Garter snakes are North American colubrid snakes that belong to the genus Thamnophis. Most members are called garter snakes, but a few are called ribbon snakes instead.
Many different species of garter snake are kept in captivity. Since there are so many species of garter snake, you may be wondering:
How big do garter snakes tend to get?
On average, most garter snake species will be between 23 and 30 inches long as adults. However, some species can reach up to 5 feet long. They are typically slender so they also tend to be fairly light.
Many species of garter snake stay fairly small.
The average common garter snake (T. sirtalis) is 22 inches long including the tail. Some very large individuals can measure up to 54 inches long. Most species of garter snake are found at maximum lengths in the 25-35 inch range.
This makes them a relatively small snake for most species. They also tend to be light, weighing around 5 ounces for medium-sized species.
This small size means they typically target smaller prey like frogs, newts, lizards, and fish. Many species also eat worms like earthworms or nightcrawlers.
Most species will only take on rodents or other mammals on occasion. This is partly because most rodents are a bit too large for the average garter snake to take on.
Since most species stick close to bodies of water, aquatic prey is also easier to find. Ribbon snakes are even smaller and thinner on average than garter snakes. Their name partly comes from how thin these snakes are.
Largest and Smallest Garter Snakes
The largest garter snake is the aptly named giant garter snake (Thamnophis gigas). These snakes live in a very limited range in the wetlands of central California.
They typically reach lengths between 3.1 and 5.4 feet. These snakes are very endangered since they are aquatic and rarely travel far from water.
Since their natural habitat was destroyed, fragmented populations are left. The smallest garter snake is the exiled garter snake (Thamnophis exsul). It is both the smallest and rarest since only ten specimens have been collected.
The largest of these was only 18 inches long. It has been collected from three localities in northeastern Mexico.
Common Captive Species
The most common garter snakes in the pet trade are the eastern garter snake (T. sirtalis sirtalis), the California red-sided garter snake (T. sirtalis infernalis), plains garter snake (T. radix), and the checkered garter snake (T. marcianus).
All of these species are easily found and come in a variety of unique colors and patterns. Most people who own a garter snake will likely have one of these species.
If a snake in a pet store is just called a garter snake without the exact species, it is most often one of these. The plains garter snake is a larger garter species and tends to be around 3 feet long as an adult. The other common species rarely get past 26 inches in length, with a few that can exceed this up to around 40 inches for most species.
While the plains garter snake needs a fairly typical enclosure for a snake, the smaller garter species are great for those who can’t fit a huge enclosure.
Most will be very happy in an enclosure that is 3 feet long. This is a big contrast to snakes like the ball python that need at least 4 feet for a male and up to 6 feet for a female.
Garter snakes are generally lightweight. The various common garter snake subspecies rarely weigh over 5 ounces for an adult. This make them very light compared to many other species.
Larger species will weigh more, but they are compartively light snakes. Since garter snakes rely on strong jaws and eat live prey, they do not have the heavy muscles of many other common pet snakes.
Pet snakes are prone to obesity, so they may weigh more than average.
Pet snakes also tend to grow to longer lengths since they have a reliable source of food that they don’t need to hunt down. This can result in more growth in young snakes.
Size at Birth
The vast majority of garter snake species are tiny at birth. The mothers carry live young, so larger litters will have comparatively smaller babies than a smaller litter.
The California red-sided garter starts life at a length of 5-8 inches. Eastern garter snakes average slightly longer at a maximum of 9 inches.
All but the largest garter snakes stay in this range, with most looking like small adults and having fairly similar proportions. Due to their small size, feeding newborn garter snakes can be difficult in captivity.
They cannot eat whole pinky mice so they either need the mice cut up or they need earthworms or fish instead. Some keepers have success with the smallest size of sausage made for reptiles.
If you ever intend to breed garter snakes, make sure you have multiple options for feeding the young available since they are much smaller than other snake species.
Garter snakes are mostly small snakes compared to other species. Very few commonly bred species get larger than a few feet long.
This makes them easy to handle for beginners, even if some species are nervous and likely to bite. They are easy to keep and house even if you have limited space for an enclosure.
If you have any questions or comments, please leave them below. If you have an adult garter snake, please leave a comment with the species and how large they are.