8 minute read
Going To Bat For The Creatures Of The Night | Scientists Hope New And Ongoing Efforts Can Boost These Special Species
BY ANNA MARIE ZORN
Anna Marie Zorn has background as a science writer and is communications manager for the National Wildlife Federation’s Great Lakes Regional Center.
For over a decade, “Old Bat” — as she’s lovingly but perhaps not creatively monikered — has flown from her hibernation site without fail every year to end up at the same roost in Wisconsin.
Since Old Bat was tagged in 2011, the team of conservation biologists and mammal ecologists at the DNR who study bats have found her over and over in the same summer home. This little brown bat native to the state is one of the survivors of white-nose syndrome, a devastating fungal disease.
White-nose syndrome arrived in the state around 2014 and wiped out much of Wisconsin's hibernating bat population. Up to 90% of Wisconsin’s native species of hibernating bats — the little brown bat, big brown bat, tricolored bat (formerly the eastern pipistrelle) and northern long-eared bat — have disappeared.
But not all bats succumbed to the disease, and now, nearly a decade later, the scientists who study them are keen to know why. With some species like the northern long-eared bat being listed as federally endangered, the team is hopeful that solving this mystery will be key in helping other bats to survive as well.
A SHIFT AND MICROCHIPS
As white-nose syndrome swept through the state and bat populations plummeted, scientists initially thought to eradicate the disease. Ten years later, it is endemic, a constant presence in bat communities.
The focus has now shifted, according to Jennifer Redell, DNR conservation biologist and cave and mine specialist.
“At this point, we’re really interested in why bats are coexisting with the fungus,” she said. “The bats made it through that initial wave of the disease invasion, and we want to find out why that is.”
To do this, the team has implemented a few tactics, including Passive Integration Transponder tagging, which allows them much more insight into bat behavior.
Despite being very long-lived, bats are tiny mammals; they can't fly with a GPS collar weighing them down. Traditional banding of bats is time-consuming and difficult. PIT tags, on the other hand, are easier to monitor.
PIT tags are tiny microchips, the same size and kind used for domestic cats and dogs, that ping when they pass specific antennae set up to capture bat movement. While PIT tagging is not new technology nor unique to the state, Wisconsin has expanded on it to have antennae at both summer and winter sites to record movement between the two habitats.
"It's special to Wisconsin," Redell said. "It's just the tip of the iceberg. We're going to learn a lot more going forward."
DATA-DRIVEN PROTECTION PLANS
One reason this work is so important is because it gives information on bat behaviors and habitats. In other words, if researchers know where bats are and what they're doing, the DNR can do a better job of protecting them.
"We want to support the persisting colonies and understand how we can help," said J. Paul White, mammal ecologist and team lead for the DNR bat program.
Before PIT tagging, there were few connections state scientists could see of bat travel from a summer site to a winter site. Since PIT tagging, the team has gathered multiple data points indicating bats make trips from summer roost to winter hibernating spots several times between May and August before settling in to hibernate for the winter.
Researchers have hypothesized that mother bats may be teaching their pups how to find locations to hibernate, White said.
“Now, we’re looking to see if this tells us what times of year they might be more vulnerable and how we can help them survive these long journeys back and forth,” he said.
BENEFITS OF BATS
Bats — on top of being adorable, furry, flying machines — are critical parts of the ecosystem and the economy.
“Studies have shown that bats can eat 1,000 mosquito-sized insects every hour,” Redell said.
The U.S. Geological Survey notes that considering only the sheer number of insects bats consume, they save agriculture anywhere from $3.7 billion to $53 billion a year on pest-control measures.
Despite these incredible financial numbers, Redell said, “bats traditionally have been misunderstood, underfunded and understudied,” though the arrival of white-nose syndrome has improved this somewhat. Biologists across the state and nation are working together to learn more about bats to support conservation.
Some of this work is already being seen in timber management. Heather Kaarakka, a DNR conservation biologist, is leading the work on habitat conservation for forest bats.
The hibernating bat species use trees for foraging and roosting, as well as for giving birth. Before pups can fly on their own, Kaarakka said, mothers often will leave to find food, leaving the pups in those roosts.
“We’ve done work that shows they’ll move around and need multiple roosts during the summer,” she said.
The forests play a critical role for the bats, and poorly timed timber harvest could harm them or take away much-needed habitat.
COLLABORATION AND VOLUNTEERS
To ensure forest bats in the Great Lakes region have safe access to the trees they need, the Wisconsin, Michigan and Minnesota DNRs are collaborating to devise a conservation plan that responsibly manages timber cutting to protect forest-dwelling bats like the northern long-eared.
Recently listed as federally endangered, the northern long-eared bat has all but disappeared from Wisconsin. While researchers once found many northern long-eared bats, they now have sites where they may find only a single bat.
Finding just one bat where there used to be many might seem depressing, but it’s meaningful.
“People forget that even zero is a number. It’s important data,” White said.
He underscored the critical role community members played when white-nose syndrome first blindsided the nation in the early 2000s. Through community monitoring programs, Wisconsin residents collect data like the acoustic sounds of bats that are using echolocation, the way bats navigate by bouncing sound off objects and insect prey.
Over the years, this has helped the DNR determine how many bats are still flying the night skies.
“You can’t say enough about how much the volunteers shaped how we understand bats,” White said. “If not for them, we wouldn’t have the information we have today.
“They’ve done a great job of surveying our high-priority sites. We’re very thankful.”
REASON FOR HOPE
Along with PIT tagging and traditional counting in winter sites, ongoing monitoring programs show there may be some good news on the horizon.
Little brown bat populations have stabilized, and some seem to be climbing back. Wisconsin is home to a significant hibernating site that saw a 17% population increase since it bottomed out a few years ago, Redell said. About 37% of the number of bats once found at that site exist now.
Through conservation programs and collaboration with other state and national departments, it may be possible to see bat populations continue to grow. But the team is cautious in its optimism, understanding that, at such low numbers, bat species remain vulnerable to other unforeseen diseases or habitat changes.
Still, that doesn’t stop them from smiling every time Old Bat or one of their other decades-old veterans returns to their summer roost.
It’s a gratifying feeling, White said: “It’s tough not to get excited about a bat who went through the whitenose syndrome disease cycle and came out on the other end.”
LEARN MORE
Bats are vital to many ecosystems, but the effects of white-nose syndrome have been disastrous for populations in Wisconsin and nationwide. The DNR is working hard to support these important species, and there are many ways you can help:
• Join a community science monitoring program to be more inclusive.
• Report sick and dead bats.
• Correctly build and place bat houses.
• Garden organically with fewer pesticides.
• Plant night-blooming flowers to attract insects.
The Wisconsin Bat Program offers details on how to get involved on behalf of bats — wiatri.net/inventory/bats. And the Winter 2021 issue of Wisconsin Natural Resources includes detailed instructions for “How to Build a Bat House” — dnr.wi.gov/tiny/1776. For general bat information and additional bat resources, check dnr.wi.gov/tiny/886.
