American Beaver, Castor canadensis
Common Name: beaver, Canadian beaver, American beaver, flat-tail, bank beaver
Species: Castor canadensis
General Description The American beaver is the largest rodent (Rodentia) in North America and the second largest in the world. The colour of their coats vary from yellowish brown to almost black. However, reddish brown is most common. The beaver’s coat is waterproof because it is supplied with a constant source of preening oil which is worked into its fur. A beavers weight ranges from 35-65 pounds ( 15-30kg). The full body length of a beaver is 3-4 feet (90-120cm), including its 16 inch ( 41cm) flat tail. The most obvious sign of the presence of a beaver is trees that have been cut down in an area where the top of the stump and the bottom of the cut tree look like they’ve been carved like cones. The trees can also be still standing but look like they have been gnawed at. Another sign that beavers are present is the build up of branches, logs and mud that stands out of the water of a pond or another aquatic environment that would probably constitute their dam. The beaver is very distinguished in Canada because it is the country’s national symbol.
Geographical Distribution and Habitat Requirements The beaver is found all throughout Asia, Europe and North America. There are more beavers in Canada and the United States than anywhere else in the world. Beavers are present all throughout New Brunswick. They are most common in forested areas, but also expand to unforested habitats, where there is water near deciduous (broad-leaved) trees or shrubs. Because they are aquatic rodents, an aquatic habitat is necessary.
General Biology The American beaver is a seasonal food catcher. Throughout the winter, it has a woody diet (decidous tress and shrubs) but it switches to a herbaceous diet (ferns, algae, aquatic plants, etc) when new growth appears in the spring. Beavers prefer to eat aspen, poplar, birch and willow,( which tastes like filet mignon to them). They will gather food in various sites but will always return home to eat it. Food collecting in the fall is vital to their survival because it supplies them with their food for the entire winter. Their home range size is often 125m or more from the pond. A beaver takes only one mate for its entire life and is able to reproduce at the age of two years old. Mating occurs during the winter, in the water, and the kits are born in the family lodge in the late spring (May-June). The gestation period is about 100 days and an average litter is 3 or 4 kits. The beaver constructs burrows along the sides of the pond banks and also underwater ones that lead to the inside of their lodges. The beaver is a nocturnal animal that does not hibernate nor does it enter torpor. Beavers are excellent swimmers and divers. Valve-like structures cover over both the ears and nose when the beaver dives. They can swim underwater for up to half a mile and hold its breath for 15 minutes. They live to be about 12 years old. Beavers have a special flap of skin behind their front teeth which enables them to carry things in their mouths without swallowing water. Beavers have two main modes of communication. One is that they leave a scent in places where they’ve been, and the other is by slapping their tales against the water.
Conservation Castor canadensis is not currently endangered in our environment. However, before the turn of the century it was in danger of going extinct due to widespread hunting for its pelts and tails. In the 1930’s a beaver conservation movement took place and the government responded by closing trapping seasons on beaver for many years. It has been reintroduced to many environments in which it had been stripped of by trappers. The populations of Castor canadensis are now at their carrying capacity in most areas, however, they are starting to move into rural areas and are beginning to cause problems for the residents.