San Francisco Garter Snake

Kids' Species Information

San Francisco Garter Snake

10 year-old girl admiring SF garter snakeSTATUS

Endangered. This means that they are in danger of dying out. Read a San Francisco Chronicle story about how one of our biologists took her 10 year-old daughter to try to find them in the wild.

The SF garter is often called the most beautiful snake in the U.S. Because they are so beautiful, some people collect them illegally.

So there are quite a few SF garter snakes in private hands. Read a story about how we obtained 10 of these snakes. They are at the San Francisco Zoo. The photo at the top of this page shows kids looking at one.

DESCRIPTION

The first things you notice are the turquoise blue body and bold stripes.

The stripe pattern is black, red-orange, black. The stripes run along the snake's "shoulders."

Large adults can reach a meter in length. (3 feet)

SF garter snakes sometimes go into a dormant state during summer months when their ponds dry up. They use rodent burrows for this. On the coast, they hibernate during the winter. Farther inland, they may be active year-round.

SF garter snakes are active during the day. They may hunt after dark on warm evenings.

Garter snakes are not dangerous. In California, only rattlesnakes have venom that is dangerous to humans.

FOOD

Adults mainly eat small frogs such as the CA red-legged frog (143 KB PDF). (These are listed as threatened!) They are one of the few animals able to eat the toxic CA newt. Young snakes depend on Pacific tree frogs.

HABITAT

Densely vegetated ponds near open hillsides.

MATING

Females give live birth from June through September. Litters average 16 babies.

PREDATORS

Birds such as hawks and herons. Other snakes. Domestic cats and other small mammals.

Adult bullfrogs probably prey on smaller San Francisco garter snakes. This may be a factor in their decline.

RANGE

Historically, from about the San Francisco County line south to Año Nuevo Point and Waddell Creek. Much of this range is private land. We don't know how much is still inhabited.

THREATS

Loss of habitat from agricultural, commercial and urban development. Illegal collection.

Decline of the CA red-legged frog. It is an essential prey species. Bullfrogs. They prey on both San Francisco garter snakes and California red-legged frogs.

We are working with the CA Dept. of Fish and Game, the National Park Service, Golden Gate National Parks Conservancy, the CA Dept. of Parks and Recreation and other partners to provide habitat.

The Park Service created two wetlands at Mori Point in Pacifica. They are habitat for California red-legged frogs and Pacific tree frogs. These frogs are the garter snake's favorite food.

WHAT YOU CAN DO

Mostly its up to adults to save the SF garter snake. You can help by keeping your pets where they don't harm snakes.

See What You Can Do to Help Wildlife and Plants (201 KB PDF) for ideas about protecting the environment.

EXPLORE

Visit the San Francisco Zoo. If you live in the SF Bay area, your teachers may be able to have someone from the zoo bring snakes to your classroom.

Wherever you live in California, there are zoos and nature centers where you can see and learn about snakes.

If you are lucky enough to see an SF garter snake, it will probably slither away quickly. Do not try to pick it up. It may bite you or poop on you. Anyway, it is against the law to mess with endangered species.

Photo credits: Carley Sweet, U.S. Fish & Wildlife Service

Words to Learn

Biologists who study snakes, frogs, turtles, salamanders and other reptiles and amphibians are called herpetologists.

Herpetologists call garter snakes Thamnophis sirtalis. Scientific names are in Latin or Greek.

The SF garter snake is a subspecies. So entomologists add tetrataenia. This makes the full name Thamnophis sirtalis tetrataenia.

Garter snakes are in the Colubridae family. This family includes most of the species of snakes found in the western United States.

Hibernaculum: The place an animal goes to hibernate.

Estivate: To enter a dormant state similar to hibernation during the summer.

CA garter snakes are active during the daytime. Biologists say they are diurnal. Animals who are active at night are called nocturnal.