Associations of Small Mammals on the Central High Plains of Eastern Colorado

Abstract

Small mammal associations were sampled in six habitats on the central High Plains of eastern Colorado. The habitats consisted of grazed and ungrazed riparian woodland, sand sage- brush, and shortgrass. Ordination analysis revealed that grazing had the least effect on small mammal associations in shortgrass and the greatest effect on associations in riparian woodland. Moreover, grazed sand sagebrush supports a mammalian fauna more nearly like that of shortgrass than that of ungrazed sand sagebrush. These observations on the effects of grazing are interpreted in terms of understory vegetation. The mammalian fauna of the semi-arid central High Plains has been less extensively investigated than have those of mountainous regions to the west or the subhumid prairie to the east. Small mammal associations on the cen- tral High Plains have been characterized for only three types of habitat- riparian woodland in northeastern Colorado (Beidleman, 1954; Archibold, 1964); upland communities in southeastern Wyoming (Maxwell and Brown, 1968); and northern shortgrass prairie in northeastern Colorado (Grant and Birney, 1979). The purpose of this study was to characterize small mammal associations at six sites, three grazed and three ungrazed, in eastern Colo- rado. Unlike Grant and Birney (1979), who described community structure of small mammals in nine different regions of North American grassland, our objective was to relate small mammal associations to attributes of their local environments within one region of the Great Plains.