The beaver is the largest rodent in Rocky Mountain National Park reaching a length of three to four feet. They are a rich, brownish color and have a broad, flat tail. The slapping of this tail is often used to warn the rest of the beaver colony of impending danger.
They are best known for their construction and maintenance of dams and lodges. The beavers use shrubs and fallen trees as both food and building materials. Their long, front incisors are their tools for gnawing down trees. They can remain submerged under water for up to 15 minutes. Their dams may reach a height of seven feet and a length of 1000 yards. The pond created by the beaver dam protects the beavers from predators and also provides a good habitat for a variety of other wildlife. In the long-term a beaver dam's pond may become a meadow and even one day the meadow may become a forest.
Beavers form nuclear families of a pair of adults, yearlings, and the kits. Several such families may live together in a large colony. They breed in April or May and have a gestation period of about 120 days. There is one litter a year. The kits are small but fully furred with their eyes open. Beavers can live as long as 19 years.