||The Mammals of Texas -
Chiroptera : Family
Vespertilionidae : Myotis austroriparius Rhoads
Description. A small bat with dense,
dull, woolly fur; upperparts brownish to sooty; fur of
underparts with white tips and black bases, the general
white appearance contrasting sharply with the upperparts;
cranium globose and normally with a low sagittal crest.
Dental formula as in M. lucifugus.
External measurements average: total length, 88 mm; tail,
36 mm; foot, 9 mm; forearm, 38 mm. Weight, 5-7 g.
Distribution in Texas. Southeastern
United States; occurs westward to the Pineywoods region
of East Texas.
Habits. M. austroriparius
is predominantly a cave bat in that part of its range
where suitable caves occur. But in Texas, and in most of
Louisiana, it seeks out roosts in human habitations and
structures. Outside of caves, it has been found in
crevices between bridge timbers; in culverts and drain
pipes; in boat houses, barns, and the attics of houses;
and in hollow trees. The bats are usually closely
associated with water and when they leave their diurnal
roosts late in the evening (usually about dark), they fly
to nearby ponds and streams over which they forage and
from which they drink. They fly low over the water,
usually within 60 cm of the surface, capturing insects.
Specific foods are not known but small moths, midges,
mosquitoes, and flies are probably of importance.
Where suitable caves are available,
both males and females congregate in large numbers in
late March and April to bear their young. In caveless
areas, old buildings may serve as nursery sites.
Parturition occurs in late April to late May and the
young are large enough to fly 5 or 6 weeks later. The
southeastern myotis is unusual among bats of the genus Myotis
as it usually gives birth to twin offspring; other Myotis
usually having only one young per year. At birth, the
young bats weigh slightly more than 1 g each. They grow
rapidly, and sexual maturity is reached in both sexes
before the bats are a year old.
Their most important predators appear
to be rat snakes, corn snakes, opossums, and certain
species of owls. Large cockroaches may prey on newborn
young that fall to the ground.
Photo credit: Merlin D. Tuttle, Bat Conservation