Beaver (Castor canadensis) are the world’s best wetland engineers and are an integral part of the Wyoming Wetlands Society’s (WWS) mission to protect and enhance wetlands for future generations. Although wetlands comprise less than 2 percent of the western U.S. landscape and are being rapidly lost to development, they provide numerous ecological services and habitat for over 80 percent of the region’s wildlife. Almost half of endangered and threatened species in North America rely upon wetlands.

As beaver attempt to reclaim their ancestral lands, the same behaviors that make beaver a keystone species essential to the creation and maintenance of wetlands result in conflicts with humans.  Although WWS recognizes the importance of beaver as a keystone species, we also realize that they can cause real problems in inhabited areas. Since 2004, WWS has been assisting private landowners by live trapping problem beaver at no cost to the landowner. Many of the beaver we live trap are those that are damaging expensive landscaping, obstructing irrigation head gates, or flooding yards and roads.  Sometimes it is all of the above. The beavers trapped in this program are relocated to suitable but unoccupied areas of the Gros Ventre River Drainage and adjacent drainages to restore and enhance wetland habitat.

WWS increased its efforts in the beaver relocation program in 2007 with cooperation from Wyoming Game and Fish Department (WGFD) and Bridger-Teton National Forest (BTNF). Funded by private donations, grants from the Wyoming Wildlife and Natural Resource Trust (WWNRT) and the WGFD, WWS was able to relocate thirty-three beaver in 2009 alone. Many of these beaver have established territories and are creating or enhancing wetland habitat in the BTNF. WWS has plans to continue the beaver relocation program through at least 2016 with the hope of reestablishing beaver throughout the BTNF and other areas in northwest Wyoming.

A Brief History of Beaver in Wyoming

Prior to European settlement, beaver were found in high densities throughout North America, but were nearly exterminated by 1900 to meet the demands of European fashion (primarily for felt hats). Populations before European settlement are estimated to have been as high as 600 million, occupying nearly every watershed in North America from northern Alaska to central Mexico. The first exploratory missions into what is now Wyoming in the early 1800s were to seek out the last remaining populations of beaver living in high mountain streams. Early trappers like Jim Bridger and Davey Jackson not only lent their names to the Wyoming landscape, but also unwittingly precipitated major ecological shifts resulting from the nearly complete eradication of beaver from the ecosystem.

By the time the first permanent settlers arrived in Wyoming the landscape had already undergone major changes. The old beaver dams had deteriorated, streams no longer cascaded from pond to pond, and much of the wetland habitat had shifted to meadows. The wet meadows were the best areas for early agricultural endeavors and were the first to be settled, minimizing opportunities for beaver to become reestablished.

In the early 1900s the state of Wyoming, along with the rest of the nation, decided that no matter the value of beaver to trappers or as fur hats, they would always be more valuable to the citizens of Wyoming as curators of our wetlands. Beaver were given protection by the state and were reintroduced to many watersheds. By the 1950s the program was considered a resounding success and restrictions on trapping were lifted. Beaver trapping soon reached levels comparable to those found during the height of the fur trade and local populations have been diminished. Current North American populations are estimated to be between 6 and 12 million. Without healthy populations of beaver, wetland complexes and associated ecological services have once again deteriorated throughout the region.

Old hay meadows, once a mosaic of wetlands, are being lost to (sub)urban development. These areas are permanently lost as wetland habitat, so it is unlikely that beaver populations will ever return to historical levels. However, because beaver are so important to wetlands (and wetlands are so important to everyone else), WWS believes that healthy populations of beaver should be maintained anywhere there is not irresolvable conflict with humans.

Beaver Biology and Ecology

The beaver (Castor canadensis) is North America's largest rodent. Adult beaver typically weigh 45 to 60 pounds, but have been known to grow to over 100 pounds and over a meter long. Beaver have been called "Little People” and “sacred centers”, while their wetlands were the “earth’s kidneys”. Beaver are vegetarians, subsisting solely on woody, herbaceous and aquatic vegetation. They do not eat fish or other animals. Beaver may be monogamous for life and breed once a year. The young kits stay with their parents 2-3 years before dispersing to find new habitat and a mate. There are usually six to seven beaver in an established family. Reproduction rates are density dependent and populations self-regulate. While some beaver behavior is instinctive, they also learn by imitation and from experience. The leading cause of mortality is predation of kits and trapping of adults.

Beaver have many special adaptations. Beaver teeth never stop growing, and their incisors are self-sharpening, creating a chisel-like cutting surface. The beaver's large flat tail serves as a rudder when swimming, a prop when sitting or standing upright, and a storehouse of fat for the winter. Large webbed hind feet are ideal for swimming and hand-like front paws allow them to manipulate objects. Beaver have excellent senses of hearing and smell. When swimming underwater a protective transparent membrane covers their eyes, flaps close to keep water out of their nostrils and ears, and inner lips allow them to carry sticks in their mouths without inhaling water. Beaver fur consists of short fine hairs for warmth and longer hairs for waterproofing. They groom their fur daily to keep it waterproof, and frequently groom each other's fur. They have castor glands on the under side of their abdomen from which they can excrete an oily substance (castor) that they use in the grooming process and to mark their territory.

Beaver impound water with dams and dig canals to stabilize water levels, provide safety from predators and increase safe access to food. The resulting ponds and wetlands create habitat for a diverse array of aquatic and wetland associated flora and fauna. Wetland biodiversity can exceed that of tropical rainforests and coral reefs. Beaver are critical to the survival of native trout, moose, swans, and other waterfowl in the western U.S. where riparian and wetland habitats comprise less than 2 percent of the landscape yet provide habitat for greater than 80 percent of wildlife species. The seasonal flooding of riparian communities associated with beaver dams brings new nutrients and increases the value of forage for moose and other ungulates. Besides being a keystone species, beavers reliably and economically maintain wetlands that can sponge up floodwaters, prevent erosion, raise the water table, recharge drinking water aquifers, maintain stream and river flow, moderate drought, purify water of silt and toxic pollutants, and act as natural fire breaks in conifer dominated landscapes.



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