Family VESPERTILIONIDAE 83 



(80-104 mm.); hind foot \x-' _- inch (9.5-14 mm.); ear from 

 notch Yi~Y% inch ( 13 — 17 mm.). 



The skull is short, broad, particularly between the eyes, and 

 unique among Illinois bats in having a single incisor, canine, and 

 premolar in each side of the upper jaw. Dental formula: 

 I 1/3, C 1/1, Pm 1/2, M 3/3. 



The evening bat is frequently confused with the big brown 

 bat, but it can be readily told by its smaller size and its shorter 

 forearms (about l^s inches or 35-37 mm.). It differs from the 

 little brown bat and other species of Myotis in having blunt and 

 curved (rather than pointed and straight) tragi, only six teeth 

 in each side of the upper jaw (rather than nine), and a skull 

 that is broader through the interorbital region. 



Life History. — In summertime, the evening bat seeks refuge 

 in buildings, foliage, or hollows of trees. Apparently it is 

 colonial. The absence of winter records for Illinois indicates 

 that bats of this species migrate southward. The evening bat 

 has a feeding and flight behavior that is said by some observers 

 to be much like that of the little brown bat; the flight of the 

 evening bat is said by other observers to be more steady and 

 straight. Members of this species commence feeding early in 

 the evening, often while the sun is still shining. A female usually 

 gives birth to a pair of young each year. 



Distribution. — The evening bat is abundant in southern 

 Illinois and at least as far north as Urbana; also, it is known 

 in the northeastern part of the state. The subspecies occurring 

 in Illinois is Nycticeius humeralis humeralis ( Rafinesque). The 

 known range of the species extends from eastern Maryland to 

 southern Michigan and southwestward and southward to north- 

 eastern Mexico and southern Florida, fig. 50. 



CORYNORHINUS RAFINESQUII (Lesson) 



Southeastern Big-Eared Bat 



Description. — The southeastern big-eared bat, fig. 58, is 

 grayish brown or smoky brown. The under parts are silvery, 

 not buffy as in the closely related western big-eared bat, Cory- 

 norhinus townsendii. The enormous ears are nearly 1 ' j inches 

 long and are joined near their bases above the forehead. Lumps 

 are present on each side of the muzzle in front of the eyes. The 

 top side of the tail membrane is not furred. 



