Fluttering Concern

ENDANGERED NORTHERN LONG-EARED BATS PLAY IMPORTANT ROLE IN LOCAL ECOSYSTEM

By J.D. Willoughby

You are likely to have never seen the tiny northern long-eared bats, given their size and reticent behavior. But they are here, flying all around us. More importantly, they play an important role in the ecosystem, feasting on flying pests.

But despite their vast range—Maryland is just one of 37 U.S. states that are home to the bats—and a seemingly never-ending food supply, the northern long-eared bat is endangered, threatened by a deadly fungus.

Photo courtesy Pete Pattavina/USFWS

The brown bats are small, very small, nothing like your fanciful Halloween images. From wingtip to wingtip, they spread to about nine or 10 inches. As their name implies, they have almost cartoonishly big ears.

While migratory, they don’t go far. They move into various spots depending on the season. Caves and mines are often their winter habitat. They wriggle into cracks and crevices within those spots to wait out the winter. Constant temperature, high humidity and lack of air currents are the most important features of a winter spot, called a hibernaculum.

Photo courtesy Marvin Moriarty/USFWS

Frederick, it turns out, is a perfect spot for bats. The nearby mountains have small caves ideal for hibernation. After winter, pregnant bats roost in small colonies and each give birth to a single pup beginning in late May through July. Baby bats can fly when they are just 18 days old. During the summer, bats roost in buildings, hollow trees, behind shutters, under loose or shaggy bark, and under shingles. They are not picky about whether the hollows are in live or dead trees. 

The long-eared bat is difficult to find, but with special equipment, it’s possible to hear their chirps and squeaks. Imagine being in the woods and trying to listen for a friend who might be at the top of a tree or at the next ridgetop. Their noises are about as loud as human voices, but they’re difficult to separate from all the other critters calling out.

In spring, summer and fall, the bats thrive on the plethora of night-flying insects here. One bat can eat up to 3,000 insects each night. Moths, flies and beetles are at the top of a list that includes mosquitoes, but they will eat almost anything that is available when they are hunting. With Maryland now reporting its first case of locally acquired malaria in 40 years, bats could be one way to reduce the disease. But the bat populations would need to rebound for that. 

Photo courtesy Steve Taylor/University of Illinois

Northern long-eared bats are considered whispering bats, according to Megan Zagorski, Western Region biologist with the Mayland Department of Natural Resources’ Wildlife & Heritage Service. “They hunt under the forest canopy, making them more difficult to find,” she says. They use echolocation to find their food while they are flying through the forest and collect most of their food by gleaning—grabbing insects that are sitting on twigs or leaves. Just after dusk and just before dawn are their most active feeding times and the best time to spot bats if they’re in your area. Bat species will be difficult to distinguish from one another while they’re on the wing, but any bats are a sign of a healthy ecosystem. 

The northern long-eared bat was listed as threatened in 2015 and was reassessed in 2021. The bats were listed as federally endangered by the U.S. Fish and Wildlife Service in January 2023. Their status could mean additional requirements for habitat conservation plans for certain timber harvesting, infrastructure and even wind energy projects. 

White-nose syndrome is the main culprit for reducing the bat population. The disease was accidentally brought to the United States in the early 2000s, says Jonathan Reichard, assistant national coordinator for the Fish and Wildlife Service’s White Nose Syndrome Program. It is a fungus that has killed millions of North American bats. Hibernation is when bats are most susceptible to the fungus and it can kill entire colonies in some cases. “White nose syndrome affects 12 species of bats, some more than others. The northern long-eared bat shows high levels of mortality,” says Reichard. Though it’s primarily transmitted from bat to bat, humans may also carry it from cave to cave on their gear and clothes. Anyone venturing into tourist caves here in the eastern U.S. should decontaminate gear or leave it at home before going to any caves out west or in other countries, says Sabrina Deeley, Fish and Wildlife Service biologist with the Chesapeake Bay Ecological Services Field Office. 

Photo courtesy USFWS

“It’s difficult to know a lot of the places they hibernate, but the ability to measure bats in summer corroborates their decline,” says Reichard. Deeley notes there is a stark decrease from the number of bats that were documented prior to the fungus arriving to today. “Maryland is also home to the proposed endangered tricolored bat and the little brown bat,” says Deeley. Both are affected by the fungus. A U.S. Geological Survey study discovered that 90 percent of three species of bats, including the long-eared bat, were killed by the fungus in fewer than 10 years. 

Losing even a small percentage of bats can have significant consequences on insect populations. One study showed that insect density was three times greater when bats were taken out of the area, particularly on defoliating insects; this led to a five-fold increase in defoliation of small trees. Bats also help manage crop pests, like corn earworms, that can reduce yields. 

Summer habitats are important to protect. Any development that removes forest can affect the northern long-eared bat. That includes new roads, commercial development and even the installation of wind turbines. Protection of the winter hibernation sites and forested areas in Frederick are also critical to helping the bats rebound. 

Homeowners can also play an important role in protecting the bat by leaving hibernating bats alone and not entering caves. Leave dead and dying trees with hollows standing if they are not in danger of falling on people or property. These trees not only house bats, but other critters, as well. 

Bat boxes can be a great way to attract bats to your area. They’re especially important from April through August when bats need a place to raise babies. They also are great daytime roosting spots. Be sure to get a box that meets the requirements for local bats. Bat Conservation International provides guidelines on how to build bat boxes and where to put them on your property. 

Photo courtesy USFWS

Bat Conservation International also provides a basic guide to gardening for bats. The main features of a bat garden are stinky or fragrant plants and white- or light-colored flowers that attract insects. Oaks are one of the best trees to have around because they host so many insects, more than any other tree. Any plant or tree that hosts moths will be a terrific one for bats. “The northern long-eared bat is an interior forest species so leave dead snags standing when they aren’t a hazard,” says Zagorski.

Water sources are also important for bats. A stream or pond will invite them to your yard. They often grab water on the wing, so the bigger the better. Turning off outside lights will also help bats since the illumination can confuse them and hurt their hunting.

Other Maryland bat species may be declared endangered in the coming years. It will be up to all of us to create inviting and safe habitats for them to survive.