Left: San Francisco Garter Snake; Photo Credit: Jessica Weinberg, NPS
Top Right: Alameda Whipsnake; USFWS Photo
Bottom Right: Western Rattlesnake; Photo Credit: Paul Johnson, NPS

Snakes comprise an important part of ecosystems throughout the San Francisco Bay Area. The park network contains an extensive array of habitats that support a diverse range of serpent species. Although many species have maintained stable populations, most still face pressures of human development and habitat encroachment. Several species of snakes are commonly found stretched out on the surface of roadways to absorb the heat of the asphalt, and this habit makes them particularly vulnerable to being killed by cars.

The strikingly colorful San Francisco garter snake (Thamnophis sirtalis tetrataenia) is threatened by habitat loss as well as collection by reptile fanciers and breeders. It is the most jeopardized of the area’s species, having been listed as federally endangered since 1967. The federally threatened Alameda whipsnake (Masticophis lateralis euryxanthus) can be found in the East Bay parks. Although snakes are often feared and reviled by many people, the Western rattlesnake (Crotalus viridis) is the only species in the park network that poses a potential threat to humans. If you are lucky enough to encounter a snake, give it space and take a moment to watch it undisturbed.