BEAVER Castor canadensis

The beaver (Castor canadensis) is the largest rodent in North America. It is easily recognized by its large, flat, bare, scaled tail and fully webbed rear feet. Beaver range in North America includes most of the United States and southern Canada. The beaver played an important role in the early colonization of North America, as trappers came in search of pelts. At one time, the beaver population had declined to the point that they were absent from most of their range. However today, beaver populations have rebounded and, in some areas, they create conflicts with humans.

Vermont Wildlife Fact Sheet

Physical Description A beaver’s head is relatively similar to that of an aquatic small and round with large, well mammal than a terrestrial one. Beavers normally have dark developed incisor teeth for brown fur with lighter highlights gnawing wood. As with other The front feet of a beaver are but some with black, white, and rodents, these teeth grow not webbed, but have strong silver coats have been reported. continually. If opposing teeth do claws for digging. Front legs are The under fur is very dense, not match correctly, allowing tucked up against the chest short, and waterproof, with normal wearing and sharpening when the beaver swims. The sparse, coarse, shiny guard hairs action, they can grow rear feet are large and webbed protruding through. excessively to the point where for powerful swimming and provide support when walking An average adult beaver eating is nearly impossible and starvation results. Flat-surfaced over mud, like snowshoes. weighs 40 to 60 pounds. The When swimming at normal heaviest known beaver weighed molars at the rear of each jaw grind the beaver’s food. speed, these feet are paddled 110 pounds and was taken by alternately, similar to the way Vernon Baily in 1921. Baily Beaver are well adapted to people swim. When the beaver caught the record-setting beaver their aquatic environment. The swims at higher speeds, it on the Iron River in Wisconsin. ears, nose, and mouth of the undulates its whole body up and The beaver is a muscular, beaver are well adapted to down, like that of a seal. In this compact animal with strong, swimming underwater. A clear situation, the rear feet and tail short legs, each having five toes membrane functions, like an work together as a rudder, with heavy claws. Its broad, inner eyelid, and covers the eyes allowing for quick changes in horizontally flattened tail (unlike when the beaver is underwater direction. so that it can see clearly. Its ears, the muskrat’s which is vertically The rear feet of the beaver flattened), serves as a rudder and nose, and mouth can also be closed underwater. have five toes. Each toe has a paddle. On land it supports the claw, but the second toe from beaver when sitting up. It also Beaver can stay underwater the inside of each rear foot has a functions as a warning signal to for up to 15 minutes due to their large, double claw, which is other beavers when it is slapped ability to efficiently transfer used to comb the fur and catch hard against the water’s surface. oxygen from the lungs to the parasites. While combing its fur, Additionally, it helps to regulate bloodstream and to tolerate a the beaver applies a water- body temperature through build-up of carbon dioxide in repellant oil, which comes from controlled blood flow. the body. Their heart is more two glands located under its tail. These glands are distinctly Vermont Fish & Wildlife Department FW 1/2009 Beaver Fact Sheet ♦ 1 different from the larger ‘castor’ In late winter, before the (food cache), pulling mud or scent glands that produce litter of the year is born, the rocks over the base stems. The castoreum, a yellowish, pleasant mature two-year old beavers are pile soon becomes waterlogged -smelling oil, that is deposited either driven away by their and settles to the bottom. A on small mounds of mud and parents or leave on their own to family of eight beavers requires acts as a scent communication establish a new colony. one ton of bark to survive the between beaver. These scent winter. posts vary in size from one small Beavers communicate by patty to a mound of them as high leaving scent and by making soft Habits and Habitat as two feet. whining sounds. The young beavers vocalize often. Splashes Beavers are found in The sexes are difficult to motivate the kits to swim and Vermont along wooded streams, distinguish except for pregnant tail slapping on the surface of marshes, lakes, and ponds. They or nursing females. Four the water teaches them how to seek areas of flowing water mammary glands are evident signal for danger. where the volume of water is when the young are nursing. A reliable or still waters where beaver has a ‘cloaca’, similar to Beavers live up to 11 years in water levels are consistent. An that of bird, fishes, and the wild, but those in captivity abundance of desirable trees for amphibians. This is a chamber have reached 20 years of age. food and construction of their containing reproductive, lodges and dams is also intestinal, and urinary systems important. Dams, lodges, with a common external burrows, and canals are built in opening. the selected area. Life Cycle Beavers are one of the only animals, other than humans, that A beaver colony is usually actually modifies the existing comprised of three generations: habitat to suit its own needs. the adult male and female, their Food Items Beaver wetlands are cyclic. yearlings, and the kits of the Beavers move into an area and year. These colonies average a Beavers are herbivores and build a dam, some of which can half dozen or so individuals, consume bark, leaves, twigs, and be very large. The dam creates a although as many as twelve roots growing near water. The pond that allows the beavers to have been recorded. most preferred food is the inner access food more easily without bark of deciduous trees, called having to move too far from the Beavers tend to mate for life, the cambium layer. During water. For the first seven to ten but there are exceptions to this warm months, the beaver’s years, beaver ponds are rule. The breeding season peaks menu includes bulrushes, incredibly productive, and the in mid-February. The gestation sedges, pond lily roots, and food web extremely complex. period averages 106 days, and a other aquatic plants. Their Small microorganisms provide single litter is born each year. woody diet includes the bark of food for insects and other Litters vary from one to nine poplar, alder, paper birch, invertebrates, which provide kits, but three to five is normal. willow, gray birch, red oak, red food for amphibians, which maple, cherry, and viburnum. provide food for fish, which Kits are born from mid- White cedar, hemlock, black May through early June. They provide food for birds and spruce, red spruce, white pine, are fully furred at birth but their mammals, and on and on. As the pitch pine, balsam fir, and larch eyes can only open slightly. beaver begins to run out of are also eaten, sometimes even They weigh 8 to 22 ounces and available food, it attempts to when more preferred foods are are about 12 inches in length expand the size of the pond to readily available. (including the tail). The kits access more. Usually after 10-20 begin to swim when they are Since beavers do not years, the food supply is only a few days old. At two to hibernate in the fall, they store depleted, and the beavers three weeks, they begin to eat their food (branches of edible abandon the site for someplace solid food and are weaned at trees) for winter in a large better up or down stream. The about six weeks. underwater pile near the lodge Beaver Fact Sheet ♦ 2 abandoned pond eventually Abundance Throughout beaver today. Beaver are more reverts to meadow, grows a new History susceptible to predators when food source in the form of on land. Once they make it to willows, alders, and aspen, and Prior to European water, however, the odds of the process starts over again. settlement, there may have been their survival are much greater. as many as ten times the number Beavers live in bank dens of beaver that presently exist in Humans trap beavers for (hollowed out tunnels in the New England today. The their pelts, castor secretion, and banks of rivers or ponds) or in unregulated trapping that for food. It is likely, however, lodges. The lodges are built out occurred as a result of the early that predation levels today are of sticks, stones, leaves, grass, fur trade, coupled with the lower than what they were sod, and mud. Branches are first clearing of the New England during pre-European times in piled together, then the beavers forests in the 1700s to mid-1800s Vermont. Prior to European swim up underneath the pile to for farming, virtually eliminated settlement, Native Americans, hollow out a central living beaver from Vermont by the wolves, and mountain lions quarter. This inside chamber is beginning of the 1800s. In 1910, probably killed more beaver built above the waterline and is beaver were protected by state than today’s trappers, coyotes, connected to the outside with law and began to make a slow bobcats, and other predators one or more underwater tunnels. comeback. The Vermont Fish & combined. Throughout history, The outside of the lodge is Wildlife Department reintro- beaver have provided a covered with sticks and mud, duced beaver into Vermont from naturally healthy, organic and which insulates it in the winter. New York and Maine in the renewable source of protein for The inside chamber is then lined 1920s and 1930s. The human consumption. The U.S. with grass and shredded bark. reintroduction coincided with Department of Agriculture rated There is also a ventilation hole to the abandonment of many of beaver meat higher in protein the outside that allows fresh air Vermont’s farms, and the and lower in fat when compared to circulate inside the chamber. subsequent reforestation created on a pound-for-pound basis an excellent habitat for the with beef. The lodges are almost growing beaver population. To always well placed at a natural Management Efforts ensure the success of the low point with solid anchor reintroduction program, points on each side of the brook Beaver are North America’s Department staff live trapped or stream. A long dam is often preeminent keystone species; and transferred beaver to zigzagged to make use of that is, they create habitat for unoccupied flowages around the intermediate anchor points. many other species including state. By the 1940s and 1950s, Structures are constantly mammals, birds, plants, fish, beaver had again become well maintained when they are not and invertebrates. Beaver established in Vermont. The first iced in. Additional dams are increase biological productivity 15-day open trapping season often built upstream or in many ways. The wetlands was set in 1950. Aerial surveys downstream from the main dam they create in the forests conducted on the Green to create smaller reservoirs that increases the diversity of the Mountain National Forest in the increase the safe foraging range. landscape. This is important 1980s and 1990s indicated that A family of beaver can build a 35 even after a beaver abandons a beaver population levels had -foot dam in a week. wetland. When dams decay increased by 120% in the ten through lack of maintenance, Beavers are most active in years between surveys. flowages initially become wet late afternoon and throughout meadows. Like ‘active’ flowages, Predators the night. They try to stay in the these meadows are unique water or as close to the water as Historically, wolves, habitats that also have great possible. Beavers swim at speeds mountain lions, and Native natural value. Beaver are an of about 2 mph, and can stay Americans may have been the ancient species that have been underwater for as long as 15 beaver’s major predators. Black widespread and abundant for a minutes without coming up. bears, coyotes, bobcats, and long time. All aquatic and semi- fishers occasionally prey on aquatic species in existence

