Mass Gatherings
Tens of thousands of snakes emerge at the Narcisse dens every spring
Manitoba's Narcisse Snake Dens erupt with red-sided garter snakes each spring as enormous numbers surface from winter dens to mate.
Video: Manitoba Parks. Embedded from the original YouTube source.
The mechanism
Why this happens
The snakes overwinter below the frost line in limestone dens and emerge when spring conditions warm enough for their annual mating period.
Season & place
Where this event happens
Narcisse, Manitoba, Canada · Seasonal den emergence. Timing and local conditions can vary from one occurrence to the next, so current local guidance matters when planning around a recurring event.
The event is driven by geology as much as biology. Manitoba's Interlake limestone provides deep winter refuges that allow huge numbers of garter snakes to survive cold winters together.
What to know
- The main spring spectacle usually lasts only a few weeks.
- Males often emerge first and gather around females in large mating balls.
- The snakes are harmless, but visitors should use designated viewing areas and avoid disturbing them.
If you go
Watch without becoming part of the problem.
Follow local closures and wildlife guidance, keep a responsible distance, avoid blocking migration or access routes, and do not disturb roosts, nesting areas, dens, or concentrated animals for a photo. Conditions and access rules can change quickly.
Good questions
What people usually want to know
Why are there so many snakes at Narcisse?
The area's limestone bedrock provides suitable communal winter dens below the frost line, allowing very large numbers of garter snakes to overwinter together.
When do the Narcisse snakes come out?
The strongest spring viewing is generally from late April into May, depending on weather.