Restoring a Desert Oasis to Bolster Narrow-Headed Garter Snake Populations

Have you slept in a tent alone—a tent
Out under the desert sky—
Where a thousand thousand desert miles
All silent round you lie?—
The dust of the aeons of ages dead,
And the peoples that trampled by?
Have you looked in the desert’s painted cup,
Have you smelled at dawn the wild sage musk,
Have you seen the lightning flashing up
From the ground in the desert dusk?

-From The Lure of the Desert Land by Madge Morris Wagner

The Southwestern United States is an arid region often associated with deserts, cacti, and rattlesnakes. But rivers, springs, and wetlands thread through it like arteries bringing vital resources to the landscape. These aquatic refuges provide lush areas that support an amazing diversity of amphibians, reptiles, and fish. Among the headwater streams of the Colorado River Basin and beyond lives the narrow-headed garter snake, a federally-listed Threatened snake that, like the habitats it occupies, needs our help.

These grayish-brown snakes reach four feet in length, and their most recognizable characteristic is their namesake flattened elongated heads. As excellent swimmers that feed on fish and other aquatic life, they take to the waterways to forage—and their unique head shape reduces drag as they strike to catch their prey. If threatened themselves, they emit a musk—a foul-smelling substance created in special scent glands (this makes them a joy to capture).

These long-lived snakes are live-bearing. They don’t lay eggs—the young are born as perfect miniatures of the adults. They’re most common in New Mexico, in the Colorado River Basin, but their numbers are dwindling even there.

Narrow-headed garter snakes face the same threats that many amphibians and reptiles do—habitat loss and fragmentation and competition from invasive species—plus, their habitat has recently started to see a significant increase in catastrophic fires and floods. Riparian areas are often destroyed or altered by human activities, such as dam construction, water withdrawals, and agricultural development. As a result, the snake’s habitat is becoming increasingly fragmented, which can reduce its ability to move and find food, mates, and suitable nesting sites.

Invasive species are a pressing threat, too; nonnative bullfrogs and crayfish now live in these wetlands in abundance, decimating the prey base and eating vulnerable young narrow-headed garter snakes. Quality habitat does still exist in patches, but in many cases, the areas between these that should connect them are overrun by difficult-to-remove invasive species. On top of that, the increasing number of destructive wildfires due to years of fire suppression in the region often choke wetlands with dirt and ash.

Saving this species is an uphill battle, but we have a plan. Protecting and restoring riparian habitats is critical, and so is reducing habitat fragmentation and improving connectivity between areas of high-quality habitat. In fact, programs to do just that are already underway thanks to the support of several grants.

For example, we’re removing invasive crayfish and bullfrogs. These invaders not only have significant adverse impacts on the microhabitats the snakes inhabit, they’re also causing degraded landscapes between swaths of healthy habitat. Controlling invasive species ensures connectivity between the remaining pockets that can support these snakes. Plus, we’re working to improve stream health in the areas where they remain.

Through these efforts, we’re restoring the health of these vitally important southwestern ecosystems, and conserving the narrow-headed garter snake is a big part of that. Its conservation requires a combination of habitat protection, restoration, and management actions, as well as public education and research. We still have much to learn about the narrow-headed garter snake’s movements, behavior, and habitat preferences. And we need to do so quickly because its importance to the system cannot be overstated.

Before their decline, these snakes knitted together the food web, serving as both predator and prey in a western aquatic system that is relatively low in diversity, making each member key to the system’s functioning. With your help, we hope to restore them to their historic role, along with the ecosystem they call home.