|The Mammals of Texas -
Western Small-footed Myotis
Chiroptera : Family
Vespertilionidae : Myotis ciliolabrum (Merriam)
Description. A small Myotis
with small feet, short ears, and relatively long tail;
ratio of tail to head and body about 95; ratio of foot to
tibia 40-45; upperparts light buff to warm buff, with
slight tricolor effect; individual hairs blackish
basally, succeeded by pale intermediate section and
flaxen tips; underparts pale buff to nearly white;
muzzle, chin, ears, and tragus blackish; sides of face
from muzzle to ears blackish brown. Most easily confused
with the small-footed M. californicus
(see same for differences). Dental formula as in M.
californicus. External measurements average: total
length, 79 mm; tail, 37 mm; foot, 7 mm; ear, 13 mm;
forearm, 33 mm. Weight, 4-5 g.
Distribution in Texas. Restricted in
Texas primarily to the Trans-Pecos region, although two
records are known from the High Plains of the Panhandle
(Armstrong and Randall counties). A small, resident
population may occur in this area in the vicinity of Palo
Habits. In the western United
States, these bats are inhabitants of the deserts,
semideserts, and desert mountains. Their daytime roosts
may be in crevices and cracks in canyon walls, caves,
mine tunnels, behind loose tree bark, or in abandoned
houses. These bats hibernate in suitable caves or mine
tunnels within the range occupied in summer. Bats
observed in winter are often found wedged deeply into
narrow cracks and crevices in the rock ceilings of old
mines. When probed from these crevices they are able to
fly, which indicates they do not go into a deep winter
Western small-footed myotises appear to
have similar feeding and foraging habits as the
California myotis, but their specific food habits have
not been recorded. They may feed over water and close to
the ground over desert chaparral vegetation. This bat is
strong enough to take off from the surface of water.
The reproductive habits of this bat are
not known. Records indicate that the single young born
annually appears in late May to early July.
Remarks. In previous editions of
this bulletin, this bat was regarded as a subspecies of Myotis
leibii; however, recent taxonomic work on this
broadly distributed species has shown that M.
ciliolabrum should be elevated to specific status.