Mountain Beaver Facts
Mountain beavers (Aplodontia rufa, are considered by many taxonomists
to be the world's most primitive living rodent species. They are not really
beavers, but were so named because they gnaw bark and cut off limbs in a manner
similar to true beavers.
Mountain beavers live in moist forests, on ferny slopes, and are occasionally found in damp ravines in urban areas. Their worldwide range is the coastal lowlands and coastal mountains of southern British Columbia (from the Fraser Valley to the Cascade Mountains), western Washington, western Oregon, and south into California.
Most people don't know mountain beavers exist and some still continue to question that fact even after they've heard about the animals.
Facts about Washington's Mountain Beavers
Food and Feeding Habits
Mountain beavers live in moist forests, on ferny slopes, and are occasionally found in damp ravines in urban areas. Their worldwide range is the coastal lowlands and coastal mountains of southern British Columbia (from the Fraser Valley to the Cascade Mountains), western Washington, western Oregon, and south into California.
Most people don't know mountain beavers exist and some still continue to question that fact even after they've heard about the animals.
Facts about Washington's Mountain Beavers
Food and Feeding Habits
- Mountain beavers are herbivores and
eat a wide variety of plants.
- Food items include all above and
below-ground parts of ferns, salal, nettles, fireweed, bleeding heart,
salmonberry, brambles, dogwoods,
vine maples, willows, alders, and conifers. Mountain beavers also eat rhododendrons and other ornamental perennials, shrubs, and trees. - Food items are eaten on site,
temporarily stored outside burrow entrances, or placed in caches inside burrow
systems
- Mountain beavers will climb into
trees to lop off living branches that are up to 1 inch in diameter.
- Mountain beavers have primitive,
inefficient kidneys and must drink 1/3 of their body weight in water every day.
Burrow System
- Mountain beavers dig tunnels 6 to 8
inches in diameter throughout their territories, which may be 2 acres or more,
depending on food and cover availability, and population density.
- Tunnel systems, or burrow systems,
are located in or near thick vegetation, and tend to radiate out from a nest
site. Mountain beavers have been found using tunnels that are 10 feet
underground.
- Burrow systems may contain ten or
more exits and special chambers for nesting, feeding, storing food, and storing
droppings.
- Unoccupied mountain-beaver tunnels
and chambers are used by mice, moles, voles, rats, cottontail rabbits, weasels,
mink, spotted skunks, and salamanders.
Reproduction
- Mountain beavers are solitary except
during the breeding season.
- Breeding takes place from February
to April.
- Two to four young are born after a
28- to 30-day gestation period.
Mortality
- Mountain beavers are eaten by
bobcats, coyotes, large owls, fishers, and occasionally cougars and bears.
Weasels and mink (primarily large males) eat young mountain beavers.
Large numbers of mountain beavers are often trapped to prevent damage to newly seeded or planted commercial forests.
This information was provided by the Washington State Department of Fish and Wildlife, Russell Link, and Michael Holmquist
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