the Illinois Department of Conservation, and the Illi- 

 nois Department of Transportation are involved in 

 cooperative research programs studying the distribu- 

 tion and ecology of Illinois bats, with emphasis on 

 learning more about such endangered species as the In- 

 diana bat. Everyone can help protect and preserve bats 

 simply by leaving them alone and avoiding the dis- 

 turbance or destruction of their habitat. 



Habitats for Illinois bats include caves, aban- 

 doned mines, bridges, trees, vacant and occupied 

 buildings, and just about any other kind of shelter. Illi- 

 nois bats are grouped into two categories, tree bats and 

 cave bats, depending upon the type of shelter (known 

 as roosts) they use as well as their respective require- 

 ments and behavior, and their morphological adapta- 

 tions. 



Tree Bats 



Tree bats are more solitary and nomadic than cave bats. 

 They roost singly or in small family groups that consist 

 of a female and her offspring. Tree bats migrate in re- 

 sponse to cold temperatures and seldom enter caves or 

 mines to hibernate. The uropatagium (the flight mem- 

 brane between the legs, enclosing the tail) is more fully 

 furred than it is in cave bats, providing added protec- 

 tion from the elements. For reasons not fully under- 

 stood, the fur of tree bats is much more colorful than 

 the drab brown and gray pelage of cave bats. 



Evening Bat, Nycticeius humeralis. This '/3-ounce, 

 brownish evening bat lacks distinctive features and col- 

 oration. Because of its black membranes and ears, it is 

 often mistaken for the big brown bat (see Cave Bats). 

 During summer, it primarily inhabits older, abandoned 

 buildings, although it can be found in hollow trees or 

 beneath loose bark. Females (seldom more than 150 in 

 a group) establish maternity colonies in these habitats 

 and produce a single litter that characteristically has 

 two pups. Although this species has been reported 

 throughout Illinois, including Chicago, during the 

 summer, it is encountered very infrequently. 



The evening bat is apparently absent from Illinois 

 during the winter, but its winter range outside the state 

 is virtually unknown. This bat accumulates large fat 

 reserves in autumn, reserves that are sufficient for 

 hibernation or a long migration. 



Hoary Bat, Lasiurus cinereus. The largest and most 

 colorful bat in Illinois, the hoary bat, has a wingspan ot 

 up to 16 inches and weighs more than IVi ounces. 

 Many of its hair tips are white, giving a frosted or hoary 



appearance. Females are much larger than males and 

 give birth to two pups among the foliage of trees. Sel- 

 dom seen by most people, this heavily furred bat occurs 

 statewide during spring and summer. 



A strong, fast flyer, the hoary bat is an accom- 

 plished migrant. Often moving in large groups, these 

 bats spend the winter in the southeastern United 

 States, Mexico and Guatemala, although they have 

 been reported from Indiana and other more northern 

 states during winter months. Generally absent from 

 Illinois during winter, this bat is sometimes found on 

 lawns or sidewalks either dead or near death after 

 autumn migrations that proved too strenuous or too 

 hazardous. 



Red Bat, Lasiurus horealis. This beautiful, medium- 

 sized bat can be bright red-orange to yellow-brown. It 

 weighs up to Vi ounce and has an 11- to 13-inch wing- 

 span. A very common species in Illinois, the red bat 

 can be found in virtually every county during the sum- 

 mer. Solitary bats roost in daytime retreats near the 

 ground among the leaves of trees or shrubs. Several red 

 bats were once found hanging together on the under- 

 side of a sunflower leaf. Perhaps more than any other 

 bat species, it feeds on insects attracted to lights. 



Females typically have a single litter of three pups, 

 occasionally as few as one or as many as five. Blue jays 

 prey on their flightless pups (and on those of all other 

 bat species) as do crows and snakes. Red bats are unique 

 among Illinois bats in that males can be easily dis- 

 tinguished from females by their much more reddish 

 pelage. 



Very little is known about wintering sites of red 

 bats, but they probably hibernate in trees in southern 

 states. Like their close relative the hoary bat, they are 

 sometimes found during autumn migrations and can 

 often be seen flying in late afternoon on warmer winter 

 days. 



Silver-haired Bat, Lasionycteris noctivagans. Weigh- 

 ing less than Vi ounce, this medium-sized bat has a 

 bearlike face and beautiful dark, silver-tipped fur on its 

 back. It can be found in forested habitats throughout 

 Illinois; however, its occurrence in Illinois can be con- 

 sidered sporadic and its exact status remains unknown. 

 A typical day roost for this bat is under loose bark, but 

 some have been found in hollow trees, woodpecker 

 holes, birds' nests, and even mines. Females typically 

 give birth to two young, but almost nothing is known 

 about the summer maternity roost sites of females. 



Silver-haired bats apparently do not migrate great g 



