The San Francisco Gartersnake (Thamnophis sirtalis tetrataenia), one of North America’s most endangered snakes, persists in fragmented habitat across San Mateo and northern Santa Cruz counties. To avert extinction, San Francisco Zoo & Gardens, in partnership with the U.S. Geological Survey, National Park Service, U.S. Fish & Wildlife Service, California Department of Fish and Wildlife, Golden Gate National Parks Conservancy, and Midpeninsula Regional Open Space District, has launched the first head-start program for this species. This collaborative conservation initiative builds on decades of work—from managing confiscated snakes in the 1990s to advancing research on genetics, fecundity, and population modeling that informed our approach. In 2025, the program achieved a major milestone with the collection of gravid females from the wild and the successful birth of neonates at the Zoo, marking the first head-started cohort for future reintroduction. We present the methodology behind our head-starting efforts, early outcomes from the inaugural cohort, and critical next steps needed to recover this iconic species. This project demonstrates how long-term partnerships, applied research, and zoo-based conservation programs can directly contribute to reversing population declines in one of California’s most imperiled reptiles.

Tiffany May is an ecologist specializing in aquatic ecosystems and amphibian conservation. She has supported Yosemite's aquatic ecology program and worked with USGS to protect amphibian populations in Southern California. Tiffany previously managed a disease ecology lab at the University of Nevada, Reno, focusing on Batrachochytrium dendrobatidis (Bd). Her master’s research at San Francisco State University centered on reintroducing Yosemite toads and using telemetry to track their survival. She is now a Field Conservation Supervisor at San Francisco Zoo and co-founder of HERpetologists et. al, an organization supporting women and gender minorities in herpetology. Tiffany holds dual degrees in Anthropology and Wildlife Ecology.