Beaver
Castor canadensis
Family Castoridae

Characteristics:
* Fur rich brown.
* Tail naked, scaly, flattened, and shaped like a paddle, 6" wide and 9-10" long.
* Front teeth huge, broad, and flat. Skull and jaw muscles highly modified to allow teeth to take large bites out of the trunks of many species of trees.
* Hind feet webbed.
* Head and body length: 25-30".

Natural History:
* Habitat: Streams, lakes, ponds, with trees or alders nearby. Builds dams and elaborate lodges out of sticks and mud. The lodges are conical, with underwater entrances.
* Range: Throughout nearly all of the United States and Canada.
* Behavior: Beavers gnaw trees in a characteristic hourglass pattern, until the tree falls over and can be used in a lodge or dam. They are primarily nocturnal and eat the bark and twigs of aspen, poplar, birch, maple, willow, and alder.
* Lifespan: 15-20 years.
* Native. After extensive hunting by European settlers, the beaver was exterminated, but was then re-introduced to northeastern North America and is now very common in natural areas.

Connections!
* Beavers are slow swimmers but have a strong affinity for water - they can remain submerged for up to 15 minutes. Because of their dams, they are also water conservationists, sometimes competing with man and disrupting the spawning of fish.

* One beaver lodge contains one beaver family - parents, babies, and young beavers under two years of age. At two, the younguns are kicked out of the house and must fend for themselves. Young dispersing beavers often fall prey to dogs or are killed by automobiles.

* Beavers, "Nature's Engineers", are the mascot of the Massachusetts Institute of Technology. They also appear on the Canadian nickel.

* You can see the beaver in the top photo in the Wellesley College Science Center! The photo at the bottom shows an area where a beaver dam is located; the trees are dead because the dam has flooded their local habitat.