Fig. 40. Distribution of the silver-haired bat. Lasionycteris noctivagans, in Washington.
The size and flight of the silver-haired bats are distinctive, and after some experience it is possible to identify them in the air. It is an early flier, usually appearing just after the swallows roost. They fly at a considerable height, rarely coming within forty feet of the ground. The wings are moved with a "fluttery" motion, and their flight is interrupted by frequent short glides. They fly more rapidly than the big brown-bats, and twist and dart sideways more frequently. Compared with big brown-bats, silver-haired bats are relatively gregarious, and six to a dozen individuals were seen in the same area. They generally hunt in sweeping circles, from fifty to one hundred yards in diameter. In the daytime the silver-haired bats hide beneath slabs of loose bark on dead trees. Near Cottage Lake, King County, two individuals were found beneath the bark on an old, lightning-blasted stub. The dark color of the bats blended with the charred surface of the stub.
This species feeds mainly on forest insects and for this reason is probably of considerable value to man. The stomachs of specimens were usually crammed with the remains of small, soft-bodied insects.
Corynorhinus rafinesquii (Lesson)
Long-eared bat
Description.—Diagnostic characters of the long-eared bat are: medium size (total length about 4 inches); dull, grayish-brown color; exceptionally long ears (over 1 inch from notch); thin, tissue-like membranes; and paired "lumps" on the rostrum. The dental formula is: i. 2-2/3-3, c. 1-1/1-1, p. 2-2/3-3, m. 3-3/3-3 = 36.
Fig. 41. Long-eared bat (Corynorhinus rafinesquii intermedius), female with young; Boulder Cave, Kittitas County, Washington, July 20, 1928. (Fish and Wildlife Service photo by T. H. [Scheffer], No. B-33332.)
Long-eared bats range from southern British Columbia to southern Mexico. Three species are listed by [Miller] (1924: 82), one of which (rafinesquii) is divisible into five geographic races.
This bat is colonial and is not uncommonly found in caves, mine shafts, and darkened attics of old buildings. It is of scattered distribution throughout the state. In Washington its distribution in winter is unknown. A specimen from Friday Harbor, San Juan County, taken in March, 1936, indicates that it hibernates in the state. [Whitlow] and [Hall] (1933: 245) give a detailed account of individuals found hibernating in winter near Pocatello, Idaho.