|Scientific Name:||Eptesicus fuscus|
|Species Authority:||(Beauvois, 1796)|
|Taxonomic Notes:||Subgenus Eptesicus. Caribbean forms reviewed by Timm and Genoways (2003).|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Miller, B., Reid, F., Arroyo-Cabrales, J., Cuarón, A.D. & de Grammont, P.C.|
This species is listed as Least Concern in because of its wide distribution, presumed large population, occurrence in a number of protected areas, tolerance to some degree of habitat modification, and because it is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category.
|Previously published Red List assessments:|
|Range Description:||The Big Brown bat is found from southern Canada to Colombia and Venezuela; Greater Antilles; Bahamas; Hispaniola, Dominica and Barbados (Lesser Antilles), also in Alaska (Simmons 2005). A record from northern Brazil is dubious (Davis and Gardner 2008).|
Native:Barbados; Belize; Canada; Colombia; Comoros; Costa Rica; Cuba; Dominica; Dominican Republic; Guatemala; Haiti; Honduras; Jamaica; Mexico; Nicaragua; Panama; Puerto Rico; United States; Venezuela, Bolivarian Republic of
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||It is reasonable to speculate that populations of the big brown bat have increased with an increasing number of human habitations (Baker 1983). Big brown bats can survive up to 19 years in the wild and males tend to live longer than females. Most big brown bats die in their first winter. If they do not store enough fat to make it through their entire hibernation period then they die in their winter roost. 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 1999).|
|Current Population Trend:||Increasing|
|Habitat and Ecology:||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 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).
Eptesicus fuscus is an insectivorous bat. It preys primarily on beetles using its robust skull and powerful jaws to chew through the beetles' hard chitinous exoskeleton. It also eats other flying insects including moths, flies, wasps, flying ants, lacewing flies, and dragonflies (Baker 1983). One study indicated that juvenile E. fuscus ate a greater range of softer food items in their diets, compared to adults. The same study also indicated that bats having survived their first winter (yearlings), did not differ significantly in diet from the adults (Hamilton and Barclay 1998).
|Major Threat(s):||Big Brown Bats are fairly common and are not of any special conservation concern.|
|Conservation Actions:||It is found in a number of protected areas through its geographic distribution.|
|Citation:||Miller, B., Reid, F., Arroyo-Cabrales, J., Cuarón, A.D. & de Grammont, P.C. 2016. Eptesicus fuscus. The IUCN Red List of Threatened Species 2016: e.T7928A22118197.Downloaded on 23 May 2017.|
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