The western small-footed bat (''Myotis ciliolabrum''), also known as the western small-footed myotis, is a species of

vesper bat Vespertilionidae is a family of microbats, of the order Chiroptera, flying, insect-eating mammals variously described as the common, vesper, or simple nosed bats. The vespertilionid family is the most diverse and widely distributed of bat famili ...

native to North America.

Description

Western small-footed bats are relatively small bats, having a total length of , and a wingspan of about . They weigh just , with females being larger than males. Their fur is yellowish-brown in color, with paler, sometimes white, underparts. The muzzle and chin are black, as are the long ears. The tail is in length, but is almost entirely enclosed within the

uropatagium The patagium (plural: patagia) is a membranous body part that assists an animal in obtaining lift when gliding or flight. The structure is found in extant and extinct groups of flying and gliding animals including bats, birds, some dromaeosau ...

, with only the tip extending beyond it. As the common name indicates, the feet are unusually small, being about half the length of the

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

. The bats have a wing aspect ratio of 6.1 and a

wing loading In aerodynamics, wing loading is the total mass of an aircraft or flying animal divided by the area of its wing. The stalling speed of an aircraft in straight, level flight is partly determined by its wing loading. An aircraft or animal with a ...

of 6.7 N/m², which are both relatively low values for bats. They are very similar in appearance to the closely related

California myotis The California myotis (''Myotis californicus'') is a species of vesper bat. It is found in British Columbia in Canada, Guatemala, Mexico, and in the western United States, including California. Description The California myotis is a small (70– ...

, with which they share some of their range; the two species can be distinguished in that the latter does not have the black "face mask" of the small-footed species.

Distribution

Western small-footed bats are found across much of the western half of North America, from southern

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

and

Saskatchewan Saskatchewan ( ; ) is a province in western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North Dak ...

in the north down to

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

Zacatecas , image_map = Zacatecas in Mexico (location map scheme).svg , map_caption = State of Zacatecas within Mexico , coordinates = , coor_pinpoint = , coordinates_footnotes = , subdivision_type ...

, and Nuevo León in the south. Within this region, they are most common arid and semiarid habitats, such as deserts and badlands, but may be found in pine or juniper forests, especially at higher elevations. They are found from . Two subspecies are recognised: * ''M. c. ciliolabrum'' - Western and southern parts of the range, from British Columbia to

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

* ''M. c. melanorhinus'' - Northeastern parts of the range, from

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to th ...

Biology and behavior

Western small-footed bats are nocturnal and insectivorous, feeding on moths, beetles, and flies. Their flight is slow but maneuverable, and they often feed close to water or to rocky bluffs. Their echolocation calls vary in different parts of their range, but have been recorded as lasting 1-3 milliseconds, with a sweep of 60 down to 40 kHz in

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

state. They often roost during the day in caves, but may also be found in smaller crevices, artificial structures, or under loose bark. Males typically roost alone, but females may gather into small groups of up to nineteen individuals when nursing young. They hibernate during the winter, typically alone. The bats give birth to a single young between June and July. The young are hairless and born, and have been recorded as weighing .

References

{{Taxonbar, from=Q1833362 Mouse-eared bats Bats of Canada Bats of Mexico Bats of the United States Bat, Western Taxonomy articles created by Polbot Mammals described in 1886 Taxa named by Clinton Hart Merriam