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  The Mammals of Texas - Online Edition

Western Small-footed Myotis
Order 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.

Species distribution mapDistribution 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 Duro Canyon.

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 sleep.

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.