Several animals are quite the engineers: oriole nests that hang below the limb always amaze me, bees and wasps create intricate hives, and many animals make dens or tunnels. But the most easily recognized engineer in nature is the beaver. They have entered our language through such constructions as “busy as a beaver” or an “eager beaver.” Nearly hunted to extinction in the heyday of the fur trade, they were responsible for the exploration of large portions of the young United States as hunters went further afield to trap them for their valuable pelts. They were reintroduced in Indiana in 1935. Now they can be found in nearly every Hoosier county.
There is definitely one “eager beaver” somewhere on North or South Twin Lake—or at least there has been from time to time. At the east end of North Twin there are the remains of a lodge, but it doesn’t have any fresh cuttings on it and last year I saw a goose nesting on it, so I’m pretty sure that beaver moved on or was removed. I have seen a newer-looking lodge on South Twin, but it’s not very large. However, the Indiana DNR webpage says that Indiana beavers don’t usually build large lodges like you might find farther north, but instead they build a modified bank burrow. But whether he’s living there or not, he has been busy. On the south shore of North Twin there are two huge cottonwoods that our local beaver has been working on for over two years. He has completely girdled one tree and it no longer produces leaves and the second tree is not far behind. These trees are huge! We measured the larger one of the two, and its circumference was 10.5 feet! After some fancy measurements, we estimated the tree at a height of 70 to 80 feet. That’s quite a task for one little beaver! I have no idea what he thinks he will do with these giant trees once they fall. Even a super-beaver wouldn’t be able to move them for the purpose of building a dam or a lodge. Actually, once they fall, he can gnaw the limbs and branches to create a brush pile for his winter food source.
Beaver aren’t all that little, by the way. They can reach a length of five feet, but three to four feet is more typical. They can weigh in at 90 pounds, but usually range 40-50 pounds, according to the Minnesota DNR’s web page. They are well-adapted to their watery environment: their nose and ears have valves that close when they submerge. They have transparent eyelids so they can see while swimming without irritating their eyes. Their lips close behind the front teeth so a beaver can carry a small tree or a limb with its mouth without taking in water. They can stay submerged for up to 20 minutes, and the babies can follow their mother underwater when they are only one day old. Their front paws are not webbed and are used for grooming, digging, and carrying objects. Their hind feet are fully webbed for swimming.
They are the largest of North American rodents. And as is characteristic of rodents, their teeth keep growing and they need to chew to wear down their teeth. I would think the beaver on North Twin would just have stubs for teeth by now! But the back of the tooth is softer than the front and wears away faster, so their teeth remain chisel-sharp. According to the DNR, Indiana beaver “restrict most of their cuttings to brush and small saplings, although they are capable of felling large trees.” Hmm, maybe this guy sneaked across the border from Michigan?
I hate to think of losing those two trees that have been growing for so long, but I also think it’s wonderful that wild animals have managed to live among us despite the many obstacles we put in their way.