New York Natural Heritage Program
Eastern Small-footed Myotis
Myotis leibii (Audubon and Bachman, 1842)

Threats [-]
Some mines may suffer from collapse or closure and a few cave occurrences are probably threatened or reduced in quality due to the commercialization or frequent winter visitation by spelunkers. The main threat is disturbance during the winter hibernation period and, although this currently does not appear to be a major threat at the best sites (mines), it could be a problem at some of the cave sites. White-nose syndrome (WNS) may not be as big an issue for this species as for other Myotids. Although the species has been shown to get WNS, there is evidence that microbes or a physicological response may be protecting them from the disease. They are also the most cold-tolerant of the Myotis species in New York State which allows them to enter hibernacula later in the fall and emerge earlier in the spring, which may limit their exposure.
Bats may be particularly sensitive to environmental toxins including those found in herbicides and pesticides. Although no studies have targeted small-footed bats directly, elevated levels of persistent organic pollutants including especially PCBs, DDT, Chlordanes, and PBDEs have been found in a similar species, the little brown bat, in the Hudson River Valley in New York (Kannan et al. 2010). The levels found in the bats were only 1 to 3 times less than lethal concentrations reported from previous studies (Kannan et al. 2010). Lesser toxin levels may be expected in small-footed bats since little brown bats typically consume a greater percentage of prey with an aquatic life stage. Bats are highly susceptible to DDT residue and this chemical was widely used as a pesticide to control bat infestations in houses in the 1940s (USGS 2013). It was widely used as an agricultural pesticide in the 1950s and 60s until its agricultural use was banned in 1972. Since DDT is highly persistent (soil half-life is 2-15 years, aquatic half-life is about 150 years) (NPIC 1999), it can pose a threat to bats when there is exposure to trace residues in the environment (USGS 2013). Extensive applications of insecticides and some bio control methods, such as Btk, could also pose an indirect risk to northern myotis by reducing availability of prey.
If proper precautions are not used, cavers and researchers entering hibernacula may cause disturbance that rouses bat colonies or transport the fungus that causes WNS on their clothing (NatureServe 2013). Other potential threats may include climate change, commercial cave development, flooding and hibernacula collapse; habitat loss and fragmentation from development, hydraulic fracturing, and construction of new wind facilities; and direct mortality from wind facilities (U.S. Fish and Wildlife Service 2013).

Conservation Strategies and Management Practices [-]
Cave or mine gating should be given serious consideration at sites that may otherwise receive heavy winter usage. Fencing around openings may be sufficient at some of the more remote locations. Gates or fences will need monitoring to ensure that they remain effective. Gates over entrances must be designed in accordance with specifications that allow easy entrance by bats and do not restrict or alter air movement patterns within subterranean systems.

Research Needs [-]
Determination of the percentage of the wintering population that is visible during hibernacula counts is necessary to develop population estimates and trends. Determining the summer distribution and habitat preferences of reproductive females is also a research need (New York State Department of Environmental Conservation 2006).