Large mammalian herbivores are major drivers of plant community structure in many terrestrial systems.  Wild ungulates in particular can modify habitat through their effects on plants and this can have important influences on both birds and invertebrates.  It is unclear, however, how wild ungulate-driven alteration of habitat indirectly influences small mammals.  We studied the effects of Rocky Mountain elk (Cervus canadensis) herbivory on small mammal communities that utilize high elevation snow melt drainages in Arizona.  Using 10 ha elk exclosures and paired unfenced drainages, we examined how cessation of browsing influenced the relative abundances, richness, and diversity of small mammals.  Finally, we measured microhabitat selection of deer mice (Peromyscus maniculatus) and brush mice (Peromyscus boylii), to determine whether mice used particular habitat characteristics that were altered by elk. 

Results/Conclusions

Five years of exclusion resulted in gains in the relative abundance of all members of the small mammal assemblage, which included deer and brush mice (Peromyscus maniculatus and boylii), woodrats (Neotoma neomexicana), and voles (Microtus mexicanus).  Small mammal species richness increased in exclosures relative to controls, while species diversity showed no significant trends.  Finally, deer and brush mice selected habitats high in shrub cover, which increased inside of the exclosures.  Taken together, results show that habitat alteration by large wild herbivores can strongly structure small mammal assemblages over a relatively short time period.