So you are outside on a rainy, cold day in late winter, walking around your favorite vernal pool, and you find an Ambystoma salamander. These are the large North American salamanders that often (but not always!) live on land as adults, but migrate to breeding ponds to mate and lay eggs. Once you’ve got one of these salamanders in your had during the breeding season, how can you tell if it is a male or a female?
In an earlier post, I showed how to tell apart male and female wood frogs during the breeding season based on the shape of the front limbs. That method won’t work for spotted salamanders or other Ambystoma; instead you’ve got to look at the cloaca.
The cloaca is the orifice just past the hindlimbs in salamanders. The cloaca serves two main functions: excretion and reproduction. During the breeding season, the cloaca of male Ambystoma are enlarged, while the cloaca of females remain smaller. If you can pick up your spotted salamander and flip it over, you can easily tell its sex. Unfortunately this approach won’t work if you find an Ambystoma during the summer, because the males do not have enlarge cloaca outside of the breeding season.