Eastern Garter Snake Thamnophis sirtalis sirtalis

Male - Sampson County, NC
Photo By Scott Quint

Description: Garter snakes, named for men’s striped garters, are typically striped, having a dorsal stripe and lateral stripes on either side of the snake 2 to 3 scale rows from the ventrals. The dorsal stripe typically remains more distinct than the side stripes. The stripes can be yellow, tan, or the same as the based color and the lateral stripes are usually the same but paler. Between the stripes are dark spots that tend to be somewhat square. They typically are arranged in an alternating pattern and give a checkerboard appearance. The snakes base color is typically a light shade of brown but can vary quite a bit. The most typical variations in color are the shade of brown for the base color, but the color can also blend towards green or red slightly and in extreme cases look bluish or reddish. The ventrals are consistent with the base color and have some dark, irregular marking which tend towards the sides. The head can have some minor marking but tend to look to be unmarked most of the time. The labials are lighter than the rest of the head and often have dark stripes that run along the sutures.

     Pattern variations are minimal in garter snakes. The stripes can be sometimes faded out so that they are not obvious but usually the effect of the stripe is still present. The spots can also be faded so that they are less obvious or sometimes they align a bit

and look more like bars than checkerboards. The color is  what varies the most but extreme variation is uncommon.

     Adult garter snakes are of medium to somewhat slim build and range from 20” to over 48” with the females being the largest. Typical adults are 24“ to 30”.

     Newborn garters are from 4” to 8” and look like the adults in most all respects.

     Garter snakes typically have 19 mid-body dorsal scale rows, 131 to 153 ventrals and 52 to 80 subcaudals.

Biology and Behavior: Eastern Garter Snakes are non-venomous snakes with a generally mild disposition. They will always flee when danger threatens and will usually try to hide their heads when cornered. They will bite if actually grabbed and will expel musk, but will often calm if handled gently.

     Garter snakes are active day or night. They can be found crossing roads, moving along water’s edge or even dry areas at any time even late at night. They often make use of sheltering objects, hide on holes or any other sheltering opportunity provided to them, including resting amidst concealing plants.

     Eastern Garter Snakes are semi-aquatic and exploit food source provided by the waters edge. Frogs, toads, salamanders and fish are all taken regularly, but they also have a taste for earthworms. Young snakes, especially small ones can often feed exclusively on worms until they are large enough to go after stronger or swifter prey, though adults readily eat worms as well. More unusually garter snakes have been reported to eat other snakes, insects and even rodents and small birds, but these are unusual records. Some specimens from Virginia were found to have eaten mostly amphibians and worms, but also snakes were eaten in fewer than 5% of the snakes examined.

     Garter snakes breed from late March through July. Young snakes are birthed live in July, August and September and can number from 6 to over 100, though the average litter is 15 to 20.

     Garter snakes have been researched extensively and many studies have been done about their local behavior. They stay in localized areas, usually keeping to an area only a few hundred square yards. Springtime searches for mates and territory might move them to new areas but once settled they stay in the same general vicinity. They also seem to be very tolerant of low temperatures and become active early in the year and can be found moving, even when temperatures are in the 50’s.

Range and Locality Data:  Thamnophis sirtalis is found in every state except Hawaii and Arizona. It is even ranges into Canada and into southern Alaska. Thamnophis sirtalis sirtalis ranges from Well into Canada south to South Florida and deep into the Midwest. It has been recorded from every area in the Coastal Plains and almost every county. In fact, it is common throughout Virginia, North Carolina and South Carolina, though records are lighter in the piedmont regions of these states. It should be noted that this snake might look very different, depending on where it is found. South Florida specimens get very large and are heavier than garter snakes from the northeast. In the Coastal plains, they tend to be more consistent in size and appearance.

     Garter snakes can be found in almost every habitat except for, possibly, the driest areas. The Coastal Plains are quite hospitable and Eastern Garter Snakes are well represented in most counties. Being a moderately sized animal and having an appetite for common prey, these snakes adapt well to areas impacted by human activity and can be found in parks and other natural areas even in urban environments.

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