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Transcript of INTRODUCED RED FOX IN CALIFORNIA - Morro 2016. 9. 30.¢  Introduced red fox have...

  • State of California The Resources Agency

    Department of Fish and Game Wildlife Management Division

    INTRODUCED RED FOX IN CALIFORNIA

    by

    Jeffrey C. Lewis Kevin L. Sallee

    and Richard T. Golightly Jr.

    1993

    Nongame Bird and Mammal Section Report 93-10

  • FINAL REPORT TO

    California Department of Fish and Game 1416 Ninth Street

    Sacramento, CA 95814

    CONTRACT FG8612 (FY90/92)

    Partially Supported by California Endangered Species Income Tax Check-off Program (FY88/89); Pittman-Robertson Federal Aid in Wildlife Restoration (FY90/91, W-65-R-8, Job V-l); and California Environmental License Plate Fund (FY91/92),

    Nongame Bird and Mammal Section, Wildlife Management Division.

    INTRODUCED RED FOX IN CALIFORNIA

    CONTRACTOR

    Department of Wildlife, Humboldt State University

    Arcata, CA 95521

    AUTHORS

    Jeffrey C. Lewis Kevin L. Sallee

    and Richard T. Golightly Jr.

  • State of California The Resources Agency

    Department of Fish and Game

    INTRODUCED RED FOX IN CALIFORNIA

    by

    Jeffrey C. Lewis Kevin L. Sallee

    and Richard T. Golightly Jr.

    Department of Wildlife Humboldt State University

    Arcata, CA 95521

    ABSTRACT

    I n a t e l e p h o n e s u r v e y o f w i l d l i f e p r o f e s s i o n a l s i n C a l i f o r n i a , introduced red fox were reported from 36 of 58 (62%) c o u n t i e s i n C a l i f o r n i a . The in t roduced red fox ranged a long the Pacific coast from southern San Diego County to Marin County. They were reported in western Riverside County northward through t h e S a c r a m e n t o v a l l e y a n d w e s t e r n S i e r r a f o o t h i l l s t o c e n t r a l Shasta County. Popula t ions were cont iguous in urban a reas and may be cont iguous in rura l a reas as wel l . T h e d i e t o f t h e in t roduced red fox in the urban envi ronment was d iverse and cons is ted of b i rds , mammals , insec ts , seeds , f ru i t and human foods . Among radio-collared foxes (n = 23) in urban Orange C o u n t y , C a l i f o r n i a , f e m a l e s h a d t h e g r e a t e s t s u r v i v a l r a t e f o r b o t h j u v e n i l e s a n d a d u l t s . O v e r a l l , d i s p e r s i n g j u v e n i l e s h a d t h e g r e a t e s t m o r t a l i t y r a t e . Sources of mor ta l i ty for urban foxes i n c l u d e d c o l l i s i o n s w i t h a u t o s , d i s e a s e , a n a t t a c k b y a d o g , a n d a c c i d e n t s o t h e r t h a n v e h i c l e c o l l i s i o n s . Juveni le males were the m o s t l i k e l y t o d i s p e r s e . A v e r a g e d i s p e r s a l d i s t a n c e f o r a l l success fu l d i spersers was 9 .8 ± 1 .85 km (6 .1 ± 1 .15 mi . ) . Three o f t h e r a d i o - c o l l a r e d f o x e s w e r e k n o w n t o h a v e b r e d t h e i r f i r s t y e a r . A v e r a g e l i t t e r s i z e w a s 4 p u p s p e r l i t t e r ( n = 7 l i t t e r s ) i n 1 9 9 1 a n d 3 p u p s p e r l i t t e r ( n = 5 l i t t e r s ) i n 1 9 9 2 . Urban foxes were found to use a l l aspec ts of the urban envi ronment , f rom open f ie lds and beaches to res ident ia l deve lopments . C o r r i d o r s f o r t r a v e l f o r b o t h r e s i d e n t a n d d i s p e r s i n g f o x e s i n c l u d e d f l o o d c h a n n e l s , b e a c h s t r a n d s , r a i l r o a d t r a c k s , a n d p o w e r l i n e c o r r i d e r s . R e d f o x d e n s i t i e s v a r i e d b e t w e e n s i t e s .

