A small bat with a very small (8 mm) foot and dull to burnished brown pelage. The ears are dark, nearly black, and a distinct facial mask is frequent. It is almost impossible to distinguish from the California myotis, and only specialists can tell them apart with certainty. Total length, length of forearm and weight are 80 mm, 30 mm and 4 g, respectively. The wingspan is about 220 mm.
This bat is widespread and common in the western United States. In Colorado it occurs statewide in suitable habitat. It seems to be most common in the canyon country of the Western Slope and in rocky areas of northeastern and southeastern Colorado.
Despite its wide occurrence, little is known of habitat preferences of this species, although it is known to inhabit rocky areas and is more common at lower elevations. Summer roosts are highly variable and include buildings, mines, under bark on trees, beneath stones and a variety of other sites. The small-footed myotis is a year-round resident of Colorado. It hibernates in caves and mines alone or in small groups. Despite its small size, it is known to hibernate in open tunnels at low temperatures and low humidity, a situation one would assume is stressful. It sometimes hibernates near other bats, including Townsend's big-eared bat, at elevations to 9,500 feet.
Little is known about the reproduction of small-footed myotis. Small nursery colonies of 10 to 15 are found occasionally in caves, mines or buildings. One young per year is usual. Young are born in mid-June following a gestation of about two months.
The western small-footed myotis feeds early in the evening on small flying insects such as flies, small beetles and winged ants. This species is highly maneuverable in flight, often foraging among boulders, along cliffs or shrubs and trees.
Like most species of Myotis, the small-footed myotis is often misidentified. It can be confused with the western pipistrelle or other mouse-eared bats, especially the California myotis. Earlier information on this species in Colorado was published under the names Myotis subulatus or Myotis leibii.