While bats may not be the first thing that comes to mind when you consider the global economy, these winged mammals provide vital — and valuable — services to our society.

With the ability to consume their body weight in insects every night, bats act as nature’s pesticide by combating crop pests, saving farmers billions of dollars annually in crop damages. Along with serving as pest control to protect crops, bats play a significant role in helping plant pollination, like in regions of the American Southwest, Central America and tropical South America, where nectar-feeding bats are the sole pollinators for the agave plant — the succulent used to produce tequila.

Unfortunately, conservationists are increasingly concerned about threatened and endangered bats due to rapid population declines of many species. The primary threat to these bats is the fungal disease, white-nose syndrome (WNS), a white substance that grows on bats’ noses, ears and wings, and disturbs their hibernation. Coupled with WNS, bat populations face ongoing threats including collisions with wind turbines and loss of their summer habitat caused by deforestation.

While project developers may be most familiar with the endangered Indiana bat (Myotis sodalis) and threatened northern long-eared bat (Myotis septentrionalis), the tricolored bat (Perimyotis subflavus) and little brown bat (Myotis lucifugus) are currently being considered for federal protection by the U.S. Fish & Wildlife Service (USFWS).

Tricolored Bat

Formerly known as the eastern pipistrelle, the tricolored bat is one of the smallest bats in the U.S., weighing 2 to 8 grams. Once considered one of the most common bat species, the tricolored bat has experienced dramatic population declines in the eastern U.S. due to WNS. Unfortunately, the tricolored bat is also one of the species most commonly killed by the spinning blades of wind turbines.

The Center for Biological Diversity recently petitioned the USFWS to list the tricolored bat under the Endangered Species Act (ESA). This petition will trigger a 90-day finding from the USFWS that will determine whether the tricolored bat warrants federal protection as an endangered species. If the USFWS finds that protection may be warranted, a more thorough review will occur, resulting in a 12-month finding that may propose a listing status for the tricolored bat. Federal protection of the tricolored bat would have the potential to affect construction projects at sites in forested areas of the eastern U.S.

Little Brown Bat

The little brown bat’s appearance, behavior and habitat are similar to those of the Indiana bat and northern long-eared bat. With a broad distribution — ranging from northern Florida to central Alaska — the little brown bat can be found roosting in tree cavities, under tree bark and in abandoned buildings during the summer, and hibernating in caves in the winter.

The little brown bat was considered the most common North American bat species until the emergence of WNS caused steep population declines throughout the eastern U.S. Although populations in the West haven’t seen the same dramatic effects, a recent discovery of WSN on a little brown bat in Washington State is a formidable omen for bat populations in of the western U.S.

Although USFWS has yet to receive a petition, it currently is considering the little brown bat for Endangered Species Act protection. While the potential effects caused if USFWS decides to protect the tricolored bat would directly affect only the western U.S., federal protection of the little brown bat could impact specific project sites across the country.

Implications of a Listing

An ESA listing for either the tricolored bat or little brown bat would have the potential to impact a much broader geographic range than what is currently affected by ESA-listed bats. While the listing of either species doesn’t appear to be imminent, project developers should be aware of the potential impacts already being raised by this changing regulatory landscape.

An experienced bat biologist can assess habitat suitability, regardless of the species involved, by documenting forest structure and availability of suitable roost trees — trees with cavities or sloughing bark — within a proposed project area, and providing valuable guidance based on that information.

Presence/absence surveys are commonly conducted using acoustic detectors, which record bat echolocation calls, or netting surveys, in which a biologists sets up fine nets across a flyway to harmlessly capture, release and track bats. Data collected through these surveys is then used to assess a project’s potential impacts and provide recommendations regarding site development.

Burns & McDonnell has a team of specialists in threatened and endangered species — professionals with many years of experience conducting habitat assessments, presence/absence surveys and consultations. If you’d like to learn more, connect with me on LinkedIn.

Photo credit: "Tricolored bat" by U.S. Fish and Wildlife Service Headquarters is licensed under CC BY 2.0.

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Josiah Maine is an assistant environmental scientist in Burns & McDonnell’s Ecological Permitting department, specializing in Endangered Species Act surveys, compliance, and consultation.