Little Lives of Earth and Form
A Tale of Two Tails —
Is it a Beaver or a Muskrat?
By Tamia Nelson
June 22, 2010
Wildlife and wild waters go together, and our canoes and kayaks give us ringside seats for every waterfront performance. Birds are among the most approachable of wild creatures, and it's a rare boater who isn't a part‑time birdwatcher. Paddlecraft are quiet — unless you hit the gunwale with your paddle, that is — and if you avoid flashing a shiny blade high in the air, you'll be astonished at how close you can drift before birds take flight. (Don't get too close, though. It's good to give all wildlife plenty of space.) I've been a keen amateur ornithologist since I was a teenager, and I never fail to marvel at how much easier it is to stalk my "prey" when afloat than when ashore. Of course, birds aren't the only denizens to be seen on and around the water. I've had close encounters with mink, otters, whitetail deer (once a mother and her fawn came to the water's edge to drink just as I was drifting by), moose, and raccoons, not to mention the occasional bear. But the mammals I meet most often in fresh water are those industrious, semi‑aquatic rodents, beavers and muskrats. I particularly enjoy watching from a distance as a graduating class of young explorers takes a shakedown cruise around its home waters.
And I know that others share my enthusiasm. I have been surprised, though, just how many paddlers have trouble telling muskrats and beavers apart, let alone distinguishing their sign. But sign is sometimes all a paddler sees. So let's begin there, with…
Signposts on the Water
Everyone knows that beavers build dams, and for once, what everyone knows is true. Canoeists and kayakers marvel at the animals' engineering proficiency, even as they haul their craft across the resulting obstacles. Here's a specimen dam, built at the outlet of a mountain pond:
The dam is the six‑foot‑high arch in the foreground. The prominent mound in the middle distance is a lodge. (I'll have more to say about lodges in a bit.) A beaver dam really is an engineering masterpiece, weaving local materials — limbs from felled trees, mud, and small stones — into a sophisticated compression‑arch structure capable of withstanding repeated pummeling from spring floodwaters.
Luckily for paddlers, not all beaver dams are as high as six feet. Some rise no more than a few inches above the outflow stream, as in this case:
Here, a dam spans a narrow channel in a bog. The dam was once higher, but it's been deliberately breached to allow spring floodwaters to pass with a minimum of delay. Later in the year, as the runoff from the surrounding hills slows from a surge to a trickle, the breach will be repaired. Materials for the job are already being stockpiled. In fact, if you look closely, you can see a freshly‑peeled limb floating in the water, just upstream of the dam. Anytime you see "beaver sticks" in the vicinity of a dam, it's a safe bet that it's being actively maintained. Typically, the sticks collect in underwater middens, like this one:
And more often than not, such middens have their origins in a beaver family's "dormitory feasts" during the long winter months. Once the succulent inner bark has been eaten, however, the peeled limbs are stored away for later use. Beavers need no lessons from us when it comes to recycling!
The larger midden above adorns the edge of a lake. Like the pyramid of empty wine bottles left on the table after an old‑fashioned publisher's lunch, it's a testament to many a satisfying meal, eaten in pleasant surroundings. (The gray shape in the water isn't a beaver's head, by the way, nor is it the nose of a seal gone badly astray. It's the underside of a water‑lily leaf, folded back on itself by a wind‑driven wavelet.) The limbs whose bark provided the original feast came from beaver‑felled trees, of course, some of them harvested far from the water's edge. Here's the aftermath of a typical logging operation:
That's a fresh stump in the foreground. A weathered stump, closer to the water, is a legacy of an earlier foraging expedition, as is the half‑felled tree to its left. Stumps like these are unmistakable indications that beavers have been busy, with the chisel‑like gouges left by their incisors clearly visible:
But what of muskrats? Don't they also dine on tree bark? And could these stumps be evidence of a muskrat's desperate effort to get something to eat? In a word, no. Muskrats aren't lumberjacks. In fact, whereas beavers are committed vegetarians, muskrats are contented omnivores, always ready to tackle a fish course or round off a meal with a few mussels, crayfish, or snails. They're happy chowing down on aquatic plants, too, of course, and they'll even nibble the buds from the ends of twigs, but that's it. They don't have the stomach for bark. Still, it isn't always easy to tell who's been eating dinner. Consider this photo:
The peeled sticks admit of no doubts: a beaver has had a good meal. But there are fragments of cattail in the picture, as well. The remnants of the beaver's feast? Or a muskrat's? It could be either — or both. (In the warmer months, herbaceous plants make up by far the greater part of a beaver's diet. Bark takes a back seat.) Let's look for more evidence, shall we?
