bat research

Bat Flash! NatGeo’s “Virus Hunters” Spreads Groundless Claims About Bats

Bat Flash, Disease

11/2/2020

By Merlin Tuttle

I viewed the National Geographic documentary series titled, “Virus Hunters,” with substantial disappointment. Warnings of growing reliance on bush meat and industrial farming were justified. However, coverage of wildlife too often exaggerated risks from bats. 

Bats are exceptionally easy to trap in large numbers, have few defenders, and are easily misunderstood. This makes them prime targets for scary speculation that is exceptionally lucrative in gaining media readership and unprecedentedly large grants. And unfortunately, the opinions of leading virologists who doubt that virus hunters can predict or prevent pandemics were left unmentioned.

The 2017 study that reported more viruses in bats than in other mammals sampled nearly twice as many bats as all other mammalian orders combined. Since most viruses have yet to be discovered, new ones can be found wherever we look. And because bats are an ancient group of mammals, it is not surprising that they sometimes host ancestors of modern species. A 2020 study, concluding that bats harbor no more viruses than other animals, has been largely ignored.

Hundreds of thousands of Straw-colored fruit bats (Eidolon helvum) beginning their evening departure from a city park in Ivory Coast, Africa. Cities often provide the only homes safe from commercial hunters who sell them for people to eat. Despite such large numbers having lived in close association with humans throughout recorded history, they have not caused disease outbreaks. Their remarkable safety record casts grave doubt on recent speculation of their being dangerous carriers of disease.

Documented transmission of any disease from a bat to a human is exceedingly rare, and the risk is near zero for anyone who simply does not handle them. Hundreds of thousands of bats live in city parks across Africa. Yet there are no verified cases of Ebola transmission, despite huge efforts to find such an association. In fact, despite repeated assertions, there are no documented cases of Ebola, MERS, or SARS-CoV-2 viruses ever having been found in a bat, much less transmitted from a bat to a human. In truth, bats have one of the world’s finest records of living safely with humans. For example, in Austin, Texas countless thousands of visitors have safely viewed the spectacular emergences of 1.5 million free-tailed bats for decades without a single incident of disease transmission.

I have safely studied bats for more than 60 years, including publishing five articles in their defense in National Geographic. It is sad indeed to see bat survival threatened due to the same, traditionally respected, organization spreading groundless claims that bats can defecate deadly viruses by simply flying overhead. People seldom tolerate and often kill animals they fear, and none are more vulnerable than bats. Please, in your future coverage of Virus Hunters, put bat risks and benefits in perspective. The irresponsible spreading of falsehoods needs to stop.

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Bat Flash! Unveiling the Real World of Bats in a Time of Misinformation

Bat Flash

9/15/2020

By Danielle Cordani

The avalanche of speculative reports associating bats with COVID-19 seems never ending. However, at a time of scary misinformation, bat researchers and conservationists worldwide are discovering new reasons to appreciate bats, some decades in the making.

In Central America, researchers from the Free University of Berlin analyzed communication between bat mothers and their pups. Just like humans talking to a baby, adult greater sac-winged bats (Saccopteryx bilineata) alter the “color” and pitch of their pup-directed vocalizations. Not surprising, this breakthrough indicates parent-offspring communication in bats is more complex than previously assumed. Further investigation of social feedback during vocal development in young bats may reveal even more shared language features between bats and humans.

A greater sac-winged bat (Saccopteryx bilineata) in Panama.

Across the Atlantic, a team of scientists in Africa used novel methods to describe more accurately the differences among bats. It turns out—as is common when studying bats—there is more than meets the eye. Comparison of the penis bones, echolocation calls, and genes of African vesper bats revealed three new species and two new genera. The discovery could mean new identification techniques for the often-indistinguishable group and clearer protections for unique bats and their ecosystems.

A banana pipistrelle (Afronycteris nana), showing its tiny size and one of its adhesive pads used for clinging to the inside of unfurling leaves.
Banana pipistrelles roosting in an unfurling banana leaf in Kenya.
Perhaps the most publicized bat discovery of 2020 was conducted by a group of scientists from Israel. Their groundbreaking study presents never-before-seen evidence of “cognitive mapping” in non-human animals. Using revolutionary tracking technology, Egyptian fruit bats (Rousettus aegyptiacus) proved extremely sophisticated and efficient at navigation. Bats relied on goal-directed memory maps rather than landmark cues or sense of smell, seldom foraging at random.

Despite great scientific advances, improved communication is needed to successfully interpret and share bat values with others. Douglas MacFarlane and Ricardo Rocha have taken this into account. By applying conversation psychology, they provide communication guidelines that can help neutralize negative associations between bats and disease. Even scientists with good intentions may inadvertently undermine their message by failing to debunk misinformation.

Falsehoods and fear are easily created through misunderstandings. For example, in Iran and the Mediterranean, myths of mercury-containing “bat nests” began circulating over social media, inciting needless environmental destruction. In response, Iranian researcher, Dr. Hossein Zohoori, teamed up to create Mercury Mirage, a powerful documentary that discredited the untruths with stunning visual evidence.

We congratulate all who are persevering in unveiling the real world of bats in times when investigation, attention and resources have been so severely misdirected toward disease speculation. Discoveries of bat sophistication and values, and effective communication, have never been more important.

An Egyptian fruit bat (Rousettus aegyptiacus) pollinating a baobab flower in Kenya.
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Bat Flash! Misleading Article Harms Bats and Public Health

Bat Flash

7/17/2020

By Merlin Tuttle

A disappointing number of authors and publishers are spreading the false narrative that bats are exceptionally high-risk sources of deadly viruses. The July 12 edition of The Washington Post contained an article titled, “Why do bats have so many viruses?” The author, Rachel Ehrenberg, was apparently unaware of the most recent analysis of viral risks.

We urge Rachel and other Washington Post journalists to review Mollentze and Streiker’s April 28, 2020 comprehensive analysis, published in the Proceedings of the National Academy of Science. Their paper titled, “Viral zoonotic risk is homogeneous among taxonomic orders of mammalian and avian reservoir hosts” concluded that bats are no more likely than other animals to host disease.

Virus hunters have focused search efforts disproportionately on bats, apparently because bats are exceptionally easy to sample in large numbers and have few defenders. Referring to the Covid-19 outbreak, Zhang and Holmes concluded that surveillance of coronaviruses in animals other than bats is critical to protecting against future outbreaks.

Sensational speculation, exaggerating bat association with scary viruses, has led to a serious bias that impedes our understanding of viral pandemics and creates a perfect storm of media publicity. This feeds into our broader academic crisis—the misallocation of large grants for splashy, attention-getting “research” that promotes career advancement over high-quality, reproducible scientific investigation. Such bias threatens to misdirect limited public health resources and halt, or even reverse, decades of conservation progress.

It’s time publishers, authors, researchers, and decision-makers let go of the premise that bats are uniquely dangerous sources of disease and end biased sampling and unsupported speculation. Instead, we need to identify true sources of human infection and insist on accurate reporting that leads to actual prevention.

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49th NASBR in Kalamazoo, Michigan

Conservation

The 49th Annual North American Symposium on Bat Research was held in Kalamazoo, Michigan on October 23-26, 2019. It was hosted by Amy Russell and Maarten Vonhofm amidst a quintessential Midwestern autumn. There’s no better place to keep up with the latest bat research technologies and discoveries or for graduate students to explore career options. Many of the researchers attend every year, developing lasting friendships and invaluable networking opportunities. Not surprisingly, this is Merlin’s favorite group. He hasn’t missed a meeting in 49 years. This year, Merlin joined Brock and Sherri Fenton and Price Sewell in presenting an enthusiastically received pre-conference workshop on bat photography.

Our hospitable hosts, Amy Russell and Maarten Vonhofm.

Merlin especially enjoys opportunities to encourage students in conservation-related careers and takes great pride in the achievements of those he has helped. Four joined Merlin for the organization’s annual “Lunch with a Mentor” program to discuss career path choices, conservation interests, and of course, to hear a few of Merlin’s wild adventure stories.  They also got a perspective from Teresa who sat in on the meeting. (Check out Advice for Young People Interested in Science and Conservation) (more…)

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A Model Example of Bat Recovery Potential

Conservation, Field Work/Photography

By Merlin Tuttle
9/25/19

 

Long Cave, in Kentucky, like many others, has a long history of human occupation with little record of prior use by bats. It was mined for saltpeter, a key ingredient of gun powder, during the war of 1812 and was subject to commercial tourism, probably beginning at about the turn of the century, ending by the 1930s.

Rick Toomey and Merlin Tuttle waiting for group to enter bat-friendly gate at Long Cave.

 

Huge passages trapped cold air and remained cool year-round, offering major opportunities for bat hibernation. Roost stains from past bat use were widespread, and the cave clearly had potential to shelter millions. As recently as 1947 some 50,000 bats, presumed to be largely the now endangered Indiana myotis (Myotis sodalis), continued to return in winter. Nevertheless, entrance barriers built to exclude non-paying tourists, increasingly restricted air flow, eventually culminating in a concrete wall and a nearly solid door. (more…)

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Experiencing Texas Bats

Field Work/Photography, Members

By Renee Anna Cornue
4/22/19

As MTBC’s Photo Collection Administrator, much of my responsibility lies behind a computer screen. I’d seen thousands (about 120,000 if we’re being real) of photographs from Merlin’s most-active field work days, preparing me for what to expect as much as photographs can. I’d seen mist nets, harp traps, banded bats, guano piles, and evidence of the bats’ incredible diversity.

Though fortunate to see Austin’s bats in a variety of ways, I’d never worked with bats first-hand. On this trip, I was most excited to step away from the desk and learn how bats are studied in the field, especially surrounded by knowledgeable and talented peers.

As with MTBC’s past adventures, our trip was a hands-on working trip with invaluable time and expertise contributed by leading colleagues from varied specialties. We were in the company of expert bat researchers, photographers, videographers, rehabilitators, consultants and passionate citizen scientists as we searched for some of the least known bats in the U.S.

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Counting Free-tailed Bats in Bridges

Bats, Conservation

9/10/18
By Merlin Tuttle

Merlin inspects Brazilian free-tailed bats (Tadarida brasiliensis) moments after removing them from their bridge crevice roost for counting.

For many years we’ve wondered just how many Brazilian free-tailed bats (Tadarida brasiliensis) could cram into a single 18-inch-deep bridge crevice. Accurate counts of large colonies are difficult no matter how they’re made. However, when estimating bridge colonies, it would help if we knew the number, using an average horizontal foot of crevice.

The solution seemed easy. Two years ago, Glen Novinger, an MTBC member and I, inserted two, three-quarter-inch-thick wooden frames, each encompassing a square foot of interior space, into bridge crevices of the same width while the bats were out feeding. The idea was to later slowly remove them, forcing those roosting inside to exit into a cloth-lined bag from which we would count them.

However, the bats were full of surprises. The first night we waited patiently till half an hour after we’d seen the last ones leave—or at least that was what we thought! But when we approached to install our devices, roughly half remained inside. I couldn’t help but wonder how many emergence counts had missed those that, for whatever their reasons, didn’t emerge at sundown. (more…)

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Texas Department of Transportation Celebrates Bats

Bats, Conservation, Lectures

8/28/18
By Merlin Tuttle

 

The Texas Department of Transportation (TxDOT) has set world records when it comes to helping bats, and that special help is paying big dividends for Texans and for countless visitors. Thanks to the enthusiastic early leadership of Supervising Bridge Engineer, Mark Bloschock and the continuing efforts of Stirling Robertson, now in charge of Strategic Projects, and John Young, an Environmental Specialist, TxDOT is taking great pride in its accomplishments.

On August 21, Stirling and John organized a special bat evening for 30 of TxDOT’s most important media and public information officers. They each received a copy of Department’s new guide to bat watching at state bridges, attended my 20-minute presentation at TxDOT headquarters, then joined me for a special Congress Avenue Bridge bat watching evening. We were delighted when we learned that Mark, who is now retired, would be able to join us.

Merlin speaking to TxDOT media and public relations staff.

Merlin entertaining TxDOT staff with bat facts while waiting for Congress Ave Bridge bats to emerge.

The bats performed beautifully, and Stirling reported, “There has been overwhelming positive response to your talk and the whole event. Good stuff!” A big thank you to Stirling for making this event possible! We look forward to future collaboration and many more bats in Texas bridges.

 

 

Emerging bats providing America’s most famous urban wildlife spectacle.

 

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Mosquito Eating in Bats

Bats, Organic Pest Control

8/9/18
By Merlin Tuttle

For decades, bat biologists have debated the extent to which bats prey on, and potentially reduce mosquito populations. However, recent research suggests bats may be eating far more mosquitoes than yet suspected. Amy Wray and associates (2018) relied on newly refined techniques that provide greater sensitivity. In their paper, titled “Incidence and taxonomic richness of mosquitoes in the diets of little brown and big brown bats,” they reported that these common species eat a greater variety of mosquitoes, and catch them more frequently than previously suspected.

A little brown myotis (Myotis lucifugus) in Wisconsin. Just one of these bats can catch 1,000 mosquito-sized insects in a single hour.

They tested guano samples from 22 locations in a range of habitats, across the State of Wisconsin, from May 17 through July 29. Seventy-two percent of little brown myotis (Myotis lucifugus) samples contained mosquitoes representing 15 species, more than twice as many as big brown bats (Eptesicus fuscus). But even the larger big brown bats, previously thought to feed mostly on beetles and moths evidenced mosquito-eating in 33 percent of samples. Frequency of mosquito-eating remained constant throughout the active season in big brown bats but declined slightly in little browns.

Little brown myotis (Myotis lucifugus) from Tennessee.

A third of big brown bats (Eptesicus fuscus) in Wisconsin fed on mosquitoes.

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Bats and Chocolate Production

Bats, Organic Pest Control

By Merlin Tuttle
6/6/18

While conducting her Ph.D. thesis research, Bea Maas and her team (Maas et al. 2013) collected data that would surprise even her. When insect-eating bats and birds were excluded from cacao trees in Sulawesi, Indonesia, the crop yield fell by 31 percent. And when she compared losses due to night versus daytime exclusion, bats versus birds, she discovered that bats accounted for 22 percent of the prevented losses.

A control site in the same study (poles without netting).

To obtain such data, Bea selected 15 plantations where she enclosed 120 cacao trees in 60 exclosures (like huge, mesh cages) constructed of nylon mesh. There were four exclosure treatments per plantation, one daytime, one nighttime, one day and night, and one always left open as a control.

A bat/bird exclosure in Sarawak, Indonesia, built with bamboo poles and commercial nylon monofilament netting with a mesh size of 2 x 2 cm. These were opened and closed like curtains daily.

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