NORFOLK — An overflow crowd packed into the Norfolk Library Saturday, Jan. 14, for Stephen DeStefano’s talk on “The Life and Habits of the North American Beaver,” the first lecture in the Great Mountain Forest’s Forest Lyceum series of lectures this winter and spring.The subtitle of the lecture is “The most interesting animal to-day extant” — a phrase taken from the introduction to A. Radclyffe Dugmore’s 1914 book, “The Romance of the Beaver.”DeStefano is the leader of the U.S. Geological Survey’s Massachusetts Cooperative Fish and Wildlife Research Unit and a research professor at the University of Massachusetts in Amherst.DeStefano proceeded methodically, noting that the North American beaver (Castor canadensis) is a rodent and is found all over North America. It has also been introduced successfully in Europe and Patagonia.He then took a quick detour into prehistory — most notably, a description of the giant beaver that got to be as big as 8 feet tall and 200 pounds, and existed from about 1.4 million years ago and died out about 10,000 years ago (something to consider when a beaver dam is causing inconvenience.)Castor canadensis is “a real specialist” in the art of gnawing and taking down trees, DeStefano said admiringly.“Their teeth are always growing, so if they don’t gnaw, the teeth will grow right into the head.” Beaver factsThe North American beaver, while industrious, is considerably smaller than its ancient relative — 2 to 3 feet long, with a tail of half a foot to one and a half feet, and tipping the scales at between 30 and 70 pounds. The highly prized fur ranges in color from chestnut to almost black, with a light gray underfur.The babies (“kits”) are between 9 and 15 pounds, and can see and swim almost immediately.The first year of a beaver’s existence is idyllic. They spend the bulk of their time in the water, DeStefano said. “They don’t need to get a summer job.”Beavers have poor eyesight, but their senses of smell and hearing are excellent. They typically live between 5 and 10 years.The North American beaver has a fusiform body — wide in the middle and tapered at either end. The ears and nostrils have valves, which allow the animal to submerge without water coming in. A beaver can stay under water for 15 minutes, as any fisherman who has worked a beaver pond can confirm.The big, flat tail serves as a rudder while swimming, as support while on land and as a warning when slapped on the water — as the above-mentioned angler can also confirm.(Personal note: I once fished a high mountain stream in northern New Mexico with a friend. We found a beaver pond and gingerly began casting our flies. My friend got bored and moved on, but I was more patient. Just as I hooked into a decent fish, there was a huge “FWAAP” noise behind me, and just a few yards away was a large beaver sporting lots of teeth and an irritated expression. He started toward me, or so I believed, and I scrambled out, losing the trout and my dignity in the process. My friend was sitting against a tree, laughing helplessly and making comparisons to President Jimmy Carter’s 1979 encounter with a killer rabbit.)The front feet are well-equipped for construction and grooming. Yes, grooming — with the oils from the castor and anal glands.Castor canadensis mate at three years, and do so annually, in January and February. “So there are beavers out there up to something right now,” said DeStefano. They are monogamous.The gestation period is 100 to 110 days. Litters typically have three or four kits, and the young beavers stay with the parents for two years, usually.The beaver is a strict herbivore, which explains why they get along with fish. They are particularly fond of alders, aspens and willows. DeStefano said that distribution of those species often coincide with beaver populations.They also eat blueberry, dogwood, cattails and water lilies.A good sign that a particular habitat is nearing the end of its usefulness to the beavers is when they start gnawing on oak or pine.Information on damsWhy do they build dams? To create habitat. The beaver lodge entrance is under water, which keeps predators out.The dams, which can get up to 10 feet tall and can be found in all sorts of watercourses, require constant maintenance.Beavers are nothing if not diligent. “The sound of running water gets them going,” said DeStefano, “Poke a hole in a dam and watch.”The lodge is the focal point of the beaver’s life. A typical lodge is 20 feet wide and 7 feet high, with multiple chambers, entrances and areas where the building materials are arranged loosely to allow ventilation.Beavers