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The mountain beaver (Aplodontia rufa) is a medium-sized rodent in the family Aplodontiadae. There are no other species in the family. Average adults weigh 2.3 pounds (1,050 g) and range from 1.8 to 3.5 pounds (800 to 1,600 g). Average overall length is 13.5 inches (34 cm), including a rudimentary tail about 1 inch (2.5 cm) long. The body is stout and compact. The head is relatively large and wide and blends into a large neck with no depression where it joins the shoulders. The eyes and ears are relatively small and the cheeks have long silver “whiskers.” The hind feet are about 2 inches (5 cm) long and slightly longer than the front feet. Mountain beavers often balance on their hind feet while feeding. The front feet are developed for grasping and climbing.
Mountain beavers are found in the Pacific coastal region from southern British Columbia to northern California. They range westward from the Cascade Mountains and southward into the Sierras. Numbers are higher and populations are more continuous in the coastal Olympic Mountains and in the coast range of Washington and Oregon than elsewhere. In the southern limit of its range, populations are more scattered but sometimes locally abundant.
Exclusion: Use plastic mesh seedling protectors on small tree seedlings. Wire mesh cages are somewhat effective, but large diameter cages are expensive and allow animals to enter them. Exclusion from large areas with buried fencing is impractical for most sites.
Cultural Methods/Habitat Modification: Plant large tree seedlings that will tolerate minor damage. Burn or remove slash to reduce cover. Tractor scarification of sites will destroy burrow systems. Remove underground nests to reduce reinvasion.
Frightening: Not applicable.
Repellents: 36% Big Game Repellent Powder has been registered for mountain beaver in Washington and Oregon.
Toxicants: A pelleted strychnine alkaloid bait was registered in Oregon but may be discontinued.
Fumigants: None are registered.
Trapping: No. 110 Conibear® traps placed in main burrows are effective but may take nontarget animals using burrows, including predators. Welded-wire, double-door live traps are effective and selective, but are primarily useful for research studies and removal of animals in urban/ residential situations.
Shooting: Not applicable.