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the type as determined by Chi.-square data (Appendix 3, Part 1) <br /> The deer mouse was the only species captured in the other two vegetation <br /> types sampled, upland sagebrush and grassland pasture. As a result, the species <br /> diversity index was 0.0 for boti types. Relative abundance indices was <br /> also low for both types with 0.8 individuals/100 trap nights for upland <br /> sagebrush and 0.4 individuals/100 trap nights for grassland pasture. <br /> As a result of the low number of captures, the deer mouse did not reveal an <br /> affinity for any type sampled. <br /> Assuming that trapping results reflect actual relative abundance of small <br /> mammals in each of the types sampled, it is evident that both upland sage- <br /> brush and grassland pasture do not provide good small mammal habitat at <br /> the Nucla site. Predation, conl)etition with G unison's prairie dogs (see <br /> below) , lack of appropriate food and/or nesting requirements,and the homogene- <br /> ity of the types (reduced number of small mammal niches) are all possible <br /> reasons for the low populations levels observed on these t�%o types. Con- <br /> versely, the riparian type provides habitat for two small mammal species with <br /> narrow habitat requirements, the western harvest rrouse and meadow vole. <br /> Both are generally found in riparian situations only (Leichleitner 1969) . <br /> moreover, the riparian type , in the form of an increased vegetation cover, <br /> results-in bath more species and a higher population level in this habitat. <br /> Small Mw mal Species. The deer arouse was captured in all vegetation types <br /> sampled in the study area. "his nocturnal species is probably the most <br /> abundant and widespread irammal in Colorado (Lechleitner 1969) . The deer <br /> muse occurs in a variety of habitats, from deserts to marshes and from prai- <br /> ries to above timberline. A total of 4 deer mice were captured, representing <br /> a total relative abundance over all types of 0.7 individuals/100 trap nights. <br /> The deer mouse did not show an affinity for a particular habitat type. The <br /> sex ratio of all deer mice captured was 0.75 females and 0.25 males. <br /> fleadow vole habitat includes mist areas with abundant supplies of grassos, <br /> sedges or other green, succulent vegetation. The only habitat with these <br /> characteristics in the study area is riparian and was the only habitat in <br /> -29- <br /> J u N i i �9eo <br />