o r e t i c a l maximum i s 300%, due t o o v e r l a p between t r e e , s h r u b , and g r o u n d l a y e r s . A l t h o u g h a r o u g h g r a d i e n t o f v e g e t a t i o n c o v e r was e v i d e n t , some p l o t s were s i m i l a r w i t h r e s p e c t t o o t h e r f e a t u r e s . In o r d e r t o d e t e r m i n e j u s t how s i m i l a r p l o t s were t o e a c h o t h e r w i t h r e s p e c t t o a l l 19-h a b i t a t f e a t u r e s , t h e c o r r e l a t i o n c o e f f i c i e n t , ' r ' ( W o o l f , 1968) , was c a l c u l a t e d . These r e s u l t s a r e p r e s e n t e d i n T a b l e 3. P l o t s w h i c h f e l l i n t o g r o u p s by v i r t u e o f b e i n g h i g h l y c o r r e l a t e d (r>.90, s i g n i f i c a n t a t a = .01) were: Downtown-F a l s e C r e e k (DT, F C ) , Queen E l i z a b e t h - M a c K e n z i e - C o l l i n g w o o d (QE, MK, CW), and C o l l i n g w o o d - S h a u g h n e s s y (CW, SH). Many h a b i t a t f e a t u r e s were h i g h l y c o r r e l a t e d ( A p p e n d i x 4 ) . T h e r e f o r e t h e h a b i t a t f e a t u r e s have been p l a c e d i n t o g r o u p s o f h i g h l y c o r r e l a t e d f e a t u r e s ( T a b l e 4) and e a c h p l o t d e s c r i b e d by t h e t o t a l c o v e r o f t h e s e g r o u p s ( T a b l e 5 ) . Thus t h e g r a d i e n t o f u r b a n i z a t i o n c an be d e s c r i b e d i n terms o f 3 gro u p s o f i n d e p e n d e n t l y v a r y i n g h a b i t a t f e a t u r e s . The h i g h l y u r b a n p l o t s , DT and FC, h a d v e r y l i t t l e t r e e and T a b l e 2 : D e s c r i p t i o n o f P l o t s : C o v e r b y H a b i t a t F e a t u r e s % C o v e r H a b i t a t P l o t F e a t u r e s * DT ' FC ' WE QE MK CW SH UB S L A N T 2 •7 2 2 2 9 20 0 22 1 22 9 14 4 0 . 0 F L A T 35 1 4 3 4 3 3 3 0 0 0 0 0 0 0 5 0 0 ROAD 15 0 19 7 1 3 4 11 7 14 6 8 8 10 4 0 . 0 L A N E 4 8 4 1 8 0 4 6 4 2 5 1 3 0 0 . 0 PVT+S 40 2 27 1 1 3 8 6 8 6 7 7 7 8 2 0 . 0 LAWN 0 9 1 9 26 8 53 3 48 3 43 8 51 1 0 . 0 D<7. S 0 8 0 2 0 9 3 5 3 7 8 2 10 9 1 2 . 2 D>7. 5 0 1 0 5 2 4 0 6 0 0 8 3 8 5 5 2 . 1 C<7 . 5 0 0 0 0 1 7 1 2 1 0 2 6 3 3 4 . 3 C > 7 . 5 0 0 0 0 0 3 0 2 0 4 1 1 2 6 • 1 8 . 4 DBEVG 0 0 0 0 0 1 0 0 0 0 0 0 1 6 0 . 0 D<1 . 5 0 0 0 0 0 1 0 0 0 0 0 0 0 6 0 . 0 D>1 . 5 0 0 0 0 0 2 0 3 0 4 0 5 0 3 2 9 . 9 C < 1 . 5 0 1 0 1 0 3 0 4 0 1 0 3 0 3 2 . 6 C > 1 . 5 0 0 0 0 0 2 0 6 0 3 0 3 0 3 1 . 3 E < 1 . 5 . 0 1 0 . 0 0 . 1 0 . 2 0 . 3 0 3 0 3 1 2 . 2 E > 1 . 5 0 . 0 0 . 1 0 . 1 0 . 1 0 . 1 0 4 1 0 6 . 4 HERB 0 . 3 1. 1 0 . 8 0 . 6 2 . 2 3 3 2 6 0 . 0 WEED 0 3 0 4 0 6 0 0 0 5 0 4 0 8 31 . 9 T o t a l C o v e r 1 0 0 . 4 1 0 1 . 3 1 0 6 . 1 1 0 6 . 3 1 0 6 . 0 1 1 5 3 1 2 1 7 1 8 7 . 1 T o t a l V e g e t a -t i o n C o v e r 2 . 6 4 . 3 3 4 . 6 6 2 . 0 5 7 . 3 6 9 . 5 8 4 . 2 1 8 7 . 1 A r e a s a m p l e d b y ' O n - S i t e M e t h o d 1 0 0 1 1 0 0 % .26% " 2 7% 2 5 % .32% 3 3 % 0 . 3 % * F o r m e a n i n g o f a b b r e v i a t i o n s s e e T a b l e 1 , p g . 1 5 . 26. T a b l e 3: C o r r e l a t i o n s among P l o t s w i t h R e s p e c t t o H a b i t a t F e a t u r e s C o r r e l a t i o n C o e f f i c i e n t ( r ) P l o t s DT FC WE QE MK CW SH UB DT .95 .54 - . 31 - . 32 - .44 - . 40 - .46 FC .68 - .27 - .28 - .40 - . 36 -.42 WE - .40 . 37 . 26 . 33 - .43 QE - .99 .93 ,89 - . 27 MK . 93 . 87 -.29. CW - . 9.7 - .20 SH - .09 UB S i g n i f i c a n c e L e v e l : a= .01; r= 0.575 27. T a b l e 4: Groups o f C o r r e l a t e d H a b i t a t C h a r a c t e r i s t i c s B a s e d on c o r r e l a t i o n s s i g n i f i c a n t a t a = .01, e x c e p t where i n d i c a t e d by *, where a = .05. Groups have been s u b d i v i d e d where n e c e s s a r y t o i n d i c a t e r e l a t i o n s h i p s w h i c h were margin-a l l y s i g n i f i c a n t . Group 1 a) ROAD, LANE B) PVT+S*, FLAT* Group 2 : SLANT, LAWN, HERB FOOD Group 3 a) D<7.5, C<7.5 FHD1, HFD2, FHD3, TOTVEG, HFD b) D>7.5, C>7.5, D<1.5, D>1.5, D<1.5, D>1.5, E<1.5, E> 1.5, WEED, TDD, TDC see T a b l e 1, pg. 15 f o r meaning o f a b b r e v i a t i o n s . 28. T a b l e 5: Summary D e s c r i p t i o n o f H a b i t a t T o t a l P e r c e n t C o v e r by H a b i t a t Groups o f H a b i t a t F e a t u r e s * 1(a) 1(b) 2 3(a) 3(b) C o m m e r c i a l , I n d u s t r i a l . (DT, FC) 221 71% 5% 1% 1% A p a r t m e n t (WE) 21% 47% 31% 3% 4% T y p i c a l R e s i d e n t i a l (QE, MK) 18% 7% 74% 5% 2% O l d e r R e s i d e n t i a l (CW) 14% 8% 70% 11% 12% 'Woody' R e s i d e n t i a l (SH) 13% 9% 68% 14% 15% Woodland (UB) 0% 0% 0% 17% 171% B a s e d on c o r r e l a t i o n s between h a b i t a t f e a t u r e s when a l l 8 p l o t s a r e i n c l u d e d ( see T a b l e 4) • * L e g e n d 1) t y p i c a l l y u r b a n f e a t u r e s 2) t y p i c a l l y s u b u r b a n f e a t u r e s 3) t y p i c a l l y w o o d l a n d f e a t u r e s s h r u b c o v e r ; o v e r 90% o f t h e a r e a i n t h e s e p l o t s was cov-e r e d by pavement and f l a t - r o o f e d b u i l d i n g s . The WE p l o t a l s o h a d a h i g h c o v e r ( a b o u t 70%) o f t h e s e f e a t u r e s , w i t h many h i g h - r i s e a p a r t m e n t b u i l d i n g s . A r e a c o v e r e d by t r e e s and s h r u b s i n WE was about 7% and t y p i c a l l y s u b u r b a n f e a -t u r e s ( s l a n t - r o o f e d b u i l d i n g s , l a w n s , g a r d e n s ) a c c o u n t e d f o r 30% o f t h e t o t a l c o v e r . QE and MK p l o t s were c o v e r e d p r i m a r i l y by t h e l a t t e r f e a t u r e s , as were CW and SH. The f o r m e r were more t y p i c a l o f s u b u r b a n h a b i t a t s i n V a n c o u v e r w i t h c o v e r by w o o d l a n d f e a t u r e s ( s h r u b s , d e c i d u o u s and con-i f e r o u s t r e e s , weeds) b e i n g u n d e r 10%. CW was an o l d e r sub-^ u r b a n a r e a w i t h o v e r 20% c o v e r by w o o d l a n d f e a t u r e s , w h i l e SH was even more 'woody' w i t h a b o u t 30% c o v e r by t h e s e . Lawns were most e x t e n s i v e i n QE and SH, c o v e r i n g a b o u t 50% o f t h e a r e a . The h i g h e s t p e r c e n t c o v e r by h o u s e s was f o u n d i n MK and CW. The h a b i t a t s t r u c t u r e o f t h e p l o t s was a l s o d e s c r i b e d i n terms o f t h e d i v e r s i t y o f l a y e r s o f v e g e t a t i o n and t y p e s o f s t r u c t u r e s ( f o l i a g e h e i g h t d i v e r s i t y , and h a b i t a t f e a t u r e d i v e r s i t y i n d i c e s , T a b l e 6 ) . The r e l a t i o n s h i p between t h e s e i n d i c e s and v a r i o u s h a b i t a t f e a t u r e s i s shown i n A p p e n d i x 4. F o l i a g e h e i g h t d i v e r s i t y (FHD) f o l l o w e d t h e g r a d i e n t o f t o t a l v e g e t a t i o n c o v e r , w i t h t h e l o w e s t FHD i n h i g h l y u r b a n p l o t s and t h e h i g h e s t FHD i n w o o d l a n d , a p a r t m e n t and t y p i c a l r e s i d e n t i a l p l o t s were q u i t e s i m i l a r w i t h r e s p e c t t o FHD, as 30. T a b l e 6: Measures o f H a b i t a t D i v e r s i t y Index P l o t FHD1 FHD2 FHD3 HFD DT 0.12 0.14 0.91 1.77 FC 0 .18 0.21 1. 00 1.53 WE 0. 55 0.65 1.47 1. 88 QE 0.59 0.70 1. 34 1.67 MK 0 . 59 0. 69 1. 38 1.67 CW 0. 77 1.02 1. 66 1.97 SH 0. 79 1. 04 1.63 2 .12 UB 1.03 1.49 1. 49 2 . 04 H a b i t a t D i v e r s i t y = - E p . l o g p. ; p^ i s t h e p r o p o r t i o n o f t h e i * " * 1 h a b i t a t f e a t u r e . D e s c r i p t i o n o f I n d i c e s FHD1: 3 l a y e r s . t r e e s , s h r u b s , LAWN § g a r d e n s FHD2: 6 l a y e r s . t a l l t r e e s , s h o r t t r e e s , t a l l s h r u b s , s h o r t s h r u b s , LAWN, g a r d e n s FHD3: 9 l a y e r s . f l a t - r o o f e d b u i l d i n g s , s l a n t -r o o f e d b u i l d i n g s , pavement, p l u s t h o s e i n FHD2 . HFD: 19 l a y e r s . A l l h a b i t a t f e a t u r e s as p e r T a b l e 2. 31. were o l d and woody r e s i d e n t i a l p l o t s . H a b i t a t f e a t u r e d i v -e r s i t y was l o w e s t i n i n d u s t r i a l and h i g h e s t i n woody r e s i d e n -t i a l p l o t s ; i t d i d n o t p a r a l l e l t h e u r b a n i z a t i o n ( o r p e r c e n t v e g e t a t i o n c o v e r ) g r a d i e n t . A n o t h e r means o f d i s t i n g u i s h i n g h a b i t a t s , b u t one n o t d i r e c t l y r e l a t e d t o h a b i t a t a p p e a r a n c e , was t h e amount o f f o o d p r o v i d e d by man. The r e s u l t s o f t h e q u e s t i o n n a i r e w h i c h p r o v i d e d t h i s i n f o r m a t i o n a r e summarized i n T a b l e 7. I n o r d e r t o o b t a i n a c o n s e r v a t i v e e s t i m a t e o f t h e amount o f f o o d p r o v i d e d by p e o p l e from t h e s e r e s u l t s , i t was assumed t h a t p e o p l e who f a i l e d t o r e t u r n t h e q u e s t i o n n a i r e d i d n o t f e e d b i r d s t o any s i g n i f i c a n t e x t e n t . T h i s a s s u m p t i o n i s r e a s o n a b l e i n t h i s c a s e s i n c e t h e r a t e o f q u e s t i o n n a i r e r e -t u r n s was v e r y h i g h ( T a b l e 7 ) . T h e r e f o r e t h e amount o f f o o d p u t o u t f o r b i r d s i n t h e a p a r t m e n t p l o t (WE) was p r o b a b l y u n d e r e s t i m a t e d t o a g r e a t e r d e g r e e , s i n c e a v e r y s m a l l p o r - 1 t i o n ( a b o u t l / 1 2 t h ) o f t h e h o u s e h o l d s i n t h i s a r e a r e c e i v e d forms. F i g u r e s f o r t h e c o m m e r c i a l and i n d u s t r i a l a r e a s (DT, FC) were b a s e d on f i e l d n o t e s . I t i s assumed t h a t t h e amount o f f o o d p r o v i d e d u n i n t e n t i o n a l l y , and p e r h a p s o u t s i d e t h e s t u d y a r e a s , was a more s i g n i f i c a n t s o u r c e o f f o o d f o r b i r d s i n c o m m e r c i a l and i n d u s t r i a l p l o t s ( a n d p e r h a p s a p a r t -ment) t h a n t h a t p r o v i d e d i n t e n t i o n a l l y w i t h i n t h e p l o t s . The b i o m a s s o f f o o d r e q u i r e d by b i r d s i n e a c h p l o t has b e e n r o u g h l y e s t i m a t e d u s i n g f i g u r e s f r o m Emlen (1974) f ° r T a b l e 7: Q u e s t i o n n a i r e R e s u l t s • A B C D E. # F o r m s % R e t u r n e d % o f A t h a t * A m o u n t o f F o o d I o f D w h i c h i s P l o t D i s t r i b u t e d F e e d B i r d s F e d i n W i n t e r n o t F e d a t o t h e r S e a s o n s DT 0 - - ( e s t i m a t e d ) 1 ( e s t i m a t e d ) 0 F C 0 - • - ( e s t i m a t e d ) .1 ( e s t i m a t e d ) 0 WE 100 20 11 40 0 QE 72 39 29 • 81 12 MK 1 4 6 50 36 3 45 8 CW 1 2 8 55 33 87 8 SH 40 55 38 . 7 5 23 UB 0 - - ( e s t i m a t e d ) 0 ( e s t i m a t e d ) 0 * A l l a m o u n t s o f f o o d p r e s e n t e d a s k g / 4 0 h / m o n t h . T a b l e 7 ( c o n t i n u e d ) N u m b e r o f r e t u r n s i n W h i c h t h e f o l l o w i n g s p e c i e s w e r e c i t e d b y r e s i d e n t s a s v i s i t o r s a t t h e i r f e e d e r s . S p e c i e s ( s e e T a b l e 9 ) P l o t CP S HS H F A R GWG NWC BCC O J R S F BB WE 1 1 . 6 0 3 1 1 0 3 0 0 QE 1 15 1 3 2 7 7 1 5 2 0 0 MK 4 40 39 6 22 12 14 7 4 3 3 CW 3 19 20 1 17 1 5 1 3 ' 5 5 0 SI I 1 4 9 4 4 3 1 5 4 2 0 T o t a l 10 79 87 13 53 24 28 30 18 10 3 the b i r d biomass/density r a t i o and the rate of food con-sumption (Table 8). These calculations indicate that since i n one case much more food is provided than birds are consuming, that b i r d biomass and consumption have l i k e l y been underestimated using these figures. Never-theless the food provided by man i s substantial i n r e l a -tion to the t o t a l amounts required by birds in the sub-urban pl o t s . Those species which were most commonly fed by people were sparrows (mostly House Sparrows presumably; Passer  domesticus), the S t a r l i n g (Sturnus v u l g a r i s ) , American Robin (Turdus migratorius), Black-capped Chickadee CP arus  a t r i c a p i l l u s ) , Dark-eyed Junco (Junco hyemalis), North-western Crow (Corvus caurinus), and Glaucous-winged Gull (Larus glaucescens) (Table 7). In a l l r e s i d e n t i a l habitats these birds comprised over 50% of the b i r d density year-round (Table 12). V i r t u a l l y a l l b i r d species encountered in the urban plots were c i t e d by residents as having used feeders, but I f e e l that except for some of those l i s t e d above, this could not have contributed s i g n i f i c a n t l y to these species' diets except during times of food shortage. Other species were infrequently seen by residents at t h e i r feeders. 