little brown bat (Myotis lucifugus lucifugus)


This is a small to medium size myotis, with glossy fur that is a dark yellow-brown to olive brown. . The face, ears, and membranes are dark, with the membranes sparsely or not furred. The total length is 85-98 mm with a wingspread from 222-269 mm. It has a weight of 5-14 grams and the female is slightly larger than the male. This species mates primarily in the fall, and there is delayed fertilization until spring ovulation, after depart from the hibernacula. Nursery colonies of several to 1000 or more females form in late April-May in warm dark locations. The summer colony may disperse to several hibernacula, and the hibernating colony may come from many summer colonies. When not hibernating, these bats emerge to forage at late dusk, and often repeat hunting flight patterns. They may use waterways, escarpments, even highways for orientation only. The mean life expectancy of the males was 1.55 years and for females 1.17-2.15 years (closer to 2.15).


Migration generally is north to south, but some in all directions. There are 13 caves with 100-1000 individuals of this species and eight caves with more than 1000. This species will roost in caves, buildings, rocks and trees, under bridges, in mines and in tunnels. They also may dwell in man-made structures. This is one of the most abundant insectivorous bats in Virginia. They are found in all forested regions.


Moths are a major part of the diet as well as midges, mayflies and aquatic insects. Lactating bats select larger insects than males or nonparous females. They are very effective at feeding in patches of insects. They forage at about 10-20 feet over trees, lawns, pastures, and about 1-2 meters over open water. They may sweep low over water for drink before they begin foraging.