The largest North American rodent and the only one with a broad, flat, scaly tail, the Beaver is now common and widespread, even in areas it did not inhabit during pre-colonial times. The modifications it makes to the environment by felling trees and building dams result in changes to plant, animal, and microbial communities that are sometimes desirable and sometimes not. Learn more about the Castor canadensis, more commonly known as an American Beaver, in this easy-to-read species overview by the Smithsonian's National Museum of Natural History.