35. T a b l e 8: E s t i m a t i o n o f Food B i o m a s s R e q u i r e m e n t s o f B i r d C o m m u n i t i e s i n W i n t e r I o f Food R e q u i r e -ments p r o v i d e d a t P l o t Food R e q u i r e m e n t s F e e d e r s WE 191 16 QE 67 91 MK 168 158 CW 103 63 SH 162 35 * Food R e q u i r e d = k g o f b i r d s / 4 0 h x 0.25 k g / d a y x 30 days/mo, x .25 ( . c o r r e c t i o n f a c t o r f o r f o o d w a s t e ) k g o f b i r d s = X2To\irds X b i r d d e n s i t y ( f r o m E m l e n , 1974) 36. B i r d C e n s u s e s A t o t a l o f 282 c e n s u s e s were made d u r i n g t h e c o u r s e o f one y e a r , a m o u n t i n g t o some 250 h o u r s o f o b s e r v a t i o n . E s t -i m a t e s o f t h e mean d e n s i t i e s o f e a c h s p e c i e s r e s u l t i n g f r o m t h e s e c e n s u s e s a r e p r e s e n t e d i n A p p e n d i x 4. E s t i m a t e s o f mean t o t a l b i r d d e n s i t y v a r i e d f r o m 130 p e r 40h i n i n d u s t r i a l h a b i t a t t o 525 p e r 40h i n a p a r t m e n t ( F i g u r e 3 ) . The a v e r a g e number o f b i r d s p e c i e s was l o w e s t (4) i n i n d u s t r i a l h a b i t a t and h i g h e s t (10.5) i n woody r e s i d e n t i a l ( T a b l e 1 1 ) . S i x t y - t w o s p e c i e s were e n c o u n t e r e d d u r i n g t h e s t u d y ( T a b l e 9 ) , a l t h o u g h s e v e n t y - f i v e p e r c e n t o f t h e s e were r e l a t i v e l y r a r e a t c e r t a i n t i m e s o f t h e y e a r , b e c a u s e o f , f o r example, m i g r a t o r y b e h a v i o u r . P r e s e n c e / a b s e n c e o f t h e most abundant t r a n s i e n t s p e c i e s was u s e d t o d e l i m i t d a t e s o f S p r i n g and F a l l m i g r a t i o n . Those s p e c i e s w h i c h most s t r o n g l y i n f l u e n c e d t h e s e d a t e s were the W i l s o n ' s W a r b l e r Qfi.%1sonia  p u s i l l a ) , Song S p a r r o w ( M e l o s p i z a m e l o d i a ) , G o l d e n - c r o w n e d K i n g l e t ( R e g u l u s s a t r a p a ) , D a r k - e y e d J u n c o , V i o l e t - g r e e n s w a l l o w ( T a c h y c i n e t a t h a i a s s i n a ) , B a r n Swallow ( H i r u n d o . , r u s t i c a ) , Rufous Hummingbird ( S e l a s p h o r u s r u f u s ) , and W h i t e -crowned Sparrow (Z o n o t r i c h ! a l e u c o p h r y s ) . L a r g e p u l s e s o f t h e s e s p e c i e s were o b s e r v e d e i t h e r i n S p r i n g o r F a l l (Appen-d i x 4) . The l e n g t h s o f t h e v a r i o u s s e a s o n s a r e g i v e n i n T a b l e 10 The d a t e s u s e d t o d e l i m i t s e a s o n s were compared w i t h p u b l i s h e 37. Figure 3: Mean t o t a l b i r d density in each plot versus t o t a l percent vegetation cover. Only b i r d densities for Summer and Winter seasons have been graphed. T a b l e 9.: L i s t o f B i r d S p e c i e s No. Code Common Name S c i e n t i f i c Name 1 CP Common P i g e o n Columba l i v i a 2 S S t a r l i n g S t u r n u s v u l g a r i s 3 CM C r e s t e d Mynah A c r i d o t h e r e s c r i s t a t e l l u s 4 HS House Sparrow P a s s e r d o m e s t i c u s 5 GWG G l a u c o u s - w i n g e d G u l l L a r u s g l a u c e s c e n s 6 HF House F i n c h C a r p o d i c u s m e x i c a n u s 7 AR A m e r i c a n R o b i n T u r d u s m i g r a t o r i u s 8 SSP Song Sparrow M e l o s p i z a m e l o d i a 9 OJ D a r k - e y e d (Oregon) J u n c o J u n c o h y e m a l i s 10 BCC B l a c k - c a p p e d C h i c k a d e e P a r u s a t r i c a p i l l u s 11 RST R u f o u s - s i d e d Towhee P i p i l o e r y t h r o p t h a l m u s 12 NWC N o r t h w e s t e r n Crow Cor v u s c a u r i n u s 13 BB Br e w e r ' s B l a c k b i r d Euphagus c y a n o c e p h a l u s 14 VT V a r i e d T h r u s h I x o r e u s n a e v i u s 15 RSF Common F l i c k e r C o l a p t e s a u r a t u s 16 VGS V i o l e t - g r e e n Swallow T a c h y c i n e t a t h a l a s s i n a 17 GCK G o l d e n - c r o w n e d K i n g l e t R e g u l u s s a t r a p a 18 WW W i n t e r Wren T r o g l o d y t e s t r o g l o d y t e s 19 S'J S t e l l e r ' s J a y C y a n o c i t t a s t e l l e r i 20 EG E v e n i n g G r o s b e a k H e s p e r i p h o n a v e s p e r t i n a 21 RG R u f f e d Grouse B a n a s a u m b e l l u s 22 BW Be w i c k ' s Wren Thrysomanes b e w i c k i i 23 HWK u n i d e n t i f i e d hawks A c c i p i t e r spp. 24 RCX Ruby-crowned K i n g l e t R e g u l u s c a l e n d u l a 40. T a b l e '9 ( c o n t i n u e d ) Njo. Code Common Name S c i e n t i f i c Name 25 RH Rufous Hummingbird S e l a s p h o r u s r u f u s 26 WCS W h i t e - c r o w n e d Sparrow Z o n o t r i c h i a l e u c o p h r y s 27 AW Y e l l o w - r u m p e d W a r b l e r D e n d r o i c a c o r o n a t a 28 BS B a r n Swallow H i r u n d o . r u s t i c a 29 CBC C h e s n u t - b a c k e d C h i c k a d e e P a r u s r u f e s c e n s 30 TW Townsend's W a r b l e r D e n d r o i c a t o w n s e n d i 31 AG A m e r i c a n G o l d f i n c h S p i n u s t r i s t i s 32 BHC Brown-headed C o w b i r d M o l o t h r u s a t e r 33 GCS G o l d e n - c r o w n e d Sparrow Z o n o t r i c h i a a t r i c a p i l l a 34 WWA W i l s o n ' s W a r b l e r W i l s o n i a p u s i l l a 35 MGW M a c G i l l i v r a y ' s W a r b l e r O p o r o r n i s t o l m i e i 36 YW Y e l l o w W a r b l e r - D e n d r o i c a p e t e c h i a 37 OCW Orange- crowned W a r b l e r V e r m i v o r a c e l a t a 38 OSF O l i v e - s i d e d F l y c a t c h e r N u t t a l l o r n i s b o r e a l i s 39 WT W e s t e r n T a n a g e r P i r a n g a l u d o v i c i a n a 40 WV W a r b l i n g V i r e o V i r e o g i l v u s 41 PSK P i n e S i s k i n S p i n u s p i n u s 42 SVS Savannah Sparrow P a s s e r c u l u s s a n d w i c h e n s i s 43 FS Fox Sparrow P a s s e r e l l a i l i a c a 44 FC u n i d e n t i f i e d f l y c a t c h e r s E p i d o n a x spp. 45 BHG B l a c k - h e a d e d G r o s b e a k P h e u c t i c u s m e l a n o c e p h a l u s 46 BTP B a n d - t a i l e d P i g e o n Columba f a s c i a t e 47 ST S w a i n s o n ' s T h r u s h C a t h a r u s u s t u l a t u s 48 REV Red-eyed V i r e o V i r e o o l i v a c e u s 49 V u n i d e n t i f i e d v i r e o s V i r e o spp. 41. T a b l e 9 ( c o n t i n u e d ) No. Code Common Name S c i e n t i f i c Name 50 DW Downy W o o d p e c k e r . D e n d r o c o p o s p u b e s c e n s 51 PF P u r p l e F i n c h C a r p o d a c u s purpure.us 52 WF W e s t e r n F l y c a t c h e r Epi-donax . d i f f i c i l i s ' . 53 GHO G r e a t H o r n e d Owl Bubo v i r g i n i a n u s 54 PM . P u r p l e M a r t i n P r o g n e s u b i s 55 CN Common Ni'ghthawk C l i o r d e i l e s ' m i n o r 56 PW. P i l e a t e d W o o d p e c k e r D r y o c o p u s p i l e a t u s 5 7 RBN R e d - b r e a s t e d N u t h a t c h S i t t a c a n a d e n s i s 59 W u n i d e n t i f i e d w a r b l e r s D e n d r o i c a s p p . 60 NT H e r m i t T h r u s h C a t h a r u s g u t t a t u s 61 CWX C e d a r Waxwing B o m b y c i l l a c e d r o r u m 62 CS Common S n i p e C a p e l l a g a l l i n a g o R e f e r e n c e : A m e r i c a n O r n i t h o l o g i s t s ' U n i o n , 1957. and 197,3. Table 10: Seasons: S p r i n g : Summer : F a l l : Winter : S p r i n g M i g r a t i o n Dark-eyed Junco : Song Sparrow : V i o l e t - g r e e n Swallow : Barn Swallow : White - crowned Sparrow : Warbler s p e c i e s : F a l l M i g r a t i o n Dark-eyed Junco : Song Sparrow : V i o l e t - g r e e n Swallow : Barn Swallow : White-crowned Sparrow : Warbler s p e c i e s : Dates o f A r r i v a l and Departure of Some Species A p r i l 11 - May 31 • June 1 - August 2 5 August 26 - October 21 October 22 - A p r i l 10 disappeared from p l o t s between March 19 and A p r i l 8 disappeared from p l o t s between A p r i l 10 and A p r i l 22 appeared i n p l o t s from May'/' to May! 18 appeared i n p l o t s from May 7 to May 20 appeared i n p l o t s from A p r i l 20 to May 10 appeared i n p l o t s from A p r i l 20 disappeared from p l o t s by May 30 appeared i n r e s i d e n t i a l p l o t s between Sept. appeared i n r e s i d e n t i a l p l o t s between Sept. disappeared by August 5 disappeared by Sept. 13 disappeared by Oct. 6. appeared by August 29 disappeared by October 21 14 and Oct. 3 and Oct. 43. Table 11: Summary of Bird Census Results SPRING Plot Bird Species Diversity CH'D Cumulative Number of Species Mean Number of Species Evenness Mean Total Bird Density DT 1.05 6 4.57 0. 59 390. 0 FC 1.25 7 4. 33 0. 64 140. 3 WE 1. 72 12 7.67 0. 69 583.2 QE 1.32 12 6.50 0. 73 178.3 MK 1.62 16 7.63 0.58 391. 0 CW 1.93 24 8. 56 0.61 366. 5 SH 2 .10 23 12.17 0.67 380. 3 UB 2.57 23 12. 00 0.82 260.4 SUMMER DT 1.11 7 5.25 0.57 393. 8 FC 0. 89 8 3. 38 0.43 151.6 WE 1. 72 10 6. 50 0 . 75 - 468.8 QE 1. 51 14 5. 90 0.57 16 8. 4 MK 1. 30 13 6.25 0. 51 411. 5 CW 1. 74 13 6. 31 0.68 253. 7 SH 1.99 17 9. 09 0 . 70 396. 8 UB 2. 62 22 10.11 0.73 211. 5 44. T a b l e 11 ( c o n t i n u e d ) FALL B i r d C u m u l a t i v e Mean Mean S p e c i e s Number o f Number o f T o t a l B i r d P l o t D i v e r s i t y S p e c i e s ? S p e c i e s E v e n n e s s D e n s i t y c m DT 0. 84 5 4.17 0. 52 435.0 FC 1.16 8 3.80 0.56 111. 3 WE 1.63 12 7. 40 0. 66 481. 4 QE 2. 09 18 7.80 0. 72 173.6 MK 1. 72 2 0 6.57 0. 57 329. 2 CW 2.20 21 8.83 0. 72 339. 2 SH 2.27 25 11. 14 0 . 70 472. 3 UB 1. 88 17 8. 00 0. 66 434. 8 WINTER DT 1.00 5 4.03 0.62 400. 0 FC 1. 34 8 4. 36 0. 64 114. 8 WE 1. 74 12 7.62 0 . 70 567.9 QE 1. 74 12 6.67 0. 70 190.9 MK 1. 73 15 8.17 0.64 470 . 9 CW 1.92 17 7. 70 0.68 366,5 SH 2.15 19 10. 00 0. 73 342. 2 UB 2. 03 18 8.67 0. 70 477.1 45. Table 12: Numerically Dominant-Bird Species Proportions of t o t a l b i r d density for the three most abundant species i n each pl o t Season — — Mean Plot Spring Summer F a l l Winter T o t a l DT CP .63 CP . 64 CP .75 CP .66 S -.20 S . 16 S . 11 S . 15 HS . 13 HS .13 HS .09 HS .13 .96 .93 .95 .94 CP .52 CP . 75 S . 31 S . 11 HS . 09 HS . 09 .92 . 95 CP . 53 CP . 50 S .33 S .28 HS . 08 HS . 08 . 94 . 86 S . 34 CP . 31 S . 31 S . 34 CP . 26 HS . 24 CP .27 CP .25 HS . 14 S .22 HS .25 HS . 19 . 74 . 77 . 83 . 78 QE S .32 S .49 S .38 S .44 HS .23 HS .25 HS .17 HS .22 AR .20 AR _^12 WWA ^09 OJ _^ 08 TT5 .86 .64 .74 .75 MK S .35 S .43 S .42 S .44 HS .35 HS. .41 HS .32 HS .26 AR _^12 AR JL07 AR _^07 AR :L07_ .82 .91 .81 .77 .82 CW s . 37 S . 35 S . 34 S .41 AR . 18 AR .21 HS .15 OJ . 13 WWA . 14 HS .19 AR . 10 HS .13 .69 .75 • . 59 .67 SH S . 36 AR .25 AR .30 S . 26 AR . 20 S .25 S . 20 OJ .21 WWA .12 HF . 13 HS . 09 AR . 14 .68 .63 . 59 .61 UB WW .17 BCC .33 BCC .40 GCK .27 BCC .15 WW .15 WWA .20 BCC .26 AR .13 RST .11 GCK ^K> PSK ^L5 .45 .59 .70 .68 .61 See Table 9 for meaning of species' abbreviations. m i g r a t i o n d a t e s f o r v a r i o u s s p e c i e s i n t h e V a n c o u v e r a r e a ( C a m p b e l l e t a l . , 1974) and g e n e r a l l y f o u n d i n a c c o r d a n c e . I b e l i e v e t h a t t h e d i v i s i o n o f t h e d a t a i n t o s e a s o n s may be j u s t i f i e d on t h e grounds t h a t t h e r e i s v a r i a t i o n i n t h e b i r d c o m m u n i t i e s w i t h s e a s o n t h a t s h o u l d n o t be i g n o r e d , D e s p i t e t h e d i v i s i o n o f c e n s u s d a t a i n t o s e a s o n s , t h e r e was c o n s i d e r a b l e f l u c t u a t i o n w i t h i n e a c h s e a s o n i n t h e e s t -i m a t e s o f t o t a l b i r d d e n s i t y i n e a c h a r e a ( f o r e x a m p l e s , see F i g u r e s 4, 5, 6, and 7 ) . Some o f t h i s v a r i a t i o n i s undoubt-e d l y a t t r i b u t a b l e t o s a m p l i n g e r r o r , b u t o t h e r f a c t o r s s u c h as f l o c k i n g b e h a v i o u r a r e a l s o i n v o l v e d . I t i s c l e a r f r o m t h e s e F i g u r e s t h a t f l u c t u a t i o n c e n t e r e d a r o u n d a mean v a l u e f o r e a c h p l o t , w i t h i n s e a s o n s . The mean v a l u e s were s i m i l a r f o r d i f f e r e n t p l o t s i n some c a s e s ( T a b l e 1 1 ) . I n o t h e r c a s e s , t h e e s t i m a t e s o f mean d e n s i t y d i f f e r e d n o t i c a b l y between sim -i l a r h a b i t a t s . F o r example, d e n s i t y o f b i r d s i n c o m m e r c i a l h a b i t a t was a p p r o x i m a t e l y t h r e e t i m e s g r e a t e r on t h e a v e r a g e t h a n i n i n d u s t r i a l h a b i t a t ( T a b l e 11, F i g u r e s 4 and 5 ) . S i m i l a r l y , t h e e s t i m a t e o f t o t a l b i r d d e n s i t y i n t h e MacKen-z i e p l o t was a p p r o x i m a t e l y t h r e e t i m e s t h a t i n Queen E l i z a b e t h ( F i g u r e s ' 6 and 7 ) . These c o m p a r i s o n s i n d i c a t e t h a t l a r g e d i f f e r e n c e s i n t o t a l d e n s i t y between p l o t s a r e p r o b a b l y r e a l , b u t t h a t s m a l l d i f f e r e n c e s between e s t i m a t e d means f o r some p l o t s may n o t be s i g n i f i c a n t , owing t o t h e v a r i a b i l i t y between c o u n t s . S m a l l d i f f e r e n c e s between p l o t s o r s e a s o n s w i l l h o t 47. F i g u r e 4: F l u c t u a t i o n between counts o f t o t a l b i r d d e n s i t y and number o f s p e c i e s p e r sample i n the Downtown (commercial) p l o t . F i g u r e 5: F l u c t u a t i o n between counts o f t o t a l b i r d d e n s i t y and number o f s p e c i e s p e r sample i n the F a l s e Creek ( i n d u s t r i a l ) p l o t -48. FIGURE 4 49. F i g u r e 6: F l u c t u a t i o n between counts o f t o t a l b i r d d e n s i t y and number o f s p e c i e s p e r sample i n the MacKenzie ( " t y p i c a l r e s i d e n t i a l " ) p l o t . F i g u r e 7: F l u c t u a t i o n between counts o f t o t a l b i r d d e n s i t y and number o f s p e c i e s p e r sample i n the Queen E l i z a b e t h ( " t y p i c a l r e s i d e n t i a l " ) p l o t . 