The Hippo


May 25, 2020








Little Brown Bat. Courtesy Photo.

Bats still struggling
How local populations have suffered and how to help


 A recent survey of bat hibernacula — the abandoned mines and caves where they sleep through the winter — found that bat populations are continuing to struggle with the devastating effects of white nose syndrome. Researchers are still working on solutions, but New Hampshire biologists suggest small ways residents can help them out.

The latest
The onslaught of white nose syndrome began in the state around 2009, when the fungus began irritating the bats and causing them to prematurely wake from their slumber, exhaust their natural fat stores and ultimately die. 
When New Hampshire Fish and Game did its 2008 survey of hibernacula, it counted nearly 4,000 bats. Reviewing these same hibernacula a decade later, it found just 26. Some species were hit harder than others.
“Little brown bats in particular — we only saw one this year,” said Fish and Game biologist Sandi Houghton.
Once the most populous species of bat in the Northeast, their numbers in the state dropped from 3,135 to one in the past 10 years. Other species of bat have also been decimated, such as the northern long-eared bat. 
Houghton said there are about a dozen known hibernacula in the state but they surveyed four hibernacula in this winter survey. They hope to check different hibernacula next year. 
This is the first survey they performed in the past three or four years, Houghton said, because they wanted to give the bats a chance to hibernate in peace and maybe rebound their numbers a bit. That didn’t seem to happen.
All local species except the big brown bat (which saw some declines but not nearly as much as others) are now listed as state endangered.
Glimmers of hope
There are research projects across the country to find a solution to the problem. Houghton said some are experimenting with UV-C light to irradiate the fungus, but bats can get easily reinfected and the light may not reach places under the wings or armpits of the bats where the fungus has taken up residence. The fungus lacks a gene sequence that allows it to repair cell damage caused by UV light, making it a sort of vampire fungus. 
Researchers are also looking for ways to support natural survivors.
“There are some that are surviving,” Houghton said. “They’re still getting white nose syndrome, but they’re not dying from it.”
They may hold some potential adaptation that future generations can benefit from. Bat species in Europe, where the fungus originates, have evolved an adaptation to the fungus over millions of years. So a long-term solution in North America may be far off.
Still, biologists have found that some little brown bats are surviving despite having the disease, especially in places like New York, where it was first discovered.
A study that included New Hampshire found some banded bats survived and returned to their regular roosting locations. 
That was the case with some bats that hibernate in a cave in Vermont and return to a barn in Charlestown, New Hampshire, to roost, according to Susi von Oettingen, endangered species biologist for the U.S. Fish and Wildlife Service. One of the reasons the bats do well there is that the barn owners are careful not to disrupt them.
“The landowners are particularly bat conservation oriented,” von Oettingen said.
Still, she said the survivors are in very low numbers.
“I don’t want to call the population stable, but it doesn’t seem to be crashing as it did,” von Oettingen said.
The recovery is going to take decades, she said. And von Oettingen doesn’t expect to see the same population numbers as we saw pre-white nose syndrome in her lifetime.
One of the reasons it will take so long for population to grow back is that bats only give birth to one pup per year.
Helping out
There are ways residents can help bat populations take hold and rebound. 
Houghton said one way is to stay out of old mines and places where bats hibernate. Disturbing them will make it harder for them to survive the winter.
Once they leave their hibernacula, they’ll need a place to roost. Humans can provide some of those places.
“A bat house can definitely provide potential habitat,” Houghton said. “If they are in your barn, you can continue to let them use your barn.”
Guano is always an issue when bats use the interior of a barn or shed, but Houghton said folks can set up false ceilings to keep the guano from dropping on their belongings. Even a simple tarp will do the trick. 
Another approach von Oettingen suggests is putting a bat house inside of a barn. That way, the bats will concentrate into a single location, which helps them share body heat for the young and makes the guano more manageable. 
Houghton said you can also set up bat houses in trees or on the sides of buildings. But location does matter. Bat houses need to be at least 12 to 15 feet above the ground and facing the south/southeast with a lot of sunlight hitting it during the day.
You want to make sure there isn’t anything below it you don’t want guano to fall on. If it’s on a tree, Houghton said it’s also important to make sure there aren’t any branches just under the house that an owl can perch on and use to prey on the bats.
There also needs to be a consistent source of fresh water nearby for the bats to drink from.
Bigger houses are better than smaller ones, according to von Oettinger, because bigger groups of bats will be able to cluster together. And if you can get 100 or so bats on your property, it will make a noticeable dent in pesky night-time insects like mosquitoes. 
Houghton said people can find a lot more tips at the Bat Conservation International website at  

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