Wildlife Damage Management, Internet Center for


Date of this Version

January 1993


Extension Circular 1144, Extension Service, Oregon State University, Corvallis, O.E. Smith, director. This publication was produced and distributed in furtherance of the Acts of Congress of May 8 and June 30,1914. Extension work is a cooperative program of Oregon State University, the U. S. Department of Agriculture, and Oregon counties.


Damage to conifer regeneration by mountain beavers, more commonly called boomers, results in significant losses in Western Oregon annually. Most of the damage is to 1- to 5-year-old conifer seedlings. Where populations are high, repeated clipping by mountain beavers can cause loss of production through poorly stocked acres-even reforestation failures.

Damage can continue on saplings up to 15 to 20 years old; however, newly planted seedlings are particularly vulnerable. In a few instances, extensive burrowing can undermine the roots of larger trees enough to topple them.

This publication will help you design a program to reduce mountain beaver damage in your forest plantations to acceptable levels. First, we discuss mountain beaver biology to familiarize you with some of the animal's behavior; this will help you control its damage. Then we discuss control techniques.

Finally, we discuss integrating control methods with silvicultural practices as a way to maximize the effect of your control program.