Facing extinction: The plight of New York’s tricolored bat

Populations of hibernating bats continue to see dramatic population losses due to white-nose syndrome

By Lauren Yates

The tricolored bat, one of New York state’s six hibernating bat species, is headed to the endangered species list, a top state biologist said.

The bat is one of many decimated by a fungus called white-nose syndrome (WNS), which continues to spread across the United States and Canada.

The U.S. Fish and Wildlife Service, which maintains the list of federally endangered species under the Endangered Species Act, says it is still evaluating the tricolored bat’s status and has not finalized a publishing date for its determination.

However, Ashley Meyer, a state Department of Environmental Conservation wildlife biologist, said on Tuesday that she expected the listing to become official this summer.

The tricolored bat was first proposed for the endangered species list in September 2022. These bats have lost 98% of their population in the state since 2006 because of white-nose syndrome, or WNS, according to Meyer. She said the Lake George area hosts the state’s largest population of tricolored bats. 

Hibernating bat populations hit hard

There are nine species of bats in New York. Three  – the hoary, silver-haired and eastern red bats – are migratory and usually travel to milder climates for the winter.

But six of the state’s species – the little brown bat, the big brown bat, northern long-eared bat, Indiana bat, tricolored bat and small-footed bat – hibernate in caves and mines across the Adirondacks. It’s in these caves, where many bats huddle together for the winter months, that white-nose syndrome thrives and spreads.

Hibernating cave bats typically wake up to stretch their wings every couple of weeks, but they quickly go back to sleep so they don’t use up their energy stores for the winter.

Meyer said that white-nose syndrome causes bats to wake up more often, use more energy and ultimately die of starvation.

White-nose syndrome was first detected in Albany County caves around 2006, likely imported from Europe or Asia. Within a few years, the fungus decimated New York’s bat populations. The little brown bat has lost 91% of its population in New York, according to Meyer, falling from around 350,000 bats in 2006 to less than 50,000 in 2010. 

She said the northern long-eared bat, which was listed as endangered in March 2023, is “nearly wiped out” in New York at a 99% population loss, and Indiana bat populations — which have been considered endangered since the 1960s — have dropped by 78% since the discovery of white-nose syndrome.

The fungus has since spread to at least 40 states and eight Canadian provinces, according to Meyer. 

Efforts to track bats’ progress

While Meyer described the population decline as having a “bottlenecking” effect — with a sharp initial decline like those seen in little brown bats — she said bat populations have seemed to stabilize. The little brown bat has even shown some steady resilience to WNS over the last several years. 

“They seem to be the only species that we’re aware of that has developed any kind of adaptation to white-nose,” Meyer said.

But because bats birth only one to two pups per year, any population comebacks would be a slow process.

“Any kind of rebound will take decades, if not centuries, to see,” Meyer said.

Meyer declined to name any specific caves bats use to rest over the winter in the Adirondack region.

The DEC surveys such hibernacula every year to track populations, but it’s the department’s policy to keep the locations of listed species confidential.

 But there are several abandoned mines across the Adirondack region that host all six of the state’s hibernating bat species. The DEC advises people to stay away from caves during the winter to avoid disturbing these sensitive populations.

Scientists are still trying to find a fix for WNS, testing vaccines and anti-fungals and even attempting to disinfect hibernacula with UV light. So far, there’s not a widespread cure. 

Migrating bats also face threats like habitat loss and fragmentation, as well as wind turbines, but Meyer said she could “gladly” report these populations are doing well despite the odds.

Bats are essential to the ecosystem as a primary predator of insects. Meyer said bats are estimated to save the agricultural industry around $3.7 billion dollars per year with their natural pest control. They’re also the sole pollinator of some plants, like agave.

“If you like tequila, you can thank a bat,” Meyer said.