AMERICAN BATS — HANDLEY 175 



at a temperature of 45° F. in almost-covered aquaria stocked with 

 drinking water. 



Movements: Coclo-um (1956a, p. 51) classified the movements of 

 bats in three major categories: Diurnal movements (routine daily- 

 movements in quest of food and water), local migrations (irregular 

 movements from one roost to another without regard for season), and 

 seasonal migrations (seasonal movement from one roost to another, 

 perhaps as little as ten miles or less apart) . These categories overlap 

 and are not clearcut. Consequently, some movements are difficult to 

 classify. 



Diurnal movements: H. H. T. Jackson (field notes) encountered 

 P. tovmsendii in the month of August in a cave at the east side of 

 Montezuma Well, Arizona. During the day the bats occupied the 

 dark interior parts of the cave, but late in the afternoon they were to be 

 found in the partially lighted section near the entrance. At this time 

 they were unusually wild and the slightest noise or shadow caused 

 them to retire to the deeper parts of the cave. Twente (1955b, p. 727) 

 described a similar light-sampling behavior of P. townsendii in a 

 cavern in Kansas. Toward evening the bats moved from the depths of 

 the cavern to lateral depressions near the entrance. From these 

 stations they made periodic sorties to the entrance until nightfall 

 allowed their departure from the cavern. 



Many authors have noted that P. townsendii leaves its daytime 

 retreat only after darkness has fallen. Dalquest (1947, p. 24) believed 

 that the species had never been observed in its hunting flight. Pear- 

 son, et al. (1952, p. 274) stated that it is a relatively late-flying species, 

 emerging from its roosting structure after dark and not returning 

 untn almost dawn. 



On the other hand, Vernon Bailey (field notes) reported that in the 

 Sundance region of Wyoming : 



These are the earhest bats seen flying in the evening, and they seem to come from 

 various parts or openings in the canyon walls. When they first come out it is 

 light enough to see their long ears as they fly about. Their flight is rather slow 

 and they would be easy to shoot .... 



Bailey (1930, p. 181) again saw big-eared bats in early evening flight at 

 Yellowstone National Park, and shot two (1936, p. 387) one evening at 

 McKenzie Bridge, Oregon, when they circled about at the edge of the 

 forest. Krutzsch and Heppenstall (1955, p. 127) shot a P. townsendii 

 in Utah as the bat foraged in the early twilight. Hamilton (1943, 

 p. 102) watched big-eared bats leave a West Virginia cave during the 

 late dusk. The cave opening was well above the valley floor, and the 

 emerging bats first flew yet higher, soaring and circling at a height of 

 several hundred feet until it was too dark for successful shooting. 

 Then they descended to within a few feet of the ground. 



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