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threatened and/or endangered

Common Garter Snake Thamnophis sirtalis


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Common Garter Snake, Valley subspecies
credit: Wilson44691

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Family: Colubridae, Colubrid Snakes view all from this family

Description Pattern of yellow stripes on a brown or green background. 7 upper lip scales. Keeled scales in rows of 19. Single anal plate.

Endangered Status The San Francisco Garter Snake, a subspecies of the Common Garter Snake, is on the U.S. Endangered Species List. It is classified as endangered in California. This subspecies has suffered as its habitat, in San Mateo County, has been consumed by urban growth. The residential and industrial development of the Bay Area and the attendant degradation of water quality have limited this snake's habitat severely. Collectors, coveting it for its rarity and beauty, have further depleted the small populations.

Subspecies Eastern - yellow stripes, between stripes double row of spots. Ontario, Minnesota, Iowa, Missouri, Arkansas, and e. Texas to Atlantic coast from s. Newfoundland to Florida.
Texas - back stripe orange. Texas & on Oklahoma border, isolated population in Texas panhandle.
Red-spotted - Light back stripe on black. nw. Oregon and extreme sw. Washington; coastal California.
Valley - back stripe well defined. Nevada, Oregon, Idaho, Utah, Montana, and Washington through British Columbia to Alaska.
New Mexico - Similar to red sided. Rio Grande Valley, Colorado through New Mexico to Texas.
Maritime - absent back stripe. Canadian Maritime provinces, Quebec to New England.
Red-sided - variable orange/red bars between back stripes. British Columbia, Alberta, MacKenzie, c. Saskatchewan and s. Manitoba to Great Plains & Oklahoma-Texas border.
Puget Sound - I scale row for back stripe instead of 2. British Columbia to Washington.
Chicago - side stripes break to vertical bars. Illinois, Wisconsin, and ext Indiana.
Blue-striped - Yellowish/tan stripe on brown. Florida peninsular to Wakulla County and Withlacoochee River.
San Francisco - Continuous stripe formed by red markings between back and side stripes. San Mateo County, California.

Breeding Live young. breeds March-May, gives birth June-August. 7-85 young in a litter. 13-23cm (5-9") long when born.

Habitat Wet meadows, marshes, prairie lands, drainage ditches and woodland near water.

Range Across North America from coast to coast. Not desert areas of Southwest.

Discussion Most common in America. Active during the day. Hides in vegetation. Diet includes frogs, toads, salamanders and earthworms. Adapts to cool weather so active year round in souther areas but hibernates in large groups. When captured will expel a musk or bite but tempers quickly. Docile soon after. Longest living was 10 years.