Muskrats remain active during the winter

It may look like a whole colony of muskrats has overtaken a wetland in the winter.

Mounds of plants are pushed up all around, but most likely it's not as many muskrats as it appears.

Muskrats do not hibernate during winter, and they also don't store food in their lodges like beavers do. That means that they need to find food and eat daily, even in cold weather.

They still live in their main lodges, but ice covering the rest of its habitat restricts it to finding food underwater. Yet, it still needs to breathe.

A muskrat surfaces though a thin layer of ice, wearing several pieces on its head and back. Photo: Tom Koerner/USFWS

So a muskrat will use its sharp teeth to cut holes in the ice around its lodge, up to 100 yards away. Then it covers the holes with plant material and mud, creating a little hut where it can poke up through the ice, breathe, rest and eat. It will swim to its feeding grounds from its lodge, chew off a piece of food and take it to a push-up to rest and eat.

Muskrats can dive for up to 15 minutes due to a decreased heart rate and oxygen stored in its muscles. It stays warm in the frigid water due to its thick, waterproof fur. To stay warm, groups of muskrats will also huddle together in their lodges to share bodyheat.

Muskrat push-ups only last during the winter, and then they collapse as the ice melts in the spring. The main lodge remains intact.