50. FIGURE 6 "j " F~" M ' A M J . J A S 0 N D J 1975 D.ATE F IGURE 7 be d i s c u s s e d . A n a l y s i s o f v a r i a n c e r e s u l t s i n d i c a t e d t h a t o v e r a l l , t h e r e were s i g n i f i c a n t d i f f e r e n c e s between p l o t s and s e a s o n s i n mean t o t a l d e n s i t y . M u l t i p l e r a n g e t e s t s i n d i c a t e d w h i c h p l o t s and s e a s o n s were s i g n i f i c a n t l y s i m i l a r and w h i c h ones w e r e n ' t ( A p p e n d i x 5a). S i n c e e s t i m a t e s o f numbers o f s p e c i e s and r e l a t i v e abundances o f d i f f e r e n t s p e c i e s w i t h i n p l o t s were r e a s o n a b l y c o n s i s t e n t , I b e l i e v e t h a t e s t i m a t e s o f t h e s e can be m e a n i n g f u l l y compared. The c e n s u s r e s u l t s a r e summarized i n T a b l e 11. E s t i m a -t e d mean t o t a l d e n s i t y , mean number and t o t a l number o f s p e c i e s , as w e l l as b i r d s p e c i e s d i v e r s i t y and e v e n n e s s a r e g i v e n f o r e a c h p l o t and s e a s o n . B i r d s p e c i e s d i v e r s i t y was h i g h e s t i n S p r i n g , l o w e r and much t h e same t h r o u g h Summer, F a l l , and W i n t e r ( T a b l e 1 1 ) . I t was l o w e s t i n t h e p l o t s w i t h t h e l e a s t v e g e t a t i o n c o v e r ( c o m m e r c i a l , i n d u s t r i a l ) and h i g h e s t i n t h o s e w i t h t h e most v e g e t a t i o n c o v e r (woody r e s i d e n t i a l , w o o d l a n d ) ; t h u s b i r d s p e c i e s d i v e r s i t y d e c r e a s e d w i t h u r b a n i z a t i o n . Number o f s p e c i e s a l s o d e c r e a s e d w i t h u r b a n i z a t i o n , t h o u g h t h e h i g h e s t number was f o u n d i n wooded r e s i d e n t i a l a r e a s r a t h e r t h a n i n w o o d l a n d i n some s e a s o n s . In most p l o t t h e h i g h e s t number o f s p e c i e s was f o u n d i n S p r i n g , w h i l e num b e r s i n Summer, F a l l , and W i n t e r a l l were s i m i l a r and l o w e r . Number o f s p e c i e s f l u c t u a t e d l e s s between s e a s o n s i n com-m e r c i a l , i n d u s t r i a l , and a p a r t m e n t p l o t s t h a n i n a r e a s w i t h 52. g r e a t e r v e g e t a t i o n cover. The evenness of b i r d s p e c i e s ' abundances decreased s l i g h t l y w i t h u r b a n i z a t i o n . Seasonal changes were not pro-nounced except i n i n d u s t r i a l , o l d e r r e s i d e n t i a l , and wood-land p l o t s . T o t a l b i r d d e n s i t y was not r e l a t e d to the amount of v e g e t a t i o n cover ( u r b a n i z a t i o n ) . For example, i n F a l l the d e n s i t y of b i r d s was estimated to be approximately the same i n commercial and woodland p l o t s . There was a general sea-sonal change i n t o t a l b i r d d e n s i t y , w i t h lowest d e n s i t i e s i n Summer, int e r m e d i a t e d e n s i t i e s i n Spring and F a l l , and high-est d e n s i t i e s i n Winter. However seasonal changes may have been n e g l i g i b l e i n commercial, i n d u s t r i a l , and t y p i c a l r e s -i d e n t i a l (Queen E l i z a b e t h ) p l o t s (Table 11, Appendix 5a). A small number o f s p e c i e s were n u m e r i c a l l y dominant i n the urban and suburban h a b i t a t throughout the year: the Domestic Pigeon, S t a r l i n g , House Sparrow, and American Robin. These s p e c i e s are omnivores, feed p r i m a r i l y on the ground, and the f i r s t three nest e x t e n s i v e l y on or w i t h i n b u i l d i n g s (Weber, 1972). The three species which were most abundant i n each p l o t are l i s t e d i n Table 12 along with estimates of t h e i r d e n s i t i e s as a p r o p o r t i o n o f the mean t o t a l b i r d den-s i t y i n each p l o t . In summary, the abundance of each b i r d s p e c i e s on e i g h t study p l o t s was surveyed f o r one year. Survey r e s u l t s were 53. d i v i d e d i n t o s e a s o n s , and t h e d i f f e r e n c e s between s e a s o n s and p l o t s w i t h r e s p e c t t o t o t a l b i r d d e n s i t y , b i r d s p e c i e s d i v e r s i t y , e v e n n e s s , and numbers o f s p e c i e s were examined. T r e n d s between p l o t s i n b i r d s p e c i e s d i v e r s i t y and s p e c i e s numbers may be r e l a t e d t o t h e amount o f v e g e t a t i o n c o v e r , i . e . t h e d e g r e e o f u r b a n i z a t i o n . A few s p e c i e s o f b i r d s d o m i n a t e d a l l b u t t h e w o o d l a n d p l o t s . D i s t r i b u t i o n and Abundance H i l d e n (1965) s t a t e s t h a t h a b i t a t s e l e c t i o n i n b r e e d i n g b i r d s i s p r i m a r i l y g o v e r n e d by i n n a t e b e h a v i o u r . A summation o f d i f f e r e n t e n v i r o n m e n t a l s t i m u l i r e s u l t s i n r e l e a s e o f a " s e t t l i n g r e s p o n s e " ; t h u s p s y c h o l o g i c a l r e s p o n s e t o e n v i r -o n m e n t a l f a c t o r s i s i m p o r t a n t i n h a b i t a t s e l e c t i o n . I t i s g e n e r a l l y b e l i e v e d t h a t s u c h " s i g n s t i m u l i " a r e o f t e n g e n e r a l t e x t u r a l o r s t r u c t u r a l c h a r a c t e r i s t i c s o f t h e l a n d s c a p e , and p r e s e n c e o f o t h e r a n i m a l s , r a t h e r t h a n t h e s p e c i f i c h a b i t a t c h a r a c t e r i s t i c s w h i c h u l t i m a t e l y d e t e r m i n e s u r v i v a l ( e . g . f o o d , s h e l t e r ; H i l d e n , 1965). R e l e a s e o f a s e t t l i n g r e s p o n s e a l s o depends on t h e l e v e l o f i n t e r n a l m o t i v a t i o n t o b r e e d . I f t h i s m o t i v a t i o n i s h i g h b u t p r e f e r r e d h a b i t a t i s i n s h o r t s u p p l y , t h e n a t e r r i t o r y may be e s t a b l i s h e d i n s u b o p t i m a l h a b i t a t ( S v a r d s o n , 1 949). Thus t h e r a n g e o f h a b i t a t s i n w h i c h a s p e c i e s may be f o u n d depends on t h e s p e c i f i c i t y o f h a b i t a t s e l e c t i o n , t h e a v a i l -a b i l i t y o f p r e f e r r e d and a l t e r n a t i v e h a b i t a t s , and i n t e r n a l hormonal conditions. The hypothesis examined here stresses the importance of s p e c i f i c i t y in habitat selection, and predicts that differences i n the structure of urban habitats w i l l a ffect the d i s t r i b u t i o n and abundance of birds. The birds observed can be divided into three groups based on th e i r "residence" status and migratory patterns. Throughout the year a large proportion of the individuals in each plot were resident birds that breed l o c a l l y . During Spring, Summer, and F a l l , migrants were also present. Most migrant species were transients; they did not remain through-out the Summer to breed. During F a l l , Winter, and Spring, a group which I s h a l l refer to as Winter residents was pres-ent . MIGRATORY SPECIES Migratory species are l i s t e d in Table 13. Most of . , these were found only i n plots with high vegetation cover (Figure 8). These species (with the exception of swallows) were probably selecting general foliage c h a r a c t e r i s t i c s of the environment. Total vegetation cover and foliage height d i v e r s i t y were highly correlated with the abundances of many of these species (Appendix 5b). However, the number of migrants in the woodland plot was lower than expected, especially in F a l l , though this may have been a resu l t of the d i f f i c u l t y of adequately sampling this habitat-55. Table 13: Resident Status of B i r d Species i n Vancouver Species present year-round Transient Species (except (resident) f o r rare winter occurrences) Common Pigeon S t a r l i n g (Spring, F a l l ) House Sparrow Crested Mynah Glaucous-winged Gull American Robin (Spring, F a l l ) House Finch Song Sparrow Dark-eyed Junco Black-capped Chickadee Northwestern Crow Varied Thrush (Spring, F a l l ) S t e l l e r ' s Jay Evening Grosbeak Brewer's Blackbird Common F l i c k e r (Spring, F a l l ) Golden-crowned Kinglet Winter Wren Ruffed Grouse Bewick's Wren Ruby-crowned Kinglet White-crowned Sparrow (Spring, F a l l ) American Goldfinch (Spring, F a l l ) Pine S i s k i n Fox Sparrow (Spring, F a l l ) Chesnut-backed Chickadee Downy Woodpecker Great Horned Owl Pi l e a t e d Woodpecker Busht i t Red-breasted Nuthatch ( F a l l ) Rufous-sided Towhee Barn Swallow Violet-green Swallow Savannah Sparrow Golden-crowned Sparrow Brown-headed Cowbird Rufous Hummingbird Band-tailed Pigeon Swainson's Thrush Hermit Thrush Red-eyed Vireo Warbling Vireo Orange-crowned Warbler Wilson's Warbler Townsend's Warbler Yellow-rumped Warbler M a c G i l l i v r a y ' s Warbler Western Flycatcher O l i v e - s i d e d Flycatcher Cedar Waxwing Western Tanager Black-headed Grosbeak Common Nighthawk Purple Finch Common Snipe (Seasons i n parentheses i n d i c a t e that some populations are migratory) : from Campbell et. a l . , 1974. 56. F i g u r e 8: Number o f m i g r a n t s p e c i e s per p l o t v e r s u s t o t a l p e r c e n t v e g e t a t i o n c o v e r , d u r i n g seasons o f peak m i g r a t i o n . F I G U R E 8 20 16 40 80 120 160 Total Vegetation Cover (%) 58. W i l s o n ' s W a r b l e r was b y f a r t h e most abundant m i g r a n t i n S p r i n g and F a l l , b u t d i d n o t s t a y t o b r e e d . T h i s s p e c i e s was common i n some r e s i d e n t i a l p l o t s d u r i n g m i g r a t i o n , e s p-e c i a l l y i n S h a u g h n e s s y and C o l l i n g w o o d . I t was h i g h l y c o r -r e l a t e d w i t h t h e c o v e r o f d e c i d u o u s t r e e s , and was s e e n f o r -a g i n g m a i n l y i n v e g e t a t i o n o f t h i s t y p e . I t i s p o s s i b l e t h a t t h e amount o f d e c i d u o u s t r e e f o l i a g e s e r v e s as a " s i g n s t i m u l u s " , so t h a t W i l s o n ' s W a r b l e r r e s p o n d s t o t h i s f o l i a g e i n s e l e c t i o n o f h a b i t a t d u r i n g m i g r a t i o n . I n t e r a c t i o n w i t h n o n - f o l i a g e - r e l a t e d c h a r a c t e r i s t i c s o f t h e u r b a n e n v i r o n m e n t does n o t a p p e a r t o be a s i g n i f i c a n t f a c t o r a f f e c t i n g t h e d i s t r i b u t i o n o f W i l s o n ' s W a r b l e r . I n d e e d , B a r n and V i o l e t -g r e e n Swallows may be t h e o n l y common m i g r a n t s w h i c h a r e s i g n i f i c a n t l y i n f l u e n c e d by man's c o n s t r u c t i o n o f b u i l d i n g s , s i n c e t h e s e s p e c i e s use them i n n e s t i n g . H i l d e n (1965) s t a t e s t h a t h i g h l y s o c i a l s p e c i e s o f b i r d s may r e s p o n d t o t h e p r e s e n c e o f o t h e r i n d i v i d u a l s and s p e c i e s r a t h e r t h a n t o e n v i r o n m e n t a l c o n f i g u r a t i o n s , when s e l e c t i n g h a b i t a t . T h e r e f o r e c o r r e l a t i o n s were examined between c e r t a i n s p e c i e s i n o r d e r t o a s s e s s w h e t h e r some m i g r a n t s . were u s i n g s o c i a l f a c t o r s i n h a b i t a t s e l e c t i o n . S m i t h (1975) d i s c u s s e s t h e r e l a t i o n s h i p between m i g r a n t p a s s e r i n e s and r e s i d e n t b i r d s i n t h e t r o p i c s . He o b s e r v e d t h a t m i g r a n t s j o i n f o r a g i n g f l o c k s o f r e s i d e n t s and keep i n c o n t a c t w i t h t h e s e by r e s p o n d i n g t o a n o i s e r e s e m b l i n g 59. " s p s h i n g . " T h i s s o u n d i s o f t e n u s e d b y . b i r d w a t c h e r s t o a t t r a c t b i r d s i n t o v i e w . S p e c i e s t h a t f o r m t h e n u c l e i o f l o c a l m i x e d - f o r a g i n g f l o c k s a r e t h e B l a c k - c a p p e d C h i c k a d e e and G o l d e n - c r o w n e d K i n g l e t ( p o s s i b l y a l s o D a r k - e y e d J u n c o and B u s h t i t ) . The c h i c k a d e e a n d k i n g l e t w e r e h i g h l y c o r -r e l a t e d ( r > . 9 0 ) d u r i n g m i g r a t i o n s e a s o n s . M i x e d s p e c i e s f o r a g i n g f l o c k s were s o m e t i m e s o b s e r v e d composed o f t h e s e s p e c i . e s w i t h v a r i o u s w a r b l e r s . I n d e e d , W i l s o n ' s a n d Town-s e n d ' s W a r b l e r s were q u i t e h i g h l y c o r r e l a t e d w i t h . t h e c h i c k a d e e a n d k i n g l e t , as w e l l as w i t h v a r i o u s h a b i t a t f e a t u r e s ; so t h a t b o t h s o c i a l a n d n o n s o c i a l f a c t o r s may be i m p o r t a n t i n h a b i t a t s e l e c t i o n among some m i g r a n t s i n t h e p r e s e n t s a m p l e . P e r h a p s m i g r a n t s i n t e m p e r a t e a r e a s f i r s t r e c o g n i z e g e n e r a l f e a t u r e s o f t h e l a n d s c a p e , t h e n f o l l o w r e s i d e n t b i r d s i n s e a r c h o f f o o d . S m i t h ( 1 9 7 5 ) r e a s o n e d t h a t m i g r a n t s i n t h e t r o p i c s may cue on f l o c k s o f r e s i d e n t s i n o r d e r t o t a k e a d v a n t a g e o f t h e r e s i d e n t ' s k n o w l e d g e o f l o c a l f o o d resources ( a n d / o r p r e d a t o r s ) . A c c o r d i n g t o t h i s i n t e r p r e t a t i o n o f t h e m i g r a n t s ' r e -s p o n s e t o " s p s h i n g " , t h e r e s i d e n t n u c l e u s s p e c i e s know where f o o d i s l o c a l l y a b u n d a n t ; i f t h e m i g r a n t s ' . d i e t s a r e s i m i l a r i n . some way to t h o s e o f t h e r e s i d e n t s , the m i g r a n t s can t h e r e f o r e b e n e f i t f r o m f o l l o w i n g t h e r e s i d e n t s . The q u e s t i o n then- a r i s e s w h e t h e r r e s i d e n t s p e c i e s i n g e n e r a l a r c d i s t r i b -u t e d d i r e c t l y i n r e s p o n s e t o l o c a l a v a i l a b i l i t y o f f o o d o r 60. o t h e r e s s e n t i a l ( u l t i m a t e ) f a c t o r s , o r w h e t h e r t h e y a r e r e -s p o n d i n g t o f e a t u r e s w h i c h a r e (in u n d i s t u r b e d systems), cues f o r t h e s e . I s h a l l h y p o t h e s i z e t h a t r e s i d e n t s p e c i e s a r e d i s t r i b -u t e d more i n r e s p o n s e t o p r e f e r r e d e s s e n t i a l r e s o u r c e s t h a n a r e m i g r a t o r y b i r d s , t h o u g h I c a n ' t t e s t t h i s d i r e c t l y . I n th e f o l l o w i n g d i s c u s s i o n W i n t e r r e s i d e n t b i r d s a r e c o n s i d e r -ed a l o n g w i t h permanent r e s i d e n t s . The f o r m e r were p r e s e n t i n t h e c i t y f o r a l a r g e p o r t i o n o f t h e y e a r , t h e r e f o r e i t i s assumed t h a t t h e y a l s o s e l e c t e d h a b i t a t u s i n g f a c t o r s w h i c h were e s s e n t i a l f o r t h e i r s u r v i v a l . RESIDENT SPECIES The f o l l o w i n g s p e c i e s were t h e most common permanent r e s i d e n t s i n u r b a n a r e a s : D o m e s t i c P i g e o n , S t a r l i n g , House Sp a r r o w , G l a u c o u s - w i n g e d G u l l , House F i n c h , A m e r i c a n R o b i n , N o r t h w e s t e r n Crow, and B l a c k - c a p p e d C h i c k a d e e . Common W i n t e r r e s i d e n t s were t h e Song S p a r r o w , D a r k - e y e d J u n c o , V a r i e d T h r u s h , and G o l d e n - c r o w n e d K i n g l e t . I s h a l l b r i e f l y d e s c r i b e t h e r a n g e o f e a c h o f t h e s e s p e c i e s w i t h i n V a n c o u v e r and r e -l a t e t h e s e t o some c h a r a c t e r i s t i c s o f t h e e n v i r o n m e n t w h i c h a r e e s s e n t i a l t o them, and may be d i r e c t l y a f f e c t i n g t h e i r d i s t r i b u t i o n . 