Center for Biological Diversity

For Immediate Release, April 27, 2021


Brian Segee, (805) 750-8852,

Northern Mexican Garter Snake Gains 20,326 Acres of Protected Critical Habitat in Arizona, New Mexico

TUCSON, Ariz.— In response to nearly two decades of action by the Center for Biological Diversity, the U.S. Fish and Wildlife Service today finalized critical habitat protection for the northern Mexican garter snake under the Endangered Species Act.

“Critical habitat protections will benefit not just this pretty garter snake, but people too by protecting some of the region’s rapidly dwindling cienega and streamside habitats,” said Brian Segee, a Center senior attorney. “The northern Mexican garter snake and most of the rest of the Southwest’s aquatic fauna is on a fast train to extinction. It’s a serious crisis that hardly anyone’s talking about.”

This aquatic, secretive garter snake was historically found in all of Arizona’s major watersheds, in addition to the upper Gila and San Francisco headwater streams in southwestern New Mexico. Invasive species — including bullfrogs, sportfish and crayfish — and habitat destruction have eliminated most U.S. populations. The status of populations in Mexico is largely unknown, but the same threats are present.

The Center first submitted a scientific petition to list the northern Mexican garter snake under the Endangered Species Act in 2003, but the Fish and Wildlife Service did not list the species until more than a decade later, in 2014. The agency proposed protecting more than 420,000 acres of critical habitat for the snakes along with the listing proposal, but failed to finalize those habitat protections. The Center also reached a settlement with the Service requiring the final critical habitat designation issued today.

“After such a long delay, we're disappointed that the Fish and Wildlife Service protected a much smaller area than originally proposed,” said Segee. “For these snakes to fully recover, more of their fragile remaining habitat must be protected.”

Critical habitat designation requires federal agencies to avoid actions that result in damage or destruction of the garter snake’s habitat.


The northern Mexican garter snake is primarily olive in color and has three lateral stripes that run the length of its body with a yellow stripe down the back. In the United States, the species is most commonly found between 3,000 and 5,000 feet in cienega wetlands as well as river habitat that includes pools and backwaters. The snake feeds primarily on native fish and leopard frogs.

The northern Mexican garter snake historically existed in every county in Arizona, with additional populations in New Mexico and Mexico. It has been eliminated from a large portion of that range, with remaining populations found in areas including the Verde River, Santa Cruz River, Bill Williams River, and San Pedro River watersheds in Arizona, and the upper Gila River watershed in New Mexico. The Fish and Wildlife Service estimates that more than 80% of the species’ remaining populations occur at low densities and are likely not viable.

The 20,326 acres of critical habitat designated today is in La Paz, Mohave, Yavapai, Gila, Cochise, Santa Cruz, and Pima counties in Arizona and Grant County in New Mexico.

Northern Mexican garter snake. Photo courtesy of USFWS. Image is available for media use.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.

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