Microhabitat partitioning by two chipmunk species (Tamias) in western Colorado

We examined microhabitat use of sympatrically occurring Tamias minimus (lea st chipmunk) and T. rufus (Hopi chipmunk) in a pinon-juniper/sagebrush vege tative community near Molina, western Colorado, from October 1994 to June 1 999. This community is dominated by 2 major microhabitat types: shrub (sage ; Artemisia spp.) and tree (pine and juniper; Pinus edulis and Juniperus sc opulorum). Small mammals were live-trapped, marked, and released throughout this study. When it was the most abundant Tamias species on the study plot s (1994-1997), Tamias minimus captures were associated with trees. Tamias r ufus also exhibited this association but was captured at very low abundance s during this period. Tamias rufus abundance was much greater, on average, than that of T. minimus between 1998 and 1999. During this time T. minimus captures were not associated with trees, but T. rufus captures remained ass ociated with trees. As has been previously reported for other Tamias specie s, the greater abundance of 1 of 2 coexisting congeners in select areas may play a role in the microhabitat use of these 2 chipmunk species.