Fur
Beaver fur is a soft luxurious coat that keeps
the animal comfortable in all temperatures, on land or underwater.
[112] It was these qualities that historically kept them in constant
demand for the making of coats, top hats, robes, and clothing trim in
Europe and the eastern US.
[113] Their fur has two layers. The outer
layer consists of coarse, long, glossy guard hairs which vary in color
from yellowish brown to reddish-brown to black. Their underfur consists
of dense, short, fine hairs that are grayish to brown. The inner layer
of fine hair, together with a substance called castoreum, provide the
waterproof barrier which keeps the beaver's skin dry underwater.
[114] [115] Castoreum is a strong smelling oily substance that is
actually an attractant to many other animals. It is secreted by castor
glands near the base of the tail. The beaver will comb its fur with its
front feet, and two split nails on its hind feet to spread the oil over
its whole body.
[116] [117] Beavers also have a thick layer of
fat beneath their skin, which provides insulation from freezing water
during winter.
[118] During the winter beavers are less active, and
primarily maintain body temperature by staying in their well-insulated
lodge.
[119]
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Predators
The predators beavers face will
vary from region to region, but include wolves, lynxs, bears, coyotes,
common red foxs, bobcats, owls, otters, minks, alligators, wolverines,
weasels, hawks, eagles, dogs, humans, and most other large mammalian
carnivores.
[120] [121] [122] [123] [124]
[125] [126] An adult beaver is a good fighter and can usually escape
into the water.
[127] This allows them to fight off or avoid most of
their predators.
[128] Kits are far more vulnerable than adults and
need the protection of older beavers.
[129] For all beavers, water is
their best defense and refuge from predators, since they cannot move
very fast on land.
[130] [131] When on land beavers are
constantly on the alert, frequently stopping to sniff the air and look
around for danger.
[132] At the first sign of a predator, they will
retreat to the water and try to warn the other beavers in the area by
slapping the water with their tail. This produces a startlingly loud
noise.
[133] Predators, however, are not the only dangers for the
beaver. Accidents such as falling into abandoned wells, and traffic
collisions represent another common cause of mortality.
[134]
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Behavior
Beavers are a docile, gentle animal with a strong aversion to biting.
[135] In
fact, in some Native American dialects the word for "beaver like" also
means "affable." This is not to say that a beaver will never bite. It
is best to avoid a hissing or blowing beaver as these are signs that it
feels frightened or cornered.
[136] Some behavior is instinctive to
beavers, such as patching a dam at the sound of running water, but they
also learn from experience and by imitating others.
[137] At the age of
two years old, beavers will migrate to find their own territory. This
is the most dangerous time of life an adult beaver will ever face. The
journey may be over 10 miles, and is sometimes overland, where the
beaver is most vulnerable.
[138] Beavers are mostly nocturnal, sleeping
by day, and foraging for food and doing construction work at night.
[139] While they can occasionally be seen during the day, the best time
is an hour before dark or early in the morning at sunup.
[140] Beavers
communicate primarily with posture and scent marking. For scent
marking, beavers erect dome shaped mounds, like a small lodge,
sometimes measuring as much as a foot (.3 m) tall and 3 ft. (.9 m)
across. They will then rub castoreum on the mound to mark their
territory.
[141] Vocalizations are also used especially by the young,
who among other things, can make a sound similar to a duck quacking.
Adult beavers may sometimes grunt as they work, but are generally
silent.
[142] As was noted earlier, tail slapping is used to warn of
predators, but can communicate other emotions as well.
[143]