This species is most often detected during hibernation. In recent years, it has been counted at approximately 125 hibernacula. Recent surveys have greatly increased the number of localities above those known historically; the number of hibernacula may be significantly larger than currently known. Intensive cave and mine surveys have been undertaken in most states where the species occurs, but some sites probably remain unsearched in most states.

The total count for all hibernacula is approximately 3,000 individuals, with roughly 60% of the total number from just two sites in New York. Some of the occurrences probably have not been surveyed completely, and some individuals are undoubtedly missed within some sites because they are hibernating in portions of mines or caves that cannot be reached or easily observed.

This bat always has been considered to be relatively rare (Barbour and Davis 1969). Numbers are reduced in a few sites where older counts are available, and a few historical sites are apparently no longer occupied, but whether these observation reflect declines or changes in distribution is unknown. In Vermont, Myotis leibii has been consistently found in very small numbers and often not detected at all during periodic surveys of various hibernacula dating back to 1934 (Trombulak et al. 2001).

Habitat is mostly hilly or mountainous areas, in or near deciduous or evergreen forest, sometimes in mostly open farmland. In Pennsylvania, Mohr (1976) found this species mostly in heavy hemlock forests in the foothills of mountains that rise to 2,000 feet (600 meters). Unpublished data from the Kentucky Heritage Program indicate that summer roosts include caves, coal mines, buildings, and bridges over rivers (in expansion joints). Warm-season roosts include buildings, towers, hollow trees, spaces beneath the loose bark of trees, cliff crevices, and bridges. Tuttle (1964) reported two individuals found in April in Tennessee under a large flat rock at the edge of a quarry surrounded by woods and cow pastures. In Ontario, about 12 of these bats were found in July behind the door of a shed that was kept open (i.e., positioned against the wall) (Hitchcock 1955). They have been seen resting in limestone caves in West Virginia in spring and summer (Krutzsch 1966).

By far most records come from observations of bats hibernating in winter in caves and mine tunnels. Hibernation occurs in solution and fissure caves and mine tunnels (including coal, iron, copper, and talc mines). Situations near the entrance where the air is relatively cold and dry seem to be preferred (Barbour and Davis 1969), though sometimes deeper locations are used (Schwartz and Schwartz 1981). Roost sites often are deep in crevices, or under rocks on the cave floor, where the bats can be very difficult to find (Davis 1955, Krutzsch 1966, Martin et al. 1966). These bats are usually found singly or occasionally in small clusters, but many may be packed in a crevice; often they hang among other species (Marin et al. 1966). In tight places the body may be horizontal, even belly down. On cave walls, the forearms are somewhat extended rather than parallel to the body axis. Dunn and Hall (1989) noted that 52% of Pennsylvania hibernacula were small caves of less than 150 m (500 feet) in length. Like many other bat species, this one typically forages over ponds and streams.

The range extends from New England, southeastern Ontario, and southwestern Quebec south and west to southeastern Oklahoma, Arkansas, northern Alabama, northern Georgia, and northwestern South Carolina (Menzel et al. 2003). Within this range, the distribution is very spotty, and the bulk of the occurrences and largest populations are in New York, Pennsylvania, West Virginia, and western Virginia. Hall's (1981) map should be taken as potential range; there are no records of this species ever occurring in some parts of the indicated distribution (e.g., Illinois; Jim Herkert pers. comm). This species is apparently extirpated in Connecticut and Ohio (where it is known from only one specimen). Elevational range extends to at least 700-800 meters in several states and to at least 1,125 meters in Kentucky (Best and Jennings 1997).

There is a strong conservation easement held by The Nature Conservancy (TNC) on the second largest occurrence. TNC has a management agreement giving limited protection to the largest occurrence and one occurrence with apparently good viability is on National Park Service land in Arkansas. Several occurrences with fair to poor estimated viability in various states are either owned by TNC or are on Federal land.

Summer surveys throughout the species known range should be a high priority for inventory work. Winter hibernacula surveys should continue with emphasis on searching sites which have not been surveyed, improving counts in sites which have not been completely or thoroughly surveyed, and monitoring some portion of the known sites on a regular basis (perhaps every other year as recommended for Myotis sodalis sites) to establish baseline population trend data.