Almost everyone can identify a “garter snake” in New Mexico!
But here’s the problem:
There are multiple species and sub-species of garter snakes! Therefore, figuring out the identity of the SPECIFIC snake you are observing can be challenging. This is especially true since many of them have similar appearances and behaviors.
Today, you are going to learn about 6 garter snake species in New Mexico!
- *Just a quick note – to be officially considered a garter snake, the species must be in the genus Thamnophis*
#1. Western Ribbon Snake
- Thamnophis proximus
- Adults range from 17 to 50 inches in length. A slender snake with a long tail!
- Coloration is blackish, brown, or olive with three light-colored stripes; one down the back and one down each side.
- The sides and top of the head are dark, and the upper lip is whitish.
Did you see a slender garter snake in eastern New Mexico with a long tail?
If so, it was probably a Western Ribbon Snake! This semi-aquatic species is rarely found far from a water source. They typically occupy brush-heavy areas around streams, lakes, ponds, and other water bodies. You may also spot them basking on rocks, flat vegetation, and dry sandy areas near water.
The Western Ribbon Snake has an incredible, unique hunting technique. As they move over land, they make quick, light thrusts of their head and upper body in different directions in sequences of three. It’s similar to a strike, but with their mouth closed. This action disturbs resting frogs, which alerts the garter snake to their location. From there, the ribbon snake uses its superior speed to catch its prey.
If they feel threatened, this species will flee into the water or hide in thick brush. Their coloration provides superb camouflage in dense, brushier areas. If grabbed, they rarely bite but will thrash around, defecate, and release musk from their anal glands. This species can also shed its tail to escape, but unfortunately, the tail doesn’t regenerate like some lizard species.
Currently, the Western Ribbon Snake has a healthy population, but that doesn’t mean it doesn’t have threats. Aquatic habitat degradation and loss and pesticides and road chemicals are believed to have serious negative impacts on their numbers.
#2. Terrestrial Garter Snake
- Thamnophis elegans
- Adults range from 18 to 41 inches in length.
- Most adults have three yellow, light orange, or white stripes; one down their back and two down their sides.
- Coloration is widely variable. Individuals may be brownish or greenish. Some have red and black spots between the stripes, and occasionally all black individuals are found.
This garter snake can be difficult to identify in New Mexico!
Even trained herpetologists have issues! Its coloration varies widely, and there are believed to be 6 subspecies, although scientists still debate this.
Terrestrial Garter Snakes occupy various habitats, including both grasslands and forests. They can even be found in mountainous areas up to 13,000 feet above sea level. As the name suggests, they’re primarily found on land. But interestingly, these garter snakes can swim well!
This species is the only garter snake in northwestern New Mexico with a tendency to constrict prey! Most garter snakes grab their prey quickly and just swallow, rubbing their prey against the ground if necessary.
Terrestrial Garter Snakes aren’t aggressive or dangerous, but they do possess mildly venomous saliva! It can cause a muscle infection or even kill some muscle tissue. Most bites on humans just cause pain and some swelling.
#3. Plains Garter Snake
- Thamnophis radix
- Adults average 36 inches in length.
- Coloration is gray-green with a distinctive orange stripe down the back and a greenish-yellow stripe down each side.
- Distinct light yellow spots on the very top of the head!
Plains Garter Snakes are only found in northeastern New Mexico in prairies and grasslands near freshwater sources. They have a fairly large population and adapt well to human-modified landscapes, and you may spot them near abandoned buildings, trash heaps, or vacant lots.
This species is considered to be one of the most cold-tolerant of all snakes! In fact, they will even come out of hibernation on warmer winter days.
The Plains Garter Snake feeds primarily on earthworms, slugs, and small amphibians. However, they have also been observed preying on small mammals and birds, including the Eastern Meadowlark and Bank Swallow.
#4. Black-necked Garter Snake
- Western Black-necked Garter Snakes are dark olive with an orange-yellow stripe down the back and a yellow to white stripe down each side. It can be up to 42 inches long.
- Eastern Black-necked Garter Snakes are smaller and only grow up to 20 inches in length. They have a checkered pattern of black and yellow on their body, in between their three stripes.
- Both subspecies have a gray head that contrasts strongly with the body. In addition, there is a dark blotch on each side of the neck.
This species is found in many habitats, including desert scrub, plains, arid grasslands, and pine-oak woodlands. They’re almost always found in New Mexico in association with water sources such as streams, ciénegas, and cattle tanks.
There are two sub-species of this garter snake; the Western AND Eastern. They look different (see photo above), but they also behave uniquely. The Western subspecies (Thamnophis cyrtopsis cyrtopsis) are water snakes and most often found in the actual water. The Eastern (Thamnophis cyrtopsis ocellatus) subspecies prefer to live on DRY LAND that is very close to water.
The Black-necked Garter Snake’s preferred prey is frogs, toads, and their tadpoles, including poisonous species like the Sonoran Desert Toad. However, they have been known to feed on a wide range of other prey, including earthworms, skinks, salamanders, crustaceans, and birds.
Black-necked Garter Snakes adapt well to introduced species like the American Bullfrog. They have also benefited from the creation of cattle tanks since these snakes are dependent upon water.
#5. Checkered Garter Snake
- Thamnophis marcianus
- Adults are typically 18 to 24 inches in length.
- Coloration is typically greenish. They have three yellow or orange stripes; one down the center of the back and one down each side.
- Look for a distinctive black checkerboard pattern on its back.
- Cream or yellow crescent marks on each side of the head are followed by a dark blotch on the neck.
The Checkered Gartersnake is most commonly found in New Mexico in desert and grassland habitats. Look for them near water sources, such as rivers, lakes, wetlands, cattle tanks, canals, and ditches. Living in arid conditions, these garter snakes are incredibly good at finding water sources.
These garter snakes are active both day and night, depending on the temperature. For example, they are more nocturnal during the heat of summer.
Checkered Gartersnakes are opportunistic predators who feed on a wide variety of prey. They typically consume frogs, salamanders, toads, earthworms, small fish, lizards, snakes, slugs, and crayfish. However, they’ve also been reported to eat mice, raw horse meat, and other snakes of their own species in captivity!
Their populations are not currently threatened. Luckily, they tolerate human development relatively well, although draining wetlands and other water sources harm their population. These garter snakes are also able to co-exist with introduced species like the American Bullfrog.
#6. Mexican Garter Snake
- Thamnophis eques
- Adults may grow up to 44 inches in length. Coloration is black, brown, olive, tan, or rust.
- Three creamy yellow stripes, one down the back and one down each side, may have dark blotches on each side of the neck.
- Noticeably large head compared to other garter snakes, black outlined scales on the lower face.
This secretive garter snake is hard to find in New Mexico! Their preferred habitats are near water sources with DENSE vegetation.
The best time to find Mexican Garter Snakes is in the morning, when they’re often active or basking in the sun, or in the early evening. They are highly aquatic and primarily feed on frogs and fish. Try walking close to a water’s edge, where you may see one fleeing into the water!
Sadly, this snake has been listed as threatened under the U.S. Endangered Species Act since 2014. Their decline was believed to have been caused by habitat destruction and the introduction of non-native species.
Do you need additional help identifying garter snakes?
Try this field guide!
Which of these garter snakes have you seen in New Mexico?
Leave a comment below!