There’s no mistaking a North American beaver (Castor canadensis) for another semi-aquatic mammal, such as an otter. Beavers are bigger, beefier and, of course, more dentally prominent. In fact, as the continent’s largest rodent, beavers can weigh up to 70 pounds, and their flat, wide tails can grow as long as 14 inches. In Arizona, you’ll find these plump engineers along montane streams, as well as near lakes and riparian areas. As mostly nocturnal creatures, beavers chew on tree trunks under the cover of darkness, then use the felled wood to build their dams. Mud serves as mortar, twigs as thatch. Beavers are very familial in nature, with each mating pair sharing a lodge. And, despite those monster chompers, they’re not really into meat. They prefer to munch on leaves, aquatic plants and tree bark instead.