1936] 



MAMMALS OF OREGON 



383 



In the Walker collection are 2 specimens taken at Tillamook on 

 June 28, 1914, and September 22, 1924. These scattered localities 

 over the State do not give a definite idea of the range and abundance 

 of the bats, because in the heavy timber where they are most abund- 

 ant few specimens can be obtained owing to the dense foliage and 

 early darkness. 



Little is known of their general habits and still less of their places 

 for spending the winter months. Specimens are occasionally taken 

 in spring or fall as far south as Texas and New Mexico, but it seems 

 probable that they have regular migratory routes to certain caves 

 or to warm valleys where they spend the winter. 



Economic status. These bats are undoubtedly of special value in 

 protecting the forests from insects although there is little positive 

 information as to the species of insects consumed. 



PIPISTRELLUS HESPERUS HESPERUS (H. ALLEN) 

 LITTLE CANYON BAT 



Scotophilus Hesperus H. Allen, Monograph Bats of North Amer., p. 43, 1864. 



Type. Collected at Old Fort Yuma, Calif., by Maj. G. H. Thomas, United 

 States Army; cataloged October 31, 1861. 



General characters. Size very small (pi. 52, 5), spread of wings 8 or 9 

 inches, color pale buffy gray, strongly contrasted with black ears and mem- 

 branes ; ears rather short ; tragus blunt with tip bent forward ; total number 

 of teeth, 34. Color of fur buffy gray, all over; membranes, feet, ears, and 

 nose black or blackish. 



Measurements Spread of wings, 204 to 225. Total length, 75 ; tail, 30 ; foot, 

 7 ; forearm, 30. Weight of adults 4 or 5 g, males averaging smaller than 

 females. 



Distribution and habitat. From a wide range over lower Sonoran 

 deserts from Texas to eastern California and Nevada these tiny bats 

 come into the valleys of eastern and northern Oregon in rather 

 limited numbers (fig. 99). 

 Specimens have been taken 

 from "Watson, Riverside, 

 Princeton, Alvord Valley, 

 both sides of the Co- 

 lumbia at the mouth of 

 the Deschutes, and Al- 

 mota, Wash. In summer 

 temperature these valleys 

 are close to Lower Sono- 

 ran Zone, although not 

 marked by sufficient num- 

 ber of species to be 

 mapped as such. The 

 presence of the bats here 

 may be considered as 

 either an element of Lower 

 Sonoran or as a slight overlapping of range into the edge of Upper 

 Sonoran Zone. 



General habits. The name of canyon bat has been given these 

 midgets from their abundance in the canyons of the deserts where 

 they fairly swarm out of the cliffs and canyon walls in the early 



FIGURE 99. Range of little canyon bat, Pipistrcllus 

 Hesperus, in Oregon. 



