Posted on Apr 16, 2022 43
What do beavers eat, why do they build dams, and why does a beaver have orange teeth? Read about it in our material devoted to the Beaver Day, which is celebrated on April 7.
Once upon a time, beavers were mass hunted for their beautiful fur, and by the beginning of the 20th century, beavers had practically disappeared from Europe. However, their population was partially restored artificially. Now the beavers are not among the endangered species; in the international Red Book they are listed as “Least Concern”.
So, what interesting things do we know about beavers, except that they build dams?
A beaver’s front teeth are orange because their tooth enamel contains iron
Beavers are strict vegetarians, eating only plant foods, mostly wood (their favorite menu is aspen, poplar, birch, and willow). It takes very strong teeth to chew wood. Iron makes them very strong. And besides, since the front surface of the teeth, covered with “iron” enamel, is worn down slower than the white dentin on the back side, the beaver’s teeth are self-sharpening when he is busy doing his favorite thing.
The beaver’s tail serves several functions at once
The broad tail is used as a rudder when swimming; in addition, by flapping it on the water, the animal warns other beavers of approaching predators. On land, the tail serves as a support, allowing the beaver to sit upright, as well as a counterweight when dragging heavy logs in its teeth. Finally, zoologists speculate that the tail may store excess fat (like the humps of a camel).
Dams are needed to keep a body of water from freezing over
Why do beavers build dams? Several purposes: protection from predators, regulation of flow (beavers prefer reservoirs with a slow current, quiet dams).
By deepening the dam, beavers ensure the reservoir does not freeze to the bottom. This is important because the bottom stores supplies for the winter. Beavers poke branches into the bottom, which keep fresh for a long time this way.
Beavers have engineering skills.
Dams have different shapes depending on the speed of the current: if the stream is calm, the dam will be straight. If the current is fast, it will be curved: the curve provides stability. If the current is very strong, upriver the beavers erect small additional dams. In addition, passages are left in the dam to release excess water. Beavers judge whether the dam is okay by the noise of the water and instantly identify a problem if the murmuring somehow changes.
Beavers build dams alone or in groups, and then the entire group acts in concert according to one common plan.
If there is no place to dig a burrow on the bank of a body of water because it is too boggy, the beaver constructs a hut right on the dam or on a shoal made of twigs, mud, and rocks, with underwater entrances. Some beaver huts are large enough to fit a man. Beavers keep the inside of the huts clean. If the water level in the river rises, the owner raises the floor of the hut or burrow (in the latter case, by scraping the earth from the ceiling).
Beavers are good for the environment
These animals play an important role in creating habitat for many aquatic organisms. Ecosystems “ennobled” by beavers increase biodiversity - particularly the number of waterfowl species. Beavers also do a lot of good things for humans. Thanks to dams, a sufficient level of ground water is maintained. In addition, dams, like any wetland, serve as natural barriers when rivers overflow, saving from flooding and bank erosion.
Beavers are monogamous, but not necessarily faithful
A hut or burrow (and a dam) is built by a young pair or by a young male looking for a female. In their hut, if there is no force majeure, the pair will live their whole life. Beavers mate in January and February, and from one to eight cubs are born in April and May. On average, the cubs live with their parents for up to two years, and then the grown-up youngsters go in search of their “half”.
A curious nuance: Eurasian beavers, according to genetic studies, remain faithful to each other in a pair, while the Canadian beaver is not so faithful: not always the father of the family is the biological father of the cubs.Perhaps this is because of a different social behavior: North American beavers are less aggressive and live more compactly.
The world’s largest beaver dam is 850 m long.
It is in Buffalo National Park in the Canadian province of Alberta. It is a vast park, larger in the area than Switzerland. And the dam was first spotted not from the ground, but from space - it was found on a satellite image in 2007, when using images to study changes in the permafrost in this part of Canada. Experts believe the dam has been built by several generations of beavers since the 1970s.
Beaver secret used in perfumes
A fragrant secret called castoreum is secreted from special glands near the anus. Beavers use it to mark territory and look for a mate - the composition and smell of the beaver’s stream is as unique as their fingerprints. Since castoreum has a vanilla odor, it used to be used in perfumery and food industry, but now it is practically not used because of its high cost (thankfully, there are synthetic substitutes). But up to now, many people believe in the healing properties of beaver urine, which supposedly increases immunity and improves sexual function in men. There is no clinical evidence for this, but castoreum is sold as a remedy for “folk medicine”, for the sake of which beavers are grown on farms and the secret is got without killing the animals.