Here our journey of exploration takes an unavoidably scatological turn. After all, whatever goes into one end of any animal's gut sooner or later comes out the other. So these one‑inch‑long scats are clear evidence that a muskrat has eaten recently and well — on at least two different occasions. (One dropping is obviously more weathered than the other.) And how do I know that they came from a muskrat and not a beaver? Easy. Beaver excrement is usually larded with small, sawdust‑like wood chips. Moreover, beavers seldom relieve themselves on dry land. What bears do in the woods, they do in the water. Which helps to explain why beaver scat is a rare sight, indeed. Still, a determined search of the shallows will often yield…er…pay dirt, as in this instance:
There are no less than four beaver droppings visible here. They're oval to round in shape and pale in color — though the tannin‑stained water lends them a golden gloss (pay dirt, indeed!) — and, yes, they look a lot like compressed sawdust.
OK. That's enough potty‑talk. Now let's step back and take a look at domestic architecture. Both beavers and muskrats dig bank burrows — the European beaver to the near exclusion of all other types of home — but their signature sign in North America is the lodge.
That's a muskrat house in the foreground, with two beaver lodges arrayed behind it. Muskrats build their houses from mud and aquatic plants, while a beaver lodge is constructed by packing mud and small stones around a matrix of debarked branches and other vegetation. The resulting composite is then hardened by sun and frost until it resembles an untidy adobe, and it has some of adobe's structural qualities, as well, resisting assault by all but the largest and most determined predators. The entrance (or entrances, for there is sometimes more than one) are underwater, and the interior "apartment" usually has two rooms, a porch‑entryway and a main living area. Beavers are fastidious housekeepers, always going "outside" to answer nature's call. They're highly social animals, too. A lodge may shelter several generations at one time. Occasionally a beaver family will even play host to a muskrat houseguest, though it's more usual to see one or more muskrat houses built alongside the much larger beaver lodge. And this disparity in size bring us to the next topic:
Taking the Measure of Beavers and Muskrats
Both animals are air‑breathing mammals, but they're superbly adapted to life in the water, being excellent swimmers who are capable of holding their breath for many minutes at a time. The beaver is by far the larger of the two, however, with a full‑grown adult commonly weighing as much 50 pounds, more than ten times the weight of the largest muskrat. Still, despite this striking disparity in size, it can be surprisingly difficult to tell if the silent swimmer you saw for only a few seconds, at an unknown distance from your boat, was a muskrat or a beaver. Luckily, the animal's tail has a tale to tell any careful observer. A beaver's tail is a broad, flat, fleshy paddle, covered in black scales, and while a beaver can submerge silently whenever he (or she) chooses to, a startled animal is more likely to give a thunderous alarm first, slapping the water's surface with his tail before diving out of sight.
Here's a sketch comparing the two animals side‑by‑side:
The beaver measures three and a half feet from nose to tip of tail (the dowager's hump in my sketch is typical of a beaver's stance ashore); the muskrat is no more than half as long. And whereas the beaver's tail resembles the aptly named beavertail paddle in shape and proportion, the muskrat's tail is narrow and keel‑shaped — "laterally compressed," rather than flat. A swimming beaver's tail is commonly invisible, at least until he sounds the alarm. A muskrat's tail, on the other hand, can usually be seen moving from side to side, in a sinuous motion not unlike that of a sampan's yuloh, or sculling oar. The opposite is true if you turn your attention from the animal's tail to his head, however. A swimming beaver's ears are quite prominent; a muskrat's, inconspicuous.
As might be expected in animals who construct elaborate shelters, both beavers and muskrats have dextrous, almost human‑like hands. Here's a muskrat enjoying a hearty snack of cattail stalk:
Beavers sit down to eat when possible, too, though both they and muskrats will snatch a meal on the go in the water if time presses. Anthony Jancek, who snapped the shot of the snacking muskrat, was fortunate enough to catch up with a couple enjoying breakfast together on a pond near his home, only days after ice‑out. The male is the larger of the two, and it looks like he wants to get his mate's attention…
Now here's a muskrat swimming:
Can you see the tail? Not hard, was it? Beavers, on the other hand, aren't usually giving anything away:
In this telephoto shot of a retreating beaver, you can see his ears quite plainly, but his tail is nowhere to be seen.
Want a little more practice? Thanks to reader Heidi Perryman, President of the conservation group Worth a Dam, you can get it. Check out this short YouTube video:
The Worth a Dam website is well worth a visit, too. (Just click on the link in the paragraph above the video window.) It's chock‑a‑block with fascinating photos and videos — a labor of love and a valuable resource, all rolled into one.
By now you've probably gotten a pretty good handle on the ways to tell beavers from muskrats at a glance. So the next time you're out paddling, be sure you keep your eyes peeled. You never know what you might see. Canoes, kayaks, and SOTs make great blinds for watching wildlife. Don't let a single opportunity pass.
Beavers and muskrats share our love of wild waters, but despite their striking disparity in size, these toothy cousins aren't always easy to tell apart. That said, a little close observation goes a long way, and with a few minutes' practice you'll soon be able to distinguish the principal actors in any riparian drama, even without a program. After all, it's just a tale of two tails!
Copyright © 2010 by Verloren Hoop Productions. All rights reserved.