61. Domestic Pigeon Pigeons were most abundant in "commercial" habitat, but were also quite abundant i n "apartment" and " i n d u s t r i a l " habitats. They were found in much lower density in a l l r e s i d e n t i a l areas. Two factors are thought to be control-l i n g the abundance of the Domestic Pigeon: food provided by man, and s u i t a b i l i t y of buildings for roosting and nest-ing. Flat-roofed buildings with numerous ledges and eaves were quite common i n the commercial, apartment, and indus-t r i a l areas, though the quality of these buildings for roosting was perhaps r e l a t i v e l y low i n the i n d u s t r i a l area. Murton et a l . (1972) found that s p i l l e d grain and si m i l a r foodstuffs were the most important factors determining the abundance of pigeons in dockside areas. Since the com-mercial plot was the closest one to grain-shipping f a c i l i t y i e s , i t was to be expected that the highest density of pigeons should be found there. S t a r l i n g Starlings were most abundant i n the r e s i d e n t i a l areas with less than 80% vegetation cover, peaking i n abundance in habitats with 40 to 60% vegetation cover (Figure 9). The presence of grassy areas (lawns) may be a c r i t i c a l factor determining S t a r l i n g abundance i n c i t i e s , since this i s the i r preferred foraging microhabitat (Weber, 1972). Lawn was 6 2 . Figure 9: Estimates of St a r l i n g density per plot versus t o t a l percent vegetation cover. The mean den-s i t i e s in Summer and Winter have been graphed. Figure 10: Estimates of Black-capped Chickadee density per plot versus t o t a l percent vegetation cover. The mean densities i n Summer and Winter have been graphed. 63. F I G U R E 9 winter 40 " 80 ' 120 180 T o t a l Vegetation Cover (%) F I G U R E 10 T o t a l Vegetat ion Cover (%) p l e n t i f u l i n most h a b i t a t s where S t a r l i n g s were abundant. However, my r e s u l t s i n d i c a t e t h a t f o o d s u p p l i e d by p e o p l e may be o f a d d i t i o n a l importance. S t a r l i n g s were most abunr dant i n the p l o t i n which the amount o f f o o d p r o v i d e d by r e s i d e n t s f o r b i r d s was g r e a t e s t CMacKenzie), not i n the p l o t where p e r c e n t o f a r e a c o v e r e d by lawn was g r e a t e s t (Queen E l i z a b e t h ) . R e g r e s s i o n r e s u l t s i n d i c a t e d t h a t i n S p r i n g and F a l l , the a v a i l a b i l i t y o f c o n i f e r o u s t r e e s may i n f l u e n c e S t a r l i n g d i s t r i b u t i o n (Appendix 5b). S t a r l i n g s r o o s t communally i n t r e e s a t t h e s e times o f y e a r (Jumber, 1956). House Sparrow D i s t r i b u t i o n o f the House Sparrow was v e r y s i m i l a r to t h a t o f the S t a r l i n g . H i g h e s t d e n s i t i e s o c c u r r e d i n t y p i c a l r e s i d e n t i a l and apartment h a b i t a t s , though House sparrows • were found i n a l l urban h a b i t a t s . There was a sharp drop .' i n t h e i r abundance when t o t a l v e g e t a t i o n cover exceeded 60%. Glaucous-winged G u l l T h i s s p e c i e s was most abundant i n Downtown and the West End. Garbage i s p r o b a b l y the g u l l ' s o n l y f o o d i n these p l o t s . Food s c r a p s were a l s o a v a i l a b l e i n r e s i d e n t i a l a r e a s , but g u l l s were not n e a r l y as abundant t h e r e . T h e r e f o r e the d i s t r i b u t i o n o f the Glaucous-winged G u l l , p r i m a r i l y a c o a s t a l s p e c i e s , may be more a f f e c t e d by the p r o x i m i t y of the former areas to the ocean than by the amount of garbage a v a i l a b l e . The presence of t a l l b u i l d i n g s f o r perches ..... and look-out posts may a l s o have a f f e c t e d t h e i r d i s t r i b u -t i o n . House F i n c h This s p e c i e s was most abundant i n apartment and woody r e s i d e n t i a l p l o t s i n S p r i n g , Summer, and F a l l . The only s t r u c t u r a l f e a t u r e s which c l e a r l y d i s t i n g u i s h e d these p l o t s from a l l others was the presence of broad-leaved evergreen t r e e s . It i s d o u b t f u l that t h i s f e a t u r e a c t u a l l y i n f l u e n c e the d i s t r i b u t i o n of the House Fin c h however, s i n c e i t was a comparatively i n s i g n i f i c a n t a t t r i b u t e of the h a b i t a t i n both p l o t s . Regression r e s u l t s i n d i c a t e d a r e l a t i o n s h i p , with coniferous t r e e d e n s i t y . In Winter, d e n s i t y of the House Fin c h dropped i n woody r e s i d e n t i a l h a b i t a t and i n r creased i n t y p i c a l r e s i d e n t i a l (MacKenzie). This change may have been i n response to the much g r e a t e r q u a n t i t y of b i r d seed a v a i l a b l e i n the more densely populated t y p i c a l r e s -i d e n t i a l h a b i t a t (Table 7 ) . American Robin The r o b i n was commonly found i n a l l h a b i t a t s except commercial and i n d u s t r i a l . Abundance was g r e a t e s t i n woody r e s i d e n t i a l h a b i t a t , where t o t a l v e g e t a t i o n c o v e r was a b o u t 80%. In W i n t e r , t h e r e were r e l a t i v e l y few r o b i n s i n o l d e r and woody r e s i d e n t i a l h a b i t a t s . T h i s i n d i c a t e s t h a t m i g r a n t r o b i n s w h i c h a r r i v e i n V a n c o u v e r e a c h S p r i n g t o b r e e d , may-p r e f e r r e s i d e n t i a l h a b i t a t s w h i c h have more t h a n 70% v e g e t a -t i o n c o v e r . T h i s c h o i c e o f h a b i t a t may be b a s e d on t h e amount o f d i f f e r e n t t y p e s o f v e g e t a t i o n c o v e r . M u l t i p l e r e g r e s s i o n s i n d i c a t e d t h a t t h e r e was a p o s i t i v e r e l a t i o n s h i p between c o v e r o f c o n i f e r o u s t r e e s and s h r u b s and r o b i n d e n s i t y ( A p p e n d i x 5b ) . S i n c e Thomas (1973) o b t a i n e d a s i m i l a r r e -s u l t f o r r o b i n s c e n s u s e d i n s u b u r b a n h a b i t a t , and c o n i f e r s a r e n o t p r e f e r r e d f o r e i t h e r f o r a g i n g o r n e s t i n g p u r p o s e s (Weber, 1972) , I s u g g e s t t h a t c o n i f e r s may be p r e f e r r e d as p e r c h e s o r e v e n i n g r o o s t s . N o r t h w e s t e r n Crow T h i s s p e c i e s was f o u n d , a t l e a s t o c c a s i o n a l l y , i n a l l h a b i t a t s . ' I t was most abundant i n t y p i c a l , o l d e r , and woody r e s i d e n t i a l p l o t s . My o b s e r v a t i o n s i n d i c a t e d t h a t e n v i r o n -m e n t a l c h a r a c t e r i s t i c s w h i c h may have been o f i m p o r t a n c e t o crows d u r i n g S p r i n g and Summer were t a l l t r e e s , f o r n e s t i n g p u r p o s e s . Lawns and g a r b a g e may have b e e n o f i m p o r t a n c e i n W i n t e r . Thus, crows were most abundant i n woody r e s i d e n t i a l hab-67. i t a t i n Spring and Summer, and i n t y p i c a l r e s i d e n t i a l hab-i t a t in F a l l and Winter (Appendix 4). Black-capped Chickadee Although found i n a l l habitats with 351 vegetation cover or more, the Black-capped Chickadee was primarily a woodland bi r d . Its abundance was roughly proportional to the t o t a l vegetation cover (Figure 7). Thomas (1973) and I bothifound that the amount of coniferous trees may be used to predict the abundance of chickadees (regression results not presented). Coniferous trees are frequently used as roosts by flocks of chickadees i n F a l l , Winter, and possibly early Spring (Odum, 1942). Odum (1942) also found that b i r d seed provided i n res-i d e n t i a l areas attracted chickadees in the Winter. My ques-tionnaire results indicate that chickadees eat at b i r d feedr ers i n Winter to some extent, but the number of chickadees in urban plots was not higher i n this season than at other times of the year. During F a l l , however, the abundance of chickadees within urban areas i s best predicted by the amount of food (bird seed) provided by man (Appendix 5b). Winter residents The Song Sparrow and Dark-eyed Junco were found in a wide variety of urban habitats during Winter and migration 68. s e a s o n s . They were most abundant i n o l d and woody r e s i d e n -t i a l h a b i t a t s . My s t a t i s t i c a l r e s u l t s ( A p p e n d i x 4, 5b) com-b i n e d w i t h f i e l d o b s e r v a t i o n s by Weber (,1972), i n d i c a t e t h a t g a r d e n s and s h r u b b e r y may be f e a t u r e s o f t h e e n v i r o n m e n t t o w h i c h t h e s e s p e c i e s a r e r e s p o n d i n g i n a p o s i t i v e manner. The V a r i e d T h r u s h and G o l d e n - c r o w n e d K i n g l e t were most abundant i n w o o d l a n d h a b i t a t , t h o u g h t h e V a r i e d T h r u s h was f o u n d i n most u r b a n h a b i t a t s d u r i n g t h e W i n t e r . S e a s o n a l changes i n f o o d a v a i l a b i l i t y o r f o o d p r e f e r e n c e s may c a u s e t h e s e c h a n g es f r o m u r b a n t o w o o d l a n d h a b i t a t . Summary M i g r a t o r y b i r d s p r o b a b l y use s t r u c t u r a l c h a r a c t e r i s t i c s o f f o l i a g e o r t h e p r e s e n c e o f r e s i d e n t s p e c i e s i n l o c a t i n g s u i t a b l e h a b i t a t d u r i n g m i g r a t i o n . On t h e o t h e r h a n d , I h y p o t h e s i z e d t h a t r e s i d e n t s p e c i e s o f b i r d s a r e d i s t r i b u t e d more i n d i r e c t r e s p o n s e t o a v a i l a b i l i t y o f e s s e n t i a l r e s o u r c e s and p a r t i c u l a r f o o d s , t h a n a r e m i g r a n t s . I n s u p p o r t o f t h i s , some r e s i d e n t s p e c i e s w h i c h a r e n u m e r i c a l l y dominant i n a r e a s w i t h l e s s t h a n 70% v e g e t a t i o n c o v e r a p p e a r t o be d i s t r i b u t e d i n p r o p o r t i o n t o t h e amount o f f o o d p r o v i d e d by man. P a r t -i c u l a r t y p e s o f b u i l d i n g s may i n f l u e n c e d e n s i t i e s o f Domes-t i c P i g e o n s and G l a u c o u s - w i n g e d G u l l s . R e s i d e n t s p e c i e s , ' s u c h as t h e A m e r i c a n R o b i n and B l a c k - c a p p e d C h i c k a d e e , w i t h h i g h e s t abundances i n a r e a s w i t h o v e r 70% v e g e t a t i o n c o v e r , a r e d i s t r i b u t e d i n p r o p o r t i o n t o c o v e r o f v e g e t a t i o n o r p a r t -69. i c u l a r types of foliage. Characteristics of the Bird Communities Community ch a r a c t e r i s t i c s may be described in a number of ways. I w i l l r e s t r i c t this aspect of the discussion to description of species d i v e r s i t y , and description of the abundance of individuals i n r e l a t i o n to t o t a l b i r d density and the trophic structure of the communities, DIVERSITY OF SPECIES There was a positive l i n e a r relationship between b i r d species d i v e r s i t y (H 1) and foliage height d i v e r s i t y (.Figure 11). Since foliage height d i v e r s i t y and t o t a l vegetation cover decrease with urbanization, b i r d species d i v e r s i t y , number of species, and evenness also decrease l i n e a r l y with the gradient of urbanization. These results support the hypothesis that c h a r a c t e r i s t i c s of urban b i r d communities are related to habitat structure. MacArthur and MacArthur (1961), Karr and Roth (1971), Willson (.1974), and others have observed a l i n e a r relationship between b i r d species d i v e r s i t y and foliage height d i v e r s i t y in natural areas, though Karr and Roth, and Willson both found a c u r v i l i n e a r relationship between b i r d species d i v e r s i t y and t o t a l vege-tation cover. The f i r s t result suggests that urban communities of birds are fundamentally s i m i l a r to those i n natural areas so 70. F i g u r e 11: Mean b i r d s p e c i e s d i v e r s i t y (Summer) i n e a c h p l o t v e r s u s f o l i a g e h e i g h t d i v e r s i t y . The i n d e x FHD2 (s e e T a b l e 6, page 30) has been u s e d h e r e . The r e g r e s s i o n l i n e i s s i g n i f i c a n t a t t h e 0.05 con-f i d e n c e l e v e l . 