Man’s best friend may be dogs, but a farmer’s best friend is arguably bats. And a spreading fungal disease affecting bats may cost the agriculture industry 3.7 billion dollars or more.
All bats in the United States eat insects, some eating half their bodyweight or more each night.
The Northern Long-Eared Bat is being federally threatened by an invasive fungal disease called white-nose syndrome, which dissolves tissue in the bats wings. WNS was confirmed in Nebraska in 2017, and according to whitenosesyndrome.org, has killed more than 6.7 million bats in the U.S. since 2006.
The bat was recently found at the Homestead National Monument of America, leading to researchers from the University of Nebraska-Lincoln examining the bat’s habits in hopes to help it thrive.
“The white-nose fungus increases their metabolic rate in the winter when they’re supposed to be hibernating, so they run out of their fat stores quicker and can starve to death,” Ben Hale, a bat biologist for Environmental Solutions and Innovation, said. “If there’s a bat that goes into the summer with a bigger belly, there’s a better chance they can survive the winter.”
Chris Fill is the project lead for locating the Northern Long-Eared Bat at Homestead. A graduate student in the College of Agricultural Sciences and Natural Resources at the University of Nebraska-Lincoln, Fill put several acoustic detectors out to look for the bat in southeast Nebraska, which is how they were found at Homestead.
“They kind of look like game show cameras, but they have a microphone,” Fill said. “When bats fly around at night, they can see just as well as we can, but they use sonar – high-frequency calls – that kind of bounce off their surroundings, and it comes back to them and makes a mental image. That’s what they use to navigate. So this detector, if a bat gets close enough to it it’ll start recording those. Different bat species have enough variability between their calls that if you get quality calls, you can identify what bat made that noise.”
Fill said that the detectors only show what species are in an area, not how many of them there are, which is why surveys are done at different sites.
For the past week, Hale, Fill and Fill’s technician, Anna Oetting, set up fine, mesh nets called mist nets in the forest outside Homestead’s Education Center to catch the bats. Once the bats are caught, they’re removed from the nets and checked on their breed, age, gender, wing length, how much they’ve eaten and whether they’re sexually active.
So far they’ve caught five of the eight species Fill’s detectors found: the Hoary, Northern Long-Ear, Evening Bats, Big Brown Bats and the Eastern Red Wing.
Species that aren’t the Northern Long-Ear are marked with white out so they know if it gets caught again. The Northern Long-Ear, however, is studied for WNS.
Hale said they found one bat with WNS at Homestead where the wings were healed from WNS, but said it was likely because the bat caught it towards the end of hibernation season, making it easier to find food and water.
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Most of the Northern Long-Ear bats caught at Homestead are considered adults, but were born sometime this year.
Hale said finding bats with WNS at Homestead does not mean Homestead has the fungus.
They also placed radio transmitters between the Northern Long-Ear’s shoulders with skin bonding glue, which falls off after a couple of weeks. The radio transmitters help track the individual bats to see their movements and roosting habits so people can aid them.
“They’re using Homestead as a roost and as a feeding site, too,” Fill said. “They’re mostly sticking along this Cub Creek that runs through here, but there are some that once we tag them, they just kind of book it and we never hear from them again. We just scare them too much.”
Where the Northern Long-Ears roost is important to Homestead, because they don’t want to destroy an area a federally threatened species is using. Since Northern Long-Eared Bats are generalists, their roosts vary from old trees to a pile of logs. Hale found one roosting inside Homestead’s fence.
“So we’re just curious about the variety of trees that these bats would use…Basically, I’m systematically putting out detectors in different fields with different levels of tree cover, like resources for bats, and I’m trying to sort of map out on an individual field level how far bats are going into the field,” Fill said.
Fill said all the agriculture locations he’s been to had bats, which some farmers weren’t aware of.
Hale said research studies are being conducted to help bats with WNS.
“There’s a kind of bacteria that actually eats the fungus and slows the growth,” Hale said. “There’s been some captive studies where basically dying bats were collected and then put in artificial hibernation chambers and treated with a bacterium that targets the fungus. It increased their health, helped them make it through the winter. But nothing for widespread cave use. Nobody wants to go spraying bacterium that’s lab-made into a cave like that.”
The team recommends that people not kill bats when they see them. Or, like bird houses, they can build a bat house: a wooden structure with slots bats can enter.
Hale said bat houses should be placed on roughly 15-foot high poles that are south facing and away from other structures.
“If they’re on an isolated telephone pole, or you put your own pole in the ground and it’s 15 feet high, that kind of stick out like a sore thumb for them when they’re echolocating… They want it to have a high degree of solar exposure so that those roosting areas can get to be the right temperature to finish gestation and have their babies in a healthy way. That way they’re not using a lot of energy to try and keep themselves warm.”