STATUS: Threatened. That means we are concerned about the species but that they are not in danger of extinction right now.
DESCRIPTION: The giant garter snake is one of the largest garter snakes. They are at least 162 centimeters long. (About 64 inches.) Females tend to be longer and heavier than males. They weigh 500 to 700 grams. (About 1 to 1.5 pounds) .
The back of a giant garter snake varies from brownish to olive. There is a checkered pattern of black spots. A yellow stripe runs down the center of the back. Along the sides are light colored stripes. The underside is cream to olive or brown. Sometimes it is orangish. And common garter snakes are only 46-140 cm long. Otherwise, the two species look very similar. Garter snakes are not dangerous. In California, only rattlesnakes have venom that is dangerous to humans.
FOOD: Small fishes, tadpoles and frogs.
HABITAT: Agricultural wetlands and other waterways in the Central Valley. (Irrigation and drainage canals, sloughs, ponds, small lakes, streams.)Most of the natural habitat has been lost. So lots of snakes live in rice fields. Rice fields provide hundreds of thousands of acres of habitat for the species.
HABITAT NEEDS: Enough water to provide food and cover during the active season. (Early-spring through mid-fall) Wetland plants such as cattails and bulrushes. (These are for cover and foraging.) Grassy banks and openings in vegetation for sunning.
Winter refuges: Small mammal burrows and other crevices above flood elevations. Giant garter snakes are dormant during the winter so they need places like this to hang out.
SEASONAL LIFE CYCLE: Giant garter snakes are most active from early spring through mid-fall. Between April 1 and May 1, they emerge and start hunting for food. Around October 1, they start looking for winter retreats. By November 1, they are in winter retreats and mostly stay there until spring. Some may bask or move short distances on warmer days.
MATING: Males reach sexual maturity in three years, females in five. The breeding season extends through March and April. Females give birth to live young from late July through early September. Brood size varies. It ranges from 10 to 46 young. (See photo of young snake, left) Young immediately scatter into dense cover. They typically more than double in size in the first year.
PREDATORS: These include raccoons, skunks, opossums ("possums"), foxes, hawks, northern harriers, egrets, bitterns and great blue herons.
RANGE: Mainly the Sacramento Valley of California. Some isolated populations in the San Joaquin Valley.
THREATS: Habitat loss and fragmentation. Flood control activities. Changes in agricultural and land management practices. Predation from introduced species, parasites, water pollution.