I spent the last couple of days at my parents’ new place, house-sitting for them as they returned to the old house one final time (hopefully) to complete the paperwork for the sale of the property. I returned home this afternoon, in the rain. When I got home, Dan asked me if I’d seen the muskrat. He took me out to the side of the house where he’d seen it last. It wasn’t in the same spot, but a peek into the two basement window wells turned up the little critter. Dan commented that it had already fallen into one of the wells; this time it was in the other. It was just hunkered down in a corner, looking a little soggy and disgruntled but otherwise fine.
It was small, and appeared to be a youngster. Heaven only knows what it was doing way out at our house. Although there are tiny little ponds here and there, the closest significant water source is a marsh-bordered creek a kilometer (0.6 miles) away. Presumably it was dispersing from its natal territory, looking for a new place to call home. Muskrats have relatively quick breeding cycles, with the female giving birth a month after mating, and the young weaned and independent at just six weeks of age. The female may have two or even three litters in a summer, often giving birth to the subsequent litter before the first one is completely weaned. They can potentially have three litters in three months, each bearing five to ten young. That’s a lot of baby muskrats! It comes as no surprise, then, that they suffer a high mortality in their first year, and the high birth rate has evolved to counteract that.
Dan scooped him up in my butterfly net to get him out of the window well, and deposited him in the grass. Muskrats even when full grown don’t get that big, only about 1 kg (2.2 lb) on average, and 50 cm (19.6 inches) long from nose-tip to tail-tip. About half of that length is tail. Their tail is flattened vertically, like a fish’s, and is used in the same manner while swimming. Although they superficially resemble beavers in their general shape and scaly tail, they’re actually more closely related to field mice, being, essentially, a large field mouse that has adapted to life around water. Beavers and muskrats and field mice all belong to the same order, Rodentia, so it’s not surprising then that they should seem similar.
Once released from the net, the muskrat scurried across the grass to the nearby lilac bush. He could move quickly, and I just got one sort of blurry shot before he was in the shrub. They’re most at home in the water, however, and spend the majority of their life in or near it. They build their burrows into riverbanks or along lake or pond edges, with the entrance to the burrow underwater. In the winter, they create “push-ups”, hollow mounds of vegetation that protrude through the ice, in which they can eat and rest undisturbed. I found a few of these last winter.
They get their name, muskrat, from their resemblence to rats (even though they’re more closely related to mice), and from two musk glands they have near their anus. In the breeding season these swell and exude a yellowish musky substence that the muskrats use to mark locations along frequent travel routes such as their lodge or conspicuous land features. The purpose of the scent marks isn’t clear, but is thought to be a form communication between individuals, perhaps within a family group, or maybe as territorial markers.
Once in the relative safety of the lilac bush, the muskrat hunkered down and wouldn’t budge. Check out his feet in this photo. Those long claws are used for digging in banks when building their burrows, as well as in foraging underwater. Much of their diet is made up of cattails, especially the roots. Many nights at our last house we’d hear the sound of chewing coming from down at the lake edge. There was a muskrat that had a burrow in our shore there, and he’d often make meals of the cattails that lined the banks. We rarely saw him during the day. If cattails are scarce, muskrats will also eat other aquatic vegetation such as bulrushes, horsetails or pondweeds. And if plant matter in general is hard to find, they can and will turn to protein sources such as fish, frogs or even clams. That would explain all of the empty mussel shells we’d see around our shoreline.
Unlike beavers, muskrats only have a moderate amount of webbing on their back feet. Most of their foot power is from hairs that line the toes, creating a paddle-like effect. They use their feet mostly when swimming at the surface, where their tail acts as a rudder. When underwater, their tail provides most of the propulsion, and their feet help with the steering. They have the ability to slow their heart rate and metabolism, and have a high tolerance for carbon dioxide in the blood, the combination of which allows them to stay underwater for up to 15 minutes at a time.
When I got a tad too close with the camera, the muskrat bared his teeth and even lunged at me. He was fierce! While they’ll usually escape to deep water if they have the option, muskrats are very courageous when confronted on land, even if not cornered. They can be very vicious, inflicting deep wounds with those sharp rodent teeth. Despite this, they suffer heavy predation from mink, as well as snapping turtles, pike, coyotes and wolves, fishers, wolverines, lynx – basically any large carnivorous vertebrate.
The sharp cutting teeth are primarily used in chewing vegetation. Muskrats are specially adapted for eating underwater, something that most land-dwellers would be unable to do. Their front teeth project in front of their cheeks, and they can close their heavily muscular cheeks behind their incisors, essentially closing off their mouth and airway while they’re cutting vegetation. Once they’ve cut some food, they can close the front of their mouth and open their cheeks to allow them to chew and swallow it.
After I’d run off a few photos, we backed off and let the little guy be. We kept Raven inside to allow him to wander off without being harassed (also for Raven’s safety – she could get a sharp bite on the nose if she got too close, which undoubtedly she would). When I went back out to check on him after an hour or two, he was gone, and I was unable to relocate him. Hopefully en route to better habitat than our grassy meadow.