Red-sided garter snake
Thamnophis sirtalis parietalis
The red-sided garter snake is famous for aggregating in huge numbers in Manitoba during the breeding season. Each spring, thousands of these snakes emerge from underground. The males tend to come out first, and then court the females as they surface.
Because these snakes breed in such huge numbers, they make an excellent model for the study of reproduction. It is relatively easy to get very large sample sizes, and they are very resistant to disruption. They also adapt very well to captivity, making laboratory research feasible. For these reasons, the red-sided garter snake is arguably the best studied reptile in the world.