SPECIES ASSESSMENT FOR BREWER ’S SPARROW (SPIZELLA BREWERI ) IN WYOMING prepared by 1 2 PAULA L. HANSLEY AND DR. GARY P. BEAUVAIS 1 545 West Fir Way, Louisville, Colorado 80027 2 Wyoming Natural Diversity Database, University of Wyoming, Dept. 3381, 1000 E. University Ave., Laramie, WY 82071, 307-766-3023 prepared for United States Department of the Interior Bureau of Land Management Wyoming State Office Cheyenne, Wyoming September 2004 Hansley and Beauvais – Spizella breweri September 2004 Table of Contents INTRODUCTION ...............................................................................................................................................3 NATURAL HISTORY ........................................................................................................................................3 Morphological Description ...................................................................................................... 3 Vocalization ....................................................................................................................................5 Taxonomy and Distribution ..................................................................................................... 6 Taxonomy .......................................................................................................................................6 Distribution and Range....................................................................................................................8 Breeding Range ........................................................................................................................8 Winter Range............................................................................................................................9 Casual Records .........................................................................................................................9 Historical Records ..................................................................................................................10 Habitat Requirements............................................................................................................10 Breeding ........................................................................................................................................10 Migration.......................................................................................................................................12 Winter............................................................................................................................................12 Area Requirements........................................................................................................................13 Landscape Pattern .........................................................................................................................13 Movement and Activity Patterns ............................................................................................14 Dispersal........................................................................................................................................14 Migration.......................................................................................................................................14 Daily Activity................................................................................................................................15 Reproduction and Survivorship..............................................................................................16 Breeding Behavior.........................................................................................................................16 Breeding Phenology ......................................................................................................................17 Fecundity and Survivorship ..........................................................................................................18 Population Demographics......................................................................................................18 Limiting Factors............................................................................................................................18 Metapopulation Dynamics ............................................................................................................19 Genetic Concerns ..........................................................................................................................20 Food Habits...........................................................................................................................20 Food Items.....................................................................................................................................20 Foraging Strategy..........................................................................................................................21 Foraging Variation ........................................................................................................................21 Community Ecology...............................................................................................................21 Predation .......................................................................................................................................21 Competition...................................................................................................................................22 Parasites and Disease ....................................................................................................................22 Symbiotic and mutualistic interactions .........................................................................................23 CONSERVATION ............................................................................................................................................23 Conservation Status ..............................................................................................................23 USDI Fish and Wildlife Service....................................................................................................24 USDI Bureau of Land Management..............................................................................................24 USDA Forest Service....................................................................................................................24 State Wildlife Agencies.................................................................................................................25 State Natural Heritage Program ....................................................................................................25 Other..............................................................................................................................................26 Page 1 of 49 Hansley and Beauvais – Spizella breweri September 2004 Biological Conservation Issues..............................................................................................26 Abundance.....................................................................................................................................26 Trends............................................................................................................................................27 Abundance Trends..................................................................................................................27 Extent and Connectivity Trends .............................................................................................27 Habitat Trends ........................................................................................................................28 Range Context...............................................................................................................................28 Extrinsic Threats and Reasons for Decline ...................................................................................29 Anthropogenic Impacts...........................................................................................................29 Stochastic Factors (e.g., weather events)................................................................................32 Natural Predation....................................................................................................................33 Protected Areas.......................................................................................................................33 Intrinsic Vulnerability ...................................................................................................................33 Habitat Specificity ..................................................................................................................33 Territoriality and Area Requirements.....................................................................................34 Susceptibility to Disease.........................................................................................................34 Disperal Capability.................................................................................................................34 Reproductive Capacity............................................................................................................34 Sensitivity to Disturbance.......................................................................................................34 Genetic Factors .......................................................................................................................34