75,000 Snakes Swarm To Narcisse: Inside The World's Largest Snake Gathering

In Manitoba, Canada, you can find the world's largest concentration of snakes at the Narcisse Snake Dens. Each year, around 75,000 red-sided garter snakes gather in these dens, which are limestone sinkholes offering shelter from the extreme cold. While the area can experience temperatures as low as -45 degree celcius, the sinkholes provide a warmer environment for the snakes to survive. Despite being about the size of a living room, these sinkholes become temporary homes for tens of thousands of snakes, creating a remarkable natural spectacle.

According to a November 2023 study published in Behavioural Ecology, some snakes mingle not too differently from other social animals around us. Butler's garter snakes, for example, show a complex social structure sorted by age and sex.

According to Forbes, these dens provide perfect hibernation conditions for red-sided garter snakes. A subspecies of the common garter snake, Thamnophis sirtalis parietalis, red-sided garter snakes are found across North America. However, the unique environment of Manitoba's Interlake region offers conditions unlike anywhere else.

Here, winter routinely drops below -30 degree celcius, and snow buries the prairie for nearly half the year. For an ectotherm whose body temperature hinges on the temperature in its surroundings, that would be a death sentence. But beneath the wind-scoured fields of Narcisse lies a subterranean sanctuary forged by time. The bedrock here is limestone-soft, porous and ancient.

Roughly 450 million years ago, this ground was the floor of a tropical sea teeming with marine life. Over aeons, water dissolved the calcium carbonate, etching deep fissures and caverns into the stone. These underground sinkholes and crevasses stretch several metres below the surface-deep enough to stay below the frostline but just above the water table.