||The Mammals of Texas -
Little Brown Myotis
Chiroptera : Family
Vespertilionidae : Myotis lucifugus (Le Conte)
Description. A small bat; hairs of back
with long, glossy tips that produce a conspicuous sheen;
pelage long and full, longest hairs about 10 mm;
upperparts ranging from bronzy brown to olive brown;
underparts grayish with rich, buffy suffusion;
interfemoral membrane sparsely haired above about to line
joining knees; foot relatively large, a little more than
half the length of tibia; ratio of tail to head and body
less than 80; dorsal profile of skull gradually rising
from relatively short rostrum. Dental formula as in M. californicus. External measurements average: total length,
85 mm; tail, 35 mm; foot, 9 mm; ear, 13 mm; forearm, 39.5
mm. Weight, 7-9 g.
Distribution in Texas. This
species is known in Texas by only one specimen (U.S. Nat.
Mus., 21083/36121) from Fort Hancock in Hudspeth County.
Habits. This bat spends the
daytime in crevices in canyon walls, caves, attics, or
other places of concealment and emerges shortly before
dark. Its flight is erratic and relatively slow.
In the northeastern United States,
these bats may migrate up to 320 km between winter and
summer ranges, but in the west they are believed to
hibernate near their summer range. As cold weather
approaches the bats move to suitable caves, mine tunnels,
or other quarters where they hibernate and sleep through
the winter. During the period of preparation for winter,
males and females are found together and breeding takes
place, but the ova are not fertilized at that time. This
habit of breeding in the fall has led some students to
estimate the gestation period of this species to be 300
days; however, the period of gestation is actually 50-60
days. The sperm from the fall mating are retained in the
reproductive tract of the female and fertilization of the
ova does not take place until the following spring,
shortly before the bats leave their winter quarters. This
ability is known as "delayed fertilization." A
short breeding period may also occur in the spring. The
single young is born in June or July.
Food consists of insects captured in
flight. Remains of small, night-flying beetles, bugs, and
flies have been identified in their stomachs. These bats
forage primarily over or near water.
Photo credit: Merlin D. Tuttle, Bat Conservation