Cool critters: A beaver that’s not a beaver or rat that swims is a muskrat

On a bike bath that runs alongside Paradise Creek in Moscow, several people stopped to observe a furry brown animal moving effortlessly through the murky, slow-moving water. “It’s a beaver!” one of them yelled.

But as the critter drew closer, a long, skinny tail trailing behind its body revealed a case of mistaken identity. It was a muskrat.

Right up there with coyotes being mistaken for wolves and bobcats for mountain lions, muskrats “are among the most commonly misidentified wildlife in North America,” according to the Nature Conservancy.

Which is intriguing, because muskrats are more abundant and widespread than beavers. Despite being found throughout much of the United States and parts of Canada and Mexico, many people don’t know much about these semi-aquatic mammals or how to identify them.

Beavers get all the glory. Although no song about the beaver has made the top 5 of the Billboard Hot 100 chart – remember the schmaltzy 1976 hit “Muskrat Love,” by Captain and Tennille?

While muskrats and beavers are rodents that share some similar features, they’re not even close relatives, said district wildlife biologist Mark Vekasy of the Washington Department of Fish and Wildlife.

“The two species belong to different families, with the muskrat being more closely related to the vole than it is to the beaver,” he said.

Also, despite the rodent’s “rat” part of its name, the muskrat isn’t a rat. Its long tail may resemble that of a rat, but it has a much different role: to steer the animal through water like a rudder. As for the musk part of its name? It comes from the musky signature odor the mammals exude to communicate with each other, particularly during breeding season, Vekasy explained.

Muskrats and beavers are native to North America. Both species have waterproof brown fur, dark beady eyes and whiskered noses. They also have webbed hind feet, spend most of their time in water, eat aquatic plants (although the muskrat will eat frogs and snails in winter) and often share the same slow-moving waterways such as creeks, marshes, ponds and reservoirs. Furthermore, both are most active around sunset and throughout the night, but are still seen in broad daylight.

With all these similarities, how to know if it’s a muskrat or beaver you see paddling by?

Appearance-wise, “there are some key differences, with size being one of them,” Vekasy said.

That’s because muskrats are considerably smaller than beavers. Not quite 4 pounds, they weigh less than a Chihuahua. Beavers, on the other hand, weigh an average of 45 pounds – roughly the same as a 4-year-old child.

Muskrats have a long, thin tail, where the beaver’s is wide and flat like a paddle.

If its tail is obscured by water or vegetation, then pay attention to the animal’s swimming style, Vekasy advised.

“When a beaver moves through water, most of its body is submerged with only its head sticking out,” he explained. Conversely, a muskrat “will often swim with its head, back and tail exposed above the water’s surface.”

Another important distinction? If you see gnawed-up tree trunks, it wasn’t done by a muskrat. Only beavers chew down trees and build dams. And though both species build lodges with underwater entrances, the muskrat’s is much smaller and made with reeds, grasses and cattails, in contrast to the beaver’s building materials of sticks, logs and rocks.

So, let’s say it’s cold outside and you spot a furry brown rodent emerging from what’s obviously a beaver lodge. A beaver! you think. That is, until you see a long, skinny tail churning through the frigid water.

By using video cameras installed in lodges, researchers have discovered that it’s not unusual for muskrats to move in with beaver families during winter. Scientists theorize that muskrats are drawn to the larger size and increased safety of the beavers’ sturdy, wood-built lodges.

Meanwhile, the beavers tolerate the uninvited guests because the muskrats’ body heat helps keep their lodges warmer.