Everyone at the University of Alberta has seen, heard, or been chased by a squirrel on campus. They’re North American Red Squirrels (Tamiasciurus hudsonicus), and it’s only through intensive monitoring of these squirrels that researchers can learn more about their habits. Amanda Kelley, the teaching lab coordinator in the department of renewable resources, did her master’s degree working with the Kluane Red Squirrel Project, an interdisciplinary and inter-university project that’s been going on for almost 30 years. The Gateway talked to Kelley to learn more about the private lives of our campus friends in the trees.
The Gateway: When do squirrels reach sexual maturity?
Kelley: They’ll reach sexual maturity within their first year, so squirrels are born in the wintertime and by the following winter season they’re ready to mate.
How do they choose their mating partners? That’s actually a really interesting question. North American Red Squirrels are one of the most promiscuous squirrel species. They breed in mid-January through to mid-March and they have a scramble mating system: the female is fertile for just one day a year, and on that day several males in the area will come and visit and try to mate with her. She’ll mate with, on average, six males during that one day and she’ll have sex, on average, 22 times. Each copulation lasts less than a minute, so she’ll have, in a year, about 22 minutes of sex all in one day.
So each squirrel has its own day that they’re fertile?
That’s right. They’re not synchronized, so the males have opportunities to travel around in their area and see when different females are going into estrus. So, both males and females mate with multiple partners.
They don’t mate for life or have a specific partner?
No, just that one day. Red Squirrels are very territorial, and they are asocial. So, you may have seen a squirrel on campus barking at you, running up and making sounds, such as a rattling sound. Those kinds of vocalizations are territorial vocalizations. So each squirrel has its own little area of the forest, and it protects that area all year round — except for females on that one day when they allow other males to visit them on their territory.
The only real social interactions that Red Squirrels have are the mothers caring for their offspring, and then sex. So they are very asocial for a mammal.
Is any of the noise that the squirrels make related to mating or are they all more territorial?
They do have a mating call. The males, when they’re chasing the females around, will make a buzzing noise. It really sounds like a bee. A lot of the time when you see squirrels chasing each other on campus, it’s a territorial chase. But if you hear the buzz, then you know that it’s a mating chase.
How long are squirrels pregnant for? And then how long do they care for their offspring after that?
Gestation is about 35 days. The young will stay in the nest until they’re about 40 days old. After that, they’ll start venturing out onto the branches, learning how to be a squirrel — that sort of thing. They’ll live in their mom’s territory until they’re maybe 90 to 100 days old and then they will venture off and try to find their own little slice of the forest to call home.
You can see nests on campus that are kind of spherical, up in the trees. A squirrel nest is called a drey and they’re made out of grass and mosses and other materials they can find. They can also have nests underground though, so you’ll notice on campus in some areas under conifer trees there will be holes in the ground and there will be parts of spruce cones scattered on the ground. That’s their food cache, so they keep the cones under the ground, and then when they eat the cone, they’ll discard the outside parts.