Myotis lucifugus
(Little Brown Myotis)

Description:
The upper fur is usually brownish, long, silky, glossy, and may have a gold sheen. The tragus is blunt, about one-half the length of the ear which is narrowly rounded. When laid forward, the ear does not extend significantly beyond the nostrils. The calcar is not keeled.

Range:
From Alaska east across southern Canada to the Atlantic coast, south along the coast to Georgia and across to California, especially in forested mountain ranges and buildings, but largely absent from arid lowlands in the southern portion of its range. This species has a very broad distribution. It has been collected in over 20 counties in Idaho.

Habitat:
This bat is found in a wide range of elevations often associated with forests containing snags, old buildings, and slack-water areas with abundant insects. Site fidelity is likely common in all geographical areas. Large hibernation sites have not been documented in Idaho.

Diet:
Aquatic insects including caddis flies, mayflies, midges, and mosquitos, based upon assessments in other geographical areas.

Ecology:
Although the little brown bat is an ecological generalist able to occupy a large number of roosting conditions, very little is known about this species in Idaho. Large numbers are rarely caught at any single netting site. Little brown bats, because of their wide distribution and large populations, may be an especially good litmus species for excessive habitat conversion as a result of anthropomorphic activities. They are likely being eliminated in vacation home areas where they are considered a pest as a result of accumulation of guano and ignorance of their beneficial destruction of insects.

Probably the most common bat in North America, and one of the best studied. Most active during first 2-3 hr after sunset. Second foraging period follows midnight roost, which is lengthened by cool temperatures and low abundance of prey. Hibernates from September or October to April or May. In winter, selects temperature at or below 40° F and relative humidity of about 80%. Winter concentrations may include tens of thousands of individuals. Survival rate is low during first winter, higher in subsequent years. Most summer nursery colonies range from 50-2500 bats (average 400). Summer home range is poorly understood.

Reproduction:
Polygynous mating occurs prior to hibernation at hibernal sites. Sperm is stored over winter and fertilization occurs when hibernation is terminated. Maternity colonies form and a single pup is born after about 60 days of Gestation . Each pup weights about 25 percent of the body mass of the female.

Usually mates from September-October. Ovulation and fertilization are delayed until spring. Gestation lasts 50-60 days. Female gives birth to 1 litter of 1 young, in late spring-early summer. Female produces first young usually in first year (Indiana, New Mexico) or second year (British Columbia).

Conservation:

Status:	Unprotected nongame species
Global Rank:	G5
State Rank:	S5

Important State References:
Bonnell, M.L. 1967. Emergence and foraging behavior in small populations of Idaho bats. M.S. Thesis, Univ. Idaho, Moscow. 63pp.