Which Manitoba site is the winter home of tens of thousands of red-sided garter snakes?

Narcisse Snake Dens is the Manitoba site that serves as the winter home of tens of thousands of red-sided garter snakes.

The dens lie near Narcisse, about 6 kilometres north of the community, in a provincial wildlife management area. The snakes shelter in underground caverns formed in water-worn limestone bedrock. In spring, they emerge into the famous “snake pits,” where mating takes place before they disperse into nearby marshes and grasslands for summer feeding.

The snakes return to the dens in early autumn, and the site’s scale is extraordinary: the surrounding population has been estimated at roughly 75,000–150,000 in recent years. The red-sided garter snake is a subspecies of the common garter snake, Thamnophis sirtalis parietalis, not a separate species.

A common mix-up is confusing the dens with the snake pits. The dens are the underground winter shelters; the pits are the surface gathering areas seen during spring emergence. Conservation measures, including snow fences and tunnels beneath Highway 17, help protect migrating snakes from traffic.