Monday, November 1, 2010


I briefly espied one of our most - if not the most - aquatic mammals the other day, and find it necessary to post about them.

I took this aerial photo a few years back, of a wetland hard on the shores of Lake Erie's Sandusky Bay. Click the pic, and blow it up. You'll see lots of little brown dots in the water. They are the reason that I took the photo - muskrat lodges! Many, many muskrat lodges.

Not everyone likes these strange little beasts. It pretty much depends on your perspective, and what role marshes play in your life. If you are a marsh manager, and maintaining dikes that are leak-free is your business, you at the least will be irked by these reddish-brown rodents. Muskrats are prone to burrowing and often do so in convenient dikes next to favored wetlands, necessitating expensive repairs.

If you are like me - only a visitor to marshlands - you might like 'skrats. I do.

Over the years, I have heard people ask about these dome-like piles of vegetation many times. "Those are beavers, son", is a common mistaken identification. Nope - they are muskrat lodges, one of the classic symbols of a mixed-emergent marsh. Beavers do often make large mini-island lodges, but they tend to be wider and not so steep-sided, and make heavy use of sticks and branches. Not so with muskrats - they only use herbaceous material, and cattails are often the favored building blocks.

Tiny eyed and somewhat otterish about the face, a Muskrat, Ondatra zibethicus, peers inquisitively at me, the awkward landlubber. Believe it or not, Muskrats are closely related to voles, which are small mouselike rodents that typically frequent upland habitats.

Muskrats took to the water eons ago, and have evolved a host of features that allow them an aquatic lifstyle like few other rodents. Their fur is dense and water repellent, allowing them to spend most of their time swimming and soaking. The hind feet have webbing to aid in propulsion, and the animals can even close their ears off to keep water out.

It's the tail that is probably the most noticeable of the 'skrats' evolutionary design. This appendage is sort of a sideways beaver tail - laterally compressed, or thin and tall. It works well to propel the animal efficiently and gracefully through the drink, something that you'll notice if you get the chance to watch one swimming.

This is a Beaver, the mammal probably most often confused with a Muskrat. Take its tail and turn it sideways and shrink the thing a bit, and you've got an approximation of a Muskrat tail.

Muskrats have their fair share of enemies, and when this little fellow grows up, it'll be one of 'em. Mink, which are weasels, sometimes appropriate Muskrat lodges as their own, and upon staging the home invasion kill and eat the occupant should it be in residence.

Like them or not, Muskrats often play an important role in marsh ecology. They are voracious plant consumers, and tend to favor tall, aggressive species such as cattails (Typha) that can take over. Muskrats will keep such plants in check and create a better mosaic of open water versus aquatic plants, and thus help to diversify the flora and fauna of our wetlands.

Plus, Muskrats may be responsible for the very earth that you live on. Certain Native Americans, who knew far more about the natural world than do most of us, believed that it was the lowly muskrat that created dry land. A Muskrat, upon returning to the completely flooded earth's surface with a big dollop of mud, spread it on a large turtle's back. And thus, dry land and a home for creatures such as us was born.


Anonymous said...

Great post Jim. I always love seeing the domes when getting about in the outdoors around water.
Gary Wayne

Randy said...

I, too, have always liked these industrious little creatures! Another good article!

Jim McCormac said...

Thanks Gary and randy - glad you like the post, and are muskrat fans!

Dave said...

Love those Minks! We have one visiting our gardens...go figure...