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Wisconsin Bat Program releases 2020 program update

April 17, 2020 by Beckie Gaskill

Recently the Wisconsin bat Program put out their 2020 bat report. The report said there are more than 200 bat hibernacula in the state. Those sites include natural caves, historic mines, beer aging cellars and abandoned rail tunnels. 

Prior to bat research regarding white nose syndrome (WNS) in bats, not all hibernacula was known within the state. WNS is a fungus found in every hibernacula in the state since it was first found in Grant County. WNS has now been confirmed in four hibernating species in the state. 

In the United States, it is estimated the disease has killed approximately 6.7 million bats. It has been found in 33 states and seven Canadian providences since it was found in 2007. Five other states have detected the fungus that causes WNS. Overall, 13 species have been confirmed with the disease and eight more carry the fungus without having signs of the disease.

In Wisconsin, the report said, the winter hibernate surveys in 2019-2020 show WNS is still widespread and is still decimating bat populations. All sites surveyed were found to be infected with the fungus. Additionally, those sites which started with a small population have decreased to no bats at all. Other sites have been found to experience 72-97% decreases in populations. Not all of the news was bad, though.

“In 2019, we observed previously marked individuals in a few sites,” Paul White, SNE mammal ecologist and Bat Program lead, said. “There bats are somehow finding a way to survive with the fungus, perhaps choosing hibernation sites that are colder and less hospitable to the fungus or finding some other strategy.”

Regardless of population reduction, it was found, there was some evidence year-to-year survival of some species was increasing. One of those species showing some encouraging signs was little brown bats, which were experiencing drastic declines previously.

The Wisconsin Bat Program has started an individual banding program. Other partners in the banding program include Virginia Tech and the University of California at Santa Cruz.

A grant from the U.S. Fish and Wildlife Service has partially funded research on bat species. This is part of an initiative to support state-initiated management actions, priority research and treatment development for WNS. The grant obtained will help researchers focus on conservation and recovery for affected bats. 

“This fall, our partners took an important step forward in developing a life-saving treatment when, with our help, they tested the first vaccine administer in the wild.”

The group vaccinated little brown bats in two hibernacula and attached a PIT tag, or Passive Integrated Transponder. Readers at the entrances to those hibernacula scan for those tags as the bats fly through. This is done to help understand winter bat activity specifically. These readers can help researchers to understand if a bat is leaving the hibernacula in spring as it normally would, or if it has emerged too early. Bats infected with WNS tend to wake up too early and leave their hibernation sites, causing them to succumb to the harsh conditions. 

Using these tools, researchers hope to have good news regarding bat populations in the coming months.

During acoustic surveys last summer, big brown baits were detected in 77% of surveys. Little brown bats were detected in 62% of the surveys.  These numbers were similar to last year’s numbers. The northern long-eared bat was not detected in this year’s acoustical surveys, and the easter pipistrelle was found in only four surveys. Many surveyors experienced connectivity issues related to the GPS equipment, according to the report, unfortunately. 

The program itself, however, has grown exponentially. In 2007, it started with just 18 surveys. In 2019 that number had grown to 20 times its starting numbers. These surveys help to build a better understanding of bat behavior and where bats were found before WNS, which helps in determining the overall affect on populations across the state. This program is staffed largely by volunteers with some regional coordinators. This type of citizen science is becoming increasingly important, and, luckily, also increasingly more popular, even here in the Northwoods. There have been bat monitoring workshops in both Oneida and Vilas Counties, put on by a several different partners. With eco locator equipment becoming better and smaller, it is becoming easier for volunteers to learn the equipment and head out to do these summer surveys.

Beckie Gaskill may be reached via email at [email protected]

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