Family VESPERTILIONIDAE 79 



hibernating bats, and individuals may completely arouse them 

 selves in midwinter and even fly abroad. 



Distribution. — The big brown bat occurs throughout Illi- 

 nois. The subspecies in this state is Eptesicus fuscus fuscus 

 (Beauvois). The species is widely distributed in North Amer- 

 ica, ranging from Nova Scotia and southern Quebec in eastern 

 Canada almost to the Yukon in western Canada and southward 

 to Panama. The range includes all of the United States except 

 parts of Florida and extreme southern Georgia and Alabama. 



LASIURUS CINEREUS (Beauvois) 

 Hoary Bat 



Description. — The hoary bat, fig. 56, with a wingspread of 

 more than 13 inches, is one of the largest bats in North Amer- 

 ica. The fur is a mixture of bright buff, yellows, and deep 

 amber, with a frosting of white laid in waves over the back. 

 This white frosting gives the bat a decidedly hoary appear- 

 ance. On the throat the fur is more yellowish and on the abdo- 

 men more whitish than on the back. The tail membrane is com- 

 pletely furred and much the same color as the back. The ears 

 are short, rounded, and thickened at the rims. 



Length measurements: head and body 3-3^ inches (77-86 

 mm.) ; tail 2]. -^— 2l j inches (53-64 mm.) ; over-all 5^-5% 

 inches (130-150 mm.); hind foot about \ y z inch (10-14 mm.); 

 ear from notch about 24 inch (17-19 mm.). 



The skull is large and particularly broad, as in fig. 40<' ; its 

 length is 17-20 mm. (about -}i inch). Dental formula: I 1/3, 

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



Life History. — The hoary bat normally winters in states 

 farther south than Illinois and migrates northward in spring. 

 Some individuals spend the "summer" season in Illinois and 

 some pass through this state while going farther north. In the 

 "summer" months, the hoary bat spends the daylight hours in 

 trees, among the leaves or on the trunks. 



The hoary bat tends to be solitary; usually each individual 

 hangs alone and feeds with only one or two others. Hats of this 

 species are powerful fliers, ami their slower. Longer wing beats 

 undoubtedly permit them to have a more extensive cruising range 

 than other bats. Usually they start their evening hunting fairly 

 late, but sometimes they fly before sundown. Although bats have 



