Montana Field Guide

Adults vary from 16 to 43 inches in length. This snake is distinguished by three yellow stripes (one dorsal, two lateral) running the length of the body and a series of black spots situated between, and somewhat on, the stripes. The background color between the stripes is brownish or greenish. All-black individuals are occasionally found. A series of dark black/brown blotches covers most of the belly. There are normally eight scales on the upper lip.

Nonmigratory.

Garter snakes are found in nearly all habitats, but most commonly at lower elevations around water. Females give birth to 6 to 18 live young during summer. They eat a variety of vertebrates and invertebrates (FWP). Common near water but also found away from water. At high elev. common on rocky cliffs/ brushy talus (Brunson and Demaree 1971, Franz 1971). On prairie may be more common along brushy bottomland (Mosimann and Rabb 1952, Lewin 1963).

Generalist predator in aq/terres habitats (Anderson 1977). May specialize in amphibs during metamorph (Gregory 1984, Kephart and Arnold 1982). Diet in W MT (% by no.): leech 44, slug 24, fish 10, amphib 10 (Anderson 1977). % mml & fish increase w/ size (Gregory et al. 1980).

Birth usually occurs in Aug-Sep (CO) (Hammerson 1982), late Jul-early Aug (Pacific NW) (Nussbaum 1983).