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San Francisco Garter Snake

Thamnophis sirtalis tetrataenia

  • Family: Colubridae
  • Adult Size: 20 to 30 inches
  • Range: Restricted to the San Francisco Peninsula in San Mateo County, western central California. It is not found in the city of San Francisco or in brackish marshes near the city. Similar subspecies occur nearby.
  • Habitat: This colorful subspecies is strongly associated with ponds and streams, being found near water in open areas and forest edges.
  • Captive Lifespan: Not Applicable
  • Dangerous:
  • Care Level: Intermediate

Overview

This subspecies is considered endangered and is protected by federal law in the U.S. As such it cannot be legally kept or sold without special permits. It is occasionally available in the European market as captive-bred specimens. The care information applies to all subspecies of Thamnophis sirtalis. For a short while, this subspecies was called T. s. infernalis.

Similar to other garter snakes, San Francisco garter snakes can be housed in 20-gallon terraria with a substrate of shredded aspen, loamy soil or coconut fibers. They need a humidity of at least 60 percent to thrive, so provide a large water bowl that will be used for bathing and often feeding as well; change the water daily. This is a diurnal snake that likes to bask, so provide a basking light in one corner of the terrarium. Typical temperatures should range between 75 and 85 degrees Fahrenheit, with 90 to 95 degrees over an undertank heating pad. The temperature can be allowed to drop a few degrees at night.

In nature, this garter snake feeds heavily on frogs, small fish and tadpoles taken from the water, but like other garter snakes it usually is switched to mice as soon as possible in the terrarium. Many specimens will take pinky and hopper mice without any coaxing. Earthworms are also taken readily and provide a good food for these snakes. Feed mice twice a week or earthworms and tadpoles every other day.

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