524 University of California Publications in Zoology [ Vou. 17 
one is camped on the edge of a sloping meadow near the homes of 
these industrious mountaineers to be awakened in the still night by 
the sound of water rushing and gurgling under one’s head in a newly 
formed eanal.’’ 
Grinnell (MS, 1912) observed Aplodontia rufa californica at Blue 
Canon, Placer County, California. His notes in regard to their bur- 
rowing habits follow. ‘‘It [the colony] is now [August 30] in rather 
? 
Fig. 4. Type of habitat in which ‘‘colony’ 
was situated; 9700 feet altitude, head of Lyell Caion, Yosemite National Park, 
California. The trees are lodgepole pines; the riparian growth is willow. 
of Aplodontia rufa californica 
dry ground, though evidently wet most of, fhe year; for it is overgrown 
with luxuriant thimbleberry and ee The whole place is 
densely shaded by black oaks and spruces. At the colony located I 
saw fully 15 fresh burrows.’’ There were evident trails or surface 
runways out into the salmonberry bushes. Burrows were frequently 
coincident with water channels beneath the sod. 
In the Yosemite National Park extensive thickets of the preferred 
food plants are scarce, and here the mountain beaver must as a rule 
be content with limited tunnel systems through the narrow willow- 
