The North American beaver (Castor canadensis) is one of two extant beaver species, along with the Eurasian beaver. The beaver is the largest rodent in North America and have stocky bodies with a yellow-brown to almost black coat and a broad, flat, scaly tail. Their large skulls with powerful chewing muscles and large, orange incisors grow continuously throughout their lifetime. They have webbed rear feet and digitated front paws. The beaver's stocky body enables it to conserve heat. Beavers are active mainly at night. They are excellent swimmers and may remain submerged up to 15 minutes. More vulnerable on land, they tend to remain in the water as much as possible. The purpose of the dam is to create a deepwater refuge enabling the beaver to escape from predators. When deep water is already present in lakes, rivers, or larger streams, the beaver may dwell in a bank burrow and bank lodge with an underwater entrance.

Beavers often construct a dam a short distance downstream from the lodge to deter predators. The dam impedes the flow of the stream and increases the depth of the water that surrounds the lodge. Dams also create additional wetland habitat for fish and waterfowl and contain or impede the downstream movement of oil spilled into rivers. The North American beaver ranges in size, but some of the largest beavers reach up to 4 feet long and weigh up to 70 pounds. Beavers live in a wide variety of habitats since they can modify the environment to fit their needs. However, at a minimum, they require a permanent body of water with an adequate food supply. Beavers are foragers, so they gather food and carry it back to their territory or lodge for consumption. They are herbivores with their diet primarily consisting of leaves, twigs, bark, and aquatic vegetation. One of their favorite trees to consume are willows since the bark is high in protein and easily digestible.