BEATRICE -- 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 or more.
The Northern Long-Eared Bat is being threatened across the U.S. by an invasive fungal disease called white-nose syndrome, which dissolves tissue in the bats' wings. The disease was confirmed in Nebraska in 2017, and according to whitenosesyndrome.org it 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 just west of Beatrice, leading researchers from the University of Nebraska-Lincoln to examine its 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,” said Ben Hale, a bat biologist for Environmental Solutions and Innovation.
The bats typically eat insects, some eating half their body weight or more each night, serving as de facto pest patrols for farmers' crops, like corn.
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 UNL, Fill put several acoustic detectors out to look for the bats in southeast Nebraska. That's how Fill located the bats at Homestead.
The detectors "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 technician Anna Oetting set up fine mesh nets called mist nets in the woods outside Homestead’s Education Center to catch the bats. Once the bats are caught, they’re removed from the nets and checked to determine their breed, age, gender, wing length, how much they’ve eaten and more.
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So far they’ve caught five of the eight species Fill’s detectors identified: the Hoary, Northern Long-Ear, Evening, Big Brown and the Eastern Red Wing bats.
Species except for the Northern Long-Ear are marked with whiteout so workers know if that type gets caught again. The Northern Long-Ear, however, is kept and test for white-nose syndrome.
Hale said the researchers found one bat with the disease at Homestead that had healed wings, but he said it was likely because the bat caught it toward the end of hibernation season, making it easier to find food and water.
Researchers 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. The bats roosts vary from old trees to a pile of logs. Hale found one roosting inside a fence at Homestead.
Fill said all the agricultural locations he visited had bats living there, which some farmers weren’t aware of.
Research studies are being conducted to help bats with white-nose syndrome, he said.
“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 with birdhouses, 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.”