Mating activity and unusual mating behavior in Thamnophis scalaris.

Steven Bol (Author…)

Publication: 2020, The Garter Snake, 90: 29-33

Sunday November 17th 2019 I witnessed mating behavior in my Thamnophis scalaris breeding group. Thamnophis scalaris has a reproductive cycle that is very different from the members of the genus Thamnophis from the US and Canada. Mating season is probably (this has not been investigated in detail) somewhere in late fall (October/November) and in the wild most females are already pregnant end of November (personal observations). The females likely stay active during the wintertime (on warm and sunny days in some populations, but also this not well investigated) and babies are born somewhere in May or June in the wild.

Actual coitus with 1 male while a second one also tries to mate with the female.

Actual coitus with 1 male while a second one also tries to mate with the female.

Sunday November 17th 2019 late in the afternoon I noticed 1 male actively copulating one of the females. His body was lying beside tmales body and they were clearly locked. Little shocks went through the body of the male. In the beginning I could not see the head of neither the male nor the female and of course I did not want to disturb them. A little later the female was slowly crawling through the cage and I saw both their heads. Now I noticed that the male had his jaws around the neck region of the female. I cannot be sure whether the male was “biting” the female during the entire duration of the copulation. About 10 minutes later the pair unlocked and I saw the male basking. The female disappeared a little later.

Male biting the female during courtship.

Male biting the female during courtship.

Male biting the female during courtship.

Male biting the female during courtship.

Male biting the female during courtship.

Male biting the female during courtship.

All is quiet again and they are basking together.

All is quiet again and they are basking together.

All the time while the pair was copulating a second male also attempted to mate with the same female. He was not interested in one of the other females that was also active at that time. This second male had his chin on the back of the female, crawled towards the tail region in quite high speed, turned around and searched for the head of the female.
Once they were lying like this side by side, with the male on top, the (much) smaller male crawled back in the reverse trying to bring his cloaca close to the cloaca of the female. This part of the behavior is quite similar in appearance to the mating behavior of other member of the genus Thamnophis. Although the T.scalaris male was doing this very active and rapid with relatively high speed and precision. Which is very unique and never mentioned in literature before is that T. scalaris males are biting the females during courtship. I witnessed this second male trying to bite the female several time while he was slithering back and forth over the female. It is not very often that one discovers a never described aspect of behavior.

F. Tews (personal comment) was the first to witness and film this behavior last year in 2018 and I was very thrilled to also witness this in my breeding group for the first time.