Almost everyone can identify a “garter snake” in Montana!
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 4 garter snake species in Montana!
- *Just a quick note – to be officially considered a garter snake, the species must be in the genus Thamnophis*
#1. Red-sided Garter Snake
- Thamnophis proximus parietalis
- Normally dark green to black, but color varies.
- Three yellow stripes, one down the back and one down each side.
- As the name suggests, there are red or orange bars down their sides, located between the yellow stripes.
- Subspecies of the Common Garter Snake.
Like other garter snakes, they are habitat generalists. Look for them in Montana everywhere, including forests, shrublands, wetlands, fields, and rocky areas. Their favorite foods include frogs, earthworms, and leeches! YUM! 🙂
In some areas, after emerging from hibernation, there are not enough females for all the males. In these cases, “mating frenzies” occur, and dozens and dozens of these snakes can be found together.
To survive colder months, Red-sided Garter Snakes have to hibernate BELOW the frost line. Depending on the area they are located in, it can be hard to find suitable locations. So the few adequate hibernation dens can shelter hundreds, even thousands, of snakes! To see an example, watch the video below:
#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 Montana!
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 Montana 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 almost always found in northeastern Montana 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. Valley Garter Snake
- Thamnophis sirtalis fitchi
- Adults range from 18 to 55 inches in length.
- Coloration is brown to black with three yellow stripes; one down the back and one down each side.
- Pronounced red bars between the yellow stripes. Yellowish chin, jaw, and belly, and a black head, which often has red sides.
- Subspecies of the Common Garter Snake.
Valley Garter Snakes are found in various habitats, including forests, wetlands, scrublands, fields, shorelines, and rocky areas. They’re also well adapted to humans and are often found in urban areas.
Look for these garter snakes in Montana under rocks, logs, and other objects, which they use for cover and thermoregulation. During the winter, they hibernate, often communally below the frost line. They will use a variety of underground cavities, including mammal and crayfish burrows, rock crevices, ant mounds, as well as manmade spaces such as foundations and cisterns.
When disturbed, Valley Garter Snakes will try to escape into the water and are excellent swimmers. If captured, be prepared for them to release musk and feces onto your hands! They may also strike, but only if they feel extremely threatened.
The Valley Garter Snake is considered a species of low risk. They are quite common and adapt well to human-modified habitats. However, they are frequently killed on roadways and are sometimes killed out of fear.
Do you need additional help identifying garter snakes?
Try this field guide!
Which of these garter snakes have you seen in Montana?
Leave a comment below!