Almost everyone can identify a “garter snake” in Iowa!
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 Iowa!
- *Just a quick note – to be officially considered a garter snake, the species must be in the genus Thamnophis*
#1. Eastern Garter Snake
- Thamnophis sirtalis sirtalis
- Adults typically range from 18 to 26 inches in length.
- Coloration varies and can be mixtures of green, brown, or black. Look for a distinct yellow or whitish stripe down the center of their back.
- Some individuals may exhibit a checkered body pattern.
- Subspecies of the Common Garter Snake.
Eastern Garter Snakes are common and easy to locate in eastern Iowa!
In fact, they are typically the snake species that people come across the most. They are well-adapted to living around people and can often be found in city parks, farmland, cemeteries, and suburban lawns and gardens. Though it’s not required, they prefer grassy environments near freshwater sources such as ponds, lakes, ditches, and streams.
Look for these garter snakes in Iowa basking in the sun in grassy areas near cover.
Eastern Garter Snakes will protect themselves if they are cornered or feel threatened. For example, if you capture or continually disturb one, it will defecate and release a foul-smelling musk from glands. It’s also common for them to bite as a last resort!
The Eastern Garter Snake most commonly preys on toads, frogs, slugs, salamanders, fish, and worms. However, they are very opportunistic and will eat other insects and small animals they can overpower. They’re active during both the day and night, depending on the temperature.
These garter snakes have a high birth rate (up to 50 babies!) and adapt well to human-disturbed habitats! Because of these traits, this species is not threatened and is relatively common and widespread.
#2. 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 Iowa 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:
#3. 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 Iowa 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.
#4. 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 Iowa 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.
Do you need additional help identifying garter snakes?
Try this field guide!
Which of these garter snakes have you seen in Iowa?
Leave a comment below!