Snake experts: Ribbon or Garter?

How do I tell the difference, from a respectful distance (i.e., without trying to pick up the creature) between a common garter snake and a ribbon snake? I’ve got one of the two under my bungalow here in upstate New York, but all pictures I’ve tried looking at seem very similar.

I’m leaning toward garter, because the black parts of its body seem to have tire treads. But I’ve seen at least one ribbon snake picture in which the black parts are also somewhat patterned (though that might have just been the lighting?)

Any thoughts?

Hmmm…that can be a little difficult if you aren’t familiar with them. You’re dealing with the Eastern Garter Snake ( Thamnophis sirtalis sirtalis ) and Northern Ribbon Snake ( Thamnophis sauritus septrionalis ) in your area and both have three stripes and usually a darkish background.

Ribbon snakes are much skinnier and are more delicate looking with a proportionally smaller head, but obviously you would have needed to see both at some point to make a comparison. If there is any brown pigment occasionally getting onto the middle stripe and obscuring it, it would probably be a ribbon snake. This is opposed to the middle stripe being brownish ( they can also have a bluish or greenish tinge ), which would indicate a garter snake - ribbon snakes usually have bright yellow middle stripes, sometimes with a little orangish or greenish tinge. If you have it in hand ( and they are both quite harmless, though they might draw a little bit of blood with a bite ), the garter snake has its lateral stripes on scale rows 2 and 3, the ribbon snake on rows 3 and 4.

  • Tamerlane

Here is something else to try. Look at these two pictures:

Notice how the ribbon snake has eyes that are larger in proportion to it’s head? That might help.

Another contrasting set:

  • Tamerlane

It also appears from those images that the ribbon snake’s eyes are located more in the middle of the side of the skull, whereas the garter snake’s eyes are raised a bit toward the top of the skull. That may just be the pictures, though (and IANAherpetologist).

Well, my son caught it. I got a pretty decent look, and…I still can’t decide.

The shape of the head looks more like the ribbon snake.

But the stripe definitely seems more brownish-yellow than bright yellow, which you said would indicate garter.

Thanks for the links anyway.

OK, it stopped struggling, and I got a better look at its face. Definitely garter.

Thanks, all!

To be terribly scientific (being a herpetologist and all) about the matter, the scutellations of the two snakes differ as follows:

The garter snake Thamnophis sirtalis sp. has dorsal scales highly keeled in nineteen rows, with the first dorsolateral stripe occuring on rows two and three above the scutes (smooth belly scales).

The ribbon snake (T. sauritus also has nineteen rows of highly keeled scales. The first dorsolateral stripe occurs on the third and fourth rows of scales.

Another commonly used identifier for the ribbon snake, at least for more southern populations, is the presence of a bright yellow preocular scale. This gives the impression of bright yellow spots in front of the eyes. As already noted, the ribbon snake is far more slender and has eyes much larger in proportion to it’s head. In addition, the ribbon snake moves fluidly with its head held above the ground, whereas the garter snake moves more along the ground.

[On preview, DAMN! Tamerlane beat me to the stripes.]