Each year at the break of spring, red-sided garter snakes in Narcisse, Canada engage in an unusual ritual.
Thousands of them begin emerging from their underground dens during the last week of April and their numbers peak during the second week of May. The reason? They’re all out to mate.
Here is what goes down at the snake dens:
Like all other snakes, red-sided garter snakes, are cold-blooded. During the winter, when the temperatures drop to below freezing, they hibernate for eight months.
Manitoba, Canada is laced with sinkholes that line its superficial limestone bed rock. Underground dens form here, attracting the snakes, who see it as the ideal spot for an 8-month snooze.Thousands of snakes end up in dens as large as an average living room.
Once spring arrives, thousands of the the red-sided garters slither over one another to emerge from their lairs, forming a carpet of quivering snakes.
It's also peak breeding time: The males eagerly look for a female to mate with in the areas surrounding the den.
In the huge heap of snakes, it can be tough for the males to recognise the females, even though they're longer and wider than the males.
The male-biased sex ratio is a result of the males pouring out of the den first and awaiting the females, who typically emerge over the course of a few weeks.
Once the males are lured by a female's pheromones, several males try to court one female female by rubbing their chins along her back. This is called a 'mating ball.' The male closest to the female copulates with her, leaving a gelatinous plug inside her body that blocks her reproductive tract for about two days, warding off other males.
Then, the female can slither away from the carpet of snakes, where she'll in feed and give birth later in the summer. One female can give birth to 40-50 young at once.
However, if the female rejects the male, she can prevent his sperm from fertilizing her eggs, a mechanism called 'cryptic female choice.' She simply waits for the smelly plug to dissolve and then mates with another male.
In September, the snakes return to their dens for the winter, where scientists think they spend the next eight months in hibernation once again.
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