can build a dam in two nights.They do not hibernate (see mating). One linear mile of suitable habitat can support one or two colonies of four to eight animals apiece.When wolves were prevalent in North America, they were a major predator. (Coyotes fill a similar role today.) Black bears and big cats will also go after a beaver if the opportutunity presents itself.Young beavers, leaving the home lodge and seeking their own turf, are the most vulnerable to predators.Humans and beavers have a lengthy history, DeStefano continued. Fur trapping was of enormous, even pivotal importance to the developing economy of the North American colonies.Fur (for hats) and meat were of primary importance, but beavers were also used for perfume and medicine. DeStefano said that before the establishment of the fur trade there were an estimated 100 to 200 million beavers in North America. Today there are between 10 and 15 million.In modern times, trapping, like all hunting, is highly regulated. Connecticut had two winter trapping seasons in 2011, with mandatory participation in a pelt-tagging program.Beaver dams, where they are not wanted, can cause angst. DeStefano said in Massachusetts landowners are required to seek the assistance of state animal control agents to remove beavers and dams. In Connecticut, regulations note that licensed trappers often assist landowners with removing beavers during trapping season and that “special authorizations to trap beaver outside of the regulated season may be issued by the DEEP Wildlife Division when beaver activity threatens public health and safety or causes damage to agricultural crops.”But Connecticut frowns on live-trapping and relocating beavers, as simply moving the problem from one place to another.If a Connecticut landowner wishes to do something about a beaver dam, be aware of this Department of Energy and Environmental Protection regulation: “The installation of any water level control device at a culvert or modification of a beaver dam in any way, including breaching or removal, are considered regulated wetland activities and must be approved by the local inland wetlands commission.”DeStefano extolled the beaver and its importance to the overall environment. The cycle that begins with the creation of a beaver dam, the years of use, and its ultimate abandonment lead then to a deep wetland, followed by a shallow wetland, then a grassy meadow and, eventually, forest again.The economic importance of the North American beaver naturally led to scarcity, DeStefano said, adding that by 1750 beavers were pretty much gone from Massachusetts.They made a comeback beginning in 1928 in western Massachusetts, and by 1995 there was a relatively stable population of about 20,000. A 1996 ballot initiative restricted trapping methods, and beaver-related complaints went up.DeStefano offered some suggestions: aim for an increased tolerance for the beaver, and understanding of its role in the overall environment; avoid building in beaver habitat; wrap or otherwise protect valued trees; engage in dam removal, or install flow devices, as per regulations.Moving the beavers is “not an option,” he said. Doing so simply transports the problem, increases the risk of spreading disease and disrupts the highly structured social life of the animals.And it’s illegal, he concluded.Upcoming eventsComing up in the Great Mountain Forest’s Forest Lyceum series:Feb. 11 — Paul Barten of the Great Mountain Forest and University of Massachusetts, Amherst, on “The Shakers: Forest Conservation, Green Design, Sustainable Agriculture...200 Years Ago” (at the Douglas Library in North Canaan).March 10 — Todd Fuller of the University of Massachusetts, Amherst, on “Wolves? In New England?” (at the Norfolk Library).April 21 — Scott Heth of Connecticut Audubon in Sharon on “Forests for the Birds: Habitat Needs and Management Options for Migratory Songbirds” (at the D.M. Hunt Library in Falls Village).May 12 — Robert Thorson of the University of Connecticut with “Stone by Stone: The Magnificent History in New England’s Stone Walls” with books available for purchase (at the Norfolk Library).June 9 — A film, “Green Fire: Aldo Leopold and a Land Ethic for Our Time” (at the Norfolk Library).For more information, call 860-542-5422 or visit www.greatmountainforest.org.The Connecticut DEEP Wildlife Division provides technical assistance to individuals experiencing problems associated with beaver activity. For more information, contact the Wildlife Division’s Beaver Management Program at 860-424-3011.
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