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  The Mammals of Texas - Online Edition

Evening Bat
Order Chiroptera : Family Vespertilionidae : Nycticeius humeralis (Rafinesque)

Evening Bat (Nycticeius humeralis).  Photo by Merlin D. Tuttle, Bat Conservation International.Description. A small, nearly black or blackish-brown bat; ears small, blackish, thick and leathery; underparts paler. Immature individuals are darker than adults. Dental formula: I 1/3, C 1/1, Pm 1/2, M 3/3 X 2 = 30. External measurements average: total length, 93 mm; tail, 39 mm; foot, 8.5 mm; forearm, 36 mm. Weight, 5-7 g.

Species distribution mapDistribution in Texas. Eastern one-third of state west to about Clay County in the north and Kinney County in the south.

Habits. These bats frequent forested areas and watercourses, and utilize hollow trees as roosting sites and nurseries. They use the attics of houses and other man-made structures as roosts when natural sites are not available. They have been captured in all months of the year in Texas, indicating that they are year-round residents of the state. Their winter habits are not known. In summer the adult males and females do not use the same roosts.

Evening bats seem to have two preferred times of foraging, one in the early evening hours and then again just before dawn. Specific prey items include small night-flying insects such as bugs, flying ants, spittle bugs, June beetles, pomace flies, Japanese beetles, and moths.

Copulation takes place in the fall, but it is not known where this occurs. Two young are born to the female in late May to early June. Nursery colonies may contain several hundred individuals and at this time the colonies are usually segregated by sex, with adult males rarely encountered in the nursery colonies. The young ones, at least on occasion, accompany their mother, attached to her breast. The young bats are volant at approximately 20 days of age and are nearly adult size by 1 month of age.

Photo credit: Merlin D. Tuttle, Bat Conservation International.