Beavers are North America’s largest rodents. They are famous for building dams and lodges in aquatic areas. If you have ever wondered what beavers eat and thought only “trees,” you would be partially correct. However, beavers eat a variety of plants and have ingenious ways to make sure there is food available all year long. How beavers eat and how they engineer their surroundings play a role in their importance to the environment.
TL;DR (Too Long; Didn't Read)
Beavers are vegetarian animals that are known for felling trees for dam building and eating. Beavers prefer certain trees and other woody plants over others, but they also enjoy soft vegetation in the spring and summer.
Is a Beaver a Rodent?
Beavers are rodents. Beavers rank second only to the capybaras of South America in rodent size. They can be 3 to 4 feet in length and as tall as a foot and a half. A typical beaver weighs in the range of 40 to 60 pounds, and the largest recorded beaver weighed a startling 110 pounds! Beavers can live up to 12 years in the wild.
What Are Interesting Facts About Beavers?
Beavers stand apart from other large aquatic rodents such as the muskrat and the nutria. Muskrats have long, flattened tails and are smaller than beavers. Nutria tails are roundish, and they tend to be in between a muskrat and beaver in size. Beavers are generally brown, with very dark tails.
Beavers can run on land, but that is not their greatest skill. They fare much better in water, where they can swim as fast as 6 miles per hour. And when they need to, they can stay under water for as many as 15 minutes.
The beaver possesses a number of unique features that help it survive. Its stocky body helps to conserve heat, which helps it endure harsh winters and cold water. Beavers have exceptional orange front teeth with a special coating. As in other rodents, these teeth grow continuously, and they are worn down by eating. The teeth in the back of their mouths are flat and white rather than orange. Those back teeth serve as grinders for the food the beaver chops with its front teeth. If beavers don’t wear their teeth down over time they can actually starve because they will not be able to close their mouths and grind their food with their molar teeth. Beavers, in fact, eat with their mouths closed behind the first tooth. Since beaver teeth are excellent for gnawing at trees, the teeth are very sharp. It's a good idea never to approach or provoke a beaver. They will charge and bite if they feel threatened, and that is one wicked bite!
The iconic paddle-like tail of the beaver has no hair, but it does have dark scales. Tail shapes vary subtly depending on inheritance. The beaver uses its tail to steer as it swims. And when a beaver is on land and needs to eat trees, these sturdy tails provide balance. Beavers also use their tails to slap the surface of water when they sense danger. These remarkable tails also serve as fat reserves to aid them through winter.
Beavers must be able to find objects in dark water and other dim areas such as their lodges. Their eyes possess a special membrane that covers them while the animal is submerged. While they do not have excellent vision, their whiskers aid them in detecting things. Beaver ears contain valves that shut when they go underwater, and they have good hearing.
Beavers have dexterous front feet that can hold objects, much as a person would, although they do not have opposable thumbs. The rear feet of beavers are much larger and have webs between their toes that aid in their swimming. Their hind feet also possess a special toe called a preening toe that has a double toenail and allows beavers to comb and keep their fur in prime condition. Beavers walk on all five digits of their feet. The beaver’s claws are sharp and efficient at digging.
If you have ever wished you had more hours in a day, you might envy beavers. While humans operate on a 24-hour day length, generally nocturnal beavers do not. They live primarily under water in low light in their lodges, which changes their natural circadian rhythms. Therefore the length of a beaver day tends to range from 26 to 29 hours.
On their behinds, beavers boast castor and oil glands. These produce scent for communication and territory marking, and oil to waterproof their fur, respectively.
Beavers have interesting ways to communicate, such as the tail slap on the water for warning others. The scent from their castor glands also allows beavers to communicate information when the animals rub the scent on mounds near their homes.
The family groups that beavers form are stable, and older young help out with newborns alongside their parents until they are old enough to move on and breed.
What Is a Group of Beavers Called?
A family group of beavers is called a colony.
What Do Beavers Eat?
Beavers are strict vegetarians. Beavers tend to build their homes alongside rivers and the edges of other bodies of water, within close proximity to trees. But beavers do not simply eat just any tree they come upon. The beaver diet includes certain varieties for eating, and others for building their dams and lodges. Also, the beaver diet depends on the season. In the spring and autumn, they will eat both woody and soft flora. In the summer, most of the vegetation they eat will be soft. In winter, when there is little new growth on plants, beavers eat woody fare. Beavers have unique micro-organisms in their guts that help them digest as much as 30 percent of the cellulose they eat from plants.
Trees that make up the beaver diet include bark from willow, cottonwood, aspen, poplar, maple, birch, oak, sycamore, ash, alder, black cherry and apple trees. Beavers will gnaw on trees until they fall, and then they clip branches from the resulting logs and add them to their food stash. While beavers will sometimes eat fir, pine and other conifers, they do not favor them for food. They will often use such trees for dam building, however, or fell them to allow their favorite foods to grow instead. You can spot areas of beaver lumbering where there are sharply pointed tree trunks, with grooves from their teeth marks, as well as piles of wood shaving around the trunks. Beavers can fell as many as 300 trees in a year!
