The largest concentration of garter snakes in the world, roughly 70,000 snakes here. Every spring, the Narcisse Snake Dens are alive with tens of thousands of red-sided garter snakes as they slither to the surface from their winter dens. These snakes are ready to begin their annual mating ritual. This spectacular ritual lasts for a one to three week period in late April or early May, depending on weather conditions. The male snakes are usually first to surface and they wait patiently for the females to come out. As the larger females surface, the male snakes are eager to mate with them. This eagerness is displayed in a "mating ball" where one female is surrounded by up to one hundred males.