We often enjoyed sitting outside at dusk or on a moonlit night watching bats dart around our house and barn catching their favorite food, insects. We felt no need to put up bat houses because our almost 100-year-old barn served as one big bat house!
Several years ago, Mary Lou was sitting on our front porch around dusk when she looked up and saw bats streaming out of our roof ridge vent at the peak of our house. In better light, we noticed a small opening in the vent that allowed bats to take up residence under the peak of our roof. Although we like bats, we didn’t want them in the house for obvious reasons. We plugged up the hole following the Wisconsin Department of Natural Resources bat exclusion instructions to make sure we weren’t trapping bats, or their young, inside our house.
The DNR’s Wisconsin Bat Program website (wiatri.net/inventory/bats) offers do-it-yourself instructions and information on hiring a professional to remove bats humanely through a process called exclusion. Exclusion includes sealing a building except for primary exits, which are outfitted with one-way doors that let bats exit and prevent re-entry.
Bat exclusions are prohibited June 1-Aug. 15 to protect Wisconsin’s endangered little brown and big brown bats during their maternity seasons. Exclusions done during this period will separate mothers from their flightless pups, leaving the pups to die of starvation and potentially exacerbating the homeowners’ bat problem.
In recent years, we noticed a big decline in the bats around our property that we attribute to the dreaded bat disease fungus called white-nose syndrome that has wiped out thousands of bats in Wisconsin and other states. The Wisconsin DNR just put out a news release on how we can help save Wisconsin’s threatened bat species which is important because bats do so much good in our natural world. Here is some of what the news release said:
Protections for bat populations decimated by white-nose syndrome have been developed by the Wisconsin DNR. These include little brown bats and big brown bats, along with northern long-eared bats and tricolored bats, all are threatened species in Wisconsin. They receive legal protection, including the ban on exclusions during maternity seasons. These four bat species, which hibernate in caves and mines in the winter, have been decimated by the deadly white-nose syndrome (dnr.wisconsin.gov/topic/WildlifeHabitat/Bats)
White-nose syndrome is a devastating disease of hibernating bats that has caused the most precipitous decline of North American wildlife in recorded history. The fungal disease was first discovered in New York in 2006, has spread across the U.S. and reached Wisconsin in 2014.
White-nose syndrome does not affect humans but causes a fungus to grow on bats’ noses and skin, disrupting normal hibernation patterns and burning up energy needed to get them through long Wisconsin winters. Winter 2020 surveys show that white-nose syndrome reduced bat populations in some hibernation sites with smaller populations to zero and reduced populations at other sites by 72 to 97% from their average populations before the arrival of white-nose syndrome.
Why do we want to save bats? Bats are a vital part of keeping ecosystems, and us, healthy. They are pollinators and seed-dispersers for many plants. Bats can reduce pesky mosquitoes and night-flying insects around our homes and gardens. Bats are major consumers of agricultural and forest pests, and are predators of biting insects. Bats also play an important role in reducing risks of insect-borne diseases such as West Nile Virus. A single bat can eat up to 1,000 mosquito-sized insects an hour and the equivalent of its bodyweight every night. University of Wisconsin-Madison research revealed that bats consumed 17 distinct types of mosquitoes, including nine species known to carry West Nile virus.
How can we help bats? Build and install a bat house! Late winter/early spring is a good time to provide an alternative roost — a bat house — in the general vicinity of where bats normally enter buildings. You can find out how to build a bat house on this Wisconsin DNR website: dnr.wisconsin.gov/topic/WildlifeHabitat/BatHouse.html.
You can learn more about the science behind bats and other bat news in the DNR’s 2021 Echolocator newsletter at wiatri.net/inventory/bats/news/WBPnews.cfm.
The private Nature Education Center in Fifield operated by Tom and Mary Lou Nicholls is open seasonally by appointment only. Nicholls can be reached at email@example.com.