Illinois Is Really Cold, So Why Don’t Squirrels Freeze To Death?

It's pretty nice that we're already in the first week of January, 2025 and we haven't had to shovel tons of snow and shiver through sub-zero temperatures all that much so far this winter.

It's pretty cold right now, and it looks like Northern Illinois will be staying well below freezing for the next 10 days or more. This morning, the temperatures around here were in the middle teens with a feels-like temperature of 5 above zero, and there's more of that to come.

Whenever Northern Illinois goes into a real deep freeze, it seems as though all activity by wildlife comes to an absolute halt while the animal kingdom hunkers down to try to survive the brutal cold, except for Illinois' squirrels, who are as active as ever despite the weather conditions.

I Understand That Hibernation In Very Cold Weather Keeps An Animal Alive, But There's Just One Problem With That Here In Illinois

That problem is the fact that the squirrels running all over the place in Northern Illinois' sub-zero weather aren't hibernating.

Here in Illinois, we've got seven species of squirrels, but only 3 of them, all ground squirrels, actually avoid the bitter Illinois winter by hibernating. The four species that we're seeing being very active in the cold are tree squirrels, and they don't hibernate:

• Fox Squirrel
• Eastern Gray Squirrel
• Red Squirrel
• Southern Flying Squirrel

Illinois' Tree Squirrels Don't Freeze To Death Because Their Bodies Are Meant To Be Active All Year Round

It's all about food storage, fat distribution, and being something called a homeotherm, according to the Lincoln Park Zoo:

Which means that unlike some mammals, their body temperatures remain fairly constant throughout the year; they don’t hibernate.

Squirrels also prepare for winter by bulking up. Throughout fall, they maximize food consumption and body mass. In winter, when food is hard to come by, these reserves will help the animals survive.

One other tactic gray squirrels use to keep warm in winter is shivering. Shivering isn’t just a sign that you’re cold; it also serves as a way to keep warm. While it certainly doesn’t sound fun, gray squirrels are remarkably good at generating heat by shivering.