The Effect of Past Climatic Fluctuations on Peromyscus Leucopus Distribution in Western Kansas

Systematic trapping was conducted along streams in western Kansas, where Peromyscus leucopus had not previously been recorded. Near the Kansas-Colorado border in west central Kansas, tree distribution is restricted to riparian communities and is found only in isolated areas. Ten isolated populations were found where trees around. Perennial springs formed suitable habitat. Peromyscus leucopus were found where tree density increased, under story plants were sparse or absent, light intensity decreased, temperature decreased, and relative humidity increased. During the severe drought of 1931 through 1940 trees were practically exterminated in western Kansas and P. leucopus range was shifted east, leaving isolated populations of P. leucopus where trees survived. There has been increased rainfall in Kansas since 1940 over the mean average of 42 years preceding 1940. This increased precipitation has resulted in trees invading western Kansas and P. leucopus reinvading western Kansas.