Habitat preference in Spermophilus major and S-suslicus in recently developed sympatric zone

Since 1995 to 1997, the habitat preference in the spotted and russet sousli ks was studied in a sympatric zone developed recently (Ul'yanovsk oblast). Ninety-one pure animal colonies and two contact ones were inspected. For si x model colonies, the topography of burrows and gradients by eight environm ental factors, including composition of plant cenoses, coverage of the plan t cover, and tuff thickness, were taken into account. The Sperman's vauked correlation coefficients were calculated for analyzing the data obtained. T he russet souslik, S. major, is shown to prefer xerophytic habitats, the sp otted sauslik, S. suslicus, mesophytic ones. Mixed colonies appear in subop timal habitats; in these colonies, the rate of interspecies competition is low.