Montana Field Guide

The smooth green snake is a small to medium, slender, bright green snake with smooth dorsal scales (15 rows at mid-body), and a white or yellowish underside; each nostril is centered in a single scale; the anal scale is divided. In some regions, occasional individuals are tan, and in Texas the color may be light brown with an olive wash instead of green. Young are dark olive-gray above, hatchlings are gray to brown above; adults turn blue or gray after death. The total length is usually 30 to 51 centimeters and can reach 61 centimeters; hatchlings are about 8 to 17 centimeters long (Stebbins 1985, Conant and Collins 1991).

The smooth green snake differs from the eastern racer (Coluber constrictor) by being smaller in size, in having the nostril centered in a single scale rather than placed between two scales, and in having a single anterior temporal scale on each side rather than two. It differs from the rough green snake (Opheodrys aestivus) by having smooth rather than keeled dorsal scales. It differs from the green rat snake (Senticolis triaspis) by having fewer dorsal scale rows (15 at mid-body vs. 25 or more) and by lacking keels on any of the dorsal scales.

No information specific to Montana is known, but based upon habits in other areas of the species' range, the smooth green snake may migrate between winter hibernaculum and summer range in some areas (Vogt 1981).

Little information is available for the species in Montana, though it has been reported from residential lawns, city parks, along ditches in prairie pothole country, and around wetland complexes. Based upon onservations in other areas of its range, the smooth green snake is known to occupy meadows, grassy marshes, moist grassy fields at forest edge, mountain shrublands, stream borders, bogs, open moist woodland, abandoned farmland, and vacant lots. Periods of inactivity are spent underground, beneath woody debris and rocks, or in rotting wood. They have been found hibernating in abandoned ant mounds. Most activity is restricted to the ground, but they may climb into low vegetation, and sometimes enter water (Hammerson 1999). This species may also be found in damp meadows bordering streams and lakes as well as drier, rocky areas, but usually only if grass or similar vegetation is present.

The primary diet is small terrestrial invertebrates (moths, caterpillars, crickets, grasshoppers, spiders, etc.). In Colorado, they are reported to also feed on small crayfish and aquatic snails (Hammerson 1999). Nothing is known regarding food habits in Montana.

This snake is active during May through September in Colorado (Hammerson 1999), and probably in Montana as well (Maxell et al. 2003), although little is known about its ecology in Montana. It is mostly diurnal. Hibernation may occur with other reptile species, and groups of 100 to 150 individuals have been found together in Manitoba and Minnesota hibernacula. Sources of mortality are poorly documented. Predators elsewhere in the range include gartersnakes. Reported predators in Montana include Loggerhead Shrike and Brown Thrasher. The first voucher specimen in the state was probably killed by hail. Considered mild-mannered, the smooth green snake when handled may squirm and emit pungent, cloacal secretions.

No information specific to Montana is known. Throughout the species' range, courtship and mating behavior are poorly known. Based upon information from other locations within the species' range, females reach reproductive size in Colorado when 22 to 26 centimeters snout-vent length, or probably in about two years. Eggs are laid usually during the first three weeks of August in northern Michigan, mainly late June to late July in the Chicago, Illinois area, and July in Colorado and adjacent regions. Clutch size is 3 to 18 (generally 4 to 9). Ovipostion sites include spaces under rocks and wood, and in burrows. Eggs hatch in a few to about 30 days, early August to early September in northern Michigan, and the Black Hills of Wyoming and South Dakota; mostly early to mid-August in Chicago. Copulation has been recorded in August in Ontario. They sometimes nest communally (Fitch 1970, Hammerson 1999).

No special management activity is defined at this time. Hibernacula should not be altered or destroyed.