North American Beaver
Castor canadensis

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These large rodents are well adapted to underwater work. Their noses and ears have valves that close to keep out water, and their lips and large front teeth (incisors) let them cut and chew submerged wood without swallowing water. Paddle-shaped tails work like rudders, helping them maneuver large logs to their lodges and dams.

What They Eat
In spring and summer beavers eat tree leaves and twigs, fruit, ferns, and roots of water plants. In the fall beavers store branches underwater near the entrance to their lodge, providing an easy meal in the winter.

Where They Live
Beavers dam woodland streams to make the wetlands they prefer. Six or more beavers--parents, newborn kits, and yearlings--may live together in a lodge, either built into their dam or freestanding. They get into the lodge through underwater tunnels, passing first into a mudroom chamber before they get into the living room.

What They Do
Beavers cut down trees with their large front teeth, dig canals to transport branches and logs, and build and maintain dams and lodges. They don’t just live off the land, they modify it to fit their needs.

How They’re Doing
Due to the value of beaver fur in ancient and modern times, beavers have disappeared from many areas. When protected, they have been successfully reintroduced into their natural habitat. Today, beavers are generally doing well. In fact, Minnesota has more beavers than miles of river.

North American Beaver

Because beavers’ front teeth never stop growing, they must gnaw, chew, and chop wood constantly to keep them filed down.

Beavers’ ability to survive winter depends on the condition of their coats. They groom their fur regularly using the claws on their hind feet as a comb. A special gland at the base of the tail provides oil (like a hair tonic) that is worked into the fur to waterproof it.

A thick skull supports large teeth for gnawing, and serves the same purpose as a hard hat, helping protect beavers from falling trees.

Beaver dams can become quite large-as much as a half mile long. That’s four times as long as the entire Minnesota Trail.

The pelt of a beaver is comprised of long, coarse guard hairs over a thick, wooly undercoat. This luxuriant pelt lured early trappers and voyageurs to Minnesota and actually led to the early exploration and settlement of our state.

Beavers are slow on land, but excellent swimmers. A beaver can spend 15 minutes underwater before coming up for air.

Beavers’ tails serve many purposes:

• A prop to steady the beaver as it sits up on its hind legs to cut down a tree.
• A cushion to sit on while grooming.
• A rudder for steering.
• A place to store fat for long winters.
• An alarm paddle to slap the water’s surface and warn other beavers of danger.

Helpful hints for viewing the animals

The best way to see beavers in the wild is to visit a beaver pond in the evening. Beavers will dive, swim, and hide in their lodges if disturbed, so try to stay quiet.

At the Minnesota Zoo visit the Medtronic Minnesota Trail and observe beavers in a groundbreaking exhibit where you can view them building their den, raising young, and swimming above and below the water.  

North American Beaver

Care at the Zoo

Cutting down trees and gnawing on wood is important to beavers’ physical and mental well-being. At the zoo, keepers cut small trees and place them upright in holders in the beaver exhibit so the animals have trees to work on. The beavers, like many zoo animals, receive pine trees leftover from Christmas tree suppliers, which they cut and use to line their den.

Things you can do

A walk around the zoo will take you past several wetlands. If you want a deeper immersion, try the nearby Minnesota Valley National Wildlife Refuge or Fort Snelling State Park. Many communities have wetlands restoration projects that need volunteers. Ask at the information desk in the lodge for more info.

Sponsor a beaver at the Minnesota Zoo!

 

 

North American Beaver

Following overexploitation for the fur trade, conservation programs have re-established the American beaver throughout its historical range. It is now abundant and there are currently no major threats to this species.

Things the Zoo's done/doing

Voyageurs National Park (VNP), in northern Minnesota, supports one of the highest densities of beavers in North America. Because of the significant cultural, ecological, and scientific importance of beavers to VNP, in 2004 the park initiated a beaver research and monitoring program. Among other things, this project investigates the rate of diseases and parasites in the beaver population.

In 2007 the Minnesota Zoo provided funding to associate veterinarian Dr. Tiffany Wolf to participate in an ongoing VNP beaver research and monitoring program. She collected samples from VNP beavers to learn more about their health, and surgically implanted radio transmitters in 30 beavers to help track their movements during the winter. This project is ongoing and Dr. Wolf will continue to participate in it.

