Page "North American Beaver" Paragraph 20

Although superficially similar to the European beaver ( Castor fiber ), there are several important differences between the two species.

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 have 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 cousins, with the widest point being at the middle of the snout for the former, and in the tip for the latter.

The nasal opening for the North American species is square, unlike that of the European race which is triangular.

The foramen magnum is triangular in the North American beaver, and rounded in the European.

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.

Finally, the guard hairs of the North American beaver have a shorter hollow medulla at their tips.

Fur colour is also different.

Overall, 50 % of North American beavers have pale brown fur, 25 % are reddish brown, one fifth are brown and 6 % are blackish, while in European beavers 66 % have pale brown or beige fur, 20 % have reddish brown, nearly 8 % are brown and only 4 % have blackish coats.