Beaver Facts

  • Beaver are the second largest rodent in the world after the Capybara of South America. The average weight of a beaver is between 35 and 45 pounds. One of the largest in recent history was found on the US-Canada border weighing 110 pounds.
  • Beaver have yellow-orange teeth due to large amounts of iron which makes them extra strong. They have a hard enamel layer in the front and a soft dentin in the back so when they chew their teeth sharpen like a chisel. Also, their teeth never stop growing so they continually chew on trees and limbs; otherwise, their teeth would get too long and they would be unable to eat.
  • An ancestor of the beaver was 6 feet long and weighed over 200 pounds.
  • Beaver are vegetarians. They eat the living cambium layer under the bark of trees. Beaver take trees all year long, but once their dams and lodges are built, in the summertime they eat a lot of grasses, sedges, forbs, and even algae. During winter they rely on a food cache of limbs and branches that they’ve anchored to the bottom of a creek or pond.
  • Beaver have a cloaca—a cavity for excretion and reproduction. It also contains castor glands that excrete castoreum that beaver use to mark their territory. (I really like the smell and find it clean and fresh!) Castoreum has been used in perfumes and the manufacturing of artificial vanilla. The FDA allows the inclusion of castoreum as a food additive with the label “natural flavoring” (often found in inexpensive ice cream).
  • Castoreum is also used during grooming, a seemingly unending process, as it makes beaver fur waterproof.
  • No other animal with the exception of man so significantly alters its habitat to suit its own needs and desires. However, unlike man, beaver create ecosystems that benefit many species, including man.
  • Beaver may live in bank lodges, bank dens, and teepee lodges. They do not live in the dam. Ideally, they like to be surrounded by water as a means of protection and transportation which is why they build dams. They are not aggressive and use the depth of the water to get away from predators. Water also makes it easier to travel faster, safer, and move trees.
  • The largest dam in the world is located in Wood Buffalo National Park in Alberta, Canada. It stretches for 850m and is visible from space.
  • Beaver can hold their breath for up to 15 minutes. When they dive there’s a membrane that goes over their eyes for protection, their nose and ears close, and a flap behind their teeth allows them to carry objects, but prevents water from going down their throat.
  • Their fingers are almost as dexterous as ours and they have long claws that can grab you without scratching you. This is probably due to their constant digging.
  • Their hind feet are large and webbed and they have a double toenail that they use for grooming.
  • Their tail is large and flat and it functions as a rudder, helps them balance when standing on land, and is used to sound alarms by slapping the water. (Another name for beaver is “Flat Tails”.)
  • Generally, in Colorado, beaver mate in January/February and have their kits sometime in May. The kits are born fully-furred with eyes open, weigh a few ounces, and are able to swim, but cannot dive because they are too buoyant.
  • Beaver breed once a year. In their first year they may one to two kits, but may have more as they mature. The availability of food will affect the size of the litter.
  • Everyone participates in caring for the new kits including yearlings.
  • In my experience, when I’ve trapped kits with an adult, they are most often with their father.
  • Within their first year kits play at building dams and lodges.
  • Kits stay with their parents for two years before going out on their own.
  • Before Europeans arrived in North America the population was estimated to be between 60 and 400 million, their range stretched from the Arctic Circle to northern Mexico, and they came in many colors—black near the Great Lakes, white in Yellowstone; blonde, chocolate, and silver.