North American Beaver
Scientific Name: Castor canadensis
Beavers are the largest rodents in North America. They are primarily aquatic, with a waterproof, rich glossy reddish brown or blackish brown coat. They have fine under hairs and thick protective outer guard hairs. Beaver skulls and teeth are disproportionately large, which is crucial for cutting through thick pieces of wood.
They have large orange teeth use to cut through hard woods like maple and oak. Their teeth grow continuously, so they need to constantly file them down by chewing on wood. Their nostrils and ears are “sealable” for life in an aquatic environment. Their tails are large, flat, black, and leathery. Beavers use their broad tails to “slap” the water as a warning for nearby predators. At the base of the tail, they have castor glands, which they use for scent marking their territory.
Adult size: 335 to 46 in
Weight: 28 to 70 lbs
Life span: 10 to 20 years in the wild
Maturity: 3 years
Litter size: 1 to 4
Fun Fact
Beavers teeth are orange due to the iron in their enamel, which makes them strong enough to chew through wood!
Diet
Beavers eat the bark of trees as well as the cambium (the tissue under the bark). They also eat aquatic plants, buds and roots. Beavers have microorganisms in their guts that help break down all of the plant material they consume.
Habitat
Beavers live in wet forested areas, and build dams made of the trees they cut down with their teeth. They usually build the lodges on islands, banks of ponds and on the shores of lakes. Lodges typically have two entrances. Lodges are built by combing sticks, grass, most and mud woven together to create a dome like shape.
Behavior
Beavers typically live in family groups of up to 8 related individuals. Beavers are very territorial of their families and their dens. They mark their territories by secreting oils from their castor glands. Beavers will warn others of danger by slapping their tails against the surface of the water, creating a loud noise. They also make low groaning sounds to call out to others.
Beavers are mostly nocturnal but can be seen during the day foraging for food and materials to build dams and lodges. Beavers build dams to slow the flow of water, creating deeper water to build their lodges in.
Reproduction and Life Cycle
Beavers are monogamous and will only seek out a new mate if their previous mate dies. Both male and female beavers become sexually mature at around 3 years of age. The female’s gestation period is just a short 3 months. The young are born nearly fully developed with fur, open eyes, and the ability to swim within the first days after birth.
Females typically give birth to one litter per year in the spring or summer months. Young don’t typically leave their parents until 1-2 years of age. Both the mother and father contribute to raising and protecting the young.
Population Status
Beavers were previously hunted and trapped extensively in the 1900s but have since recovered in most of their former habitats. They are of “least concern” on the IUCN list.
Viewing
You can find beavers near bodies of water including streams, rivers, and ponds that are bordered by woodlands. They can also be found in wetlands such as marshes. Look for their characteristic lodges and evidence of beaver tree cuttings. Listen for their loud tail slaps on the water.
Range
Beavers are found throughout North America, excluding the most Northern regions of Canada and the deserts of the Southern United States and Mexico. Beavers are found all throughout NYS.
For more information on beavers in New York please visit the NYSDEC page here.
