1908] Grinnell—Biota of the San Bernardino Mountains. 17 
arrive in the region early in April, though it is then still largely 
covered with snow, which does not all leave as a usual thing until 
June Ist, so 1 was told. (See pls. 48, 114, 11s, 12, 14, 17.) 
Bear VALLEY. 
Bear valley comprises something like 16 square miles of nearly 
level plateau at from 6750 to 7000 feet altitude. Its trend is 
east-and-west and it is bordered by ridges 500 to 1500 feet higher. 
At its east end is the depression occupied by the shallow or often 
altogether dry Baldwin lake; while its west end is occupied by 
Bear lake impounded by the artificial Bear valley dain. The lake 
is some 5144 miles long by a mile or less in width, and empties 
westward over or through the dam into Bear creek, which in 
turn flows into the lower Santa Ana. Over half of its area at 
the east end is so shallow as to be more or less marshy, and this 
portion is the breeding place of numerous mudhens and American 
eared grebes, besides a few ducks and perhaps other water birds. 
Around Bear lake, up Rathbone creek, and on the south side of 
Baldwin lake, are several thousand acres of pasture land, inter- 
spersed with large areas of sage brush. The pine forest which 
clothes the walls of the valley in but few places encroaches on 
the level floor of the valley. Occasionally the latter is punectu- 
ated by a solitary western juniper, or yellow pine. Among mam- 
mals the two chipmunks (Hutamias speciosus and Callospermo- 
philus bernardinus) were common through the woods and in 
places down to the shore of the lake. Ground squirrels were 
numerous on the pastures, and trapping showed the presence of 
many Sonora white-footed mice in the sage tracts. My visits at 
Bear lake and through Bear valley were too late in the summer 
for the determination of the breeding land birds. Considerable 
numbers of species and individuals were present, but a good many 
of them were plainly visitants from various directions. (See pls. 
5, 18: 44.) 
SUGARLOAF (NorTH SIDE). 
Sugarloaf, 9842 feet in altitude, is the highest point of the 
mountains north of the Santa Ana river. It is at the east end 
of the ridge which separates Bear valley and the depression oc- 
cupied in part by Baldwin lake from the valley of the upper 
