Long-legged myotis (bat) (Myotis volans)

Physical description

Long-legged myotis are small bats, but one of the larger species of Myotis in Washington. Fur color on the back ranges from reddish brown to blackish to reddish buff. Fur on the underparts is relatively dark and extends to the undersides of the wing membranes, where it reaches the elbows and knees and is longer and denser than in other Myotis. Ears and flight membranes are blackish brown. Ears have rounded tips and are relatively short, barely reaching the nose when pushed forward. The tragus is long and slender. The foot is relatively small, about half the length of the tibia, and the calcar has a distinct keel.

Food Habits and Foraging
Moths are the dominant prey, with termites, flies, beetles, lacewings, wasps, leafhoppers, true bugs, spiders, and other invertebrates also eaten. In eastern and western Oregon and north-central Idaho, moths comprise 42-78% of the diet.

Long-legged myotis emerge from their day roosts early in the evening. Foraging activity occurs throughout the night, but is greatest during the first 3-4 hours. Prey are caught aerially along forest edges and cliff faces, inside forests, over the forest canopy, and over water. This species is characterized by rapid direct flight.

Reproduction
Mating takes place in late August or September before hibernation. Females store sperm overwinter, with ovulation and pregnancy occurring in the spring. Females produce one young per year. Timing of births is variable and probably influenced by elevation and latitude. In the Pacific Northwest, births occur between late June and mid-August.

Geographic range

Long-legged myotis are distributed from southeastern Alaska, Northwest Territories, and western North Dakota southward to central Mexico. This species has been recorded in nearly all counties in Washington.

In Washington, capture surveys have found the long-legged myotis to be the most common or second most common species at sites in the southeastern Cascades. They have been found in dry coniferous forests, but also inhabit riparian forests and dry rangeland. One study reported a strong preference for old-growth forest over fire-regenerated mature and young forests, but other studies have found broader use of different forest age classes if sufficient roosts are present. Elevational distribution ranges from sea level to 3,500 m. Males occur more commonly at higher elevations than reproductive females at some locations, including a site in Washington’s southeastern Cascades.

Roosting
Roost sites include snags and live trees with loose bark, long vertical cracks, or hollows; cracks and crevices in rocks, stream banks, and the ground; buildings; bridges; caves; and mines. In the Pacific Northwest, maternity sites have been mainly found in snags, but live trees, rock crevices, mines, and buildings are also used. A number of traits characterize the snags and trees used by reproductive females.

Roost snags and trees are typically taller and larger in diameter than other snags and trees in the surrounding canopy, are farther from neighboring tall trees, occur in areas of lower canopy closure, and are in the early to intermediate stages of decay when more loose bark remains for roosting under.  These features presumably provide bats with greater numbers of potential roost spaces as well as increased warmth from sun exposure, which hastens the growth of young. In dry forests, ponderosa pine and firs are the main species used for roosting whereas Douglas-fir is the primary species occupied in moister forests.

In eastern Washington and eastern Oregon, pregnant females roost about evenly between upslope and riparian locations, whereas nursing and post-nursing females spend much more time roosting upslope. Most maternity colonies contain fewer than 50 bats, but larger roosts of up to several hundred bats are regularly present. Males and non-reproductive females roost primarily in large snags and to a lesser extent in live or partially dead trees.

In the eastern Cascades of Washington, one study found selection for tall, large-diameter snags and trees, and a preference for grand fir, which often features loose bark.

Bridges, abandoned buildings, caves, mines, and trees in riparian habitats are used for night roosting.

Hibernation
Caves and mines are used as winter hibernacula. Hibernacula usually contain more males than females. Long-legged myotis have been found hibernating alone or in aggregations of 2-64 individuals in lava tubes in Skamania County and in caves in Klickitat County, Washington, and in Oregon. Winter surveys of more than 650 caves and 70 buildings in these states during the 1980s found this species at nine caves. Hibernation in Washington extends from about early November to late March One study reported a tendency by individuals to reuse the same hibernacula between years. Sometimes that long-legged myotis hibernate in clusters.