Family Castoridae - Beaver

Castor canadensis - American Beaver


AUDUBON (March-April 2000) - Beavers turned to the water some 30,000 years ago to escape predators.  Over it's average 12 year lifetime, a beaver will cut through hundreds, if not thousands of trees. This is made possible by two pair of open-rooted incisor teeth that will continuously grow throughout the beaver's life.  Until the 1600's 60 to 400 million beaver populated North America.  Typically, a beaver dam could be found every 500 feet along a stream, forming lakes, marshes and, as dams were abandoned, lush meadows.   Over the next two hundred years, trappers removed a vast majority of the population, leaving following settlers to presume the lush valley soils were simply part of nature's generous bounty. 

In addition to the dams' benefits to local groundwater, nutrient retention and habitat for birds and other wildlife, the eventual accumulation of soils produce fertile soils.  In Idaho, the Soil Conservation Service has used beaver since 1984 for erosion control.    After years of trying all kind of structures to control the water, they found nothing was as effective (and cost-effective) as beaver.  Additionally, local farmers have found that they didn't have to water hayfields located along beaver stream.  As one farmer said, "They work pretty cheap, and I've never seen a lazy one yet."

VIRGINIA WILDLIFE (AUGUST 1998) - Trapping beaver has lead the way to allow for the growth and expansion of this country.  Trapping occurs ahead of the homesteaders, with trapping rights in the Pacific NW causing a nine year war.  These trappers beyond civilization; beyond the frontier, were known as mountain men, explorers or pioneers.  They were business partners with the Indians.  The barter system, used in lieu of currency, dominated our nation in the 1600's and 1700's.  Among the mountain men, twelve beaver pelts bought a "trade gun" for the Native Americans. These pelts could, in turn, be used in the US market.  One beaver pelt was worth four pounds of shot, a kettle, one pair of shoes, or a pound of tobacco.

Beaver were gone from England by the late 1200's, rare in Sweden during the 1500's and close to extinction in other parts of Europe and Asia at that same time.   In 1670, the Hudson Bay Company of Virginia was chartered, and by 1733, they were shipping 200,000 of the 500,000 annual pelts to England.  In addition, secretions called castoreum, were produced by the two castor, or musk, glands.  This contains salicylic acid, the main ingredient of aspirin.  The Indians and Europeans used castoreum for treating numerous aliments including colic, epilepsy, frostbite, and hysteria.  It is still the primary ingredient in perfume fixatives.  Among beaver, it is used for marking their territory.  Beaver fur was used primarily for hats and coats.  

During the 1700's, Britain's Virginia's colonial borders including from West Virginia, western PA, Kentucky, Ohio, Indiana, Michigan, Minnesota, and Wisconsin.  Traders stretched the British territories all the way from the Great Lakes and Canada to the Northwest.  Meanwhile, the French were in control of the trade with the Hurons and Iroquois between the Allegheny Mountains and the Mississippi River.  In 1754, the French initiated the French and Indian Wars in an attempt to gain hold of the Hudson Bay Company and its Canadian market.  The move "The Last of the Mohicans" and it's sequel, "The Broken Chain", chronical the conflict between the French's Iroquois and the British Mohican Algonquian tribes.  Thanks in part to Napoleon's fading empire (and interests), Thomas Jefferson's execution of the Louisiana Purchase, opened the fur trading market all the way to the Pacific coast.   From 1853 through 1877 (including the civil war years), 3 million pelts were marketed in Europe.  This lucrative business made one trapper during this time $50,000 in one year. Then, silk replaced beaver for top hats, and the beaver market collapsed.  

 By 1900, overtrapping by the mountain men had seriously depleted the west of beaver, while homesteading and land clearing removed most from the east.  While populations began to recover, the Roaring Twenties and the model T established a new beaver trend.  With cars all the rage, and no heaters yet designed, the beaver coat became the status symbol in the society.  Trapping demands surged into the 1930's until the depression set in.  At this point, wildlife management officials took over.  In Virginia, protection of the beaver was mandated and more beaver were re-introduced into the State.  The best fur stock came in 1942-43 from Michigan and Pennsylvania.  

In the 1980's with high fur values, about a million pelts were still harvested in the US for Chinese and limited Europe, Russia and other Asian countries.  In fact, some man-made products can not replicate or improve upon certain qualities of natural garment materials and chemical science has been unable to equal or exceed the characteristics of cotton or fur.  

Pelts are "prime" during the late winter months, when they are the thickest and most shiny.  Northern pelts are considered more valuable than southern.  Virginia pelts are considered an excellent grade (remember the author), bringing in $15 -$20 for prime pelts in the last two seasons.  Today, beaver stocks are so high, they are becoming a pest in some areas (hint-hint).

A large beaver (bear sized) disappeared from North America since the Pleistocene Ice Age.  

Beaver are the only known animal whose body never stops growing (a comment seen in several books that's been challenged by major authorities).

Toes on the inside of the hind legs have evolved split toenails, used to groom it's pelage.

Without their historic predators, beaver are only susceptible as young to horned owls, large hawks, and otter.  

The average beaver colony is 6 - 12, with two acres providing the food and shelter for two years.  At three years, the young are driven away by the mother, sometimes traveling more than 30 miles from home.  In the unusual case of beaver, it is the female that travels furthest from the birthing site.  One beaver in North Dakota traveled 148 miles.

Beaver have been known to fill in culverts under roads, sometimes a hundred or more feet long, creating challenging and expensive removal process.


PENNSYLVANIA WILDLIFE (VOL.XVIII, NO.5) Beaver have been extirpated in Pennsylvania since about 1903. In 1917, a pair of beaver was released in Cameron County. Another 46 pairs were brought into PA from Ontario and New York between 1915 and 1924. By 1934, the population of over 6,000 enabled the first legal harvest. In 1997, a record 9,700 beaver were taken, with an estimated state-wide population of 33,000.

An excellent web page regarding the beaver in North Carolina is maintained by the North Carolina Wildlife Resources Commission. (Go to the "species" link at the top row.  Then, "publications", and then you'll see it listed under the NC Wildlife & Wildlife Management Publications.)