Information on the natural history of the hoary bat is meager. It was observed in the Kettle River Mountains, but none was obtained. It flew erratically and rapidly and did not appear until darkness had set in. At least two were seen above a road through a forest of western larch and ponderosa pine. Probably it breeds in the mountains of northeastern Washington and in the northern Cascades. The hoary bat is migratory, leaving the state in August and September, rarely lingering until early October. It winters along the coast of central and southern California (Dalquest, 1943: 23). =Antrozous pallidus cantwelli= Bailey Pallid bat _Antrozous pallidus cantwelli_ Bailey, N. Amer. Fauna, 55:391, August 29, 1936. _Type._--Obtained at Rogersburg, Asotin County, Washington, by G. G. Cantwell on May 28, 1918; type in United States National Museum. _Measurements._--A male from the south bank of the Columbia River, opposite Fallbridge, Klickitat County, measures: total length 113; length of tail 40; hind foot 14; ear 36; height of tragus 13; weight 19.8 grams. _Distribution._--Recorded only from localities near the Columbia and Snake rivers in eastern Washington; from Wenatchee (W.W.D.) south and east to Bly and Rogersburg (Taylor and Shaw, 1929: 9). _Description._--_Antrozous pallidus_ is more likely to be confused with _Corynorhinus_ than with any other kind of bat and can be distinguished from _Corynorhinus_ by its larger size (4-1/2 to 5 inches), lighter color, thick and leathery membranes, and shorter, wider ears. _Antrozous_ lacks the prominent "lumps" on the rostrum, characteristic of the long-eared bat. The dental formula is: i. 1-1/2-2, c. 1-1/1-1, p. 1-1/2-2, m. 3-3/3-3 = 28. The genus _Antrozous_ is confined to western United States and northwestern Mexico. Two species are recognized by Miller (1924: 84). One of these (_pallidus_) includes three geographic races. A single race is known to occur in Washington. [Illustration: FIG. 47. Distribution of the pallid bat, _Antrozous pallidus cantwelli_, in Washington.] The pallid bat chooses a crevice in a cliff, cave, or building as its daytime hiding place. Like _Corynorhinus_, it is colonial. The basalt cliffs of eastern Washington offer such ideal hiding places that pallid bats are seldom seen and consequently little is known of their habits. In the southwestern United States, pallid bats are more abundant and better known. H. W. Grinnell (1918: 355) notes that the floor of a roost of pallid bats was strewn each morning with the heads, wings, and legs of insects. Most numerous were the remains of the Jerusalem cricket (_Stenopelmatus_), a flightless insect that the bats must have secured on the ground. Engler (1943: 96) found that in captivity, pallid bats would kill and eat smaller bats and lizards confined with them.