Known to all, lucky are those who have managed to observe it. Nocturnal and cautious, it is easier to spot its tracks, which are both varied and spectacular. However, the beaver is living increasingly close to crops and residential areas. For a long time, cohabitation with the beaver was a controversial issue, which almost led to its disappearance from our regions. This rodent, with its ability to live on land and underwater, its flat, scaly tail and its imposing incisors, has fuelled legends and rumours for centuries. It's true that it's an animal with a host of special features, as extraordinary as they are numerous...
Physically, this gifted animal is easily recognised by its large size, flat tail and brown coat. But don't confuse it with its cousin the Ragondin, introduced at the beginning of the 20th century for its fur, which is much smaller and only half as heavy. It can weigh up to 20 kilos and live up to 8 years. What's more, its similarity to the human species confuses many people. This amphibian performs the same activities as we do; it builds, lives with its family and sometimes even stands upright, but it far surpasses us in its aquatic abilities.
A keen diver, the Beaver is much more comfortable and secure in the water than on land. Its adventures rarely take it more than thirty metres from water. With his webbed feet and tail, he moves quickly and silently in the water, while on land his large flippers give him a sheepish, clumsy look. The king of apnea, it can stay underwater for up to fifteen minutes with an oxygen fixation rate in its lungs of 75 %, just like our little 15 %.
Like humans and elephants, beavers are one of the only animals capable of cutting down trees - and without a chainsaw! Thanks to its teeth, which continue to grow throughout its life, it can cut down a tree as big as our arm in five minutes. Felling a tree allows it to bring up leaves, buds and bark that are inaccessible to other herbivorous mammals. Unlike most herbivores, the beaver has no enzyme to digest cellulose. Instead, it has a pouch at the bottom of its intestines containing bacteria capable of transforming plant matter into sugars. Two digestions are therefore necessary: a first passage through the intestine so that the plant matter can be denatured by the bacteria, then the beaver will eat its "pre-digested" droppings and digest them a second time to capture all the nutrients, which are now accessible thanks to the bacteria. This type of digestion, known as caecotrophy, is also known to occur in hares and rabbits.
However, the beaver's ability to gnaw through tree trunks is not just for food, but also for shelter! Its burrow, or should we say fortress, is ingenious and virtually invisible, allowing the beaver and its family to leave their home discreetly. It can only be reached via an underwater tunnel. And if the river is too small or its flow irregular, the beaver builds his famous dam. By wedging stones at the bottom, it plants branches against the current and fills in the gaps with earth. In this way, the Beaver built his own private swimming pool where he could swim and dive in peace. Architect, mason, lumberjack, diver, the Beaver can do it all!
Information taken from Nature magazine La SalamandreLe castor entre deux mondes, n°211, August-September 2012 and the ProNatura website, " Dio Castor "
Photo credit: ©Alexis Pochelon
