ANIMAL ESTATE client 1.05: BIG BROWN BAT
FOR ANIMAL ESTATES 1.0: NEW YORK
SCIENTIFIC NAME: Eptesicus fuscus
ANIMAL PROFILE: Young Big Brown Bats (called pups) are born in nursery colonies where females congregate together. The usual litter size is two bats in the eastern United States, and one pup in the western U.S. Pups are born without any fur and with their eyes closed. Immediately after the pups are born, they begin to squeak, and within 24 hours their eyes are open. For the first two weeks of life, while the mother bat is at rest, the young stay nestled under her wing. During the third week they are able to fly, and practice until they can negotiate their own turns, land, and hang well. Pups completely stop nursing from their mothers at about 9 weeks old, and at this time are able to eat insects on their own.
RANGE: the Big Brown Bat, ranges from southern Canada, through temperate North America, down through Central America to extreme northern South America, and the West Indies (Nowak 1991).
HABITAT: The big brown bat inhabits cities, towns, and rural areas, but is least commonly found in heavily forested regions (Kurta 1995). Some bats require stable, highly insulated environments in order to hibernate. Eptesicus fuscus has a more tolerant constitution so it can winter in less substantial structures. Besides human dwellings, it has been found to take up residence in barns, silos, and churches. Also, this bat has been found roosting in storm sewers, expansion joint spaces in concrete athletic stadiums, and copper mines (Baker 1983). In pre-settlement times it is presumed the big brown bat roosted in tree hollows, natural caves, or openings in rock ledges. Occasionally groups of these bats are still found living in tree cavities (Baker 1983). Recently, some were found hibernating in caves in Minnesota (Knowles 1992). The generic name Eptesicus is derived from the Greek, meaning "house flyer". All this bat needs is a small hole or warped, loose siding to gain entry into a home. Once inside, it prefers to roost in double walls or boxed-in eaves rather than attics. It is reasonable to speculate that populations of the big brown bat have increased with an increasing number of human habitations (Baker 1983).
BUILDING MATERIALS: The big brown bat hibernates in various structures, either man-made or natural environments. They prefer cool temperatures and can tolerate conditions many other bats cannot. They may become active during their winter hibernacula and can move to an optimum habitat. One banded bat was recorded to have moved to a different cave 400 yards away, during the same winter (Goehring 1972).
BUILDING MOTIVATION: Female big brown bats form maternity colonies to rear young. The size of these colonies can vary from 5 to 700 animals. Males of the species roost alone or in small groups during this time. Both sexes will roost together again in the late summer (Nowak 1994). Big brown bats choose secluded roosts to protect themselves from many predators.
THREATS: Young are often taken from maternity roosts by snakes , raccoons , and cats if they fall. Flying bats are sometimes captured by owls and falcons as they leave their roosts.
INTERESTING FACTS: Of all the North American species of bats, this is the one most closely associated with humans because of its year-round use of buildings. Big brown bats are highly beneficial to humans because they consume extremely high numbers of insects. Females must eat at least their body weight in insects each night when they are nursing young. They leave the young in the roost while foraging. One study of the big brown bat found it was capable of hibernating for 300-340 days. It was kept in a refrigerator at a constant low temperature, provided only with water (Hill and Smith 1984). Like most other bats, E. fuscus does not feed in heavy rain or when the air temperature dips below 10 degrees centigrade. In good weather they will begin foraging 20 minutes after sunset. They eat until full, and then often make use of a "night roost". This means the bat will hang under a porch or in a barn to rest while digesting its meal. It returns to its day roost before dawn (Kurta 1995).
MAKING A BIG BROWN BAT HOME: Even though big brown bats are abundant throughout the United States, their populations are decreasing every year. The population is lowing because of human disturbance (the bats are especially vulnerable when hibernating), people killing bats (especially when bats accidentally fly into people's houses), and loss of habitat. We can help big brown bats by teaching people about them, and by putting bat houses up thereby giving them a home! from the Organization for Bat Conservation. link 01 / link 02 / link 03 / link 04 / link 5
REFERENCES:
Mulheisen, M. and K. Berry. 2000. "Eptesicus fuscus" (On-line), Animal Diversity Web. Accessed November 09, 2007 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Eptesicus_fuscus.html.
Arlingham, J. 1996. Bats, Biology and Behaviour . Oxford University Press.
Baker, R. 1983. Michigan Mammals . Lansing, Michigan, USA: Michigan State University Press.
Buchler, E., S. Childs. 1981. Orientation to Distant Sounds by Foraging Big Brown Bats (Eptesicus Fuscus). Animal Behaviour , 29,2: 428-432.
Davis, W., R. Barbour, M. Hassell. February 1968. Colonial Behavior of Eptesicus Fuscus. Journal of Mammalogy , Vol 4, No. 1: pp. 44-50.
Fenton, B. 1983. Just Bats . Toronto: University of Toronto Press.
Fenton, B. 1985. Communication in the Chiroptera . Bloomington: Indiana University Press.
Goehring, H. February 1972. Twenty-Year Study of Eptesicus Fuscus in Minnesota. Journal of Mammalogy , Vol. 53, No.1: pp. 201-207.
Hamilton, I., R. Barclay. Aug 1998. Diets of Juvenile, Yearling, and Adult Big Brown Bats (Eptesicus fuscus) in Southeastern Alberta. Journal of Mammalogy , 79:(3): 764-771.
Knowles, B. Apr-Jun 1992. Bat Hibernacula On Lake Superiors North Shore, Minnesota. Canadian Field Naturalist , 106:(2): 252-254.
Kurta, A., R. Baker. 26 April 1990. Eptesicus fuscus. Mammalian Species : No. 356, pp.1-10.
Kurta, A. 1995. Mammals of the Great Lakes Region . Ann Arbor: The University of Michigan Press.
Simmons, J., M. Ferragamo, T. Haresign, J. Fritz. Aug 1996. Representation of Perceptual Dimensions of Insect Prey During Terminal Pursuit by Echolocating Bats. Biological Bulletin , 191:(1): 109-121.
Whitaker, J., S. Gummer. May 1992. Hibernation of the Big Brown Bat, Eptesicus-Fuscus, in Buildings. Journal of Mammalogy , 73:(2): 312-316.
Whitaker, J. Oct 1995. Food of the Big Brown Bat Eptesicus-Fuscus From Maternity Colonies In Indiana And Illinois. American Midland Naturalist , 134:(2): 346-360.
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