SPECIES ASSESSMENT FOR DWARF SHREW (SOREX NANUS ) IN WYOMING prepared by DR. GARY P. BEAUVAIS 1 AND DARBY N. DARK -SMILEY 2 1 Director, Wyoming Natural Diversity Database, University of Wyoming, 1000 E. University Ave, Dept. 3381, Laramie, Wyoming 82071; 307-766-3023; [email protected] 2 Wyoming Natural Diversity Database, University of Wyoming, 1000 E. University Ave, Dept. 3381, Laramie, Wyoming 82071; 307-766-3023 By Summers Scholl (2001) Wyoming Natural Diversity Database For non-profit use only; please use full citation For other uses, contact us at [email protected] prepared for United States Department of the Interior Bureau of Land Management Wyoming State Office Cheyenne, Wyoming December 2003 Beauvais and Dark-Smiley – Sorex nanus December 2003 Table of Contents INTRODUCTION ................................................................................................................................. 3 NATURAL HISTORY ........................................................................................................................... 3 Morphological Description ...................................................................................................... 3 Taxonomy and Distribution ..................................................................................................... 5 Taxonomy .......................................................................................................................................5 Distribution .....................................................................................................................................5 Habitat Requirements............................................................................................................. 7 Year-round ......................................................................................................................................7 Territoriality and Area Requirements..............................................................................................8 Landscape Pattern ...........................................................................................................................8 Movement and Activity Patterns ............................................................................................. 9 Daily Activity..................................................................................................................................9 Broad-scale Movement Patterns......................................................................................................9 Reproduction and Survivorship............................................................................................... 9 Breeding Behavior and Phenology..................................................................................................9 Fecundity and Survivorship ..........................................................................................................10 Population Demographics......................................................................................................10 Limiting Factors............................................................................................................................10 Metapopulation Dynamics ............................................................................................................11 Genetic Concerns ..........................................................................................................................11 Food Habits...........................................................................................................................11 Food items.....................................................................................................................................11 Foraging Strategy..........................................................................................................................12 Community Ecology...............................................................................................................12 Predators........................................................................................................................................12 Competitors...................................................................................................................................12 Parasites and Disease ....................................................................................................................13 Symbiotic and Mutualistic Interactions.........................................................................................13 CONSERVATION .............................................................................................................................. 13 Conservation Status ..............................................................................................................13 Federal Endangered Species Act...................................................................................................13 Bureau of Land Management........................................................................................................13 Forest Service................................................................................................................................14 State Wildlife Agencies.................................................................................................................14 Heritage Ranks and Wyoming Contribution Rank........................................................................14 Biological Conservation Issues..............................................................................................15 Abundance.....................................................................................................................................15 Trends............................................................................................................................................16 Abundance..............................................................................................................................16 Population Extent and Connectivity .......................................................................................16 Habitat Availability ................................................................................................................17 Range Context...............................................................................................................................17 Extrinsic Threats and Reasons for Decline ...................................................................................17 Anthropogenic Impacts...........................................................................................................17 Invasive Species......................................................................................................................17 Genetic Factors .......................................................................................................................17 Page 1 of 27 Beauvais and Dark-Smiley – Sorex nanus December 2003 Stochastic Factors ...................................................................................................................18 Natural Predation....................................................................................................................18 WYNDD Extrinsic Threat Rank.............................................................................................18 Intrinsic Vulnerability ...................................................................................................................18 Habitat Specificity ..................................................................................................................18 Territoriality and Area Requirements.....................................................................................19 Susceptibility to Disease.........................................................................................................19 Dispersal Capability and Site Fidelity ....................................................................................19 Reproductive Capacity............................................................................................................19 Sensitivity to Disturbance.......................................................................................................19 WYNDD Intrinsic Vulnerability Rank...................................................................................20 Protected Areas .............................................................................................................................20 WYNDD Protected Areas Rank .............................................................................................20 Formal Population Viability Analyses (PVAs).............................................................................20 CONSERVATION ACTION ................................................................................................................ 21 Existing or Future Conservation Plans...................................................................................21 Existing Regulatory Mechanisms, Management Plans, and Conservation Strategies ..................21 Conservation Elements..........................................................................................................21 Key Elements ................................................................................................................................21