71. B S D VS» F H • E (SLM/ER) Y = 0.B55B + 0«S5B3 *X N = B FIGURE II F H • E t h a t t h e s t r u c t u r a l c o m p l e x i t y o f v e g e t a t i o n seems t o be a p r i m e d e t e r m i n a n t o f b i r d s p e c i e s d i v e r s i t y . On t h e o t h e r hand, w h i l e man-made f e a t u r e s add c o n s i d e r a b l y t o t h e o v e r a l l s t r u c t u r a l c o m p l e x i t y o f t h e u r b a n e n v i r o n m e n t ( T a b l e 6) t h e y a r e i n v e r s e l y , o r n o t r e l a t e d t o t h e number o f b i r d s p e c i e s o r t o b i r d s p e c i e s d i v e r s i t y ( F i g u r e 1 2 ) , S i m i l a r l y , Emlen (1974) f o u n d t h a t when man-made f e a t u r e s were c o n s i d e r e d , b i r d s p e c i e s d i v e r s i t y and s p e c i e s number v a r i e d i n v e r s e l y w i t h t h e d i v e r s i t y o f t h e e n v i r o n m e n t . T h i s n e g a t i v e " r e -l a t i o n s h i p " may s i m p l y r e f l e c t t h e f a c t t h a t f o l i a g e h e i g h t d i v e r s i t y i s n e g a t i v e l y c o r r e l a t e d w i t h t h e amount o f c o v e r o f man-made s t r u c t u r e s . TOTAL BIRD DENSITY AND TROPHIC GROUPS T o t a l b i r d d e n s i t y v a r i e d c o n s i d e r a b l y between p l o t s , even between t h o s e w i t h s i m i l a r h a b i t a t s t r u c t u r e ( F i g u r e 3 ) . T h e r e was t h e r e f o r e no t r e n d between u r b a n i z a t i o n and t o t a l b i r d d e n s i t y . W i n t e r d e n s i t i e s were on t h e whole g r e a t e r t h a n Summer d e n s i t i e s . I n c o n t r a s t , Weber's (1972) d a t a s u g g e s t e d t h a t b r e e d i n g s e a s o n d e n s i t i e s d e c r e a s e d w i t h u r b a n i z a t i o n w h i l e W i n t e r d e n s i t i e s i n c r e a s e d w i t h u r b a n i z a t i o n ( T a b l e 1 4 ) , b u t s i n c e he c o n s i d e r e d o n l y a n a r r o w r a n g e o f h a b i t a t t y p e s t h i s c o m p a r i s o n may n o t be m e a n i n g f u l . V a r i a t i o n i n t o t a l b i r d d e n s i t y between p l o t s c an be r e l a t e d t o changes i n t h e r e l a t i v e abundance o f i n d i v i d u a l s b e l o n g i n g t o s p e c i f i c t r o p h i c g r o u p s . Weber Q 9 7 2 ) f o u n d 73. Figure 12: Mean b i r d species d i v e r s i t y (Summer) versus the man-made component of habitat s t r u c t u r a l d i v e r s i t y . The l a t t e r has been calculated by subtracting FHD2 (6 layers of vegetation) from FHD3 (9 layers, in-cluding buildings and pavement), since the addition of strata has an additive e f f e c t on d i v e r s i t y (per-sonal communication P. B e l l e f l e u r ) . The curve was f i t t e d by eye. 2.8 2.4 2.0 B S D 1.2 .8 \ o \ \ \ o o \ \ 0 \ \ ° \ \ ° \ \ \ \ .4 .2 ,.4 .6 .8 1.0 F H D 3 - F H D 2 * (see Toble 6 ) F I G U R E 12 * n o t e : the addition of strata has an additive effect on diversity. - „ . - T t h a t most o f t h e b i r d s i n r e s i d e n t i a l h a b i t a t s were o m n i v o r e s ( T a b l e 1 5 ) . As v e g e t a t i o n c o v e r i n c r e a s e d , i n s e c t i v o r e s i n -c r e a s e d i n r e l a t i v e abundance. U s i n g Weber's c l a s s i f i c a t i o n s y s t e m , I a l s o f o u n d t h a t t h e u r b a n b i r d community i s numer-i c a l l y d o m i n a t e d by o m n i v o r o u s b i r d s , p a r t i c u l a r l y i n " h i g h l y u r b a n " h a b i t a t s i n W i n t e r ( T a b l e 1 5 ) . The p r o p o r t i o n o f i n -s e c t i v o r e s d e c r e a s e s i n W i n t e r , e x c e p t i n w o o d l a n d h a b i t a t . T h i s i s as e x p e c t e d and i n d i c a t e s t h a t i n s e c t s a r e particuT.. l a r l y s c a r c e i n u r b a n a r e a s a t t h i s t i m e o f y e a r . I n b o t h Weber's s t u d y and mine, t h e p r o p o r t i o n o f o m n i v o r e s i n sub-u r b a n h a b i t a t d e c r e a s e d i n W i n t e r , w h i l e t h e p r o p o r t i o n o f g r a m i n i v o r e s ( p l u s h e r b i v o r e s ) i n c r e a s e d . The i n c r e a s e d amount o f s e e d and b r e a d p r o v i d e d by s u b u r b a n r e s i d e n t s i n W i n t e r ( T a b l e 7) combined w i t h s h o r t a g e s o f n a t u r a l f o o d s i n W i n t e r , may a c c o u n t f o r some o f t h e r e l a t i v e i n c r e a s e i n g r a m i n i v o r e s . Emlen (1974) r e l a t e d t h e dominance (90% o f t h e biomass and number o f i n d i v i d u a l s ) o f s e e d - e a t i n g b i r d s i n a s u b u r b a n a r e a t o t h e amount o f b i r d , s e e d and b r e a d p r o -v i d e d by p e o p l e . The n u m e r i c a l l y dominant b i r d s i n most u r b a n a r e a s o f V a n c o u v e r a r e t h e S t a r l i n g , House S p a r r o w , and D o m e s t i c P i g e o n . These b i r d s a r e p a r t i c u l a r l y s u i t e d t o u r b a n a r e a s s i n c e t h e y e a t a wide v a r i e t y o f f o o d s i n c l u d i n g t h o s e p r o v i d e d by man, f o r a g e m a i n l y on t h e g r o u n d , a r e n o t h i g h l y t e r r i t o r i a l d u r i n g t h e b r e e d i n g s e a s o n , and n e s t m a i n l y i n b u i l d i n g s (Weber, 1972). My d a t a s u g g e s t t h a t v a r i a t i o n i n t o t a l b i r d d e n s i t y 76. Table 14: Comparison of B i r d Community C h a r a c t e r i s t i c s with those of Weber (1972). SUMMER WINTER Habitat Type This Study Weber This Study Weber 10 (D Apartment 1. 72 1. 72 1. 74 1. 72 •r-l >-N O + J Typical Residential 1. 30 1. 81 1. 73 1. 45 fX W W U Woody Residential 1. 99 2. 21 2. 15 2. 37 <U > rH - H Woodland 2. 62 - - 2. 03 - -•H O PQ Rural - - 2. 42 - - 1. 87 Apartment 10 13 12 16 Typical Residential 13 15 15 12 Speci ichne Woody Residential Woodland 17 22 30 19 18 30 Oi Rural - - 25 - - 32 in in 0) Apartment 75 67 70 62 Typical Residential 51 67 64 58 Evenn Woody Residential 70 65 73 70 Evenn Woodland Rural -73 -75 -70 -54 Apartment 469 314 568 370 f-c Typical Residential 412 411 471 501 m +-> •H Woody Residential 397 439 342 319 Tota: Den: Woodland Rural 212 - 655 477 - 1021 Table 15: Trophic Groups of B i r d s : P r o p o r t i o n of T o t a l Number of I n d i v i d u a l s i n each Group. [: Ha b i t a t Type Trophic Group Commercial I n d u s t r i a l Apartment Suburban Woodland Rural Omnivore 97V ' 81% 82% 1 19% -Graminivore +Herbivore 2% 8% 6% 17% -I n s e c t i v o r e 1% 11% 12% 63% Omnivore 1001 . 91% 78% 24% -Graminivore +Herbivore 01 9% 16% : 11% I n s e c t i v o r e 0% 0% 6% 65% -Omnivore •- • 92% 73% 2 - 59% Graminivore +Herbivore - 1% 12% - 20% I n s e c t i v o r e 7% 15% - ' 21% Omnivore • - 91% 59%' - 75% Graminivore +Herbivore - 8% 31% - 24%-I n s e c t i v o r e - 1* 10% - . 1% Based on four study areas. Based on two study areas. 78. in areas numerically dominated by these species, was related to v a r i a t i o n in the amount of food made available by man rather than the structure of the environment as o r i g i n a l l y hypothesized. For example, the t o t a l vegetation cover i n " t y p i c a l r e s i d e n t i a l " p l o t s , Queen Elizabeth (.QE) and MacKen-zie (MK), was quite similar (Table 2 ) , yet the density of birds in MK was roughly three times that i n QE. Correspond-ing to this was a 3-fold difference in the estimated amount of food provided by residents. The higher t o t a l density in MacKenzie was primarily a result of increased abundance of the S t a r l i n g and House Sparrow, species which are known to consume food provided by people. In areas with more vegetation cover, where these species were less abundant, abundance of natural foods may have been related to t o t a l b i r d density. Some interesting relation-, ships emerge i f we assume that the t o t a l vegetation cover is an approximation of the r e l a t i v e a v a i l a b i l i t y of natural foods The Winter b i r d density in "older r e s i d e n t i a l " habitat (Col-lingwood: CW) was approximately twice that in QE, but in both areas the amount of food provided by people was about the same. However, the t o t a l vegetation cover was 10% great-er i n Collingwood than in Queen Elizabeth. Perhaps this small increase in vegetation cover, most of this being in the form of deciduous trees, resulted in this increase in b i r d density. A c r i t i c a l amount of plant cover may be re-79. quired before species which rely primarily on vegetation as a foraging substrate will 'recognize', in large numbers, the suburban habitat as suitable. Between 60 and 75% vegetation cover (.5 and 20% tree cover) , the abundances of many species changed sharply (e-g- Figures 8, 9, and 10). The species which accounted for most of the difference in total density in Q u e e n Elizabeth and Collingwood plots in Winter were the American Robin, Song Sparrow, and Dark-eyed Junco; all of which forage mostly in vegetation of various types for nat-urally occurring foods, though they also accept food from people. Interestingly, Willson 0-974) derived a related result: "The addition of trees in a vegetational series has a disproportionate effect on the addition of species, primarily by the addition rather than the expansion of guilds." Another useful comparison may be drawn between "older residential" (CW) and "woody residential" (SH) plots. Win-ter bird density was about the same in these (Table 11). Total vegetation cover was 14% higher in SH than in CW, while food provided by man was approximately 13% less. The proportions of various species' abundances changed substant-ially, with those of the American Robin, Dark-eyed Junco, Black-capped Chickadee, and Varied Thrush increasing not-iceably with vegetation cover (Appendix 3). Thus, total bird density may have changed little between woody and older 80. r e s i d e n t i a l p l o t s b e c a u s e t h e i n c r e a s e i n v e g e t a t i o n c o v e r ( n a t u r a l l y a v a i l a b l e f o o d ) was c o u n t e r e d by a d e c r e a s e i n q u a n t i t y o f f o o d p r o v i d e d by man. A m o d i f i e d a s s e m b l a g e o f s p e c i e s a p p e a r e d , t h o u g h t h e S t a r l i n g and D a r k - e y e d J u n c o were t h e most abundant s p e c i e s i n b o t h a r e a s . These r e s u l t s a r e a d d i t i o n a l e v i d e n c e t h a t t o t a l " p r o d -u c t i v i t y " o f t h e h a b i t a t , i n c l u d i n g man-made and n a t u r a l f o o d s , i s r e l a t e d t o t o t a l b i r d d e n s i t y i n c i t i e s . By con-t r a s t , W i l l s o n (.1974) f o u n d t h a t t h e r e was no r e l a t i o n s h i p between e s t i m a t e d abundance and b i o m a s s o f b i r d s i n n a t u r a l a r e a s , and the p r o d u c t i v i t y o f t h e h a b i t a t . T h i s c o m p a r i s o n s u g g e s t s t h a t t h e a v a i l a b i l i t y o f f o o d may n o t be g e n e r a l l y a l i m i t i n g f a c t o r i n n a t u r a l e n v i r o n m e n t s as i t i s i n u r b a n a r e a s w h i c h a r e c h a r a c t e r i z e d by h i g h p r o p o r t i o n s o f non-p r o d u c t i v e " c o v e r " (.pavement, b u i l d i n g s , e t c . ) . As p r e v i o u s l y n o t e d , i n c r e a s i n g f o l i a g e h e i g h t d i v e r s i t y and t o t a l v e g e t a t i o n c o v e r was c o r r e l a t e d w i t h an i n c r e a s e i n b i r d s p e c i e s d i v e r s i t y and number o f s p e c i e s . Not s u r -p r i s i n g l y , t h e r e was a c o r r e s p o n d i n g i n c r e a s e i n t h e number o f f o r a g i n g g u i l d s ( F i g u r e 13) as w e l l as an a d d i t i o n o f s p e c i e s t o e x i s t i n g g u i l d s (.Figure 14) , and a d e c l i n e i n t h e r e l a t i v e abundance o f o m n i v o r o u s g r o u n d f e e d i n g b i r d s . T h ese d a t a c o n f o r m t o M a c A r t h u r ' s (.1965) p r o p o s a l t h a t t h e number o f s p e c i e s w h i c h can i n h a b i t an a r e a i s l i m i t e d by t h e s t r u c t u r a l c o m p l e x i t y and p r o d u c t i v i t y o f t h e h a b i t a t . 