||The Mammals of Texas -
Chiroptera : Family
Vespertilionidae : Nycticeius humeralis (Rafinesque)
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.
Distribution 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