Habitat associations of desert small mammal communities at Ash Meadows National Wildlife Refuge, Nye County, Nevada

Background/Question/Methods

Ash Meadows National Wildlife Refuge (Ash Meadows NWR) is a spring-fed wetlands and alkaline desert system located in the Mojave Desert in Nye County, Nevada.  It supports 25 species of endemic plants and animals (5 currently listed as federally endangered) and is the largest concentration of endemic species in the lower 48 states.  Human activities have altered Ash Meadows NWR through peat-mining and spring diversions for irrigation purposes.  Restoration projects are currently being developed because of these large scale habitat alterations and endemic species.  My objectives were to determine how small mammal species diversity changed over time at Ash Meadows NWR which then can be eluded to assessing which habitat and vegetation characteristics small mammal species are currently selecting for.  Information on small mammal specimens collected for 2 surveys in 1891 and 1933 was used to assess species diversity changes over time.  Small mammal trap lines using Sherman live-traps were set in 18 qualitatively different habitat types for a total of 6 sampling seasons (2 each in spring, summer, and fall) throughout 2008–2009.   Habitat characteristics were quantified for each habitat type then joined to individual small mammal traps in ArcMap 9.3.  A 2-factor MANOVA was conducted to test for differences in habitat variables between habitat types and a single-factor MANOVA for differences between capture and non-capture sites.  A CCA was conducted to assess small mammal habitat associations. 

Results/Conclusions

Species diversity was similar in 1891 and during my study period; however, decreased in 1933 due to habitat alterations.  Habitats differed in structural components seasonally as well as between capture and non-capture trap sites mostly because of the unique seeps and springs system present.  In terms of habitat associations, small mammal species were primarily associated with shrub dominated areas and graminoid dominated areas.  Overall, my research reveals that shrub and graminoid dominated habitats are important for small mammal communities; however, other habitat types are equally important in sustaining biodiversity at Ash Meadows NWR.