  • TABLE OF CONTENTS

    I n t r o d u c t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    Red Fox Dis t r ibu t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Red Fox Food Habits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Popula t ion Informat ion and Dispersa l . . . . . . . . . . . . . . . . . . . . .

    R e s u l t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Red Fox Dis t r ibu t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Red Fox Food Habits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Red Fox Population Information . . . . . . . . . . . . . . . . . . . . . . . . . . .

    Fox Capture and Tagging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Su rv iva l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M o r t a l i t y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dens i ty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D i s p e r s a l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reproduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    Home Range and Land-Parcel Use . . . . . . . . . . . . . . . . . . . . . . . . . . . Movements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    Discuss ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Red Fox Dis t r ibu t ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    S t a t e - w i d e D i s t r i b u t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L o c a l D i s t r i b u t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    P o p u l a t i o n C h a r a c t e r i s t i c s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dens i ty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D i s p e r s a l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Su rv iva l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    Red Fox Use of Land and Food Resources . . . . . . . . . . . . . . . . . . . Use of Land Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Use of Food Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cooperators and Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . L i t e r a t u r e C i t e d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F i g u r e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    Page 1 3 4 4 4 5 7 7 8 9 9 9 9

    10 10 11 12 13 14 14 14 1 6 17 17 18 2 0 2 1 2 1 22 2 6 2 7 2 8 34 4 8 5 7

  • INTRODUCTION

    I n C a l i f o r n i a , t h e r e d f o x ( V u l p e s v u l p e s ) h a s b e e n repor ted to be na t ive to the S ier ra Nevada and southern Cascade M o u n t a i n s ( G r i n n e l l e t . a l . 1 9 3 7 ) . However, s i n c e t h e 1 8 9 0 ' s t h e red fox has been found in severa l a reas of Cal i forn ia which were n o t p a r t o f i t s h i s t o r i c a l r a n g e ( G r i n n e l l e t a l . 1 9 3 7 ) ; t h e s e foxes were probably fur fa rm escapees , fox hunt surv ivors , and i n t e n t i o n a l l y - r e l e a s e d p e t s o r c a p t i v e s t h a t h a v e e s t a b l i s h e d b r e e d i n g p o p u l a t i o n s . Based on morphologica l parameters , the introduced foxes from the Sacramento Valley appear more closely r e l a t e d t o t h e N o r t h e r n G r e a t P l a i n s s u b s p e c i e s o f r e d f o x ( V . v . r e g a l i s ) r a t h e r t h a n t h e S i e r r a N e v a d a r e d f o x ( V . v . n e c a t o r ) (Roest 1977).

    In t roduced red fox have es tab l i shed breeding popula t ions throughout the Sacramento Valley (Gray 1975, 1977). Gould (1980) repor ted the range expans ion of th i s popula t ion in to Cont ra Cos ta and Alameda counties, a s w e l l a s a d d i t i o n a l s i g h t i n g s i n M a r i n , Santa Cruz , Ventura , and Los Angeles counties.

    I n t r o d u c e d r e d f o x e s a r e c o n s i d e r e d a t h r e a t t o p o p u l a t i o n s o f e n d a n g e r e d w i l d l i f e i n c l u d i n g t h e l i g h t - f o o t e d c l a p p e r r a i l ( R a l l u s l o n a g i r o s t r i s l e v i p e s ) , t h e C a l i f o r n i a c l a p p e r r a i l ( R a l l u s l o n g i r o s t r i s o b s o l e t u s ) , t h e C a l i f o r n i a l e a s t t e r n (Sterna an t i l l a rum browni ) , the sa l t marsh harves t mouse (Rei throdontomys rav ivent r i s ) , Belding's Savannah sparrow (Passercu lus sandwichens is be ld ingi ) (U. S . F ish and Wild l i fe Service and U. S. Navy 1990, U. S . F ish and Wild l i fe Serv ice 1990), and the San Joaquin k i t fox (V. macrot i s mut ica) (Ral l s e t . a l . 1 9 9 0 )