In last week's Chautauqua Watershed Notes, I described the conservation benefits and ingenuity of the beaver, North America's largest rodent and valuable inhabitant of the Chautauqua Watershed. This week I'll discuss their home and family life and their keys to survival.
A pair of beaver typically mate for life, breed between December and February and bear four to five young about four months later. Newborns are ready to swim within a half-hour after birth and become skillful swimmers in about a week, although mama will carry them upon her back when she swims if needed. Although the parents produce a new litter each spring, the young from the previous year remain with the family for a second year, helping with housekeeping and the care of younger siblings.
Thus, most beaver colonies are really families of five to 10 individuals, the two adults and their offspring from the previous two breeding seasons. Family members greet each other, groom each other, wrestle, dance and play - along with caring for and maintaining their carefully constructed habitat. Most of these activities are rarely seen, however, because beaver are nocturnal and busiest at night. Upon reaching sexual maturity at 21 months of age, the young adults are sent away to disperse into new territories, build new dams and lodges, and begin their own new families.
Beaver dams, like this one at the headwater of Prendergast Creek, are found throughout the Chautauqua Watershed. There have even been attempts by beavers to dam Chautauqua Lake’s outlet.
Photo by Mark Baldwin
Lodges, as well as dams, are truly impressive. Most lodges consist of one or more compartments, each with two underwater openings for exit and entry (especially important for escaping from predators such as dogs, coyotes or bear). Living quarters for the family are in a hollow near the top of the lodge, with wood chips on the floor to absorb moisture and a vent to admit fresh air. A cache of winter food is stockpiled nearby, usually as cut branches poked into the muddy pond bottom and ready for the taking. When eaten, a branch is held like an ear of corn, and the outer cork, cambium and sweet inner bark are eagerly consumed, along with the leaves, fruits, seeds and even roots at times.
While best known for their ability to fell trees for the construction of their dams and lodges, few people realize how beautifully adapted beaver are for survival in their watery world, even in the icy waters of winter. Beaver fur, comprised of long, heavy guard hairs which overlay a dense, insulating under-fur, is highly modified to trap body warmth against the skin, so that the skin itself remains warm and dry even when the outside coat appears wet. A thick layer of fat under the skin further insulates against the frigid chill of winter. The flattened, scaly tail serves as a rudder while swimming, in addition to aiding in construction activities and providing an alarm signal when slapped against the water's surface. Special valves close off the nostrils and ears while swimming under water, and a transparent, nictitating membrane draws over each eyeball to protect against floating debris. Long sensitive whiskers allow detection of surroundings even in the underwater darkness of night, while fully webbed hind feet allow efficient swimming at up to 6 mph. Beaver lips seal the mouth by closing behind the teeth, leaving the incisors exposed to carry food and building materials to and fro. Incredibly, beaver may remain submerged underwater for a full 15 minutes before needing to come up for air.
As remarkable as they are, physically, socially and ecologically, beaver were once valued only for their pelts and were considered by many to be the single most valuable commodity in North America during the early 19th century. Uncontrolled exploitation, in response to demand from eastern U.S. and European fur markets, led to the beaver's disappearance from much of its original range. By the 1940s, however, beaver had reoccupied New York state, and new awareness of their ecological benefits, changes in forestry and agriculture and revised management strategies led to a spectacular recovery in their numbers. With their recovery have come increased beaver-human conflicts - over land, water and resources - and rarely do the beaver ever win. It doesn't have to be this way, though. If progressive thinking, human tolerance and innovative solutions are embraced, solutions can be found and mutual benefit may be gained. We need to try harder. Wherever possible, let's leave a place for wildlife, and experience a richer, more diverse and more wondrous world, even in our own backyards.
Becky Nystrom is a professor of biology at Jamestown Community College, a long-time CWC supporter and volunteer and a founding trustee of the CWC. The Chautauqua Watershed Conservancy is a local nonprofit organization that is dedicated to preserving and enhancing the water quality, scenic beauty, and ecological health of the lakes, streams, wetlands and watersheds of the Chautauqua region. For more information, visit chautauquawatershed.org or call 664-2166.