There is no mistaking a beaver-no other Arizona rodent even comes close to weighing between 30 and 60 pounds and exceeding two feet in length. Moreover, the beaver is uniquely adapted to an aquatic existence with a flattened, naked, nine to 10 inch long, oar-like tail, webbed hind feet, dense fur, and eyes positioned high on the head.
Both sexes are similar in size and possess pungent scent glands called “castors” on either side of their anus. Arizona specimens are typically a light yellowish cinnamon color in contrast to the browner animals found in other states.
Beavers were at one time found nearly everywhere in Arizona that there was permanent water. With settlement, and the desiccation of the state’s streams, beaver populations declined. This habitat loss, and in some cases, heavy trapping pressure, caused beavers to disappear from such former strongholds as the San Pedro and Santa Cruz rivers.
Introductions and natural colonizations have since enabled the beaver to recover much of its former distribution, if not numbers, and these animals can now be found along several permanent streams, some of the larger river stretches, certain shallow lakes, and even a few dirt-lined canals.
The beaver’s diet is almost exclusively plant material with the bark of cottonwoods, aspen, and willow trees being especially important. Other reported foods include tamarisk or salt-cedar, mesquite, and the roots of such tuberous aquatic plants as cattail and bulrush.
Even in those places where beavers are rarely seen, their activities are conspicuous-chiseled and felled trees, brush dams along small streams and backwaters, and stick houses or “lodges” constructed either as a separate residence or within the beaver dam itself.
In Arizona, beavers commonly dig their dens in the bank along the stream, river, or canal where they live. Whatever its construction, the den will be located above the water line, lined with cattails and grasses, and will provide a nursery area for the two to four “kits” or young beavers born in the spring.