Small Mammal Predation and Prey Handling Behavior by the Garter Snake Thamnophis elegans

Predation on small mammals is of common occurrence in some coastal populations of the western terrestrial garter snake (Thamnophis elegans). These snakes often handle mice by coiling loops of the body around the prey, much in the manner of constrictors. This coiling behavior, however, is quite variable and unstable, unlike that shown by other constricting species. There is no clear relationship between snake size and size of small mammal taken in field or laboratory. Rather, a restricted size range of mammals is eaten by a restricted size range of snakes. Coiling behavior seems to be a means of immobilizing prey rather than killing it, although death of prey sometimes occurs. Although limited anatomical evidence suggests that T. elegans should be more capable of handling difficult prey such as mice than are other sympatric species of garter snakes, T. elegans may not be very efficient at capturing small mammals in the field.