81. F i g u r e 13: Number o f f o r a g i n g g u i l d s p e r p l o t (Summer) v e r s u s t o t a l p e r c e n t v e g e t a t i o n c o v e r . The c u r v e was f i t t e d by e y e. The g u i l d s r e c o g -n i z e d were t h e same as t h o s e u s e d by Emlen ( 1 9 7 4 ) . F i g u r e 14: Number o f s p e c i e s p e r f o r a g i n g g u i l d (Summer) v e r s u s t o t a l p e r c e n t v e g e t a t i o n c o v e r . O n l y g r a m i n i v o r e ( s e e d - e a t i n g ) , and g r o u n d - and t r u n k - g l e a n i n g i n s e c t i v o r e g u i l d s have been g r a p h e d . F I G U R E 14 10 4 0 8 0 120 160 To ta l Vegetat ion Cover (%) 83. He s t a t e s t h a t t h e s e two measures a r e u s u a l l y a s s o c i a t e d , and t h e r e f o r e o n l y s t r u c t u r a l c o m p l e x i t y i s n e e d e d t o p r e -d i c t number o f s p e c i e s . As t h i s f a c t o r i n c r e a s e s , t h e number o f s p e c i e s w h i c h c a n c o e x i s t i n c r e a s e s b e c a u s e t h e e n v i r o n m e n t can be p a r t i t i o n e d i n a g r e a t e r number o f ways. Many a u t h o r s have f o r w a r d e d s i m i l a r v i e w s . F o r example, Cody (J968) c o n c l u d e d t h a t t h e c o e x i s t e n c e o f b i r d s p e c i e s i n g r a s s l a n d i s f a c i l i t a t e d by r e s o u r c e p a r t i t i o n i n g . Hab-i t a t p r e f e r e n c e s and d i f f e r e n c e s i n f e e d i n g b e h a v i o u r o f s p e c i e s m i n i m i z e n i c h e o v e r l a p i n s i m p l e g r a s s l a n d . In t a l -l e r v e g e t a t i o n , s p e c i e s a r e a l s o a b l e t o p a r t i t i o n r e s o u r c e s v e r t i c a l l y , t h e r e b y i n c r e a s i n g t h e number w h i c h c a n c o e x i s t . I have n o t e d t h e n e g a t i v e r e l a t i o n s h i p between t h e s t r u c t u r a l c o m p l e x i t y added by b u i l d i n g s , pavement, and o t h e r man-made f e a t u r e s , and t h a t o f v e g e t a t i o n and n a t u r a l p r o d -u c t i v i t y . T h i s s u g g e s t s t h a t t h e number o f ways i n w h i c h r e s o u r c e s c an be p a r t i t i o n e d i n u r b a n a r e a s i s f u n c t i o n a l l y r e l a t e d o n l y t o t h e v e g e t a t i o n a l component o f s t r u c t u r a l c o m p l e x i t y , as i t i s i n n a t u r a l a r e a s . The number and amounts o f f o o d t y p e s a v a i l a b l e may be t h e i m p o r t a n t f a c t o r s l i m i t i n g t h e number o f c o e x i s t i n g s p e c i e s once v e g e t a t i o n d r o p s t o v e r y low l e v e l s ( l e s s t h a n 5% c o v e r ) . As t h e amount o f v e g e t a t i o n i n c r e a s e s , g r e a t e r r e s o u r c e p a r t i t i o n i n g can o c c u r , and the number o f b i r d s p e c i e s i s f o u n d to i n c r e a s e . D i f f e r e n t f o r a g i n g m i c r o h a b i t a t p r e f e r e n c e s a r e f o u n d among u r b a n b i r d s p e c i e s (Weber, 1972). As v e g e t a t i o n h e i g h t and 84. number o f f o l i a g e t y p e s i n c r e a s e , m i c r o h a b i t a t p r e f e r e n c e s p r o b a b l y e n a b l e more s p e c i e s t o c o e x i s t , as M a c A r t h u r and Cody s u g g e s t . W i l l s o n (1974) examined c h a r a c t e r i s t i c s o f b i r d com-m u n i t i e s . A number o f h e r f i n d i n g s b a s e d on b i r d c o u n t s i n a v a r i e t y o f n a t u r a l h a b i t a t s c o n t r a d i c t e d p r e v i o u s g e n e r a l -i z a t i o n s by o t h e r s . She f o u n d t h a t when l i k e s t u d y a r e a s ( i . e . "wooded") were compared, s i m i l a r i t y o f b i r d s p e c i e s c o m p o s i t i o n was n o t r e l a t e d t o s i m i l a r i t y o f p e r c e n t v e g e t a -t i o n c o v e r o r f o l i a g e h e i g h t d i v e r s i t y . However, a r e a s w i t h t r e e s s h a r e d a h i g h e r p r o p o r t i o n o f s p e c i e s t h a n g r a s s y o r s h r u b b y a r e a s . I have o n l y a few p l o t s w h i c h can be compared i n t h i s way. A r e a s w i t h s i m i l a r p e r c e n t v e g e t a t i o n c o v e r s h a r e d between 60 and 80% o f t h e s p e c i e s . W i l l s o n made f u r -t h e r c o m p a r i s o n s , s u c h as between " w i d t h o f h a b i t a t n i c h e " and n u m e r i c a l dominance o f s p e c i e s , w h i c h my s t u d y was n o t d e s i g n e d t o i n v e s t i g a t e . I n c o n c l u s i o n , i t a p p e a r s t h a t d e n s i t y and d i v e r s i t y c h a r a c t e r i s t i c s o f a v i f a u n a s a r e p r i m a r i l y r e g u l a t e d by two f a c t o r s i n t h e u r b a n e n v i r o n m e n t ; th e s t r u c t u r a l c o m p l e x i t y o f t h e v e g e t a t i o n , and t h e " p r o d u c t i v i t y " o f t h e h a b i t a t . B o t h n a t u r a l f o o d s and t h o s e p r o v i d e d by man must be c o n s i d -e r e d as components o f p r o d u c t i v i t y . Emlen (19 74) c o n c l u d e d t h a t by p r o v i d i n g f o o d f o r b i r d s , human r e s i d e n t s o f s u b u r b a n a r e a s g r e a t l y i n c r e a s e t h e t o t a l abundance and b i o m a s s o f 85. b i r d s , o v e r t h a t in. n o n - u r b a n h a b i t a t . I have i n v e s t i g a t e d t h i s f u r t h e r , and f o u n d t h a t w i t h i n a c i t y , t o t a l b i r d den-s i t y (and b i o m a s s ) v a r i e s c o n s i d e r a b l y among a r e a s , depend-i n g l a r g e l y on the amount o f f o o d p r o v i d e d by p e o p l e . The e f f e c t i s n o t c o r r e l a t e d w i t h s t r u c t u r e o f the h a b i t a t . Numerous s t u d i e s i n n o n - u r b a n a r e a s have shown t h a t t h e number o f b i r d s p e c i e s i s r e l a t e d t o s t r u c t u r a l c o m p l e x i t y o f t h e h a b i t a t . T h i s was h y p o t h e s i z e d f o r t h e number o f s p e c i e s w i t h i n u r b a n a r e a s , as w e l l as f o r t h e e v e n n e s s and b i r d s p e c i e s d i v e r s i t y . However o n l y t h e s t r u c t u r a l com-p l e x i t y o f v e g e t a t i o n n e e d be c o n s i d e r e d ; man-made f e a t u r e s do n o t i n f l u e n c e the number o f s p e c i e s , o r o v e r a l l b i r d s p e c -i e s d i v e r s i t y . I s u g g e s t e d i n t h e I n t r o d u c t i o n t h a t i t m i g h t be d e s i r -a b l e t o e c o l o g i c a l l y manage b i r d s i n c i t i e s . I f t h i s i s t h e c a s e , t h e n i t i s c l e a r f r o m my r e s u l t s t h a t t h e e n v i r o n m e n t a l f a c t o r s t h a t s h o u l d be m a n i p u l a t e d a r e t h e amount and t y p e s o f f o o d made a v a i l a b l e by p e o p l e ( t o c o n t r o l p e s t s ) , and t h e amount and s t r u c t u r e o f v e g e t a t i o n (.to i n c r e a s e t h e number o f s p e c i e s and abundance o f many " d e s i r a b l e " s p e c i e s ) . 86 SUMMARY T h i s s t u d y examined the r e l a t i o n s h i p s between urban b i r d communities and c h a r a c t e r i s t i c s o f t h e i r e nvironment, i n a wide range o f urban h a b i t a t s . S i x t y - t w o s p e c i e s o f b i r d s were observed. Some o f the y e a r - l o n g r e s i d e n t s (e.g. Domestic P i g e o n , House Sparrow, S t a r l i n g ) were found i n a wide v a r i e t y o f h a b i t a t s , r a n g i n g from downtown to w e l l -t r e e d r e s i d e n t i a l , and were n u m e r i c a l l y dominant i n many o f t h e s e . W i n t e r r e s i d e n t s , s p e c i e s which were absent d u r i n g the b r e e d i n g season but p r e s e n t the r e s t o f the y e a r (e.g. Song Sparrow, Dark-eyed J u n c o ) , were a l s o common a t t i m e s , e s p e c i a l l y i n the more wooded r e s i d e n t i a l a r e a s . However, a l a r g e number o f the s p e c i e s o b s e r v e d were m i g r a n t s , such as s w a l l o w s , w a r b l e r s , and v i r e o s . Some p o p u l a t i o n s o f r e s i d e n t s p e c i e s (e.g. American Robin) were m i g r a n t as w e l l . Many o f thes e m i g r a t o r y s p e c i e s were common o n l y d u r i n g mi-g r a t i o n p e r i o d s , and not i n the b r e e d i n g season. A few, e s p e c i a l l y the W i l s o n ' s W a r b l e r , were common i n r e s i d e n t i a l areas d u r i n g m i g r a t i o n s e a s o n s , but many were found o n l y i n woodland. The average number o f s p e c i e s p e r morning count i n an e i g h t h e c t a r e p l o t v a r i e d from 4,5 i n the c i t y c e n t r e to 10.5 i n a w e l l - t r e e d r e s i d e n t i a l a r e a . Mean t o t a l b i r d d e n s i t y v a r i e d from 130 per 40h i n an i n d u s t r i a l p l o t t o 525 per 40h i n an apartment p l o t . 87. The major s p e c i f i c findings of this study can be sum-marized as follows. (.1) Bird species d i v e r s i t y , evenness of species' abundances, and numbers of species increase as t o t a l vegetation cover and foliage height d i v e r s i t y increase in an urban envir-onment . (2) There were no overall seasonal trends i n changes between seasons of b i r d species d i v e r s i t y , evenness, and numbers of species, though d i v e r s i t y was lowest during the sum-mer in a majority of plots. There was l i t t l e seasonal change i n number of species i n areas with less than 40% t o t a l vegetation cover. (3) The st r u c t u r a l complexity contributed to urban environ-ments by man-made features such as buildings i s nega-t i v e l y (or not) related to b i r d species d i v e r s i t y . This is in contrast with the trend for str u c t u r a l complexity contributed by vegetation. This suggests that s t r u c t u r a l complexity of vegetation is associated with food compon-ents of niches whereas man-made features generally are not. C4) Food provided by man probably has a great e f f e c t on the to t a l b i r d density (and biomass) i n urban areas, there-fore food is a l i m i t i n g factor. Resident species (e.g. House Sparrow, Starling) which are numerically dominant in most urban b i r d communities appear to be di s t r i b u t e d 88. i n r e l a t i o n t o t h e amount o f f o o d p r o v i d e d by man. T h i s e f f e c t i n c r e a s e s , w i t h u r b a n i z a t i o n . T o t a l b i r d d e n s i t y , h o w e v e r , n e i t h e r i n c r e a s e s n o r d e c r e a s e s w i t h u r b a n i z a t i o n ( i . e . w i t h d e c r e a s e i n v e g e t a t i o n c o v e r ) , s i n c e f o o d p r o v i d e d by man i s a m a j o r d e t e r m i n a n t o f t o t a l b i r d d e n s i t y , and i s l a r g e l y i n d e p e n d e n t o f s t r u c -t u r a l c h a n g e s i n t h e e n v i r o n m e n t . Those s p e c i e s , s u c h as w a r b l e r s , t h a t r e l y on n a t u r a l f o o d s a r e d i s t r i b u t e d i n r e l a t i o n . t o amount, s t r u c t u r e , o r c o m p o s i t i o n o f t h e v e g e t a t i o n . Thus t h e r e l a t i v e a b u n d a n c e o f o m n i v o r e s in c r e a s e s w i t h u r b a n i z a t i o n , w h i l e t h a t o f i n s c c t i v o r e s d e c r e a s e s , e s p e c i a l l y i n W i n t e r . T h e s e f i n d i n g s p a r t i a l l y c o n f i r m my o r i g i n a l h y p o t h e s i s , t h a t c h a r a c t e r i s t i c s o f u r b a n . b i r d c o m m u n i t i e s a r e a f u n c t i o n o f h a b i t a t s t r u c t u r e . Number o f b i r d s p e c i e s and o t h e r i n -d i c e s o f d i v e r s i t y , d i d i n c r e a s e w i t h i n c r e a s i n g c o m p l e x i t y o f v e g e t a t i o n s t r u c t u r e , and w i t h t o t a l v e g e t a t i o n c o v e r , b u t n o t w i t h d i v e r s i t y c o n t r i b u t e d by man-made s t r u c t u r e s . H o wever t o t a l d e n s i t y o f b i r d s , a n d d e g r e e o f n u m e r i c a l dom-i n a n c e by a p a r t i c u l a r g r o u p o f s p e c i e s ( o m n i v o r e s ) , i s a f -f e c t e d more-by t h e amount o f f o o d p r o v i d e d by man, t h a n by "the 1 1abi.tat s t r u c t u r e . 89. LITERATURE CITED American O r n i t h o l o g i s t s ' Union. 1957. C h e c k - l i s t o f N o r t h American B i r d s ( F i f t h E d i t i o n ) . 691 pp. L o r d B a l t i -more P r e s s , B a l t i m o r e . American O r n i t h o l o g i s t s ' Union. 1973. T h i r t y - s e c o n d sup-plement t o the American O r n i t h o l o g i s t s ' Union check-l i s t o f N o r t h American B i r d s . Auk 90: 411-419. Campbell, R.W., M.G. Shepard, B.A. MacDonald, andW.C. Weber. 1974. Vancouver b i r d s i n 1972. 96 pp. Vancouver Nat-u r a l H i s t o r y S o c i e t y , Vancouver. Cody, M.L. 1968. On the methods o f r e s o u r c e d i v i s i o n i n g r a s s l a n d b i r d communities. Am? Natl. > 10.2':' 107-147. E l l i o t t , H.N. 1964. S t a r l i n g s i n the P a c i f i c Northwest. I n : "2nd V e r t e b r a t e p e s t c o n t r o l c o n f e r e n c e . " N a t u r , Acad. S c i . pp. 29-39. Emlen, J.T. 19 74. An urban b i r d community i n Tucson, A r i z -ona: d e r i v a t i o n , s t r u c t u r e , r e g u l a t i o n . Condor 76: 184-197. Graber, R.R. and J.W. Graber. 1963. A c o m p a r i t i v e s t u d y o f b i r d p o p u l a t i o n s i n I l l i n o i s , 1906 - 1909 and 1956 -1958. B u l l . 111. Nat. H i s t . Surv. 28: 383-528. H i l d e n , 0. 1965. H a b i t a t s e l e c t i o n i n b i r d s : a r e v i e w . Ann. Z o o l . Fen. 2: 53-75. 9 0." H o e r l , A.E. and R.W. K e n n a r d . 1970. R i d g e r e g r e s s i o n : b i a s e d e s t i m a t i o n f o r n o n o r t h o g o n a l p r o b l e m s . Techno-m e t r i c s 12: 55-68. Jumber, J . F . 1956. R o o s t i n g b e h a v i o u r o f t h e S t a r l i n g i n c e n t r a l P e n n s y l v a n i a . Auk 73: 411-426. K a r r , J . F . and R.R. Roth. 1971. V e g e t a t i o n s t r u c t u r e and a v i a n d i v e r s i t y i n s e v e r a l New W o r l d a r e a s . Am. Nat. 105: 423-435. M a c A r t h u r , R.H. and J.W. M a c A r t h u r . 1961. On b i r d s p e c i e s d i v e r s i t y . E c o l o g y 42: 594-598. M a c A r t h u r , R.H. 1965. P a t t e r n s o f s p e c i e s d i v e r s i t y . B i o l . Rev. 40: 510-533. M u r t o n , R.K., R.J.P. T h e a r l e , and J . Thompson. 1972. E c o l -o g i c a l s t u d i e s o f t h e f e r a l p i g e o n Columba l i v i a v a r . I . P o p u l a t i o n , b r e e d i n g b i o l o g y , and methods o f c o n t r o l . J . A p p l . E c o l . 