Conservation Status– Least Concern
The American Beaver is most noticeable due to the large, flat, paddle like tail. This feels like it scaly and is a fat storage mechanism. Their fur is long and coarse on the outside while the inner hairs are short and fine. Coat colours vary from dark brown to a reddish brown; some even have yellowish or black fur. Near the lower parts of the body are scent glands which releasecastoreum an oily substance which waterproofs the fur. Underneath the skin is a thin layer of fat that keeps them warm in cold environments. The hind feet are webbed like a divers fins while the front feet are not webbed. There is a nictitating membrane that comes across the eyes when they are swimming so they can still see. Behind the incisor teeth is a membrane that seals the mouth so they can gnaw wood underwater.
American beavers are the second largest rodents in the world. The average weight range for a beaver is 10-35kg (22-75 pounds). Some reports exist of older beavers that have weighed 40-50kg (88-110lb). The beaver measures 74-90cm (20-35in) from the head to the end of the body. The tail is 20-35cm (7.9-13.8in) of extra length onto the body.
The American beaver will live for 10-20 years.
American beavers are solely herbivorous. Most of their feed comes from deciduous trees. These include aspens, willows, birch and maple. They will also eat woody shrubs. Roots from some tuberous aquatic plants also provide part of their diet.
Currently American beavers can be found throughout most of North America from Mexico upwards. The only states they are not found in are Florida, Southern California and Southern Nevada. They have been introduced to Southern Chile, Argentina and Finland. Beavers have been shown to survive well within urban environments.
Wherever the beaver lives there must be a slow flowing brook, stream or river. Occasionally they will live in small lakes or even on large rivers. They are not found in mature forests as much as in newly growing forests. If the environment is not quite right they will dam the streams to create ponds so that it is a better place to live.
106 days after they mate the female will give birth to a litter of 1 to 9 kits. The average number of kits is 3 to 5. The entire group of beavers that live in the lodge will assist in raising the kits. Just a few hours after birth the beavers can swim. They will begin exploring the outside world after a few days.
Weaning occurs after 6 weeks. After 1 ½ to 2 years the young are mature and disperse. They stay with the parents while they have the next litter. Most couples will reproduce yearly.
The American Beaver is mature after 3 years in most cases. Some of them have been seen to reproduce after 2 years though.
The beaver has a nocturnal activity pattern. Most of their activity takes place in the water as they are vulnerable on land. When threatened they slap the ground with their tail.
Wolves, bobcats, coyotes and mountain lions prey upon the American beaver. Occasionally a black bear will stick their paw into a beaver lodge and eat one. Occasionally wolverines, Canadian lynx and foxes will eat the American beaver kits.
One of the things beavers are most famous for are their lodges and dams. The beaver uses sticks, mud, rocks and grass. The dam creates water deep enough for them to escape predators and to provide water that will not freeze solid over winter. In areas where the top of the pond does freeze over the beavers will gather branches which they store under the water. By sticking these in the mud they will also create spaces where it pokes through and the pond does not freeze over.
Near to the American beavers dam is their lodge. This is either a burrow dug into the water’s edge or a mound of twigs, sticks, mud and rocks. They will normally pile the sticks and then chew an entry and some platforms along with a breathing hole out of this shell. Before winter they may apply a coating of mud which freezes solid like concrete.
Beavers are being used instead of dams in some places throughout America. They also been put to work alongside humans to help with combating erosion.
The beaver is the national animals of Canada and one of their national symbols. It appeared on the first Canadian postage stamp and is on the five cent piece.
Many engineering schools in the US use the American beaver as their mascot.
American beavers appear on the coat of arms of New York, New York City and Albany.
The American beaver was seen to be a ‘four legged fish’ which could be eaten on lent by early French Canadian Catholics.
Top – By Steve from washington, dc, usa (American Beaver) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
Bottom – By Ryanx7 (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons