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ECHOLOCATOR Volume 10
Issue 1
Feb. 2021
EC HO LO C ATO R
In A World Turned Upside Down
Thank You For Helping Us Through 2020
2 Wisconsin Bat Program • 2021
Table Of Contents
15
5 8
Wisconsin Bat Program
The Wisconsin Department of Natural
Resources (DNR) provides equal opportunity
in its employment, programs, services and
3 Editor’s Note functions under an Affirmative Action Plan. If
you have any questions, please write to Equal
Opportunity Office, Department of Interior,
4 Q & A With Bat Team Leader Washington, D.C. 20240. This publication
is available in alternative format (large print,
5 Winter Surveys Show Average 89% Drop Braille, audio tape, etc.) upon request. Please
call 608-261-6449 for more information.
Echolocator is an annual publication of the
7 Cave & Mine Catalogue Update Wisconsin Bat Program, part of the DNR’s
Natural Heritage Conservation Program. DNR
8 Acoustic Bat Monitoring Update conservation biologists statewide monitor,
research and inventory Wisconsin’s eight bat
species in collaboration with other state and
14 Wisconsin-Based Research federal agencies, universities, conservation
groups, other non-governmental
15 Diet Study Reveals Bats’ Importance To Ecosystem groups and hundreds of volunteers.
Echolocator presents bat conservation work
18 Bats With White-Nose Syndrome Prefer Suboptimal and research relevant to Wisconsin and
Habitats Despite The Consequences welcomes ideas for future articles and featured
groups.
Please contact Jennifer.Redell@wisconsin.gov
to share your suggestions.
Editor, Jennifer Redell
Graphic Design, Rebecca Rudolph
State of Wisconsin
Department of
Natural Resources
In a world seemingly flipped upside down, reaching out Box 7921
to friends helped us get by in 2020. These hibernating Madison, WI
53707
little brown bats paired up to make it through the winter.
Photo, flipped for effect: Heather Kaarakka
WISCONSIN BAT PROGRAM WEBSITE: WIATRI.NET/INVENTORY/BATS/
3 Wisconsin Bat Program • 2021
Reflections From The Editor
Hundreds Of Volunteers
Fly In To Help Bats
“What remained
By Jennifer Redell Some of our typical winter 2021 work
DNR Conservation Biologist, Bat remains on hold due to COVID-19. Our
Program Cave and Mine Specialist routine winter hibernation surveys
constant, however, will be much more limited in the
Similar to most people, COVID-19 was the dedication of coming months while we wait our
impacted our work in direct and turn for the COVID-19 vaccine and
indirect ways. Some things looked the volunteers who the possibility of again searching
the same, many tasks were modified play a vital role in caves and mines with colleagues. Our
or dropped, and we forged ahead
using technologies allowing us to
helping us understand longstanding safety practice has been
to search underground hibernacula
track bats remotely. What remained the changes we’re only with a group of people.
constant, however, was the dedication seeing in Wisconsin
of the volunteers who play a vital We’re capitalizing on technologies
role in helping us understand the bat populations due that allow us to track bats and learn
changes we’re seeing in Wisconsin to WNS. more about them remotely. Relatively
bat populations due to white-nose
syndrome (WNS).
of Wisconsin-Madison has been
” new antenna systems installed at
several hibernacula will allow us
to read the activity of bats carrying
Despite the many challenges of the instrumental in our understanding of Passive Integrated Transponders
past year, Wisconsin Bat Program bat diets in Wisconsin, and how little (PIT) tags. As we move into summer,
volunteers monitored more roosts brown bats are especially important thermal cameras and PIT tag readers
and completed a greater proportion for filling an important role as an will help us better understand what’s
of acoustic surveys during a ecosystem predator and for their going on inside roosts.
significantly shortened monitoring voracious consumption of agricultural
season. This work from dedicated pests and mosquitos. She summarizes As bats emerge from caves on to the
volunteers is critical in helping her research in this issue and we wish landscape and migrate home from
us observe how populations are her well as she begins work at the other states where they over-wintered
responding after WNS caused severe University of Wyoming to improve later this spring, we hope our outdoor
declines at the majority of Wisconsin how chronic wasting disease in deer summer work can be conducted in a
hibernation sites beginning six years can be studied. mostly normal way.
ago.
Researchers Skylar Hopkins, Kate Whatever may come, we remain
Our streamlined newsletter Langwig and Joseph Hoyt of Virginia especially grateful for the dedication
summarizes these surveys and Tech publish results of their long- of, and the inspiration provided by,
other core activities and highlights term study to see if bats alter their hundreds of volunteers working
two key partnerships. Amy Wray’s roosting preferences in hibernacula in individually or with members of their
doctoral research at the University response to the arrival of WNS. household to help Wisconsin bats.
4 Wisconsin Bat Program • 2021
Bat Q & A With J. Paul White
Right now, Wisconsin’s four cave bat
species are in their winter hibernation
sites. Since white-nose syndrome
was first detected in a Grant County
mine in 2014, the disease has spread
to hibernation sites statewide and
resulted in dramatic decreases in
overall bat populations, with losses
at sites ranging from 70-100 percent.
Little brown bats, eastern pipistrelles,
also known as tricolored bats, and
northern long-eared bats have been
hit hardest while big brown bats have
fared better.
We catch up with J. Paul White, DNR
Mammal Ecologist and Bat Program
Northern-long eared bats have fared the worst from
Lead, to understand the latest news
white-nose syndrome. Photo: Heather Kaarakka
for Wisconsin bats.
Q: Where are Wisconsin bat sense to manage forest 100 miles
populations today? Q: What’s next? from a hibernaculum when species
J. Paul White: The picture is still J. Paul White: Our mission is to work typically migrate shorter distances.
developing and we see both signs with others to identify, protect, Identifying core use areas by bats is
of encouragement and cause for monitor and manage populations also critical for understanding best
concern. of native bat species; enhance management practices for forests, as
and restore their habitats; address bats have been shown to return to the
We incorporate survey data collected human-bat coexistence, and promote same summer habitat in consecutive
by volunteers, agencies and partners knowledge, appreciation and years. In addition, little to nothing is
from winter hibernation sites, summer stewardship of bats in Wisconsin for known about the connection between
maternity roosts, and state-wide present and future generations. winter hibernacula and active
surveys using acoustic detectors to summer habitat for most bat species
record bat calls along set routes. Guided by the national plan and in North America.
Together these data describe a still the DNR’s strategy, Wisconsin’s
vulnerable cave bat population, conservation and recovery efforts will Q: What can I do to help bats?
prone to choosing “ecological traps” be prioritized to protect our sensitive J. Paul White: Bats continue to
where seemingly suitable hibernating bat population during critical points need our help as white-nose
conditions are just a deadly disguise in their life -- hibernating or raising syndrome, among other threats,
(read more about research into pups -- while controlling the disease exist in Wisconsin and throughout
these ecological traps on page 18.) (vaccine development) to the point the midwest. From respecting their
Yet, in some areas, we see resilience where bat populations may recover. privacy in the winter, to engaging in a
through summer and winter colonies citizen-based bat monitoring project,
alike, as numbers appear to have Q: Broadly, what are the research to installing bat houses to support
stabilized after hitting bottom. We’re questions we need answers for to these voracious insect-eaters, each
also seeing welcome signs of juvenile better advance recovery? little action can have a positive
recruitment, which means some J. Paul White: Understanding distances impact on learning more about their
individual bats choose wisely in their traveled and how bats use the populations and/or supporting their
hibernation strategies and/or are landscape surrounding permanent survival as an important part of
genetically better suited to cope with hibernation sites during movement Wisconsin ecosystems. Find more
the deadly fungal pathogen causing between winter and summer habitat information about ways to help on
white-nose syndrome. can aid management decisions for this Bat Frequently Asked Questions
species. For example, it makes little web page.
5 Wisconsin Bat Program • 2021
Winter Surveys Show Average 89%
Drop In Bat Populations At 55 Sites
DNR staff and Virginia Tech researchers count
hibernating bats in Wisconsin in 2015.
Photo: Joseph Hoyt
By Jennifer Redell 55 sites in early 2020. with smaller populations reduced by
DNR Conservation Biologist, Bat WNS to zero bats. Declines averaged
Program Cave and Mine Specialist Hibernating bat populations 89% from their pre-WNS average
previously exposed to WNS, populations at specific sites.
Wisconsin Bat Program staff collected particularly in years two and three
data on bat populations, species and of WNS infection, observed steep Wisconsin’s only site in its seventh
distribution from bat hibernacula declines. We continued to see bat year since infection still had four
infected with white-nose syndrome at populations in some hibernation sites bats hibernating in it, including one
Bat population at hibernation site where WNS was first detected in Wisconsin
1200
Little brown bat
Big brown bat
1000 Eastern pipistrelle
Northern long-eared bat
800 TOTAL (all individuals)
Individuals
600 2009- tree down over entrance
2014- WNS detected in March
400
2015- WNS second year
200 2016- WNS third year
0
1994 1996 1998 2000 2001 2003 2005 2007 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
6 Wisconsin Bat Program • 2021
northern long-eared bat. That handful These datasets have been entered
of bats found in 2020 represents a into the Cave & Mine Catalogue
Sobering Numbers
99.5% reduction from the site’s pre- and added to the Natural Heritage
WNS average. Since the disease was Inventory, where the location and
first detected in 2014, at least 64 sites other information will help the state • 35 U.S. states and 7 Canadian
in 25 Wisconsin counties have been and private citizens protect and provinces confirmed with
confirmed as WNS-positive or WNS- manage them. Key findings from the WNS
suspect. site visits are highlighted below. • 4 more states confirmed with
the fungus P. destructans
(Pd), causing the disease
• 12 bat species confirmed
with WNS, 6 more with Pd
• 5.7 to 6.7 million bats
estimated dead of WNS as of
2011
• Wisconsin: 64 sites in 25
counties confirmed as WNS
positive or WNS suspect.
• Bat population changes have
ranged from minor increases
at a very few sites to 100%
declines where no bats
remain in a given cave or
mine.
Notable Observations In 2019-2020 pre-WNS average.
Hibernation Season • The site where WNS was first
detected in Wisconsin, now in
• White-nose syndrome has now its seventh year of infection,
affected cave bat populations has experienced a 99.5%
in Wisconsin for seven population decline when
hibernation seasons and the compared to baseline data, as
WNS fungus is considered see in the graph on page 5.
present in hibernation sites • The DNR has focused
statewide. on understanding bat
• Two of Wisconsin’s largest survivorship, immigration/
surveyed sites are down 87% emigration and fidelity to
and 71% from their pre-WNS hibernation sites. To this end, Photo: Jennifer Redell
average populations. Both DNR and our Virginia Tech Condensation forms on an
sites originally held tens of partners banded over 1,800 eastern pipistrelle bat.
thousands of little brown bats bats between fall 2019 and
and other species. Both sites spring 2020.
are now in their fifth year of • We continue to locate a few
infection. “long-term survivor” bats in
• Hibernacula now in year six the sites where they were first
of disease progression have banded before discovery of
experienced an overall decline WNS in Wisconsin in 2014.
of over 89% compared to the
7 Wisconsin Bat Program • 2021
Cave & Mine Catalogue Update
Wisconsin’s Bat year we continued to provide support
to the project, the goal of which is
Data Aids National to determine if immunization of bats
against WNS improves their survival
Species Status and/or reduces the occurrence of
the disease. In 2020 two potential
Assessments vaccine candidates were tested for
effectiveness in little brown bats
By Jennifer Redell in the field. Additionally, timing
DNR Conservation Biologist, Bat of vaccination was tested, both at
Program Cave and Mine Specialist summer maternity colonies and
during fall swarm/early hibernation Little brown bats receive an oral WNS
Results from winter 2019-2020 at hibernacula. vaccine from USGS National Wildlife
hibernacula surveys in Wisconsin will Health Center staff. Photo: Jennifer
help determine possible protections Passive Integrated Transponder Redell
for three bat species nationally. (PIT) systems were installed at the
In spring 2020, the DNR submitted primary bat entrances of two study investigating movement and
bat data to the North American Bat sites in Pierce County in September transmission of Pd/WNS across the
Monitoring Program (NABAT) as part 2019 to monitor activity by research midwest.
of a nationwide data request by bats that were marked with a PIT tag.
the United States Fish and Wildlife More than 300 little brown bats were This ongoing project is providing
Service to help fill in data gaps on vaccinated and distributed among a unique look at sites before WNS
three sensitive bat species being treatment groups at two hibernacula arrived, during the infection, and
considered for federal protection: in Pierce County. During our regular after. In total, 20 sites were visited
little brown bat, eastern pipistrelle winter surveys we opportunistically one to two times in fall 2019 and
bat (aka tricolored bat) and northern re-sighted and processed (scanned, spring 2020. We provided landowner
long-eared bat. These species already band read, swabbed, wing check) access and field support when
receive state protection in Wisconsin, some of these project bats. In necessary. Samples from hibernacula
having been added to the state addition to providing onsite support environments as well as all four cave
threatened species list in 2011. during research trips, local DNR bat species were collected from fall
staff changed batteries on the PIT of 2019 and through spring of 2020,
Hibernacula data submitted to tag systems to allow for continuous ending just before state restrictions
NABAT came from 616 site visits to reading of treatment animals to were enacted due to the pandemic.
133 hibernacula in 29 counties. Sites assess seasonal activity levels and
included beer caves, railroad tunnels, survival. Take A Virtual Tour Of
caves and mines surveyed between Kickapoo Caverns
2010-2020. In total, for the three cave The field trials in early 2020 Finally, if you’re keen to explore
bat species across all survey years, demonstrated the vaccines were an underground space from the
1,045,029 bats were counted. safe for bats, and at least one comfort of home, join me on a virtual
vaccine increased survival in males tour of Kickapoo Caverns, one of
WNS Vaccine Trials Show Promise and significantly reduced levels Wisconsin’s longest cave systems
Since 2014, the Wisconsin Bat of the fungus causing white-nose and an important bat hibernaculum.
Program has worked with the United syndrome. More trials began this fall The online tour hosted by caverns
States Geological Service National in Wisconsin to test specific vaccine owner Mississippi Valley Conservancy
Wildlife Health Center, University candidates. is titled “Home to Hibernating Bats”
of Wisconsin-Madison, Mississippi and is available in two parts on the
Valley Conservancy and Virginia Tech Logistical Support Provided To WNS conservancy’s Youtube channel. The
to develop and evaluate vaccines Transmission Study tour covers general bat ecology,
to help bat populations recover, In 2020 our program continued its white-nose syndrome, how our
including undertaking the first partnership with the University program and partners study bats
vaccine trials in the wild for any of California- Santa Cruz/Virginia and the cave’s geology, history and
disease affecting bats. In the past Tech white-nose syndrome project importance as a bat hibernaculum.
8 Wisconsin Bat Program • 2021
Acoustic Bat Monitoring Update
Volunteers Take To The looked and felt very different this importantly, safely) be conducted
year. Nevertheless, once we figured alone or within a family group. Or
Water, Detect Mixed out how to safely monitor for bats in could it be attributed to an amazing
Results For Bats mid-June, mobile acoustic bat surveys core of coordinators and volunteers
began flooding in. In fact, despite who would stop at nothing to collect
By J. Paul White missing the first two months of the bat data? Both likely account for such
DNR Mammal Ecologist, bat monitoring season, looking at the a strong outpouring of data amidst
Bat Program Lead numbers – 253 acoustic surveys in 48 very trying circumstances. A sincere
(of 72) counties – one would not have thank you from the Wisconsin Bat
A Year Like No Other known our volunteers were restricted Program to everyone who participated
Unfortunately, due to....well, you by a pandemic. Perhaps their survey in the 2020 acoustic bat monitoring
know the rest of that sentence all effort was a result of an outdoor season!
too well. It’s no mystery why things activity that could easily (and more
2020 2019
150 participants 393 participants
253 surveys 376 surveys
48 counties 50 counties
109 paddling surveys 113 paddling surveys
100 driving surveys 135 driving surveys
44 walking surveys 128 walking surveys
70 surveys in Vilas County* 73 surveys in Vilas County
*County with the most acoustic surveys
Acoustic detector mounted on a kayak.
Photo: J. Paul White
Sobering Results For Two Species But catalogued. Unfortunately, not one of and streams, a finding from the bat
Better News For Little Brown Bats the nearly 15,000 bat encounters was diet study Amy Wray summarizes on
Volunteers, DNR staff and partners classified as a northern long-eared page 15 I think we can all agree that
like the United States Forest Service bat and only six were labeled as calls more little brown bats eating flies,
took part in the shortened 2020 of the eastern pipistrelle bat. The midges and mosquitoes is a good
acoustic bat monitoring season. Most acoustic silence is, regrettably, also thing. The frequency of detection is
surveys (94%) were one- or two- reflected in our winter hibernation likely bolstered by that fact that 84%
person surveys and on average lasted surveys, in which each year fewer bats of water surveys detected little brown
one hour and 20 minutes. The most of either species are observed or in bats and there were more of such
surveyed areas in Wisconsin this year some cases, not found at all. surveys than either driving or walking
were aquatic waterways (109 surveys) routes.
– thank you Vilas County! – while Fortunately, it wasn’t all bad news.
100 surveys were driven and 44 were For every three acoustic surveys Big brown bats and hoary bats were
walking routes. completed, two detected a little found on roughly 75% of all surveys
brown bat, which is good news. Since completed, making them the most
From these surveys, over 14,900 bat little brown bats commonly forage on frequently encountered species
calls were collected, analyzed and aquatic insects found at rivers, lakes followed by little brown bats (65.2%),
9 Wisconsin Bat Program • 2021
Hoary bat.
Photo: Heather Kaarakka
eastern red bats (67.2%) and silver-
haired bats (36.4%).
See page 10 for a map of most
commonly detected species. The sunset over Little Lake Butte Des Morts
just before conducting a bat survey.
Eastern pipistrelles and evening bats Photo: J. Paul White
were found only on a total of five
surveys and there were zero northern nationwide data request by U.S. Fish surveyors are active when many folks
long-eared bat encounters. and Wildlife Service to help fill in data are inside for the night, there are
gaps on sensitive bat species being opportunities to observe interesting
With the multitude of threats bats considered for federal protection. The nighttime behavior or rare wildlife.
continue to face from white-nose species -- little brown bats, eastern In some cases, we’ve passed along
syndrome to wind energy-related pipistrelles and northern long-eared observations to DNR species experts
mortality, the Wisconsin Bat Program bats – are already on Wisconsin’s that have helped confirm species in
will continue to collect acoustic bat threatened species list. Acoustic new locations or where they haven’t
data from this highly mobile and data that fit the service’s request been observed for many years, if not
secretive group of mammals to assess came from acoustic bat driving decades. Here are a few observations
Wisconsin’s bat population at the transects and stationary sources. surveyors turned in from 2020 routes:
local, state and regional level. In total, the Wisconsin Bat Program • Driving route – Central Lake
submitted 32,482 acoustic files from Michigan Coastal 1 (Shawano
A Call For Data mobile surveys spanning seven years County) – “Saw a barred owl, two
In spring 2020 the Wisconsin Bat (2013-2019) and 313,046 acoustic porcupine, three raccoons, many
Program submitted acoustic bat data files from five stationary long-term deer. Heard whip-poor-wills in
to the North American Bat Monitoring bat monitoring stations (2007-2017). Navarino State Wildlife Area and
Program (NABAT) as part of a These data were not only collected eastern gray tree frogs.”
by DNR staff but also federal partners • Paddling route - Little Tamarack
like the U.S. Forest Service, tribal Flowage survey (Vilas County)-
partners from the Bad River Band of “What a beautiful evening for a
Lake Superior Chippewa Indians and bat survey! So lucky to have my
volunteers. daughter and son-in-law to share
the experience.”
Notable Notes From This Year • Walking route - Sanders Park
We encourage you to report (Racine County) - “Nice evening,
your supplemental observations but bits of rain near 3/4 mark
whether they relate to bat activity, - hence early quit. Had trouble
the functionality of the detector walking that far - this lockdown
or other interesting notes. From has eliminated staying in shape.
birds, to amphibians, to mammals, Or whatever excuse is needed.”
to local weather conditions or
Big brown bat. other “interesting” comments, we Stay safe and best wishes for 2021.
Photo: Dave Redell will happily accept all notes. Since
10 Wisconsin Bat Program • 2021
11 Wisconsin Bat Program • 2021
Roost Monitoring Update
Even A Global Pandemic Couldn’t
Stop Bat Monitoring Volunteers From
Surveying Bats This Year
By Heather Kaarakka bats were from sites that house both which gives a little more evidence
DNR Conservation Biologist, little brown bats and big brown bats that bat populations are possibly
Bat Program Roost Monitoring or it is still unknown which species stabilizing after white-nose syndrome
Coordinator uses the roost. (WNS). Some little brown bat roosts
even went from zero bats in 2019 to 10
Like most things this year, the This year’s Great Wisconsin Bat Count to 20 bats in 2020. It’s difficult to say
pandemic played a role in how continued although the pre-volancy whether this is evidence of increasing
summer bat roost monitoring worked count – the count taken before pups populations or whether bats are
in 2020. Social distancing and safer- begin flying (volancy refers to flight) still moving among roosts as we’ve
at-home directives meant volunteers -- was delayed until mid-June. Roost discovered that they do quite a bit.
could not travel to or gather at monitors surveyed at 90 roosts in We also know there’s no set number
several of our large little brown bat June and 125 roosts in July. The first of bats at a roost and bat counts can
roosts to count bats and delayed our count in June aims to record adult change dramatically even daily.
annual Great Wisconsin Bat Count. colony sizes and the second count in
Bat monitoring volunteers are July records numbers in colonies after Little brown bats and eastern
resilient, however, and surveyors pups start flying. These differences pipistrelles continue to be the
still completed nearly 600 bat in numbers before and after pups fly hardest hit by white-nose syndrome
counts at 178 roost sites. Even more can give us a sense of reproduction at monitored bat houses and building
impressively, they monitored more in colonies. We see increases in bat roosts. While little brown bats are
roosts than ever, adding several numbers at almost every roost site starting to show some evidence of
new little brown bat roosts to our (and in acoustics surveys too) after colony stabilization and possibly even
database as well as 12 big brown bat juvenile bats begin to fly. See our recovery, eastern pipistrelles were not
roosts. infographic below for this year’s observed this year at two of the three
numbers and read more about bat summer roosts monitored. This year,
In 2020, volunteers counted a total roost monitoring in the 2020 Annual again, summer roost counts of these
of 12,844 bats, not so different from Roost Monitoring Report. two bat species mirror low numbers
the 13,408 bats counted during 774 recorded on acoustic surveys. We
surveys in 2019. Based on the highest 2020 Counts Add To Evidence Bat will continue to watch these known
count from each site, volunteers and Populations Are Stabilizing After eastern pipistrelle roosts closely in
landowners counted 7,771 little brown White-Nose Syndrome the coming years and hope that we
bats, 4,792 big brown bats but only six Like 2019, this year’s bat roost counts see bats return.
eastern pipistrelles. The remaining were similar to the previous year,12 Wisconsin Bat Program • 2021
Study Explores Linkage Between
Roost Characteristics & Bat Declines
While we were not able to start our
A little brown bat snug in a barn
project marking bats at persisting
in Jefferson County in 2019.
colonies this year, we began a
Photo: Heather Kaarakka
study looking at why there may be
differences in declines at little brown
bat roost sites. By using yearly colony
estimates collected since 2010 by
landowners and volunteers at 35
sites, we can investigate the change
in colony size year-to-year. From
these changes we can learn when the
biggest declines occurred and start
comparing the roosts using factors
such as age of the roost, how close it
is to permanent water and distance
to hibernation sites. This winter we’re
hoping to get an idea of whether
there are habitat and landscape
aspects that impact how big declines
have been and how quickly colony
sizes may stabilize after WNS.
Thermal Imaging
Project Heats Up
Another project we were able to to continue another season of daily We’re still analyzing footage, but at
pursue in 2020 used thermal cameras counts at several little brown bat one site, bat numbers and behavior
to record bat numbers and behaviors. roost sites. We placed cameras later appear similar to last year, which
Since these cameras are remote and than we hoped due to the pandemic provides more evidence some little
don’t require direct interaction with but also left them later into the fall to brown bat colonies may be stabilizing.
landowners or the bats, we were able see colony dynamics in late summer.
Thermal cameras allow
surveyors to see bats in the
dark using heat. The warm
bats and their roost are
orange and yellow while
the cooler background is
blue. Right: Three bats are
emerging from a bat condo
in Trempealeau County.13 Wisconsin Bat Program • 2021
Thank You For Your
Dedication & Information
Even a global pandemic couldn’t drives around with a microphone and the impacts that threats like
stop bat monitoring volunteers on their car to record bat calls. white-nose syndrome are having
from surveying bats this year, and it The information that hundreds of on Wisconsin’s bats. Thank you to
reminds us how much the Wisconsin volunteers have helped collect for everyone who surveyed bats this
Bat Program has benefitted from the over a decade have opened doors year and at any point since 2008. The
dedication and hard work of everyone to research that can help us learn Wisconsin Bat Program would be very
who counts bats at roost sites or more about bat biology and ecology different without you.14 Wisconsin Bat Program • 2021
Wisconsin-Based Research
Continues To Illuminate WNS
Studies with our research effects of research or census‐ with respect to how WNS
partners using data collected in related visitation frequency dynamics and impacts may differ
Wisconsin culminated in several on populations. We found no among bat species. Targets for
new publications over the past evidence that more frequent visits WNS research were highlighted.
months. These results are advancing decreased population growth This tool will be used to maximize
understanding of impacts of white- rates for any of these species. the likelihood of achieving bat
nose syndrome and informing how we These results indicate that conservation goals within the
might support bat populations during visitation frequency (1–3 research context and limitations of specific
recovery. visits per year) had undetectable real‐world scenarios.
• Results confirmed that bats are impacts on bat population growth Report: Identifying research needs
most likely to spread Pd when rates both with and without the to inform white‐nose syndrome
they are highly infectious, but additional stress of an emerging management decisions, as seen
have reduced mobility and the infectious disease. in Conservation Science and
timing of Pd introduction has had Report: Impact of censusing and Practice.
consequential effects for some research on wildlife populations, • Diverse microbial skin
bat communities. as seen in Conservation Science assemblages, including fungal
Report: Mobility and and Practice communities, may prevent
infectiousness in the spatial • In our neighboring state of pathogens (Pd) from colonizing
spread of an emerging pathogen, Michigan, several banded, male a bat’s skin. Samples collected
as seen in Journal of Animal Little brown bats aged 18-25 from bats in Wisconsin were used
Ecology (pre-print). years have been recaptured to determine that bat species
• Lower levels of Pd in caves in a hibernaculum where WNS with low skin fungal diversity and
and mines consistently meant likely has been present since abundance were more susceptible
delayed onset of WNS in bats, 2013–2014, indicating that these to WNS than bat species with
fewer and less severe infections, old and apparently healthy males higher fungal diversity and
and reduced population impacts are in their seventh season of abundance (big brown bats).
across regions. Extensive and exposure to the disease. These Report: Skin fungal assemblages
persistent environmental findings have been mirrored of bats vary based on
reservoirs led to early and by several similar recaptures susceptibility to white-nose
widespread WNS presence and at a hibernation site here in syndrome, as seen in The ISME
severe population declines. Wisconsin. This gives us hope that Journal.
Continental differences in the certain individual bats can live for • Instead of avoiding warm and
persistence or decay of Pd in the many years despite the presence deadly underground sites where
environment altered infection of WNS in their hibernaculum. the WNS fungus thrives, bats
patterns in bats and influenced Report: Exceptional Longevity continue to use them year
whether host populations were in Little Brown Bats Still Occurs, after year. Bats are mistakenly
stable or experienced severe despite Presence of White-nose preferring sites where fungal
declines from this disease. Syndrome, as seen in the Journal growth is high and therefore
Report: Environmental reservoir of Fish and Wildlife Management their survival is low. This is one
dynamics predict global infection • Using a cross-disciplinary of the first clear examples of
patterns and population impacts approach, diverse subject an infectious disease creating
for the fungal disease white-nose matter experts created an an “ecological trap” for wildlife.
syndrome, as seen in PNAS. influence diagram used to Report: Continued preference
• Out of concern that our own identify uncertainties and for suboptimal habitat reduces
research and monitoring visits prioritize research needs for WNS bat survival with white-nose
could harm hibernating bat management. Critical knowledge syndrome, as seen in Nature
populations, we quantified the gaps were identified, particularly Communications.15 Wisconsin Bat Program • 2021
Diet Study Reveals Bats’
Importance To Ecosystem
Little Brown Bats’ Big Appetite
Mosquitoes & Ag Pests Beware
A single bat can eat the
equivalent of half its body
weight in insects every night.
Amy Wray, UW-Madison
PhD researcher, identified,
quantified, and analyzed what’s
on the menu for Wisconsin
bats and why that matters. She
found:
• Bats consumed 17 distinct
types of mosquitoes,
including nine species
known to carry West Nile
Amy Wray, right, and field virus.
technician Jamie Wang set • Bats consumed 24 species of
up solar-powered traps agricultural pests, including
in 2018 to capture the black cutworm moths,
night-flying insects bats eat. fruit tree leafroller moths,
Photo: Elaine Swanson tarnished plant bugs and
spotted wing drosophila.
By Amy Wray brown and big brown bat declines • Little brown bats’ smaller
University of Wisconsin-Madison from white-nose syndrome. size makes them more
PhD Researcher agile and better adapted
Different Bat Species for capturing smaller prey.
A University of Wisconsin-Madison Eat Different Foods Sadly, these bat species are
study examining the diets of bats in Overall, we found that little brown one of the three species in
Wisconsin has revealed that different and big brown bats eat different Wisconsin most decimated
bat species target different insects prey, with big brown bats eating by white-nose syndrome, a
and highlighted the importance of more beetles and caddisflies and deadly disease of bats.
little brown bats to agriculture and little brown bats eating more moths • Declines in little brown bats
the nocturnal food web. and flies (especially certain types of due to white-nose syndrome
midges). These results were mostly may lead to short-term
Over a 4-year period, we collected 560 consistent with previous studies on increases in the abundance
guano samples to analyze bat diets bat diets in other regions, except of certain insect prey.
using molecular methods, captured Wisconsin bats tended to consume
and identified 2,003,493 insects in more insect prey typically associated
order to quantify changes in bat prey with aquatic habitats. We also found prey, further establishing their
communities, and recorded 6,245 that even though insect communities sophistication as nocturnal predators.
nights of bat calls to understand changed from week to week, bats
changes in bat activity. This study tended to eat their favorite foods Smaller Bat Species Suffer
also incorporated roost emergence regardless of the abundance of other Bigger Declines At Study Sites
counts from the Great Wisconsin Bat options. These findings suggest that Between 2015 and 2018, we
Count, with the goal of understanding both little brown and big brown unfortunately observed little brown
the ecological consequences of little bats selectively hunt for particular bat emergence counts decline16 Wisconsin Bat Program • 2021
Guano samples collected for
analysis of bat diets using DNA. Big
brown bats have big brown poops
Captured insects are sorted before (left) while little brown bats have
identification and counting by microscope. little brown poops (right).
Photo: Amy Wray Photo: Amy Wray
by about 95% at our study sites. see a statistically meaningful decline
Similarly, we detected a nearly 80% in low-frequency bat activity, which
decline in high-frequency acoustic corresponds to big brown bats but
activity around the study sites, includes other species such as hoary
which corresponds to little brown bats and silver-haired bats.
bats but also includes tricolored
bats, northern long-eared bats and Declines In Little Brown Bats May
eastern red bats. Based on previous Have A Bigger Impact On Food Web
studies and hibernacula surveys, From our insect trapping surveys,
these declines in little brown bats we found that between 2015 and
are largely attributable to white-nose 2018, the total abundance of insects A Cecropia moth captured in a
syndrome. In comparison, we found declined by nearly 50% at our black-light trap was not found in
that big brown bat emergence counts study sites. The reason for these the diets of Wisconsin bats.
declined by 40%, but this trend was declines is not totally clear and Photo: Amy Wray
mainly driven by a decline in a single could represent either a natural
large roost which may have been fluctuation or a declining trend after declines from white-nose
related to movement rather than to warranting further investigation. syndrome were observed among
white-nose syndrome. We also did not However, our study was mainly set little brown bats in Wisconsin. Since
up to address how bat population Chironomidae are one of the favored
declines influenced the abundance prey items of little brown bats, these
of insects, which we investigated results suggest that declines in little
by setting up insect traps near bat brown bats may lead to a local-scale
roosts and at paired “control” sites increase in the abundance of these
further away with lower bat activity. midges. While many studies have
shown other bat species controlling
When comparing these different insect abundance, including
experimental treatments, we found suppressing agricultural pests, our
that most insect groups displayed study suggests that little brown bats
similar patterns in abundance at may have an impact on other types of
sites near bat roosts and at sites insects too.
far from bat roosts. As a notable
exception, we saw an increase in Little Brown Bats Eat Dozens Of
the abundance of Chironomidae, Species Of Agricultural Pests
a family of midges, at little brown Since ecosystem services provided
bat roost sites compared to control by bats are always important to
A black-light trap full of
sites. These trends were observed quantify, we also looked at how many
Chironomid midges.
in 2016 and 2017, the first two years agricultural pests were present in
Photo: Amy Wray17 Wisconsin Bat Program • 2021
bat diets. At least one agricultural some resistance to white-nose as easily. Cumulatively, our studies
pest species was detected in 45% of syndrome, could potentially fill provide more evidence that little
little brown bat guano samples and in the ecological role of little brown brown bats not only influence prey
34% of big brown bat guano samples. bats as predators. We did this by communities, but also appear to have
Interestingly, before declines from comparing diet composition before a unique role as insect predators in
white-nose syndrome, little brown and after declines from white-nose the nocturnal food web. In light of
bat guano samples contained more syndrome, specifically with the goal bat population declines from white-
agricultural pests (53% of samples of quantifying whether big brown nose syndrome and other factors,
had at least one pest species) in bats would select more of the prey continuing to protect and support
comparison to guano samples previously consumed by little brown bats therefore remains important
collected after declines from white- bats. We found that following little from an ecosystem-wide perspective.
nose syndrome (16% of samples brown bat declines, there was little
had at least one pest species). change in the diet composition of These studies would not have been
This change in little brown bat diet big brown bats, and the amount of possible without the support of
composition might indicate that dietary overlap between the two bat the DNR, the many volunteers who
larger populations of bats are more species also did not increase over contributed to emergence counts,
likely to consume a higher diversity of time. While these species may appear and the landowners who allowed
insects overall, and therefore may be similar at first glance, little brown sampling of bat guano and insects
more likely to eat a greater number of and big brown bats are ecologically on their property. Study sites also
agricultural pests. distinct as predators. Little brown included Governor Dodge State
bats, with their smaller body size, Park, Yellowstone Lake State Park
Little Brown Bats, Hard Hit By are more agile and better adapted and Silverwood County Park, and
WNS, Have A Unique Role As for capturing smaller prey. As such, we are most appreciative of their
Predators In Food Web big brown bats may be somewhat participation.
Finally, we assessed whether big constrained by their larger body size
brown bats, which demonstrate and cannot capture smaller insects18 Wisconsin Bat Program • 2021
Bats With White-Nose Syndrome
Prefer Suboptimal Habitats Despite
The Consequences
Excerpted from
Virginia Tech News Sources
Since 2006, a fungal disease called
white-nose syndrome has caused
sharp declines in bat populations
across the eastern United States.
The fungus that causes the disease,
Pseudogymnoascus destructans (Pd),
thrives in subterranean habitats
where bats hibernate during the
winter months.
Bats roosting in the warmest sites
have been hit particularly hard, since
more fungus grows on their skin,
and they are more likely to die from
white-nose syndrome, according to a
new study by researchers at Virginia
Tech.
But instead of avoiding these warm
and deadly sites, bats continue to use
them year after year. The reason? Bats
are mistakenly preferring sites where
fungal growth is high and therefore
their survival is low. This is one of the
first clear examples of an infectious
disease creating an “ecological trap”
for wildlife.
Dr. Kate Langwig and Dr. Joseph Hoyt, Joseph Hoyt of Virginia Tech gently swabs the forearm of a hibernating Big brown bat in
both assistant professors from the 2017 as part of a multi-year effort to understand the impacts of WNS.
Department of Biological Sciences Photo: Jennifer Redell
in the College of Science, have been
studying little brown bat (Myotis “We see that there is a shift across still choosing to roost in warmer
lucifugus) populations in Michigan the regional bat population over sites, even though colder sites
and Wisconsin since 2012, before the time,” said Skylar Hopkins, a previous are available. But on average, bat
fungus first reached those states. postdoctoral scholar at Virginia Tech roosting temperatures have declined,
This long-term study was the perfect and now assistant professor at North because the colder-roosting bats
opportunity to see if bats alter their Carolina State University. have had higher survival rates.”
preferences across hibernacula, or
hibernation sites, in response to the “When we look at the population Now that they know that bats are
invasion of white-nose syndrome. post-invasion, we see that more preferring high mortality sites,
than 50 percent of the bats are Hopkins hopes that their data can19 Wisconsin Bat Program • 2021
be used to think about which sites about the warm sites that are acting
researchers and conservationists as ecological traps and whether we
need to prioritize for conservation should be trying to manage those
and how to conserve them. sites in a different way. Maybe there
are interventions that should be done
“Because we know that bats are doing at those si tes to prevent most of the
better in the cold sites, the cold sites population from going there each
may be good ones for us to conserve,” year and having these big mortality
said Hopkins. “We can also think more events.”
Doctors Langwig, Hoyt and Kilpat-
rick collect samples of the WNS
fungus from hibernating Big brown
bats in Wisconsin in 2015.
Photo: Jennifer RedellYou can also read