Building a Dam in Six Easy Steps

1. Choose a site: a dam requires running water and lots of nearby trees. Beavers prefer aspens.
2. Cut down some trees: Beavers eat bark, but not the insides of trees. Still they chew through with their big teeth and fell several trees each day.
3. Prep the lumber: Beavers cut off and eat the leaves and smaller branches. Everything that’s left is material for the dam.
4. Move logs to the site: For their size, beavers can drag surprisingly large trunks. Once they reach water they easily pull the floating lumber.
5. Stack the wood: Beavers are amazing engineers. Log placement takes skill to keep the early stages from washing away, eventually creating a structure that can withstand even many human attempts at demolition.
6. Repeat steps 2 to 5 many, many times.

North American Beaver

Beavers are North America’s largest rodents. Famous for modifying their environment, their heavy compact bodies, broad, black tails and large, powerful incisors are their most distinctive features. They are also known for their luxurious coats-chestnut brown to burnt umber in color. The beavers’ scientific name (Castor canadensis) describes the castor glands located at the base of their tails. These glands excrete a strong-smelling, oily substance used to for scent marking, attracting mates, and waterproofing coats.

Range and Habitat
In the Pleistocene Age, giant beavers the size of black bears roamed the Old and New World. More recently, their range extended across northern Europe and Asia, south to the Mediterranean. Due to the value of their fur, however, beavers have virtually disappeared from many areas. Today beavers inhabit the forested regions of the northern hemisphere. In North America they range from Alaska and Canada south to Rio Grande. In Europe their range includes Scandinavia, Russia, Germany, France, and Poland. Beavers need wooded areas near water where aspen, willows, cottonwood and other food trees are found.

Diet
The staples of a beaver colony’s diet are bark, cambium, twigs, leaves, aquatic plants, and the roots of deciduous trees such as willow, alder, birch, and aspen. As food supplies dwindle in an area, beavers must either forage farther away from the safety of their lodges, or move the colony to a new home.

Reproduction
Beavers become sexually mature at year at 2 years. They choose a mate for life. In Minnesota, breeding takes place from November to March, with one litter of 3-4 kits born in May or June. Kits are born with their eyes open and covered in soft fur. They weigh less than a pound at birth, but are able to follow their mothers underwater before they're a day old.

Lodge Building
Known as the “engineers of the animal world,” beavers fell trees, build dams and lodges, and digs canals. All of these activities result in a lodge home that is secure from most predators. To build a lodge, beavers need a water level of about 6 feet and typically seek out ponds ranging from 1-10 acres in size. If the pond doesn’t have the necessary water level, beavers modify it by constructing dams made of mud, grass, 6-inch thick logs, twigs, and stones. Canals are dug from feeding grounds to the pond for safe travel and floating logs.

The average beaver lodge is 5 feet high, 20 feet in diameter, and has 2 entrances below water and ice levels. Parents, yearlings, and new kits live together in one lodge. The colony usually works together to build and repair the dam, working and feeding in late afternoon and through the night. Beavers may also live in stream bank dens with underwater entrances and not attempt to build dams.

Beavers and Their Dams
Beavers are famous dam builders. But why do they do it? Beavers swim better than they waddle, so by creating ponds they create an environment where they’re more effective. The wetlands they create also provide some of a beaver’s favorite foods: cattails and water lilies.

Agents of Change
People affect animals. Animals can also have an effect on whole nations of people. For instance, beavers attracted great numbers of people to the place that is now Minnesota. Economies were formed, cultures changed, and wars fought over the trade of their soft, warm furs.

The fur trade changed with animals as well. Over 250 years, the number of beaver and other prized animals dropped. Fewer beavers meant fewer dams, gradually less wetland, and therefore less habitat for frogs, toads, and animals on up the food chain.

People Following Animals: Dakota, Ojibwe, French, British, Americans, and many others moved and traded beaver for other goods in a truly global economy. In fact, the political entity that is now Minnesota got its start because of the fur trade.