On March 22, 2022 the U.S. Fish and Wildlife Service announced a proposal to reclassify the northern long-eared bat as endangered under the Endangered Species Act. The bat, currently listed as threatened, faces extinction due to the range-wide impacts of white-nose syndrome, a deadly disease affecting cave-dwelling bats across the continent.
The northern long-eared bat is a wide-ranging, federally threatened bat species, found in 37 states and eight provinces in North America. The species typically overwinters in caves or mines and spends the remainder of the year in forested habitats. As its name suggests, the northern long-eared bat is distinguished by its long ears, particularly as compared to other bats in the genus Myotis.
Although there are many threats to the species, the predominant threat by far is white-nose syndrome. If this disease had not emerged, it is unlikely the northern long-eared bat would be experiencing such a dramatic population decline. White-nose syndrome was the main reason for listing the species as threatened under the Endangered Species Act in 2015. Since symptoms were first observed in New York in 2006, white-nose syndrome has spread rapidly throughout the species' range in the United States. Numbers of northern long-eared bats, gathered from hibernacula counts, have declined by 97 to 100% across the species’ range.
Other sources of mortality: Although no significant population declines have been observed due to the sources of mortality listed below alone, they are now important factors affecting this bat’s viability until we find ways to address white-nose syndrome.
- Wind energy-related mortality: Wind turbines can kill bats by direct collision with turbine blades. Mortality has been documented for northern long-eared bats, although a small number have been found to date. However, there are many wind farms operating within a large portion of the species’ range, and many more projects are planned in the future.
- Summer habitat loss: Highway construction, commercial development, surface mining and wind facility construction permanently remove habitat and are activities prevalent in many areas of this bat’s range. Summer habitat loss may result in longer flights between suitable roosting and foraging habitat, fragmentation of maternity colonies and direct injury or mortality.
- Winter habitat loss and disturbance: Gates or other structures intended to exclude people from caves and mines, but do not consider bat needs, may not only restrict bat flight and movement, but also change airflow and internal cave and mine microclimates. A change of even a few degrees can make a cave unsuitable for hibernating bats. Also, cave-dwelling bats are vulnerable to human disturbance while hibernating. Arousal during hibernation causes bats to use up their already reduced energy stores, which may lead to individuals not surviving the winter.
- Climate change: Changes in temperature and precipitation may influence the species’ available suitable roosting and foraging habitat and prey availability.
What is being done to help the northern long-eared bat?
- Disease management: Actions have been taken to try to reduce or slow the spread of white-nose syndrome through human transmission of the fungus into caves and mines, including cave and mine closures and advisories and national decontamination protocols. A national plan was prepared by the U.S. Fish and Wildlife Service and other state and federal agencies that details actions needed to investigate and manage white-nose syndrome. Many state and federal agencies, universities and non-governmental organizations are researching this disease to try to control its spread and address its effect.
- Addressing wind turbine mortality: The U.S. Fish and Wildlife Service and others are working to minimize bat mortality from wind turbines on several fronts. The agency funds and conducts research to determine why bats are susceptible to turbines, how to operate turbines to minimize mortality and where important bird and bat migration routes are located. The agency has and continues to work with many wind energy project proponents in developing habitat conservation plans that provide wind farms a mechanism to continue operating legally while minimizing and mitigating mortality of federally endangered or threatened bats.
- Hibernacula protection: Many federal and state natural resource agencies and conservation organizations have protected caves and mines that are important hibernacula for cave-dwelling bats.
U.S. Fish and Wildlife Service (USFWS). 2015. Endangered and Threatened Wildlife and Plants; Threatened Species Status for the Northern Long-Eared Bat With 4(d) Rule; Final Rule and Interim Rule. Federal Register 80(63): 17974–18033
White-nose syndrome response team website: www.whitenosesyndrome.org/
Northern long-eared bats spend winter hibernating in caves and mines, called hibernacula. They use areas in various sized caves or mines with constant temperatures, high humidity and no air currents. Within hibernacula, surveyors find them hibernating most often in small crevices or cracks, often with only the nose and ears visible.
Spring, Summer and Fall Habitat
During the summer and portions of the fall and spring, northern long-eared bats may be found roosting singly or in colonies underneath bark, in cavities or in crevices of both live trees and snags, or dead trees. Males and non-reproductive females may also roost in cooler places, like caves and mines. Northern long-eared bats seem to be flexible in selecting roosts, choosing roost trees based on suitability to retain bark or provide cavities or crevices. The species has also been found, although less commonly, roosting in structures, such as barns and sheds. Northern long-eared bats use forested areas not only for roosting, but also for foraging and commuting between summer and winter habitat.
U.S. Fish and Wildlife Service (USFWS). 2015. Endangered and Threatened Wildlife and Plants; Threatened Species Status for the Northern Long-Eared Bat With 4(d) Rule; Final Rule and
Interim Rule. Federal Register 80(63): 17974–18033
A dense growth of trees and underbrush covering a large tract.
A natural chamber or series of chambers in the earth or in the side of a hill or cliff. An irregular limestone region with sinkholes, underground streams and caverns.
The maximum northern long-eared bat life span is estimated to be up to 18 and a half years, as noted by J.S. Hall and others in 1968.
Hall, J.S., and F.J. Brenner. 1968. Summer netting of bats at a cave in Pennsylvania. Journal of Mammalogy, 49(4):779–781.
Breeding begins in late summer or early fall when males begin to swarm near hibernacula. After copulation, females store sperm during hibernation until spring. In spring, they emerge from their hibernacula, ovulate and the stored sperm fertilizes an egg. This strategy is called delayed fertilization.
After fertilization, pregnant females migrate to summer areas where they roost in small colonies and give birth to a single pup. Maternity colonies of females and young generally have 30 to 60 bats at the beginning of the summer, although larger maternity colonies have also been seen. Numbers of individuals in roosts typically decrease from pregnancy to post-lactation. Most bats within a maternity colony give birth around the same time, which may occur from late May or early June to late July, depending on where the colony is located within the species’ range. Young bats start flying by 18 to 21 days after birth.
Within its range, the northern long-eared bat can be confused with the little brown bat, Myotis lucifugus, or the western long-eared myotis, Myotis evotis.
The northern long-eared bat has a diverse diet including moths, flies, leafhoppers, caddisflies, beetles and arachnids.
Like most bats, northern long-eared bats emerge at dusk to feed during their active time period. They primarily fly through the understory of forested areas feeding on prey, which they catch while in flight using echolocation or by gleaning motionless insects from vegetation.
MeasurementsAverage body length: 77 to 95 mm (3 to 3.7 in)Tail length: 35 to 42 mm (1.3 to 1.6 in)Forearm length: 34 to 38 mm (1.3 to 1.5 in)Wingspread: 228 to 258 mm (8.9 to 10.2 in)
The northern long-eared bat’s adult body weight averages 5 to 8 grams (0.2 to 0.3 ounces), with females tending to be slightly larger than males.
The northern long-eared bat’s fur color can be medium to dark brown on the back and tawny to pale-brown on the underside. As its name suggests, this bat is distinguished by its long ears, particularly as compared to other bats in its genus Myotis.
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