by Lindsay Eney
May 23, 2010
Welcome to the latest installment of the BayBlog Question of the Week! Each week, we take a question submitted on the Chesapeake Bay Program website or a frequently asked question and answer it here for all to read.
This week’s question comes from Sammy: “Is a muskrat the same thing as a beaver?”
One of the most obvious differences between the two species is their size. The American beaver (Castor canadensis) is the largest North American rodent, weighing 35-68 pounds and measuring 39-47 inches in length. Muskrats (Ondatra zibethicus) are much smaller, weighing just 3-4 pounds and measuring 16-25 inches long.
Tails are another way to distinguish the two species. While the beaver’s tail is wide and flattened horizontally, resembling a paddle, the muskrat’s tail is narrow and flattened vertically.
The way muskrats and beavers use the land is also different. Beavers are the only ones that chew down trees. Tree limbs with the bark removed or lodges made of limbs and mud are telltale signs of a beaver’s presence. Muskrats also build lodges, but they are much smaller than those built by beavers and are made from marsh vegetation rather than trees.
Nutria (Myocastor coypus) are another rodent that look similar to muskrats and beavers. They typically weigh between 12 and 15 pounds and measure about 24 inches in length. Nutria are found mostly on the Delmarva Peninsula but have also been seen around the Patuxent, Potomac and Rappahannock rivers.
So if you see one of these animals in the wild, make sure to look at the shape of its tail and the overall size of its body, which are the two main ways you can tell the difference between a muskrat and a beaver.
Do you have a question about the Chesapeake Bay? Ask us and we might choose your question for the next Question of the Week! You can also ask us a question via Twitter by sending a reply to @chesbayprogram! Be sure to follow us there for all the latest in Bay news and events!