[28] North American beavers are widespread across the continental United States, Canada, southern Alaska, and some parts of northern Mexico.

The first fossil records of beavers are 10 to 12 million years old in Germany, and they are thought to have migrated to North America across the Bering Strait.

However, modern techniques generally use genetics rather than morphology to distinguish between subspecies, and currently the Integrated Taxonomic Information System (which provides authoritative[31] taxonomic information on plants, animals, fungi, and microbes of North America and the world) does not recognize any subspecies of C. canadensis, though a definitive genetic analysis has not been performed.

Such an analysis would be complicated by the fact that substantial genetic mixing of populations has occurred because of the numerous reintroduction efforts intended to help the species recover following extirpation from many regions.

The forepaws are highly dextrous, and are used both for digging, and to fold individual leaves into their mouth and to rotate small, pencil-sized stems as they gnaw off bark.

Demand for furs for hats drove beavers nearly to the point of extinction, and the North American species was saved principally by a sudden change in style.

[citation needed] The beaver possesses continuously (or constantly) growing incisors, and is a hindgut fermenter whose cecum, populated by symbiotic bacteria, helps to digest plant-based material.

Larger areas of the beaver's somatosensory cortex are dedicated to the processing of stimuli from the lips and the hands, more so than the tail and whiskers, which play a relatively minor role.

[43] Before their near-extirpation by trapping in North America, beavers were practically ubiquitous and lived from south of the arctic tundra to the deserts of northern Mexico, and from the Atlantic to the Pacific Oceans.

[62] It is located on the southern edge of Wood Buffalo National Park in northern Alberta and is more than twice the width of the Hoover Dam which spans 1,244 ft (379 m).

The dams also flood areas of surrounding forest, giving the beaver safe access to an important food supply, which is the leaves, buds, and inner bark of growing trees.

It has been hypothesized that beavers' canals are not only transportation routes to extend foraging, but also an extension of their "central place" around the lodge and/or food cache.

Beaver deposit castoreum on piles of debris and mud called scent mounds, which are usually placed on or near lodges, dams, and trails less than a meter from water.

Beavers consume a mix of herbaceous and woody plants, which varies considerably in both composition and species diversity by region and season.

[42] They prefer aspen and other poplars, but also take birch, maple, willow, alder, black cherry, red oak, beech, ash, hornbeam, and occasionally pine and spruce.

Beavers feed on wood, bark, cambium,[72] branches, twigs, roots, buds,[72] leaves, stems, sprouts, and in some cases, the sap and storax of pine and sweetgum.

[75][76][77] Perhaps due to differing habitat preferences, grizzly bears were not known to hunt beavers in Denali National Park, Alaska.

North American beavers tend to be slightly smaller, with smaller, more rounded heads; shorter, wider muzzles; thicker, longer, and darker underfur; wider, more oval-shaped tails; and longer shin bones, allowing them a greater range of bipedal locomotion than the European species.

North American beavers have shorter nasal bones than their European relatives, with the widest point being at the middle of the snout for the former, and in the tip for the latter.

The anal glands of the North American beaver are smaller and thick-walled with a small internal volume compared to that of the European species.

Also, more than 27 attempts were made in Russia to hybridize the two species, with one breeding between a male North American beaver and a female European resulting in one stillborn kit.

In the United States, extensive trapping began in the early 17th century, with more than 10,000 beaver per year taken for the fur trade in Connecticut and Massachusetts between 1620 and 1630.

Archaeological and historical evidence suggests that beaver ponds created "moth-hole like" habitats in the deciduous forest that dominated eastern North America.

The first colonial farmers were also attracted to the fertile, flat bottomlands created by the accumulated silt and organic matter in beaver ponds.

During the roughly 30 years (1806–1838) of the era of the mountain man, the West from Missouri to California and from Canada to Mexico was thoroughly explored and the beaver was brought to the brink of extinction.

[91] One such flow device has been used by both the Canadian and U.S. governments, called "beaver deceivers" or levelers, invented and pioneered by wildlife biologist Skip Lisle.

[95] In the 1940s, beavers were brought to Tierra del Fuego in southern Chile and Argentina for commercial fur production and introduced near Fagnano Lake.

[99] On balance, because of their landscape-wide modifications to the Fuegian environment and because biologists want to preserve the unique biota of the region, most favor their removal.

[104] In Europe, significant invasive populations of Canadian beaver are only present in Finland and Karelia, as the boundary between species has somewhat stabilized, but smaller occurrences have been detected elsewhere.

[104] Beaver meat is similar tasting to lean beef, but care must be taken to prevent contamination from the animal's strong castor (musk) gland.