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the type as deteiTdned by Chi-square aorta (Appendix B, tart 1). <br />The deer mouse was the only species captured in the other ttio vegetation <br />types sar~led, upland sagebrush and grassland pasture. As a result, rile species <br />diversity index was 0.0 for boti types. Relative abundance indices was <br />also low for both types with 0.8 inaividuals/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 mt reveal an <br />affinity for any type sampled. <br />Assumirog 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, con~etition with CZuuiison's prairie dogs (see <br />below), lac;c^f 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 tru types. Con- <br />versely, the riparian type provides habitat for tap small mammal species with <br />narrow habitat rPrn,; rernents, the western harvest rrouse and meadow vole. <br />Both are generally found in riparian situations only (Leichleitner 1969). <br />Nnreover, the riparian type, in the form of an increased vegetation mover, <br />results in both crore species and a higher population level iri this habitat. <br />9na11 Namnal Species. The deer irousc was captured in all vegetation types <br />sar~led in the study area. This nocturnal species is probably the most <br />abundant and widespread mammal in Colorado (Lechleitner 1969). The deer <br />mouse occurs in a variety of habitats, from deserts to marshes and from prai- <br />ries to above timberline. A total of 4 deer race were captured, representing <br />a total relative abundance over all't,~,es 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 />~~adow wle habitat includes moist areas with abnndant supplies of grasses, <br />sedges or other green, succulent vegetation. The only habitat with these <br />i characteristics in the study area is riparian and was the only habitat in <br />_29_ <br />JUN i 1 1980 <br />