Northern Long-Eared Bat

The U.S. Fish and Wildlife Service (USFWS) published a final rule reclassifying the northern long-eared bat (Myotis septentrionalis) from threatened to endangered under the Endangered Species Act. The rule takes effect on January 30, 2023. The northern long-eared bat is known to occur throughout much of New York State, including Oyster Bay in Nassau County and the entirety of Suffolk County. As per the Final Rule, the USFWS is committed to reducing the impacts of disease and protecting the survivors to recover the population.

The northern long-eared bat is about 3 to 3.7 inches long with a wingspan of 9 to 10 inches. It is distinguished by its long ears, particularly compared to other bats in its genus, Myotis. It emerges at dusk to fly primarily through the understory of forest areas, feeding mostly on moths, flies, leafhoppers, caddisflies and beetles. It catches these insects while in flight using echolocation or by using gleaning behavior, catching motionless insects from vegetation.

While the primary factor threatening the northern long-eared bat’s survival is white-nose syndrome (a disease caused by a fungal pathogen), wind energy mortality, effects from climate change, and habitat loss also influence the northern long-eared bat’s viability. As per the USFWS Species Status Report (2022), “Habitat loss may include loss of suitable roosting or foraging habitat, resulting in longer flights between suitable roosting and foraging habitats due to habitat fragmentation, fragmentation of maternity colony networks, and direct injury or mortality.”

Artificial lighting results in the loss of habitat for the northern long-eared bat. “Installation of temporary or permanent lighting can introduce barriers to movement, sever foraging areas, discourage emergence or precipitate roost abandonment. Roost adjacent lighting may modify microclimatic conditions (i.e., humidity or temperature) or cause disturbance, which may precipitate roost abandonment.” (White-nose Syndrome Conservation and Recovery Working Group 2018).

The report Use of Forested Habitat Adjacent to Highways by Northern Long-Eared Bats (Foster et al. 2019) prepared for The New England Transportation Consortium further outlines how artificial light reduces the habitat of the northern long-eared bat (NLEB): 
“Artificial light can affect roosting and foraging behavior. Bats will delay leaving roosts that are near lights (Downs et al. 2003), which reduces foraging opportunities (Jones and Rydell 1994). Light near roosts also leads to lighter and smaller juvenile bats due to delayed parturition and slower growth rates (Boldogh et al. 2007). Road lighting deters slow-flying, forested-adapted species such as NLEB (Rydell 1992, Blake et al. 1994, Stone et al. 2009). Older sodium lights and new LED lights deter forest species even at low light intensities (>3.6 lux) (Stone et al. 2012). Bats will reverse flight direction when they perceive low intensity light sources (0.6–3.2 lux) (Kuijper et al. 2008). Street lights are usually between 10–60 lux (Gaston et al. 2012), thus dimming lights to acceptable levels for bats may not be feasible. Open space foraging bats can benefit from lights with improved foraging efficiency, as insects exhibit positive phototaxis resulting in higher insect abundances around light sources (Rydell 1992, Blake et al. 1994). However, this concentrating effect on insects reduces insect prey in dark foraging areas thus decreasing prey abundance and foraging success for light phobic genera such as Myotis spp. (Eisenbeis 2006, Evens 2012). While the effects of lights on Northern Long-Eared Bat (NLEB) have not been directly assessed, NLEB is a forest-dependent species (light adverse) whose primary prey, moths, are highly phototaxic, thus it stands to reason that NLEB foraging success may be greatly reduced in lighted landscapes.” (page 7)

Blake, D., Hutson, A. M., Racey, P. A., Rydell, J., & Speakman, J. R. (1994). Use of lamplit roads by foraging bats in southern England. Journal of Zoology, 234(3), 453-462.

Boldogh, S., Dobrosi, D., & Samu, P. (2007). The effects of the illumination of buildings on house-dwelling bats and its conservation consequences. Acta Chiropterologica, 9(2), 527- 534.

Downs, N. C., Beaton, V., Guest, J., Polanski, J., Robinson, S. L., & Racey, P. A. (2003). The effects of illuminating the roost entrance on the emergence behaviour of Pipistrellus pygmaeus. Biological Conservation, 111(2), 247–252. 3207(02)00298-7

Eisenbeis, G. 2006. Artificial night lighting and insects: attraction of insects to streetlamps in a rural setting in Germany. In Rich, C. and Longcore, T. eds Ecological consequences of artificial night lighting: 345–364. Washington, Island Press.

Evens, N. 2012. Shedding light on bat activity: artificial lighting has species-specific effects on British bats. Doctoral dissertation.

Foster, Jeffrey, et al. Use of Forested Habitat Adjacent to Highways by Northern Long-Eared Bats (and other Bats). No. NETC 15-1, NETCR117. New England Transportation Consortium, 2019.

Gaston, K. J., Davies, T. W., Bennie, J., & Hopkins, J. (2012). Reducing the ecological consequences of night‐time light pollution: options and developments. Journal of Applied Ecology, 49(6), 1256-1266. Jones, G., & Rydell, J. (1994). Foraging strategy and predation risk as factors influencing emergence time in echolocating bats. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 346(1318), 445-455.

Kuijper, D. P., Schut, J., van Dullemen, D., Toorman, H., Goossens, N., Ouwehand, J., & Limpens, H. J. G. A. (2008). Experimental evidence of light disturbance along the commuting routes of pond bats (Myotis dasycneme). Lutra, 51(1), 37.

Rydell, J. (1992). Exploitation of insects around streetlamps by bats in Sweden. Functional Ecology, 744-750.

Stone, E. L., Jones, G., & Harris, S. (2009). Street lighting disturbs commuting bats. Current Biology, 19(13), 1123–1127.

Stone, E. L., Jones, G., & Harris, S. (2012). Conserving energy at a cost to biodiversity? Impacts of LED lighting on bats. Global Change Biology, 18(8), 2458–2465.

U.S. Fish and Wildlife Service. 2022. Species Status Assessment Report for the Northern longeared bat (Myotis septentrionalis), Version 1.2. August 2022. Bloomington, MN.

White-nose Syndrome Conservation and Recovery Working Group, 2018. Acceptable Management Practices for Bat Species Inhabiting Transportation Infrastructure. A product of the White-nose Syndrome National Plan ( 49 pp.