An online resource based on the award-winning nature guide

Rodents

Beavers Grooming

11-19-14  beavers grooming 241 Beavers are constantly grooming and oiling their fur in order to keep it waterproof. To groom itself, a beaver usually sits upright with its tail between its back legs protruding in front of it, exposing the cloaca – a single opening for all the functions of the scent, reproductive and excretory organs. After the beaver climbs out of the water onto land, it often shakes its head and scrubs its ears and face. Then it thoroughly scrubs its shoulders and belly. The beaver gets oil from its inverted oil glands with its front feet, and then rubs it all over its body, using both front and hind feet. The second toe of each hind foot has a split nail (see insert) which the beaver uses to distribute the waterproofing oil and to comb debris out of its fur. Without this coating of oil on their fur, beavers would soon become water soaked and would not be able to tolerate the cold water.

In this photograph, perhaps for the last time outside of their lodge before their pond freezes, beavers engage in a practice known as “mutual grooming” during which they attend to each other’s coat using their teeth instead of their feet as combing utensils. (Photo: adult on left, offspring on right)

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Sign of Beaver Activity

beaver scat 041Beavers are meticulous housekeepers, in that they almost always defecate in the water, not in their lodge, and rarely on land. Because of this, it is rare to see their scat, but fall is as good a time as any to look for it (should you wish to see it).

In preparation for winter, beavers are repairing their dams and lodges, and stock-piling a winter food supply pile of branches in the pond near their lodge. They spend a lot of time working in the water in one area, which means that signs of their presence, including scat, are plentiful in these areas. If you look in the water along a beaver dam at this time of year, it’s highly likely that you will find light-colored, kumquat-size pellets, which, as you might expect, are full of tiny bits of woody fiber. The pellets are essentially little balls of sawdust, and disintegrate easily. (Handling, for those tempted to do so, is discouraged due to giardia or “beaver fever.”)

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Woodchucks Heading for Winter Burrows

11-10-14 woodchuck 122Woodchucks are one of the few species of mammals that enter into true hibernation. When the temperatures dip into the 40’s, usually in October or November in the Northeast, most woodchucks leave their summer burrows and head for the woods, where they dig a tunnel that ends in a chamber that is well below the frost line (and therefore above freezing). Here they curl up in a ball and live off of the 30% additional body weight they put on in the fall. In order to survive until March or April, a woodchuck’s metabolism slows way down. Its heartbeat goes from 100 beats a minute to five, and its body temperature goes from 96 degrees F. down to to 47 degrees F.

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Porcupines Entering Winter Dens

porcupine IMG_2597During the summer, porcupines are almost always found out in the open. At the end of October/beginning of November porcupines den up for the winter in the Northeast, with up to a dozen porcupines sharing the same den. While some adult males will spend days at a time in a conifer, most porcupines seek out rocky crevices in which to spend the day, with a smaller number finding shelter in hollow trees. Porcupines are hardy creatures – while dens do protect porcupines from heat loss, they contain no insulation, the entrances are open and the porcupines don’t huddle together for warmth. In addition, porcupines emerge from their dens to feed at night, when outside temperatures are lowest. (And yes, that is porcupine scat that is stuck in/on the porcupine’s quills.)

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A Variety of Beaver Lodge Designs

10-20-14 beaver bank den 080Beavers are hard at work refurbishing their mud and stick lodges in preparation for the coming winter, when their movements will be restricted and they will spend both days and nights inside their lodge. When we think of a beaver lodge, we picture it in the middle of a beaver pond. This was not always the case, however, and still isn’t today. The earliest and most primitive beaver lodges consisted of a burrow in the side of a high bank with the entrance under water (see exposed bank lodge entrance in photo insert). The next advance was the addition of sticks and mud piled over the top of the bank as added protection from predators (see photo). Eventually beavers started building a complete lodge on top of the bank which had an underwater entrance. The most advanced design is the lodge we most commonly associate with beavers — one that is built up from the bottom of the pond and is completely surrounded by water. It requires the greatest amount of work but offers the greatest amount of protection to the beaver.

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Beaver-Porcupine Encounter

beaver with quills2  376A Porcupine’s 30,000 quills effectively defend it against two and four-legged enemies, and occasionally against its own species. Rarely, however, do we see evidence of this mode of defense outside of our family dogs, most of whom are challenged when it comes to learning from the experience. From the size of the quills in this Beaver, one can assume it came in contact with either the Porcupine’s upper back or neck, where the quills are longest (up to 4”). How and where this encounter took place is a mystery. Porcupines can and do swim – their quills are filled with a spongy material which may enhance their buoyancy. So it’s within the realm of possibility that these two rodents met in the water, but that seems unlikely. While some quill injuries result in death, a surprising number of victims recover. One researcher observed that the quills he saw in a raccoon’s muzzle were worn down to a stubble within a week. Due to tiny barbs on the end of the quill that contacts another animal, it can work itself into an animal’s body, but those in this Beaver will hopefully come to rest against its jawbones. As long as the Beaver can eat, its chances of survival are good. It is unlikely to get an infection from the quills, as they’re coated with fatty acids that inhibit the growth of bacteria (in case the Porcupine stabs itself?)

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Porcupettes Being Born

5-20-14 porcupine IMG_3143This newborn porcupine is about a foot long from the tip of its nose to the tip of its tail, weighs roughly a pound and has quills about one-inch long. It will nurse from its mother for the next two months, but within two weeks will be feeding on vegetation as well. Because its offspring is precocial (capable of traveling and feeding on its own soon after birth), the porcupine’s mother provides care for her one offspring only for a week or two before leaving it to fend for itself.

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