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Range and Habitat: Forested regions of the northern hemisphere,
in North America from Alaska and Canada south to Rio Grande; Europe
in Scandinavia, Russia, Germany, France and Poland. Wooded areas
near water where aspen, willows, cottonwood and other food trees
are found.
Habits and Adaptations: Well known as the engineer of
the animal world. Fells trees, build dams and lodges, digs canals.
All of these activities result in securing the lodge from predators.
A water level of about 1.8 m (6 ft) is necessary to allow the
construction of island-like lodges. Dam becomes complex construction
after kept in repair for years. Made of mud, grass, logs (15 cm,
6" thick), twigs and stones. Ponds vary from .4-4 hectares
(1-10 acres). Canals are dug from feeding ground to pond for safe
travel and floating of logs. Lodges of similar construction as
dams average 1.5 m (5 ft) high and 6 m (20 ft) in diameter with
2 entrances under water and ice levels. Parents, yearlings and
new litter live together in one lodge. Sometimes will live in
den in streambank with underwater entrance and not attempt to
build dam. Generally, colony works together building and repairing
dam. Work and feed in late afternoon and through the night. Less
active in winter, store food underwater for winter needs. Natural
enemies are bear, coyote, wolf, red fox, bobcat, otter, great
horned owl and goshawk, all captured on land except those taken
by otter.
Diet: Bark, cambium, twigs, leaves, aquatic plants, roots
of deciduous trees such as willow, alder, birch, aspen.
Breeding and Maturation: Monogamous, sexually mature at
2 years. One litter in April or May, 1 - 8 young (average 2 -
4), hair and open eyes at birth, nurse for 6 weeks. Live 15 -
20 years.
Miscellaneous: In the Pleistocene Age, giant beavers the
size of black bears roamed the Old and New World. In more recent
times, the beaver's range extended across northern Europe and
Asia, south to the Mediterranean. Due to the value of it's fur,
however, the beaver has virtually disappeared from many areas.
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