Beaver is mainly a nocturnal and semi-aquatic rodent. It belongs to the genus Castor and is presently represented by two species commonly known as the North American Beaver and the European Beaver. They are famous for constructing dams, canals and lodges. They’re the next largest rodents known all over the world. They live in colonies and create dams which are deep in water and protect them from the predators. The population of the North American beaver has declined rapidly because of excessive hunting. They’re killed for fur and the glands function as a source of medicine and perfumes. They’re known for their natural trait of making dams in the ponds in which they live. They have very sharp and powerful front teeth that are used for cutting trees for building their homes as well as for feeding. They are famous for their alarm signals. When frightened the beaver dives rapidly and slaps water with its broad tail. This noise is audible from large distances both above and below water. This behaviour acts as a warning sign for other beaver present inside water. Once cautioned by the alarm call the other beavers dive into water and do not reemerge for some time. They walk slowly on land but are powerful swimmers and can remain under water for about 15 minutes.
They are herbivorous in habit and prefer to feed on the wood of walnut, cherry, walnut, cottonwood, willow and alder trees. They also feed on sedges, pondweed and water lilies. They do not undergo hibernation but are proven to store logs in a heap under water and consume the under bark. Some piles also float over water and may be covered with snow in winter season. The fossil remains of beavers have been obtained from the peat and other superficial deposits of Britain and the continent of Europe. They have webbed hind feet and wide, scaly tail. The eye sight is somewhat poorly developed but the senses of hearing, touch and smell is very well developed. Their teeth grow continuously so they feed on wood regularly. They bear 4 incisors that are covered with a tough layer of orange coloured enamel in front and a soft dentine in the back.
Adults may attain a weight of approximately 25 kg. Females are larger than males a feature uncommon among the mammals. They live up to 24 decades. Their title is of Proto-Indo-European origin. They are very close to the squirrels bearing resemblance with the lower jaw and the skull. The European beavers are somewhat larger with bigger, less rounded heads, bigger and narrower muzzles. The tails are less oval and briefer shin bones are present which function for efficient bipedal locomotion. They have more nasal bones. The foramen magnum is round the European beavers but it’s triangular in the North American species. The anal glands of the European beaver are bigger and thin walled enclosing great internal volume as compared to North American ones. The fur color is also different in both the species. 66% of all of the European beavers have pale brown fur, 20% have reddish fur while 8% have brown coats and the rest 4% have black fur. One of the North American one 50% beavers are provided with light brown fur, 25% with reddish fur, 20% with brown and 6% have black coats.
Both the species are not genetically compatible. North American beavers are also called Canadian beavers. Beavers are common hosts of Giardia lamblia that causes giardiasis. The beaver testicles and castoreum, a bitter secretion within the Rat Poop of female or male beaver is used commercially for making medicine. Castoreum is also utilized in perfume preparation. They are national animals of Canada. They have entered the category of endangered because of habitat destruction and mass killing.