168 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ho 



oak, pine, juniper, cjTpress, madroua, and mansanita were prominent. 



Bailey (1936, p. 387) noted big-eared bats in the pine-fir-hemlock- 

 broadleaf deciduous forest of western Oregon. Findley and Negus 

 (1953, p. 237) reported a specimen captured at the edge of a spruce-fir 

 forest in Colorado. 



In Kansas, Oklahoma, and Texas, Plecotus occurs in gypsum caves 

 in the zone of meeting of tall-grass and short-grass prairies. Ozark 

 and Appalachian populations inhabit caves mostly in oak-hickory 

 forests. Originally, there were few natural openings in these forests, 

 and even today cultivated areas are mostly restricted to narrow bands 

 along valley bottoms. Some Appalachian caves frequented by big- 

 eared bats are situated in unbroken forest several miles from meadow 

 and farmland. 



Roosting sites: P. tomnsendii apparently is a true cave bat, for 

 unlilvc P. rafinesquii it has not been known to roost in trees. Many 

 populations of the western United States and Mexico have found to 

 then* liking such man-made structures as abandoned mine tunnels and 

 pits, wineries, missions, stage stations, etc., and less frequently, 

 occupied human dwellings. East of the Rocky Mountains, P. tovm- 

 sendii has been recorded only in caves; never in houses. In some areas 

 P. townsendii has been quick to appropriate man-made structures as 

 roosting places. For example, Townsend (1839, p. 325) observed 

 that it was already a rather common inhabitant of the Hudson's Bay 

 Company fm- storehouses of the Columbia River district, not long 

 after the construction of the fu'st buildings in that region. 



Pearson, et al. (1952, p. 317) theorized that since natural caves are 

 few in California, and since most known colonies of Plecotus in that 

 area inhabit man-made structures, it must have been rare in California 

 before the advent of civilization. However, beyond a certain point, 

 increasing the number of roosts does not seem to increase the popula- 

 tion. Large numbers of mine tunnels dug in the western foothills 

 of the Sierra Nevada in the last half of the nineteenth century were 

 subsequently abandoned. Despite the prevalence of apparently suit- 

 able roosts, P. townsendii does not seem to be more numerous in that 

 part of California than elsewhere. 



Roosts may be classified according to the use made of them by the 

 bats. For P. townsendii there are at least four categories: Winter 

 hibernating roosts, occupied by both sexes; summer nursery roosts, 

 utilized by females and young; ordinary summer roosts, inhabited 

 mostly by males; and summer night-time roosts, used probably by 

 both sexes. With regard to the latter, Dalquest (1947, p. 26) has 

 noted that P. townsendii, in common with several other species of 

 bats, retires to a convenient cave or buUding to hang up and rest 

 after feeding flights at night. By taking advantage of this habit, 



