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• <br />vegetation distribution (no habitat affinities), then the proportion of <br />individuals of a species encountered in a particular vegetation type would <br />correspond to the proportion of the sampling effort devoted to that <br />vegetation type. For example if 30$ of the small mammal live traps were <br />established in upland sagebrush, then 30% of the total number of individi+Ats <br />of all species captured over all sampling transects would have been caught <br />in the upland sagebrush habitat if the species were distributed randomly. <br />Conversely, if 906 of all Peromyscusdmaniculatus (deer mouse) captures <br />occurred ih the upland sagebrush type, this would indicate a definite <br />affinity of L. rraniculatus for the upland sagebrush vegetation type. <br />The Chi-square test (Snedecor and Cochran 1967) was used to determine <br />if the diffe efoes between the observed number of captures for a given <br />species in a given vegetation type and the number of captures expected on <br />the basis of a random distribution was significant. The Chi- square <br />statistic, X is given by: <br />where: <br />= observed number of captures (or encounters) for habitat i <br />o <br />E = expected number of captures in habitat i based on a random <br />distribution among habitats. <br />The calculated Chi-square value'was compared to a Cho.- square table to determine <br />if a significant difference between observed and expected number of captures • <br />occurred At the 95$ confidence level. If a significant difference did exist, <br />individual Chi- square values for individual habitats were examined to provide <br />an indication of those habitats for which a species shows an affinity or an <br />avoidance. <br />-15- <br />JUR 1 1 3980 <br />