Northern Mexican Gartersnake

Missing for 20 years, the northern Mexican gartersnake has been found.

Reptile house banner - New mexico garter snake

Many scientists believed that the northern Mexican gartersnake was extirpated, or locally extinct in New Mexico. But on June 2, 2013, the ABQ BioPark's herpetologists found three snakes in a portion of the Gila River in southwest New Mexico.

BioPark herpetologists took genetic samples and released two of the snakes on site. The third snake, a male, was transported back to the BioPark for proof of life. Experts confirmed that the snakes are indeed northern Mexican gartersnakes (Thamnophis eques megalops).

Searching for an Extinct Species

We have spent nearly three years and thousands of hours looking for this species. Although many had assumed the northern Mexican gartersnake was locally extinct in New Mexico, we thought it was still here, somewhere, undetected. This discovery means there is still hope for the species and its habitat.

In 2010, the ABQ BioPark received a grant for researching native endangered reptiles in New Mexico. The BioPark, in consultation with U.S. Fish and Wildlife Service and New Mexico Game and Fish, decided to focus efforts on narrow-headed gartersnakes and northern Mexican gartersnakes.

To Catch a Snake

In the field, BioPark herpetologists stretch 50-foot drift fences, made of woven steel mesh, along the ground, parallel to the edge of rivers and streams. Animals that run into a drift fence generally follow its path down to either end where funnel traps catch snakes. Each day, the team checks the traps and records surveys.

The ABQ BioPark herpetology team consists of seven expert zookeepers. For the past several years, the team has taken turns from April - September to camp and look for northern Mexican gartersnakes and other endangered species.

On June 1, 2013, BioPark herpetologists came to a new site and placed 20 traps throughout the area. The following morning, the team awoke to find the elusive northern Mexican gartersnake in one of the traps. Two more were caught by hand later that day. All three snakes were male, two were released, and one was transported back to the ABQ BioPark Zoo.


There are eight different species of gartersnakes in New Mexico, and telling the difference between species can be difficult. Northern Mexican gartersnakes have unique markings including lateral stripes located on specific scales.

BioPark herpetologists took genetic samples from the northern Mexican gartersnakes to verify their identification.

What's Next?

Because the found snakes were young, scientists say the population is viable and still producing offspring. Now, experts must determine how strong the population is, where else they might live and the condition of their habitat.

BioPark herpetologists currently have two male and one female snake that are part of a captive breeding program to augment the wild population. In 2016, the zoo welcomed 11 healthy baby garter snakes. Limited human interaction, natural habitat and typical prey will prevent the snakes from becoming desensitized to people.

About Northern Mexican Gartersnakes

Habitat: Live in riparian areas, hiding in cattails, willows, aquatic plants and bulrush. In the past 100 years, suitable habitat has been reduced by 90%.

Diet: Eat tadpoles, minnows and other small fish.

Size: Medium-length gartersnake growing up to 3 feet.

Color: Olive, olive-brown or olive-gray. Three stripes run the length of the body with a yellow stripe down the back. A portion of lateral stripe runs along the fourth scale row, distinguishing T. eques megalops from other gartersnakes.

Threats: Habitat degradation due to overgrazing, water diversion, drought and overuse of lands and predation from non-native animals, like bullfrogs and crayfish, threaten this species.

Status: Endangered in the state of New Mexico; candidate for federal protection under the Endangered Species Act.