Spatial Patterns in Two Syntopic Species of Microtines: Microtus ochrogaster and Synaptomys cooperi

Two years of live-trapping data were analyzed for spatial patterns within and between the species Microtus ochrogaster and Synaptomys cooperi in eastern Kansas. Within species, each sex was frequently overdispersed and nearest neighbors were of the opposite sex. When sexes were combined, each species was frequently overdispersed. There was also frequent evidence of a negative association between species. However, there was no indication of seasonal or density dependent trends in any of the spacing indices. Although M. ochrogaster was often overdispersed within a season, on one of the study areas successive inhabitants tended to select the same locations. This result is suggestive of microhabitat selection, even though the study site had been selected to minimize spatial heterogeneity. S. cooperi did not exhibit any evidence of microhabitat selection.