9:10 p.m. - 2005-03-26
The Largest North American Rodent! (New Pic 12/14/06)
One of the most interesting, and chuckle-inducing mammals is the beaver! Of course, Wendell loves beaver. I like to spell it "Beavyr"...which seems to make the name sound mysterious, evil and foreign. Like "Vampyr".
Ok, never mind. The beaver, (Castor canadiensis) is the largest North American rodent. The world's largest rodent is the South American Capybara, which can reach 100 lbs and four feet in length. Beavers are slightly smaller (although aquatic, like the capybara), reaching 25 to 30 inches and 30 to 60 lbs. Beavers live in every state and Canadian province.
The Wylde Beavyr is similar to humans in that they are one of the few animals to actively change their environment. Beavers dam streams into ponds, creating new ecosystems. These expanded wetlands help raise the water table, attract wetland birds, stablilize the flow of the stream, allowing trout to thrive downstream, and prevent water loss and erosion. As the pond gradually fills with silt, the beavers will move away, and when the pond completely dries out, fertile soil and a green meadow area remains, called a "vega" in Spanish.
Now, this process is very beautiful, circle of life, etc, but is not convenient for farmers or landowners. So beavers are often a nuisance animal.
A pic from www.linsdomain.com:
Let's focus on the physical features of the beaver. Of course they're brown and furry. Similar to other water-dwelling mammals, there are two layers to their fur: two inch long, waterproof hairs that cover a layer of fuzzy hairs one inch thick. The fur and a thick layer of fat helps the beaver stay dry and warm throughout the winter. The beaver's feet are large and webbed, and it can close its nostrils and ears while underwater. (Where it can stay submerged for up to 15 minutes!) Like a shark, the beaver has a clear protective eyelid that allows it to see while diving. And of course there's the tail!
Beavers are vegetarians. As my roommate D says, "I could f*** up that barbecued pork!", so says the beaver about a young sapling! Beavers enjoy tree bark but their favorite delicacy is the tree layer directly underneath it: the cambial, or growing layer. In order to get to more bark, beavers bite down the whole tree and strip it on the spot. If they find a rich feeding grove, the beaver might dig a canal to facilitate travel between it and its home. Beavers also eat buds, roots and plants. These sticks and small logs are stored near the lodge, either for winter storage or for more immediate consumption.
But how can beavers digest all that wood? Wood is mostly cellulose, which is undigestible by mammals. (Is anyone else picturing that Guinness Book of World Records photo of a young man with feathered hair, eating a 20 ft elm tree?!) Anyway, beavers host a bunch of microorganisms in their cecum (the area between the stomach and small intestine) which digest 30% of the cellulose.
In the "ew, gross" section: to aid in further digestion, beavers eat some of their poo a second time (similar to rabbits) to further digestion.
On Christmas Day two years ago, I joined my Dad in a trapping excursion. Like most outdoor activities, it's a good excuse to take a nice walk through the woods. Dad pointed out sticks stripped of bark in the stream and said that beavers were nearby. Indeed, we pulled two beavers (20 lb and 50 lbs) out! This last Christmas, R was going to join us in a trapping excursion! The plan was thwarted by a post-present unwrapping sewer overflow in the basement. Oh, well.
So of course beavers use these sticks, twigs, and logs to build their dams. Using mud as a sort of mortar, beavers weave the sticks across a slow moving stream. Then they build separate lodges, which appear above water as a mound or pile of sticks, as a home. The whole lodge is then covered with mud, except the very top, to allow air flow in and out. The entrance to the lodge is underwater, but the resting spaces inside are above the waterline. There is a lower "docking" area near the underwater hole, where the beaver dries off, connected to the higher and drier sleeping vector.
Now that we've described the love nest, let's discuss beaver love! Beavers live in colonies, usually headed by an adult female. She and her mate are monogamous for life, and she has babies every year. The gestation period is about 108 days, and two to eight babies (kits) are born between April and July. (Apparently Mama beaver has four nipples, FYI). The kits are weaned in six weeks to three months.
Side note: I once drew a detailed diagram of a ladder device that would allow a baby beaver access to both my aquarium and the rest of my apartment. Now that there is a broken dining room chair this idea is becoming more timely!
Beavers reach sexual maturity at about two years. They are territorial, and may travel from six to 150 miles away from their original lodge to find a new habitat.
While fur is the most obvious by-product of beavers, another is the oil they secrete from "casters" under the tail. (My Dad hangs these walnut-sized glands on his garage windowsill). The oil is used both to mark territory and to waterproof beaver fur. But humans use it to make perfume!
Like birds and reptiles, beavers have a cloaca! (See my writeup about Pigeons for more info.) Bodily, sexual and oil-secreting functions occur through this single body opening.
Beaver kits are susceptible to predation by eagles, coyote, and owls. Bobcats, wolves, mountain lions, and lynx attack adult beavers, along with black bear.
Your assignment for the summer is to keep a lookout for beaver dams and beavers! And if you see a baby beaver, contact Wendell immediately!
Wood is good,
Wendell
