Somewhere in Locust Valley — we are not at liberty to disclose the precise location — there is a house with a wide wraparound porch that every spring becomes a maternity colony for an extended family of tricolored bats. The females arrive in April, rear their pups through the spring and early summer, taking turns foraging and caring for the babies, and disperse by early July.
It is the only known maternity colony of tricolor bats (Perimyotis subflavus) in New York State, according to Casey Pendergast, a biologist at the Department of Environmental Conservation.
For local chiropterologists — scientists who study bats — this little nursery is something to be fiercely protected. In the past 20 years, at least 12 of the 47 bat species native to the United States have declined precipitously, as millions have succumbed to a highly contagious fungus commonly called white nose syndrome.
Long Island’s bats have been severely affected by the disease, yet researchers are finding that the particular climate and topography of the region may be giving them a slight survival advantage. There’s some evidence that local bats are persisting in greater numbers than elsewhere, and that gives scientists hope that they could begin to rebound.
WHAT NEWSDAY FOUNDA highly contagious virus has wiped out more than 90% of many bat species in the United States, including in New York State.Researchers are finding that the particular climate and topography of Long Island may offer local hibernating bats a slight survival advantage.Scientists are testing several prevention measures, including disinfecting hibernation sites with UV light and a vaccine.
The fungus originated in Europe and Asia, but since bats there co-evolved with the disease, they are not affected. It was first identified on this continent in 2006, near Albany, and quickly began ravaging hibernating bats. Their winter survival strategy — gathering by the thousands in dark, damp caves and abandoned mines — places them in an ideal environment for the spores to spread.
The disease is nearly always fatal, experts say, but it’s not the fungus itself that kills them. The fungus grows on the animals’ muzzles, ears and wings and causes them to wake from hibernation and set off in search of food. They find little to eat in the dead of winter and the search burns up some of the fat stores they need to survive until spring. Before long, they die of starvation.
Bats also are imperiled by habitat destruction, pesticides and climate change, noted Kevin Munroe, the Long Island preserve director at The Nature Conservancy, and by the “insect apocalypse” — the dramatic decline in insect populations worldwide. The majority of bats in the United States, and all seven species found on Long Island, “feed exclusively on insects,” Munroe said, “so their food source becoming scarce is a huge problem.”
Bats may not be the best-loved mammals on the planet, but they play important roles in the ecosystem: They pollinate wild plants and crops, disperse seeds and consume large numbers of insects.
New York’s little brown bats have declined by about 90%, according to the DEC; for some species, such as the northern long-eared bats, it’s closer to 99%. Three species of tree bats native to New York, which migrate to warmer zones in winter, are far less affected.
But Long Island has no caves or old mines, so hibernating bats tend to overwinter in smaller groups; in rock crevices, tree cavities or in old potato barns and cellars, and that seems to have slowed the spread of the fungus.
Long Island’s relatively mild winters, compared with other parts of the state, may also help some local bats survive the disease, Pendergast said. Since freezing temperatures arrive a bit later and warmer weather arrives sooner, bats can feed later in the fall and earlier in spring, and if they awaken off-schedule they may sometimes find enough insects to sustain them.
A team of researchers, including Pendergast, recorded the echolocation calls of northern long-eared bats on the East End, as well as Martha’s Vineyard and Nantucket, in 2017 and 2018 and found numbers that were “orders of magnitude higher” than in other parts of their range.
“I think there’s a little bit more here to help them to survive,” Pendergast said. “And I’m hoping this can be a population refuge that’s going to reinvigorate the rest of the coastal range.”
The researchers are continuing to monitor Long Island populations to see if that holds true. Just recently they captured several northern long-eared bats with mist nets in more developed areas of the Island such as Smithtown and Brookhaven. “That’s indicating they are likely hibernating very close by,” Pendergast said.
There’s also recent evidence that little brown bats may be stabilizing, she added.
Scientists are testing several prevention measures, including disinfecting hibernation sites with UV light and a vaccine, both of which have shown significant promise, according to the National Fish and Wildlife Service.
It’s a race against time to find workable solutions, as several species are on the brink of extinction.
So far, though, the tricolor bat colony in Locust Valley has been increasing steadily since the homeowners started tracking them in 2014, from just a few to about a dozen adults, raising singletons or, most often, twins. “It shows that they’re able to produce, they have enough food, enough foraging area, and that is a really great thing for us here on Long Island,” Pendergast said.
Ways to help
New York’s DEC, along with many government agencies and conservation groups in the U.S. and abroad, observe Bat Week every year between Oct. 24 and 31. The DEC and other experts suggest several ways to help:
Don’t enter caves between Oct. 1 and April 1. Even quiet and respectful explorers can wake a colony of slumbering bats, exacerbating their fragile condition.Leave dead trees in place, at least until winter. Mother bats use dead trees as roosts; removing them during their active months deprives them of crucial habitat. The state allows tree clearing only between Dec. 1 and Feb. 28 in Suffolk County and between Nov. 1 and March 31 elsewhere.Install a bat box. Instructions on how to build, buy and install one can be found on the Seatuck Environmental Association’s website.Help scientists monitor bat foraging sites and roosts by reporting bat sightings to BatMap LI. Casey Pendergast invites anyone who has bats roosting on their property to get in touch at wildlife.r1@dec.ny.gov; the DEC is eager to set up additional acoustic monitoring sites.
For those interested in seeing bats chasing insects at dusk, The Nature Conservancy’s Long Island preserves are good spots: Uplands Farm Sanctuary (Cold Spring Harbor), Calverton Ponds Preserve (Manorville), Mashomack (Shelter Island) and Wolf Swamp Preserve (Southampton).