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BAT SPECIES

All of the bats of Orange County are nocturnal, hanging upside down during the day in trees, caves, tunnels, and buildings.  While some female bats can give birth to 4 young, the majority only give birth to one or two per litter.  The young cling to the mother until they mature.

FAMILY VESPERTILIONIDAE

BAT     In this family of bats, the nose is simple compared to the modified structures of other families.  They have short tails, small eyes, and possess membranes (interfemoral membranes) which connect the legs and tail.  The largest group in this family is the genus Myotis, composed of small bats which possess a pointed projection (tragus) in their ear.  Myotis has the widest distribution of any bat genus in the world and includes almost 100 species.  These bats can inhabit caves and other structures ranging from crevices to sewers to large flowers.  Although virtually all species feed on insects, there are a few exceptions (Myotis vivesi and M. adversus, for example, feed on fish).  Some hibernate in caves over winter while others may migrate (Nowak, 1994).
Little Brown Myotis (Myotis lucifugus) are colonial and can live 20 years.  
 

Keen Myotis (Myotis keeni) live in small colonies and can live more than 18 years.

   
Indiana Myotis (Myotis sodalist) are colonial in winter.  While this species is once thought to have numbered more than a million indiviuals, it is now on the endangered species list.  Much of its decline is thought to have been caused by pesticide use in the 1960s.  More than 90% of the populations roosts in only 10 sites (Burton, 1987).
 
Small-footed Myotis (Myotis subulatus) are small bats, weighing only 6-9 grams. 
 
Silver-haired bats (Lasionycteris noctivagans) are solitary bats which probably migrate south in winter.  The young may cling to the mother as she flies for several days.
 

Eastern Pipistrels (Pipistrellus subflavus) are small bats, weighing only 3.5-6 grams.  Some hibernate while others migrate south in winter. 

 
Big brown bats (Eptesicus fuscus) are a common bat which feed primarily on beetles.
 
Red bats (Lasiurus borealis) are solitary bats.
 
Hoary Bats (Lasiurus cinereus) are solitary bats which migrate south in winter.  The young may cling to the mother as she flies for several days (Burt, 1976).