Monday, September 28, 2015

in cop

Female garter with two courting males. Photo Matt Burne
Out on a short walk this afternoon, I stopped just short of stepping on a small garter snake (Thamnophis sirtalis) basking in the middle of the trail. My colleague, who is interested in getting over a fear of snakes, asked if this would be good one to handle, so after a short chase, I caught it and handed it over. That went swimmingly, and even when it bit her hand and drew a little blood, it was agreed that "that wasn't too bad!"

The male is quite a bit smaller than the female in this pair.
Shortly after returning to my desk, she came in and said there was a big one near the front of the building, and did I want to see? What a treat! That big one was wrapped up with another, much smaller one. I've never seen snakes copulate before, and today, thanks to my colleague who apparently has pretty good eyes for snakes, I got to witness a couple of male garters courting a female, and one of the males in copulation with the female.

The heavily damaged tail on the female is an interesting feature, and one that will allow us to keep tabs on her going forward. We've been seeing a large garter around the office for some months, and now have a pretty good characteristic to look for which will help us determine if it is she all the time, or a collection of large garters in the area. The vent is just below this damaged area, which leads me to wonder if she experiences any difficulty in reproduction, but I expect that will remain a mystery.

Begs the question, though: how do those males know she's ready, and where she is?! My snap answer, of course, is "Pheromones!" But it turns out that's something I need to look up.

Based on the observation of four snakes within a half-hour's time, it looks like the local garter snake population has come to mating time. Not really sure where they hibernate, but I wouldn't be surprised to discover a hibernaculum in the field stone walls of the office basement.

What a nice treat for an early fall afternoon! Get out there and see what you see this fall!

~ M.R. Burne

This female's tail is heavily damaged.


  1. I hadn't thought about snakes mating in the fall, even though I've seen a number of baby garters and northern water snakes in September over the years though. Our community garden garters have been found hibernating in mulch hay bales, our giant composting pile, and around the roots of a particular blueberry bush each year. If you want to catch up on your snake mating encounters, pop over to Great Meadows in May on warm sunny days and it's a veritable water snake orgy out there!

  2. Thanks, Cherrie. I'll have to go see that! I'm wondering if these females are mating now to get a jump on the spring mating season. I've read that they can store sperm for long periods, so this could give them an advantage in getting a litter out earlier in the year. Also wondering about whether multiple males can inseminate a single litter.