Beaver Fact Sheet ♦ 3 today have evolved in their natural resource. The main- presence. tenance of beaver populations ensures the continued Beaver ponds usually production and enhancement of provide excellent brook trout valuable wetland habitat, and fishing during the first few years provides a broad array of social after the dams are constructed. benefits. The Fish & Wildlife They also provide flood control Department strives to maintain by preventing the rapid run-off as high a beaver population as of water and controlling soil possible while still maintaining erosion. levels that are compatible with Road commissioners and public uses of land and private landowners often minimizing conflicts between complain about damage done by beaver and people. Information beavers. A beaver pond next to a on beaver is collected annually road can undermine the road from each of the watersheds in and repairs can be costly. Water Vermont. The beaver trapping control devices can sometimes season begins on December 1st be installed to lower or maintain and runs through February. The stable water conditions and length and time of the open minimize conflicts between season for different areas is beaver and humans. However, determined annually based on these structures may not be population levels determined by suitable in all situations and biologists. require some regular maintenance. Even so, they often provide a better alternative to removal of the dam and destruction of available wetland. Conflicts can also be avoided by controlling the number of beaver in an area by trapping during the fall/winter trapping season. Half of the beaver taken by trappers are the result of conflicts between beaver and people. Live-trapping and transfer- ring beavers from one area to another is seldom done now, because most Vermont watersheds already have an abundance of beaver. Current Management Efforts Vermont’s beaver popula- tion is healthy, prospering, and growing. The Vermont Fish & Wildlife Department recognizes beaver as a valuable renewable

Beaver Fact Sheet ♦ 4