Some Aspects of the Ecology of the Eastern Garter Snake (Thamnophis sirtalis sirtalis) in a Semi-Disturbed Habitat in West-Central Illinois

Abstract

Certain aspects of the ecology of a T. s. sirtalis including population density, cover object selection, sexual dimorphism and geographic variation in tail length proportions were studied on the campus of Western Illinois University in McDonough County, Illinois. This area''s habitat can be classified as semi-disturbed due to heavy use by the university and students. Despite this disturbance degree, a relatively successful garter snake population seems to exist based on population density estimates. Garter snakes showed high association for cover objects, which may have been used for thermoregulation during warm and cool periods. Sexual dimorphism in tail length proportions (tail length/total length ratios) is present in this subspecies as reported previously in the literature. Geographic variation in tail length proportions exists for both males and females with 3 midwest and western races (T. s. parietalis, T. s. pickeringi and T. s. concinnus) previously studied having longer tail length/total length mean ratios than T. s. sirtalis inhabiting west-central Illinois. One of these (T. s. concinnus) had a highly significant statistical difference in ratios from T. s. sirtalis for both males and females.