384 NORTH AMERICAN FAUNA [No. 55 



evening hours and hurry to the nearest water to quench their thirst. 

 They have even been seen to come out at midday to get a drink of 

 water and go dipping down to the surface, scooping up mouthful 

 after mouthful of the refreshing fluid. Their flight is quick and 

 crooked as they zigzag overhead in quest of winged prey and their 

 skill as hunters is shown by the full stomachs of those shot for 

 specimens only 15 or 20 minutes after they have been flying'. 



Their homes are back in cracks and caverns of the cliffs where they 

 sleep through the daylight hours. The young are raised in suitable 

 places where food and shelter attract colonies of breeding females. 

 The winter sleep or hibernation carries them through the period of 

 cold and scarcity of food. As to what extent they migrate to and 

 from winter and summer ranges there is little evidence. At Watson 

 in the Owyhee Canyon Preble found them abundant in July 1915, 

 and of a series of 13 specimens all but 2 were females. In the 

 late afternoon, sometimes half an hour before sundown they would 

 often make their appearance along the river, evidently driven by 

 thirst from their dry retreats and come slowly and steadily down 

 the slopes, wasting no time in search of food but intent on quenching 

 their thirst. 



This was evidently a breeding colony, as 1 of the females collected 

 on July 19 contained 2 large embryos and 1 taken on July 21 was 

 nursing young. Judging from many records 2 young is the usual 

 number, and these are born generally in July. Breeding females 

 usually contain embryos throughout May and June, and Preble's 

 record of July 19 is the latest for embryos that has come to the 

 writer's knowledge. 



Jewett and Gabrielson collected several of these tiny bats in the 

 canyon of Trout Creek at the southern end of Alvord Valley on 

 June 21, 1930, where considerable numbers were seen flying about 

 shortly after sundown. Another specimen was obtained about the 

 middle of October 1930, at the Brown Ranch near Princeton in the 

 Malheur Valley. Jewett collected a male at the mouth of the Des- 

 chutes River on April 15, 1915, which seems to be the earliest Oregon 

 record, but no late records are available to indicate dates of hiber- 

 nation or migration. 



The stomach ^ contents of these little bats show a well masticated 

 mass of small insects, but no accurate determination of the species 

 has been made, and the undoubted value to agriculture of these little 

 animals cannot be stated in definite terms. 



NYCTERIS CINEREA (PEALE and BEAUVOIS) 

 HOARY BAT 



Vespertilio cinereus Peale and Beauvois, Oital. Raisonne, Mus. Peale, Phila- 

 delphia, p. 18, 1796 (p. 15 of English eel.). 



Type locality. Philadelphia, Pa. 



General characters. Size large, spread of wings about 16 inches, ears short 

 and rounded, partially furred, with black naked rims; top of feet and tail 

 membranes furry; fur full and soft; teeth 32; color yellowish brown, frosted 

 with white above and below ; throat and wing linings, clear buffy. 



Measurements. Average specimen: Spread of wings, about 380 mm. Total 

 length, 140; tail, 60; foot, 13; forearm, 53. Weight of adult male 20 g, not fat 

 and stomach empty. 



