In another area of the colony 6 mountain beavers were caught in 92 trap- 
nights. Grinnell and Storer (1924) said that the population of mountain 
beaver in a series of burrows consisted usually of a pair of adults. 
Hartwell (personal communication) caught 8 mountain beavers (6 males 
and 2 females) in two successive nights. Four males and 1 female were caught 
on the first night. He used 53 steel traps in the square l-acre plot site. 
ECONOMIC SIGNIFICANCE 
Damage 
Dalquest (1948) mentioned that the mountain beaver is more of a 
nuisance than a pest. Cahalane (1947) said that in its normal habitat the 
rodent rarely does any harm, although it invades gardens, cutting off plants 
and carrying them to its burrow. It is known to undermine roadbeds and 
irrigation ditches. 
‘ 
Scheffer (1952) wrote that the mountain beaver gnaws the tender bark 
of saplings or larger tree bases and roots below the snow, killing the 
plants or causing them to be blown over. Such damage occurs usually in late 
winter or early spring, when the food stores may have become depleted. 
King (1958) made a 10-year study of damage to planted Douglas-fir and 
naturally seeded conifers, He attributed two-thirds of the mortality of 
these trees to wildlife. The greatest single damage was caused by the 
mountain beaver, which destroyed approximately 40 percent of the planted 
trees and 8 percent of the natural seedlings. Staebler, Lauterbach, and 
Moore (1954) pointed out that mountain beaver damage to plantations with 
similar cover conditions varied by locality. Munger (1943) attributed 
plantation failure mainly to the mountain beaver. 
Lawrence, Kverno, and Hartwell (1961) categorized three types of in- 
juries to conifers: (1) stem clipping or gnawing of small seedlings; 
(2) branch cutting for climbing and descending; and (3) basal girdling or 
debarking. The debarking injury is shown by neatly scattered horizontal 
tooth marks and vertical claw marks. These three types of injuries have 
been found in individual trees. 
Damage caused by the varying hare (Lepus americanus) can be distin- 
guished from that caused by the mountain beaver: the hare rarely clips 
stems exceeding 1/4 inch in diameter, or taller than 2 to 3 feet; the 
mountain beaver frequently cuts stems exceeding 1/2 inch in diameter up 
to heights of 15 to 20 feet, 
As Food 
Gibbs (1960) reported that the Nisqually Indians placed high value upon 
mountain beaver meat. Suckley (1860) ate a mountain beaver, and found it 
excellent. He said it tasted much like chicken (Gallus gallus), and was far 
26 
