Springtime for Garter Snakes

It’s not spring until the garter snakes come out of hibernation. And after a winter that seemed longer and more brutal than usual, we finally got spring last week.

Last Tuesday, some of Jennifer’s students pointed her to a site near the school where Eastern Garter Snakes (Thamnophis sirtalis sirtalis) were emerging from hibernation. And when I say pointed her to, I mean told her about it by handing her a bunch of wriggling snakes, because the kids know her. The kids released the snakes where they found them, but she told me about it and we made a note to check the site out after classes were done.

The location the kids told her about was at the edge of some seriously snakey habitat: lots of ground cover, and next to a wetland that was already echoing with the calls of Wood Frogs (Lithobates sylvaticus) and Spring Peepers (Pseudacris crucifer). Which is to say, snake food. A good spot, in other words. But in our initial search we only found one snake, which musked all over Jennifer. It took us a while to find the entrance to the hibernaculum, the precise location of which I will not reveal here to ensure the snakes’ safety and privacy, but once we did we found the area fairly crawling with snakes. I had brought my Nikon D7100 with me and took some pictures.

As far as we could tell they were all males, which made sense. In Canadian climates, male garter snakes come out of hibernation before females do; the males wait for the females to emerge and then pounce on them, because mating season occurs immediately after hibernation.

All things considered, they were fairly good natured. None of them bit us, though a couple did musk, as I mentioned above. About what we were expecting.

But they were tamer still when we came back on Thursday to check on how they were doing. There were still snakes hanging around the vicinity of the hibernaculum, but this time the males kept moving back and forth between the entrance and the nearby bushes. They were also much more tame. I’d thought they were relatively good natured on Tuesday: that was in comparison with some seriously grouchy garter snakes I’d encountered at the height of summer. This time, not a single one of them musked when picked up. I don’t think they even noticed that we were picking them up. You could stroke them as they slithered by without them even reacting.

These were the same snakes we had encountered on Tuesday. (At least one we could recognize on sight: he had a kink in his neck.)

We could see one or two female snakes hiding just inside the hibernaculum entrance. (We could tell they were probably females, because female garter snakes are much larger and heftier than males: females put their energy into growth, because a larger snake can have more offspring; males put their energy into chasing females, and stay small and skinny.) I had a hunch that we should stick around in case one of those females emerged.

I was right. The males had been pacing around the entrance, and ignoring our presence, for a reason: they were blitzed out on the garter snake equivalent of testosterone. When one female snake, covered in dust and dirt, finally came out of the hole, she was promptly pounced upon by seven male garter snakes. A small mating ball was the result.

In these photos you’ll see examples of garter snake courtship behaviour: small male snakes rubbing their chins along the female’s back. Male garter snakes are devoted courters: this is the thamnophine equivalent of wining and dining. With my original male captive Red-sided Garter Snake (T. s. parietalis) I’ve seen it take weeks, but in the wild, in a mating ball, there’s rather more urgency, because the lucky male who copulates first leaves behind a plug in the female’s cloaca that makes it difficult for subsequent males to mate.

Isn’t science interesting?

Let me tell you, though, being able to interact with and photograph multiple wild garter snakes a short walk from our home was a fantastic experience for us. Made our day, it did—twice.

For the complete set of photos from our garter snake encounters, see my Flickr album.