Yuma Myotis (Myotis yumanensis)

Yuma Myotis (Myotis yumanensis)

Appearance

The Yuma Myotis is a medium-size Myotis species measuring 60-100 mm and weighing between 4-9 g. Its dorsal fur varies from pale brown to nearly black; the fur on its underside is paler. The wing membranes and ears are dark brown. The ears reach the nostrils when pushed forward; the tragus is blunt and about half the length of the ear. The calcar is not keeled. The typical Myotis skull has a steeply sloped forehead.

Natural History

Its summer day roosts are usually in buildings and other man-made structures in close proximity to water. Maternity colonies in buildings can be enormous with one of the largest known colonies of bats in British Columbia comprises 1500 to 2000 adult female Yuma Myotis. The Yuma Myotis also roosts in caves and trees, but colonies in these situations are usually small. Males roost separately from females, either alone or in small groups. Various man-made structures such as house porches, abandoned cabins and bridges can serve as night roosts. Around dusk the Yuma Myotis emerges from its day roost to hunt over lakes, rivers and streams. Although food habits have not been studied in most parts of the province, aquatic insects are probably the major prey throughout its range given this species tendency to hunt over water. An efficient hunter, the Yuma Myotis can fill its stomach in 10 to 15 minutes on a productive summer night. After feeding, it retreats to a temporary night roost near the feeding area.

Range: The Yuma Myotis is found across western North America from Mexico to southern British Columbia, where it inhabits several coastal islands including Vancouver Island, the coastal mainland as far north as Kimsquit, and the interior north to the Williams Lake region and east to Nelson.

Habitat: The Yuma Myotis ranges in elevation from sea level to 730 m in the province, where it inhabits coastal forests, ponderosa pine, interior Douglas-fir forests, and arid grasslands.

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