9: 835-874. Odum, E.P. 1942. A n n u a l c y c l e o f B l a c k - c a p p e d C h i c k a d e e -3. Auk 59: 499-531. P i e l o u , E.C. 1969. An i n t r o d u c t i o n t o m a t h e m a t i c a l e c o l o g y . 2 86 pp. J o h n W i l e y and Sons, New Y o r k . P r i n c i p l e s o f p l a n t and a n i m a l p e s t c o n t r o l . 1970. Nat, A c a d . S c i . , Wash. D.C. 5: 58-82. S m i t h , N.G. 1975. S p s h i n g n o i s e : b i o l o g i c a l s i g n i f i c a n c e o f i t s a t t r a c t i o n and n o n a t t r a c t i o n by b i r d s . P r o c . N a t n . A c a d . S c i . 72: 1411-1414. 91. S p e i r s , M.J., G. M a r k l e , and R.G. T o z e r . 1970, P o p u l a t i o n s o f b i r d s i n u r b a n h a b i t a t s , O n t a r i o C ounty, 1969. Ont. F i e l d B i o l . 24: 1-12. S v a r d s o n , G. 1949. C o m p e t i t i o n and h a b i t a t s e l e c t i o n i n b i r d s . O i k o s 1: 157-174. Thomas, J.W. 1973. The d e t e r m i n a t i o n o f h a b i t a t r e q u i r e m e n t s f o r b i r d s i n s u b u r b a n a r e a s - a p i l o t s t u d y . 245 pp. Ph.D. T h e s i s , U n i v . o f M a s s a c h u s e t t s , M a s s a c h u s e t t s . T omoff, C.S. 1974. A v i a n s p e c i e s d i v e r s i t y i n d e s e r t s c r u b . E c o l o g y 55: 396-403. Weber, W.C. 1972. B i r d s i n c i t i e s : a s t u d y o f p o p u l a t i o n s , f o r a g i n g e c o l o g y , and n e s t - s i t e s o f u r b a n b i r d s . 269 pp. M.Sc. T h e s i s , U n i v . o f B r i t i s h C o l u m b i a , B r i t i s h C o l u m b i a . W i l l s o n , M. F. 1974. A v i a n community o r g a n i z a t i o n and h a b i -t a t s t r u c t u r e . E c o l o g y 55: 1017-1029. W o o l f , C. 1968. P r i n c i p l e s o f b i o m e t r y . 359 ,pp. D. Van N o s t r a n d , T o r o n t o . Z a r , J.H. 1974. B i o s t a t i s t i c a l a n a l y s i s . 620 pp. P r e n t i c e -H a l l , New J e r s e y . Appendix 1: Sample of B i r d Census Mapsheet — U ^ r Eaca —i . I i i 1 i ! A/icnt A t ! i J Appendix 2 (a) : Questionnaire - Letter 93. Dear Resident: Birds in c i t i e s are to some people a source of pleasure, but to others a bothersome pest. Studies have shown that urban birds, notably pigeons, are often carriers of diseases deadly to man. As well, these birds sometimes foul stored goods, buildings, statues and destroy crops. Thus they not only damage the visual appearance of c i t i e s but may cause economic loss. On the other hand, birds, especially songbirds, bring a touch of nature to our c i t i e s which many people cherish. These sympathies and the apparent conflict between those who li k e birds and those who don't, led me to commence research at the University of British Columbia on the ecology of city birds. I hope to obtain information on needs and preferences of birds, which could be of use i n environmental planning. During the past year your neighbourhood has been censused regularly for birds. A study of the types of buildings and amount of different types of vegetation has also been made. Perhaps you have noticed either myself or an assistant performing these. Bird censuses w i l l continue through the winter so i f you have not yet seen one of us you may in the near future. You could help out greatly at this stage by responding to the enclosed questionnaire. I am seeking information on the feeding and housing of birds in your yard, as well as on your attitude towards birds. The questions are short and easily answered. A return envelope i s provided for your reply. Your co-operation would be very much appreciated. Thank you. Richard Lancaster Appendix 2(b): Questionnaire - Form QUESTIONNAIRE 94. Please */ where appropriate. Do you provide food for birds? If so, i s this: store bought bird seed? bread table scraps other About how much of this food do you put out in an average month? lbs. What kinds of birds have you noticed eating it? Yes No 2a. What kinds of birds do you most enjoy? b. what kinds of birds do you consider as pests? 3. Do you have any bird houses on your lot? If yes: How many pairs of birds could these accommodate? How many pairs of birds did these house this summer? What kind(s) of birds were these? 4a. Did any birds nest: in or on your house or garage? - how many? - what kind? in your trees, shrubs or garden? - how many? - what kind? b. Did you deter encourage or ignore this nesting? 5a. Would you approve i n principle of programs to increase the abundance of song birds: in the city centre? in residential areas? b. Would you approve in principle of programs to decrease the abundance of birds which are sometimes pests: in the city centre? in residential areas? Thank you very much. 95. Appendix 3. Results of Bird Censuses: Mean Density of each Bird Species (#/40 Hectares) SPRING Plot Species DT FC WE QE MK CW SH UB CP 244 3 72 9 150 0 17 .8 . 0 . 6 8 . 1 S . 7 9 42 8 197 2 57 3 137 4 137 .0 136 3 CM 2 4 HS 51. 4 11 9 83 4 40 1 136 3 44 0 27 8 GWG 8. 6 . 1. 6 1 7 0 6 HF 6. 4 4. 0 59 8 17 2 13 4 8 3 22 7 AR 1. 4 "4. 8 45 5 35 8 45 1 65 7 74 7 32 7 SSP 1 7 0 7 1 1 2 2 OJ -BCC 1 1 1 1 11 0 38 8 RST 0. 7 30 3 NWC 1. 4 0. 6 1 1 13 2 1 2 BB 25 6 0 6 VT 2 2 3 6 RSF 0. 6 VGS 10. 1 9. 3 3 3 3 3 GCK 0. 6 4 5 5. 1 4 8 WW 44 8 SJ EG 1. 5 RG 4. 8 BW 3. 6 HWK RCK 2. 2 3. 7 4. 8 RH 12. 1 WCS 3. 6 1. 1 2 AW 1. 1 1. 5 BS 31. 2 3. 6 6. 1 30. 6 9. 5 2. 4 CBC 2. 4 nv 0. 6 7. 3 AG 0. 8 5. 7 4. 5 0. 8 1. 2 BHC • 0. 8 1. 1 2. 9 7. 3 GCS 1. 1 continued 96. Mean Density of each Bird Species C*/40 Hectares) SPRING (continued) Plot Species DT FC WE QE MK CW SH UB WWA 0.8 2.9 0.6 49.6 46. 2 31. 5 MGW 1.5 YW 1 0.6 3.3 1.5 3. 6 OCW 2.9 OSF 2.2 WT 1.7 3 6 WV 1.7 4 8 PSK SVS FS 1.7 FC 0.6 BHG 9 .7 BTP 1 .2 ST 3 .6 REV 0.7 V DW PF WF -GHO PM PW RBN BT : W HT CWX CS .TOTAL 390.0 140.3 583.2 178.3 391.0 366.5 380.3 260.4 9 7 . Mean Density of each Bird Species (#/40 Hectares) SUMMER Plot Species DT FC WE QE MK CW SH UB CP 250. 6 113 . 6 143 . 1 0.9 7.4 1.9 22.0 S 63. 1 17 .2 101 . 1 82.9 178.0 89. 5 97.1 CM 1 . 2 4.3 HS 51. 9 13 . 7 113 . 3 42.1 *167.6 47.8 45.6 GWG 15. 0 0, . 5 HF 9. 4 3. .0 37, . 4 3. 0 2.2 7.3 51. 2 2.2 AR - 0, .6 19. • 2 20. 6 28.9 54.4 98. 7 18.8 SSP OJ BCC 2. , 5 4. 7 5.9 .17.4 42. 8 68. 9 RST 22.6 NWC 2. 5 1. 8 1.3 2.2 0.8 8.8 BB 7. 0 VT RSF 0.4 . VGS 8. 6 0.9 1.9 3.5 7.6 GCK WW 31.2 SJ EG RG 2. 7 BW 6.5 HWK RCK RH 0.4 2.7 wcs 1.7 0.4 AW BS 0. 6 39. 5 3. 9 9.3 27. 0 .17.6 5.4 CBC TO AG .. 0.9 2.3 1.2 7.5 BHC 0.4 1.2 2.7 GCS 0.4 continued 98. Mean Density of each Bird Species (#/40 Hectares) SUMMER (continued) Plot Species WWA MGW YW OCW OSF WT WV PSK SVS FS FC BHG BTP ST REV V DW PF WF GHO • PM PW RBN BT W HT CWX CS D T FC WE QE MK 1.3 0.9 3.5 0.4 CW 0.4 1.2 SH 0.8 0.8 0.4 0.4 0.4 UB 1.1 2.7 1.1 19.4 5.4 0.5 0.5 7.5 0.5 1.1 0.5 TOTAL 393.8 151.6 468.8 168.4 411.5 253.7 396.8 211.5 99. Mean Density of each Bird Species (It/40 Hectares) FALL Plot Species CP S CM HS GWG HF AR SSP OJ BCC RST NWC BB VT RSF VGS GCK WW SJ EG RG BW HWK RCK 1.9 RH WCS ' 1.0 AW BS CBC TW AG BHC GCS DT . FC WE QE MK CW SH UB 325 0 59 0 128 . 5 4. 2 12 .6 46 7 37 1 149 7 66. 2 137 . 3 115. 3 93 .6 1.2 5.2 40. 0 8. 6 121 4 30.1 103 .6 51. 8 41 5 22. 5 3 0 1. 9 44. 0 9.5 4 5 33. 3 - 8. 1 9.5 22 9 35.1 142. 6 15.7 1. 0 8. 1 6.9 7. 0 6.7 6. 9 0. 8 7. 1 11.2 1. 9 29.2 31. 4 • 4. 1 2.6 16. 5 8.4 25. 1 173. 2 26.6 1. 0 2.6 7. 0 5.0 2. 5 6.1 0.9 0. 6 0.8 8. 8 9.4 44.8 42.4 2.5 0.6 1.2 2.5 3.6 1.2 0.9 5.0 1.3 2.6 0.8 6.0 2.5 . w 3.1 1-0 2.5 5.0 1.9 5-1 1-7 6.4 7.5 2.5 1.9 2.4 0.9 continued 100 . Mean.Density of each Bird Species (#/40 Hectares) FALL (continued) Species Plot DT FC WE QE MK CW SH UB WWA MGW YW OCW OSF WT WV PSK SVS FS FC BHG BTP ST REV V DW PF . WF GHO PM PW RBN . BT W HT cwx CS 15.5 0.9 1.0 0.6 7.0 1.9 0. 6 1.9 31.8 37.1 88.4 1.3 2.5 0.8 20.1 0. 8 4.4 1.3 0.6 1.9 0.9 1.3 2 . 5 * 3.8. 3.3 0.6 7.3 1.2 3.6 3.1 1.2 14.5 TOTAL 435.0 111.3 481.4 173.6 329.2 339.2 472.3 434. 101 Mean Density of each Bird Species (#/40 Hectares) WINTER Plot Species DT FC WE QE MK CW SH UB CP 264 1 57. 4 142 4 2 .6 6 5 12 .9 S 60 4 31. 9 191 4 83 .4 206 . 1 150 9* 88 .9 CM 8. 8 7 .2 0 .4 3 0 HS 52 1 8. 5 110 1 41 S 121 . 2 48 1 13 .9 GWG 22. 9 6. 1 22 6 1 1 4 .1 1 0 0 3 HF 0. 7 32 3 11 1 23 7 5. 0 12 5 AR . 1. 0 34. 2 11 5 31 1 43 1 47 0 13 . 7 SSP 0. 3 11. 3 12 2 14 8 22. 6 21 0 8 1 OJ 17. 1 14. 3 21 9 49. 1 71 7 4 8 BCC 1. 2 3. 6 10 4 4. 0 39 2 124 3 RST 0. 5 1. 0 14 1 NWC 0. 4 3. 5 3. 9 8. 2 7. 0 6. 8 BB 16. 7 VT 1. 6 0. 7 3. 0 15. 2 21. 8 RSF 1. 9 1. 5 .2. 4 0. 8 VGS 0. 4 GCK 5. 4 128. 4 WW 50. 5 SJ 0. 4 0. 3 EG 1. 7 18. 2 RG BW HWK RCK RH WCS AW BS CBC TW AG BHC GCS 0.3 2.4 8.1 0.8 ^ A d j u s t e d f r o m a c t u a l w a s s u b s t i t u t e d . c o u n t c f 3195. T h e m e a n v a l u e f o r t h e s e a s o n c o n t i n u e d 102. M e a n D e n s i t y o f e a c h B i r d S p e c i e s ( #/40 H e c t a r e s ) W I N T E R ( c o n t i n u e d ) • . P l o t S p e c i e s DT FC WE QE MK CW SH UB WWA MGW YW OCW O S F WT WV P S K 1 2 . 5 6 9 . 0 S V S FS 1 . 4 F C BUG B T P ST . . 0 . 8 R E V •: V DW 1 . 0 0 . 4 P F WF GHO PM PW 0 . 4 RBN 0 . 3 BT 7 . 4 5 . 1 W ' •.. HT 0 . 4 CWX 7 . 5 1 0 . 5 CS • T O T A L 4 0 0 . 0 1 1 4 . 8 5 6 7 . 9 1 9 0 . 9 4 7 0 . 9 3 6 6 . 5 3 4 7 . 3 4 7 7 . 1 A p p e n d i x 4: S i g n i f i c a n t C o r r e l a t i o n s b e t w e e n H a b i t a t F e a t u r e s H a b i t a t F e a t u r e s t- 1 > JO . 0 > c-1 nj < + 0 a A V >; • • z tn tn a n. W 0 O A V a A V EV M M tn tn cn tn tn + + * + + + • ft + + + + + + + + + + + + + + + + + + + lit A p p e n d i x 4 ( c o n t i n u e d ) r> M tn V A V a a •n O H a b i t a t t-> M w EE HD o a IJ T? TD TD TD o o < F e a t u r e s cn cn cn td a a tn a •SLANT + + ++ •FLAT ROAD L A N E PVT+S LAWN D<7. 5 + + + + + + + ++ D>7 .5 + + + + + + + + ++ + + + C<7. 5 + + @ + + + + + ++ C>7 . 5 + + + + @ +'+ + + + + + ++ ++ B D E V G " @ D<1. 5 + @ + + + + + @ - + + + . D > 1 . 5 + + + + + + + + + + + ++ + + + + C < 1 . 5 + + + + + + + + + + + @ + + C > 1 . 5 * + + + + + + + ++ E < 1 . 5 + + @ + @ + + + E > 1 . 5 ft + + + + + + + + + + HERB WEED - * + + + + FIID1 * @ + + + + + FHD 2 ft + + + + + + + FIID3 ft + + H F D ft TDD * 8 + TDC * + TDE ft FOOD * T O T V E G * E x p l a n a t i o n o f S y m b o l s ( s e e a l s o T a b l e 1) + = P o s i t i v e c o r r e l a t i o n •+, - = s i g n i f i c a n t a t = . 0 5 - = N e g a t i v e c o r r e l a t i o n ++, - - = s i g n i f i c a n t a t = . 0 1 @ = c o r r e l a t i o n c o e f f i c i e n t g r e a t e r t h a n . 9 8 0 0 A l l m e a s u r e s w e r e s q u a r e r o o t t r a n s f o r m e d p r i o r t o c o r r e l a t i o n e x c e p t f o r FHD , H F D , T D D , T D C , TDE 105. Appendix 5 S t a t i s t i c a l Analyses Analysis of Variance A two factor analysis of variance (,Zar, 19 74) was used to examine the variance within four c h a r a c t e r i s t i c s of plot avifaunas (rising the UBC computing centre program BMD:10V). The c h a r a c t e r i s t i c s analyzed were t o t a l b i r d density, b i r d species d i v e r s i t y , number of species, and evenness of species' abundances. The sources of v a r i a t i o n were p l o t , season, and the interaction of these two. A l l sources of v a r i a t i o n were s i g n i f i c a n t (a = .05), with one exception. There was no s i g -n i f i c a n t change i n evenness with season. Duncan's multiple range tests were performed, to detect the presence of homogeneous subsets of p l o t s , seasons, and plots with respect to season, for the above-mentioned charac-t e r i s t i c s . The results follow in Appendix 5a. Multiple Regression A number of multiple regressions were performed using the TRIP program, also available at the UBC., computing centre. These were forward stepwise regressions and derived predic-tion equations for the following dependent variables: den-s i t y of each species, t o t a l b i r d density, b i r d species div-e r s i t y , evenness, number of species, and average number of species. Four sets of equations were derived for those dep-106 . endent variables which, were present i n every season. The independent variables in these regressions consisted of the percent cover of various habitat features, tree den-s i t y , t o t a l vegetation cover, amount of food supplied inten-t i o n a l l y by man, and a number of habitat d i v e r s i t y indices. Prior to regression, a number of data manipulations were made. Transformations were used to correct deviations from l i n e a r i t y . Both dependent and independent variables (except for d i v e r s i t y indices and tree densities) were transformed by taking the square root. Test runs were made f i r s t with no transformations, then with only the independent variables transformed, and compared to runs with both dependent and independent variables transformed. Transformations of the independent variables alone improved the regression equations 2 (higher r ). The additional transformation of the dependent 2 variables again increased the r in many cases, but not s i g -n i f i c a n t l y . A number of species occurred only or most abundantly i n the woodland plo t . To derive regression equations for these species I regressed the data from a l l eight plots. However, the primary purpose of this analysis was to derive prediction equations for those species which predominated i n urban areas. Therefore regression equations were also calculated with the woodland plot omitted. These sets of regression equations follow i n Appendix 5b. 10,7. A p o s s i b l e s o u r c e o f e r r o r i n t h e s e r e g r e s s i o n s was t h a t p r e d i c t i o n v e c t o r s ( i n d i c e s ) were n o t a l l o r t h o g o n a l . A method known as r i d g e r e g r e s s i o n ( H o e r l and K e n n a r d , 1971) i s t h e r e f o r e s u g g e s t e d f o r f u t u r e r e l a t e d s t u d i e s . No com-p u t e r p r o g r a m was a v a i l a b l e f o r r i d g e r e g r e s s i o n a t t h e t i m e t h a t t h i s s t u d y was c a r r i e d o u t . S e v e n t y - e i g h t p e r c e n t o f t h e s p e c i e s e n c o u n t e r e d i n S p r i n g and W i n t e r , e i g h t y - f o u r p e r c e n t o f t h o s e i n F a l l , and n i n e t y -two p e r c e n t o f t h o s e i n Summer were r e g r e s s e d s i g n i f i c a n t l y (a = . 