Other woody plant items that beavers consume include roots, leaves, vines, new twigs, sedges, shrubs, grasses, blackberry canes, ferns and new bark.
In addition to trees and woody plants, beaver food includes soft vegetation such as apples, grasses, water lilies, clover, giant ragweed, spatterdock, duck potatoes, cattails and watercress. Occasionally beavers eat mushrooms as well. Beavers will even eat corn and beans.
Beavers can store their food in a fascinating way for winter, when they are not able to access as many delicious plants. They make a muddy floor inside their lodge homes, and push sticks and branches into the mud so it will stay there and be refrigerated by the water’s cold temperature outside the lodge. This amazing food stash is called a cache and tends to be made and used in colder climates. Beavers stay busy in the fall gathering food for their cold winter and upcoming times when food is less available.
When beavers eat, they hold their food in their front legs much as people hold corn-on-the-cob, rotating the treats as they go.
Baby beavers are called kits, and they nurse from the milk of their mothers. Sometimes these kits even stand up to nurse. After about six weeks, these kits will be old enough to eat solid beaver food, which every family member helps to bring them. Young beavers will stay with their families until they reach around two years old.
Generally, beavers eat their food close to water and their lodges or dens. If the beaver food supply in an area becomes depleted, they will eventually move. This may take several years to happen, though.
For homeowners concerned about beavers intruding on their properties and eating their plants, fencing can be made to prevent this. Also planting trees that beavers do not like eating, as a sort of natural fence, may be a good idea.
Nature’s Dam and Lodge Builders
Of course, beavers are most famous for their building dams. Beavers choose dam locations based on the sound of flowing water. They make watertight dams that drastically alter aquatic bodies such as rivers and streams and ponds. Beavers take sticks, reeds, saplings and branches, and they use mud as a caulking material to build their dams. Beavers tend to build their dams in summer and fall, so be on the lookout for these impressive structures.
The dams are not the homes of beavers; they build lodges to live in, give birth, raise young and store food. These cleverly engineered lodges can be over 6 feet high and as wide as almost 40 feet! The lodge contains an entrance underwater that the beavers can access quickly, and climb through their passages to various rooms. Beavers even make a short of chimney or skylight when they build their lodges, to allow fresh air in. And beavers keep the floors of their rooms tidy with wood shavings.
While beavers are known for their dam and lodge building, when they're in areas that do not get very cold, or where there is level water like on a lake, they may not make either of these. They instead will build dens in high banks, with underwater entrances.
Beavers maintain and repair their lodges and dams constantly to keep them safe and sound for every season.
Predators of Beavers
With beavers being of a fairly large size, they are targets of larger predators, if any exist in their region. Some examples of beaver predators include cougars, wolves, bears, coyotes, bobcats, lynx, otters and mink. Large birds of prey have been known to take juvenile beavers. Occasionally, dogs can also attack beavers.
The ultimate predator of beavers is, however, humanity. Humans threaten beavers by trapping for fur pelts, polluting water in the beavers’ environment and destroying beaver habitats.
Are Beavers Friendly to Humans?
Beavers avoid interacting with humans. If they feel threatened, beavers usually retreat underwater and to their lodges. It is not wise to approach a beaver, for if they feel throated, they may attack in defense, with that very vicious bite!
A Keystone Species
Beavers are so important in ecology that they are known as a keystone species. What this means is, is that their very presence affects entire ecosystems. If beavers were removed from their environments, a chain reaction would take place affecting every plant and animal in that space, and abiotic factors such as stream flow, erosion and water quality as well. Beavers create habitats for many wetland species, and they help to aid water quality. Animals that benefit from beavers include frogs, salamanders, turtles, fish, ducks, otters, owls, insects and many other species. Their used trees also provide nesting habitat for herons and other birds.
At one point beavers were greatly threatened due to trapping. After wildlife laws were established, beavers and their habitats became more protected, and their numbers rebounded.
Look for beaver dams near rivers and streams. You may be able to spot the dams even if the reclusive beavers duck out of sight into the water. You can also trace their tail dragging marks, and their gnawed tree areas. If you see a beaver in an aquatic area, you can be assured that area is ecologically healthy.
- Washington Department of Fish and Wildlife: Living with Wildlife: Beavers
- Delaware Water Gap National Recreational Area: Beavers – Nature’s Engineers
- Animal Protection of New Mexico: General Information About Beavers
- Smithsonian’s National Zoo & Conservation Biology Institute: Beaver
- Missouri Department of Conservation: American Beaver
- State of Connecticut Department of Energy & Environmental Protection: Beaver
- Indiana Department of Natural Resources: Beaver