178 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



of frequently hanging suspended^by only one foot, and Dalquest 

 (1947, p. 29) has pointed out that the truly lethargic bat clings with 

 both feet and thumbs and presses its body tightly to the sui-face of 

 its roost-site. Among big-eared bats hibernating in the gypsum cav- 

 erns of Oklahoma and Kansas, Twente (1955b, p. 721) observed a 

 different posture. The ears were folded back along the neck, the 

 fingers were spread so that the wings effectively covered the ventral 

 surface of the body, the tail and interfemoral membrane were bent 

 down to cover the venter and hind parts of the wings, and the long 

 body hairs stood out perpendicularly. In this position the bat was 

 practically enveloped with a layer of dead air, effectively insulating it 

 from the surrounding warm air of the cavern, and helping it to assume 

 a body temperature similar to that of the substrate from which it 

 was suspended. Grinnell and Swarth (1913, p. 380) noted a similar 

 posture in lethargic big-eared bats in California. 



The normal position of the ear in the undisturbed resting bat ap- 

 pears to be coiled back and down tightly against the side of the neck 

 like a ram's horn. The posterior portion of the ear is wrinkled, rather 

 accordion-like, and there is lateral contraction in accomplishing the 

 spiral shape. The ears can be coiled independently, and sometimes 

 an individual is seen with one ear erect while the other is coiled. Ap- 

 parently the tragus always remains erect, regardless of the position 

 of the ear. Upon superficial examination, when the ear is coiled, the 

 erect tragus may be mistaken for the ear. 



Possibly P. tovmsendii sometimes adopts the common ear posture 

 of the resting P. auritus, that is, with the ear folded back against the 

 side of the neck and chest and partially concealed beneath the folded 

 wing, rather than coiled against the side of the head and neck (Grin- 

 nell and Swarth, 1913, p. 380; Howell, 1920, p. 174; Alcorn, 1944, p. 

 309). 



"When the bat is not lethargic, the ears are unfurled at the slightest 

 alarm, and move with increasing vigor as the observer approaches. 

 The sight of a tightly packed cluster of bats with long ears quivering, 

 waving, and in constant motion is a memorable one. 



Hamilton (1943, p. 102) and Mohr (1933, p. 50) noted that big- 

 eared bats lapsed into disoriented flight or fell stunned when guns 

 were discharged near them in caves. These authors presumed that 

 the auditory apparatus of P. tovmsendii is more sensitive than that 

 of bats with smaller ears. 



Voice: The voice of P. tovmsendii is difficult to describe. A high 

 pitched twittering is commonly heard both in roosts and in captivity. 

 H. W. Grinnell (1918, p. 344) noted that an individual "protested in 

 shrill cicada-like notes" when handled. Grinnell and Swarth (1913, 

 p. 380) described the voice as a "gi'ating squeak," and Dalquest (1947, 