0 5 ) . Those n o t p r e d i c t e d s i g n i f i c a n t l y were s p e c i e s w h i c h h a d a low mean abundance ( l e s s t h a n 1 p e r 40h) o r a low f r e q u e n c y o f o c c u r r e n c e ( f e w e r t h a n t h r e e s i g h t i n g s p e r s e a s o n ) , i n most c a s e s . The i n d i c e s most f r e q u e n t l y c h o s e n as t h e f i r s t e l e m e n t o f t h e r e g r e s s i o n e q u a t i o n s were: r o a d , t r e e s , s m a l l d e c i d u o u s s h r u b s , weeds, and f o o d p r o v i d e d by human r e s i d e n t s . 108. Appendix 5a Results of Multiple Range Tests The results of these tests, as summarized here, i n d i -cate s t a t i s t i c a l l y s i g n i f i c a n t s i m i l a r i t i e s among Plots and Seasons with respect to the mean values of the following b i r d community indices. B i r d Species Diversity (H 1) Evenness (J') Species Richness (S) Total Bird Density The following abbreviations are used. DT - Downtown FC - False Creek WE - West End QE - Queen Elizabeth MK - MacKenzie CW - Collingwood SH - Shaughnessy UB - U.B.C. p - Spring s - Summer f - F a l l w - Winter a l l - a l l Seasons i. Oi). A p p e n d i x 5a ( c o n t i n u e d ) Duncan's M u l t i p l e Range T e s t - R e s u l t s S i g n i f i c a n c e l e v e l f o r a l l t e s t s : a = .05 B i r d S p e c i e s D i v e r s i t y ( I I 1 ) Groups o f S i m i l a r P l o t s 1) . DT, FC 2) MK, QE 3) QE, CW, WE 4) UB, SU Groups o f S i m i l a r S e a s o n s 1) Summer, F a l l , W i n t e r 2) S p r i n g P l o t - S e a s o n I n t e r a c t i o n Groups 1) I'Cfs, f ) , D T ( s , f , w) 2) D T ( a l l ) , FC(.p, f ) 3) DT(p, f , w) , F C ( p , £, w) . 4)' DT(p) ,. FC.Cp, f , w) , MK(.s) 5) FC(p, w) , Q E ( s ) , M K ( s , f ) , U B ( f ) ' 6) . QE(.s), M K ( s , f ) , CW(w) , U B ( f ) 7) W l i ( f ) , Ql-:(s, w ) , MK(p, f, w)., CVv(w) , UB ( f ) 8) W l i ( a l l ) , Ql.!(p, ,.f, w) , MK(|», f, w ) , CW(.r.l.l), l)B(. f, w) 9) WIi(p, s, w ) , . Q E ( p , f ) , CW(p, f ) , S H ( a l l ) , UB(vv) 10) CW(f) , SI I ( a l l ) . , U B (s) 11) SI I ( a l i ) , UB(p, s) 110. Evenness (J*) Groups of Similar Plots 1) MK, FC 2) FC, CW 3) CW, UB, QE, SH, WE (highest) 4) DT (lowest) Groups of Similar Seasons 1) Spring, Summer, F a l l , Winter Plot - Season Interaction Groups 1) DT(all), FC (s), MK(s), UB (f) 2) DT(p, w), FC(s), MK(s), CW(w) , UB (f) 3) DT(p, w), FC(p, f, w), WE(f), QE(s), MK(all), CW(p, f, w), SH(p, f ) , UB(f) 4) DT(p, w), FC(p, f, w), WE(f), QE (s, f, w) ,-MKCp, f, w), CWCp, f, w), SH(p, f ) , UBCf, w) 5) DT(p), FC(p, f, w), WE(p, f, w), QE(_all), MKCp, f, w) , CW(_all), SH(all), UBCp, f, w) 6) FC(p, f, w), WE C a l l ) , QE Cp, £, w) , MKCp, f) , CW(p, s, f ) , SH(all), UB(p, s, w) Species Richness (S) Groups of Similar Plots 1) FC, DT 2) QE, MK, WE 3) MK, WE, CW 111. 4) UB 5) SH Groups of Similar Seasons 1) Summer, Winter, F a l l 2) Spring Plot - Season Interaction Groups 1) DT(p, f, w), FC(all) 2) DT(all) , FC(.P, W) 3) DT (p, s, f) , FC(p, f, v\, QECs) 4) DT(p, s ) , QE(p, s ) , MK(s), CW(s) 5) DT(s), WECs), QE(p, s, w) , MK(s, f) , CWCs) 6) WE (s , £, w) , QE(all) , MK (p, s, f) , ..CW(s , w) , UB(f) 7) WE C a l l ) , QECp, f, w) , MK(jp, f, w), CW(w) , UB (f). 8) WE(p, f, w), QE(f), MK(jp, f, w) , CW(p, £, w)., SH(s), UB(f, w) 9) MK(w), CW(p, f ) , SH(s, w), UB(s, f, w) 10) SH(£, w), UB(s) 11) SH(f), UB(p, s) 12) SH(p, f) , UB(.p) Total Bird Density Groups of Similar Plots 1) FC, QE 2) UB, CW, SH, MK, DT 3) WE 112. Groups o f S i m i l a r S e a s o n s 1) Summer, S p r i n g , F a l l 2) S p r i n g , F a l l , W i n t e r P l o t - S e a s o n I n t e r a c t i o n Groups 1) DTCp, s, W), F C ( a l l ) , Q E ( a l l ) , MK(.p, s, f ) , : CW(p, s, f ) , SHCp, W) 2) WE(s, f ) , QECp, f , w), N K C a l l ) , CW(p, s, f ) , S H ( a l l ) , U B C a l l ) , D T C a l l ) 3) D T ( a l l ) , W E C a l l ) , M K C a l l ) , CW(.p, f ) , S H ( a l l ) , UB(p, f , w) 4) D T ( a l l ) , W E C a l l ) , MK(p, s, w) , CW(w) , SHCp, s, f ) , U B ( f , w) 1 1 3 . A p p e n d i x 5b M u l t i p l e R e g r e s s i o n R e s u l t s : ... R e g r e s s i o n o n s e v e n p l o t s ; U . B . C . p l o t o m i t t e d R e s u l t s f r o m a l l s e a s o n s f o r e a c h s p e c i e s a r e p r e s e n t e d h e r e i n t h e o r d e r : S p r i n g , S u m m e r , F a l l , W i n t e r . T h e r e w e r e 28 p o t e n t i a l i n d e p e n d e n t v a r i a b l e s i n t h i s a n a l y s i s ( s e e T a b l e 1 ) . S p e c i e s R p r o b a b i l i t y E q u a t i o n ( v a r i a b l e s r a n k e d m o s t s i g n i f i c a n t t o l e a s t s i g n i f i c a n t ) CP . 84 . 0 0 14 . . 99 1 1 . . 70 D * 1 . 5 1 . 0 0 . 0 1 1 3 . . 0 8 - 1 5 , . 95 D>1 . 5 + 2 4 . 2 4 E < 1 . S - 6 . 1 7 C < 1 . 5 . 81 . 0 1 1 5 , . 6 7 - 1 2 , , 9 3 D>1. 5 . 9 5 . 0 0 7. . 09 - 1 9 . , 92 D>1 .5 + 3 3 . 8 7 E < 1 . 5 s . 75 . 01 7, . 55 + 0. . 29 RDC . 6 6 . 0 3 2. . 11 + 1 7 , , 1 3 E < 1 . S . 72 . 0 2 6, . 96 + 0, . 25 TDC . 5 7 . 0 5 5. . 22 + 1 1 . . 23 D<1. 5 CM . 9 2 . 0 1 1. ,41 _ 6. . 11 E < 1 . 5 + 1 . 0 6 HERB . 72 . 0 2 2. . 44 - 3. , 16 WEED . 9 3 . . 0 1 1. . 34 - 3. . 30 WEED + 2 . 3 9 C < 1 . 5 N . S . HS N . S . N . S . N . S . . 80 . 0 1 - 9 . , 58 + 7. .11 L A N E GWG . 9 6 . 0 0 - 5 . , 33 + 1. .19 PVTS-S + 3 . 9 0 D<1 .5 . 9 9 . 0 1 - 9 . 42 + 1. 49 P V T 5 S + 1 2 . 8 7 E < 1 . S - 1 . 8 2 E > 1 . 5 . 6 3 . 0 3 5. ,06 - 3. , 34 HERB . 78 . 0 1 6. , 85 - 3. 61 HERB H F 1 . 0 0 . 0 1 4 . 9 3 + 30 TDC - 2 . 6 9 WEED 1 .2 0 HERB -. 1 3 LAWN . 9 8 . 0 0 - 6 . 0 8 + 4 . 46 BDEVG + 3 . 8 4 L A N E . 72 . 0 2 0 . ,08 + 28 TDC . 79 . 0 1 0 . , 78 + 23 TDC 114. S p e c i e s R 2 p r o b a b i l i t y E q u a t i o n ( v a r i a b l e s r a n k e d m o s t s i g n i f i c a n t t o v l e a s t s i g n i f i c a n t . . _ oo . 0 1 4 . 4 9 + 7 . 8 2 FHD2 + 1 . 0 8 TDC - 2 . 2 8 H F D A R i o o 00 - . 5 4 +. 5 . 5 4 0 1 . . 5 + . 3 4 LAWN - 9 6 . 0 0 - . 7 8 + 7 . 5 7 C > 7 . 5 [99 . 00 - 2 . 5 3 + . 2 2 TDC .+ 3 . 6 9 HERB _ _ _ _ _ _ S S P . 6 9 . 0 2 0 . 0 3 + . 0 7 TDC , -• 1 . 0 0 . 9 6 . 0 0 . 0 0 6 . 7 7 -- 2 . 0 2 + 1 . 0 6 P V T S S -3 . 0 9 HERB + . 1 . 8 3 D>1 . 5 + 1 . 2 4 D < 1 . 5 . 12 TDC .' O J . 9 7 1 . 0 0 . 0 0 . 0 1 1 2 . 4 0 -- 5 . 2 6 + 2 . 9 2 ROAD + . 1 4 TDC + 1 . 7 4 D > 7 . 5 . 4 4 D<7...5 + 2 . 0 5 H E R B + .-. . B C C . 9 1 1 . 0 0 . 9 9 . 74 . 0 0 . 0 0 . 0 0 . 0 1 - . 8 0 + - . 8 1 + - . 3 9 + - 1 . 0 2 + 3 . 8 6 E > 1 . 5 2 . 8 6 C > 7 . 5 + . 2 0 FOOD + 1 . 7 6 D<7 . 5 . 8 0 D<7 . 5 1 . 3 9 C > 7 . 5 + 1 . 1 4 B D E V G RST . 9 3 . 0 1 0 . 5 0 -1 . 2 2 WEED + . 8 8 C < 1 . 5 1 . 0 0 . 0 1 - . 6 4 + . 7 2 D < 7 . 5 + . 0 9 F L A T - .1.6.3 E < 1 . 5 +. . . NWC . 83-. 8 5 . 70 . . 9 3 . 0 1 . 0 0 . 0 2 . 0 0 - . 6 5 + 6 . 6 0 -- . 1 4 + - . 4 0 + 3 . 9 0 E > 1 . 5 2 . 4 2 L A N E . 1 7 FOOD 4 . 8 1 D < 1 . 5 BB '. 1 . 0 0 1 . 0 0 1 . 0 0 1 . 0 0 . 0 0 . 0 8 . 0 1 . 0 1 0 . 3 1 + 1 . 3 4 + 0 . 8 1 + - 1 . 2 1 + . 3 9 FOOD -. 2 7 FOOD -. 1 6 FOOD -. 3 8 FOOD -5 . 8 9 C < 1 . 5 + . 1 3 F L A T . 3 2 LAWN - . 7 1 H F D . 1 9 LAWN - . 4 3 H F D . 2 7 T O T V E G - . 1 8 LAWN VT 1 . 0 0 . 0 0 0 . 4 9 + . 8 2 B D E V G • - . 4 2 L A N E + ' .23 H F D 1 . 0 0 . 0 1 - 6 . 5 9 - 1 . 4 2 LAWN + 1 . 6 1 T O T V E G + 2 . 5 3 L A N E R S F 1 . 0 0 1 . 0 0 . 8 5 . 71 . 0 1 . 0 0 . 0 0 . 0 2 0 . 3 8 + 0 . 2 1 + - . 5 1 + - . 4 5 + . 0 8 FOOD -. 3 5 B D E V G 3 . 2 0 E > 1 . 5 . 5 9 D < 7 . 5 . 0 9 LAWN - . 2 0 H F D - . 1 8 L A N E + . 1 0 H F D 115. Species R2 probability Equation (variables ranked most significant to least significant VGS 1.00 .01 1 . 73 + .98 LAWN - 4.01 D>1.5 - 1.47 WEED-1.00 .00 - .21 + .10 TDC + 18 D>7.5 + .01 TDD 1.00 .01 .19 + .06 FOOD - .04 TOTVEG -* .03 LAWN + GCK .97 .00 - .57 + 3.18 E>1. 5 1.00 .00 1 .02 + 1. 70 BDEVG • .8 7 LANE + .49 HFD .94 .01 - .41 + .60 TOTVEG - .64 LAWN SJ - - -. 73 .02 _ .25 + . -45 D>7.5 N .S. EG 1.00 .00 0 .40 + .67 BDEVG - .34 LANE + .19 HFD 1. 00 .00 0 .53 + .87 BDEVG : .45 LANE + .25 HFD 1.00 .00 0 .43 + . 72 BDEVG - .37 LANE + .21 HFD RCK . 88 .00 - .58 + 2.61 E>1.5 N .s. 1.00 .00 0 .18 + .30 BDEVG • .16 LANE + .09 HFD RH . 1.00 .01 0 .31 + .06 FOOD - .07 LAWN - .16 HFD - • 1.00 .00 0 .92 - 3.17 WEED + .91 FHD3 + .18 D>7.5 WCS N .s. . 88 .02 1 .14 - 1.90 WEED + .05 FOOD N .s. AW . S5 .00 - .37 + 1.69 E>1. 5 .97 .00 - .65 + 6.80 D<1.5 • 3.61 C>1.5 BS .98 .00 13 .43 + . 6. 75 FHD3 + 3.23 LANE • .81 .01 0 .62 + . 26 TDC 1.00 .01 -1 .11 + 7. 50 D<1.5 - .61 D<7.5 + .90 WEED -116. S p e c i e s R p r o b a b i l i t y E q u a t i o n ( v a r i a b l e s r a n k e d m o s t s i g n i f i c a n t t o l e a s t s i g n i f i c a n t TW N . S . 1 . 0 0 . 0 0 0 . 4 6 + . 7 6 B D E V G - . 3 9 L A N E + . 2 2 H F D A G . 9 1 . 0 1 - 2 . 1 9 + 8 . 9 5 C < 1 . 5 - . 1 0 TDC . 7 4 . 0 1 4 . 7 7 - 1 . 1 8 RAOD . 9 3 . 0 1 0 . 5 5 - 1 . 3 5 WEED + . 9 8 C < 1 . 5 BHC . 8 7 . 0 0 - 5 . 2 4 + 3 . 2 0 H F D . 9 3 . 0 0 - . 3 3 + 1 . 4 1 E > 1 . 5 GCS N . S . 1 . 0 0 - 0 1 0 . 3 1 + . 0 6 FOOD - . 0 7 LAWN - . 1 6 H F D -WWA 1 . 0 0 . 0 1 - 1 . 8 5 + 2 . 0 3 D>7 .5 - . 0 9 TDC + 1 . 0 7 D < 7 . 5 + N . S . . 8 6 . 0 0 - - 1 . 8 9 + 2 . 4 3 D < 7 . 5 MGW 1 . 0 0 - . 0 1 0 . 4 0 + . 6 7 B D E V G - . 3 4 L A N E + . . 1 9 H F D 1 . 0 0 . 0 0 0 . 3 0 + . 4 9 B D E V G - . 2 5 L A N E + . 1 4 H F D . 9 3 . 0 1 0 . 5 5 - 1 . 3 5 WEED + . 9 8 C < 1 . 5 YW '. . 75 . 01 . - 1 . 32 + 1 . 50 HERB 1 . 0 0 . 0 0 0 . 3 7 + . 6 2 B D E V G - . 3 2 L A N E + . 1 8 H F D OCW 1 . 0 0 0 . 5 7 + . 9 5 B D E V G - . 4 9 L A N E + . 2 7 H F D 117. S p e c i e s R p r o b a b i l i t y E q u a t i o n ( v a r i a b l e s r a n k e d m o s t s i g n i f i c a n t t o . l e a s t s i g n i f i c a n t , ji :  O S F 1 . 0 0 . 0 0 0 . 4 9 + . 8 2 B D E V G - . 4 2 L A N E + . 2 3 H F D 1 . 0 0 . 0 0 0 . 7 0 + 1 . 1 6 BDEVG - . 6 0 L A N E + . 3 3 H F D WT N . S . N . S . WV N . S . P S K . 99 . 9 9 . 01 . 0 1 N . S . - 2 . 9 2 + 2 . 4 9 L A N E + 1 . 0 8 B D E V G - 1 . 3 9 H F D 0 . 1 6 + . 3 2 FOOD - . 6 9 LAWN + 3 . 0 2 C > 1 . 5 S V S . 6 6 . 0 3 - . 2 7 + . 0 8 FOOD FS 1 . 0 0 1 . 0 0 N . S . . 0 0 . 0 0 0 . 4 1 + . 0 8 FOOD - . 1 0 LAWN + . 2 1 H F D -0 . 3 9 + . 6 5 B D E V G - . 3 3 L A N E + . 1 9 H F D FC N . S . 1 . 0 0 . 0 0 0 . 2 1 + . 3 5 B D E V G - . 1 8 L A N E + . 1 0 H F D 1 . 0 0 . 0 0 0 . 2 6 + . 4 4 B D E V G - . 2 2 LANE + . 1 3 H F D B T P - - -. 6 8 . 0 2 - 2 . 0 4 + 1 . 2 3 H F D . 6 0 . 0 4 - . 6 1 + 1 . 1 0 D>7 . 5 118. S p e c i e s R p r o b a b i l i t y E q u a t i o n ( V a r i a b l e s r a n k e d m o s t s i g n i f i c a n t t o l e a s t s i g n i f i c a n t . . V 1 . 0 0 . 0 0 0 . 2 8 + . 4 7 BDEVG - . 2 4 L A N E + . 1 4 H F D N . S . DW 1 - 0 0 . 0 1 0 . 70 + . 14 FOOD - . 1 7 L A M - . 3 7 H F D N . S . PF --- . ' . 7 3 . 0 2 3 . 2 1 - . 7 9 ROAD PM 1 . 0 0 . 01 - 2 . 85 + . 4 5 P V T 5 S + 3 . 9 3 E < 1 . 5 - . 2 5 C > 7 . 5 -RBN 1 . 0 0 . . 0 0 0 . 5 9 + . 9 8 BDEVG - . 5 0 L A N E + . 2 8 H F D 1 . 0 0 . 0 0 0 . 1 8 + . 3 0 B D E V G - . 1 6 L A N E + . 0 9 H F D B T - - -N . S . W - - - -• 9 7 . 0 0 1 . 3 9 + 1 . 2 5 HERB - . 9 2 L A N E . N . S . •99 . 0 1 - . 9 8 + . 8 4 L A N E + . 3 6 B D E V G - . 4 7 H F D CWX ' N . S . 119. S p e c i e s R p r o b a b i l i t y E q u a t i o n ( v a r i a b l e s r a n k e d m o s t s i g n i f i c a n t t o l e a s t s i g n i f i c a n t cs 1, .00 . 0 1 0 . 4 1 + . 0 8 FOOD - . 1 0 LAWN - . 2 1 H F D -#/40 N . S . N . S . , 8 8 . 0 2 - 1 6 7 2 . 6 9 + 1 2 1 0 . 8 3 H F D - 1 3 3 . 0 1 D>7. 5 N . S . B S D ,95 . 0 0 1, . 0 8 + . 56. C < 7 . 5 9 3 . 0 0 0, . 89 + . 0 2 TDD 9 8 . 0 0 0, .61 + . . 2 1 T O T V E G - . 0 3 FOOD 92 . 0 0 1. . 0 8 + . 5 8 C < 7 . 5 STOT 99 .0.1 1 1 . , 59 + 9 . 8 0 C > 7 . 5 - 6 . 9 5 WEED - 1 . 3 6 D > 7 . 5 1 . 00 . 0 1 1 0 . . 20 + 21 . 51 E > 1 . 5 + 2 . 1 0 L A M - 1 0 . 4 1 FHD3 + 9 3 . 0 0 3. . 78 + 14 . 0 8 FHD2 S A V 1 . 00 . 0 1 4. .11 + 2 . 9 3 B D E V G + 5 . 8 2 D < 1 . 5 - 2 . 8 7 C < 1 . 5 +.. 74 . 0 1 4 . , 34 + 2 . 74 C>7 . 5 96 . 0 0 1. ,11 + 5 . 2 4 E > 1 . 5 + 8 . 6 0 C < 1 . 5 • 85 . 0 0 3. , 4 3 + 5 . 55 FHD2 J 1 . 00 . 0 1 0 . 51 + . 50 C < 1 . 5 - . 0 0 3 TDD + . 0 7 . B D E V G 6 8 . 0 2 0 . 4 6 + . 01 TDD 1 . 00 . 0 1 0 . 4 8 - . 02 FOOD + . 0 4 LAWN + . 0 8 E > 1 . 5 + • 71 . 0 2 0 . 62 + . 0 5 C<7 . 5 N o t e : T h e f o l l o w i n g w a r n i n g m e s s a g e s w e r e g e n e r a t e d b y t h e c o m p u t e r . S u m m e r : FHD2 w a s a l i n e a r c o m b i n a t i o n o f o t h e r i n d e p e n d e n t v a r i a b l e s . F a l l : C < 7 . 5 w a s a l i n e a r c o m b i n a t i o n o f o t h e r i n d e p e n d e n t v a r i a b l e s . 

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