Partnership for Bat Conservation and Management Training

9/19/18
By Merlin Tuttle

John Chenger and Julie Zeyzus interviewing Merlin for training video on bat cave management.

In early August, we accepted a partnership invitation to develop a series of bat conservation and management training videos. Though growing numbers of biologists are studying bats, few have the breadth of experience essential to meet their widely varying conservation needs. Each species has unique requirements. In order to better share my nearly 60 years of personal experience, John Chenger founder of Bat Conservation and Management, and Janet Tyburec founder of Bat Survey Solutions, invited me to collaborate. They are providing video shooting and editing, featuring my narration and illustrations.

Teresa Nichta (left) and Julie Zeyzus shooting slow motion video of Brazilian free-tailed bat (Tadarida brasiliensis) emergence.

 

 

 

Four programs are now being edited. The first, tentatively titled “Win Friends, not Battles,” explains key approaches that have most effectively won long-term cooperation. The second features the worldwide importance of bats. The third addresses greatly exaggerated disease claims, and the fourth deals with assessing cave suitability for bats and special long-term management needs.

Bad gate that caused abandonment by a large colony of cave myotis (Myotis velifer). New owners removed the gate, and the bats are now gradually returning.

Under John’s guidance, we began field shooting on August 15, greatly aided by Teresa Nichta and John’s associate, Julie Zeyzus. For the next 10 days there was little time for sleep or even eating. On my birthday, we spent seven hours filming underground, a great antidote for thinking of getting old!

Measuring roost stains left by a formerly large colony of cave myotis in a Texas cave. Stains can last for centuries, providing an invaluable estimate of past colony size.

 

Illustrating the need for such education, one of the caves we visited in a protected nature reserve, had lost its entire colony of tens of thousands of cave myotis when fire protection permitted entrance blockage by vegetation. Another cave, also well protected by its owner, had overgrowth of an invasive, introduced plant that could have prevented restoration of a formerly large colony. It only took minutes to eliminate the threat.

 

 

 

 

Videoing Brazilian free-tailed bats close-up in crevices between box beams.
Explaining how bat-friendly bridge designs have aided Texas farmers.
Sunset emergence of free-tailed bats.

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Counting Free-tailed Bats in Bridges

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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Mosquito Eating in Bats

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

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.

(more…)

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New Bat House Research Project

Loss of natural homes in caves and old-growth forests is one of the greatest causes of bat decline worldwide. Unfortunately, many former roosts can never be replaced, leaving an increasingly urgent need for alternative shelter. Wildlife Biologist, Steve Barlow, was one of the first to test the suitability of extra large designs, and he has been experimenting for nearly 20 years. Recently he has supplied his Big Bat House design to nature centers, city parks, wildlife refuges, farmers and private landowners.

Last October, Merlin met with Steve and they agreed to collaborate in developing a new, design that they hope will be even more attractive to bats. Their research proposal was generously funded by MTBC members, Joe and Sharon Goldston, with additional help from Steve. In early April Merlin spent two days with Steve and his construction crew in Kansas brainstorming anticipated improvements.

The result is a new modular design that is much less costly to build and lighter in weight. We also anticipate it’s being even more attractive to bats. It can be mounted on just two instead of four poles, and when a first module fills, more can be added, each one housing up to 4,000 bats. Based on past experience it is quite likely that, at some locations tens of thousands can be attracted, as ability to expand will be unlimited.

(more…)

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An Organic Farmer’s Experience with Bat Houses

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View from above prior to roof attachment.  The sealed-in ceiling between the roof and roosting crevices is for enhanced thermal stability.

Nearly 20 years ago, Frank Bibin, a Georgian pecan grower contacted Merlin for advice on attracting bats to help control insect pests in his orchards. He has since gone organic and become an important advocate for building artificial bat roosts.  To learn of his results go to Pebble Hill Grove–About Bats.

Frank’s first small bat houses were put up in 1998. This video, filmed in Frank’s pecan orchard, tells his early story. It took two years to attract the first bats. Thereafter, numbers grew rapidly. Now that local bats are accustomed to using bat houses, new houses are normally occupied within 30-40 days.

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View from entry (bottom), showing 5 newly installed, 3/4″-wide roosting crevices. One of these houses shelters up to 400 bats.

Through years of testing, he has developed many new innovations. His bat houses and mounting accessories are achieving nearly 100 percent occupancy at many locations in the Southeast and are available for purchase at Frank’s website, Pebble Hill Grove–Bat Houses . Parks and nature centers are among his primary customers.  Though there are many suppliers of smaller bat houses, we know of none better than Frank’s when it comes to long-lasting roosts that attract larger numbers of bats. 

How Frank does it… (more…)

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Bat houses help rice farmers in Spain

checking a bat houseWe would like to highlight a recent study of exceptional importance to all who care about conserving bats. As one who has long promoted the potential benefits of attracting bats to artificial roosts, Merlin is especially pleased with the publication of a recent multi-year study documenting the successful attraction of thousands of bats to small, inexpensive bat houses, leading to well documented reduction of rice pests below threshold levels that require use of chemical pesticides.

The study titled, Pest control service provided by bats in Mediterranean rice paddies, appeared in the journal Mammalian Biology and is available for free download at researchgate.net.

A bat house opened to permit checking by researchers

Soprano pipistrelle bats (Pipistrellus pygmaeus), a common bat widespread across continental Europe, east to western Asia Minor, the Caucasus and Siberia

 

The researchers report that properly located bat houses were readily occupied by soprano pipistrelle bats (Pipistrellus pygmaeus), and that as numbers increased damage from rice borer moths (Chilo supressalis) fell sufficiently to eliminate further need for chemical pesticides. They additionally note that the cost of putting up bat houses was 6-8 times less than that of relying on chemical treatments. These authors also provide an invaluable summary of current knowledge of bat values to agriculture. There are numerous opportunities to expand on this pioneering research which is urgently needed. We deeply appreciate the help of Adrià López-Baucells and Oriol Massana Valeriano in providing outstanding photographic documentation of this project.

Iberian rice field where research was conducted

 

Here’s contact info for ADRIÀ LÓPEZ BAUCELLS
PhD student on Bat Ecology and Conservation

Smithsonian Tropical Research Institute – Instituto Nacional de Pesquisas da Amazônia
Lisbon University – cE3c
Museu de Ciències Naturals de Granollers

PERSONAL PAGE
PhD Project Site
Portuguese Research Group Site
Natural Science Museum of Granollers

Tel.: 351 914 413 804

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Bats eating stink bugs

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Common Slit-faced Bat (Nycteris thebaica) eating a green stink bug in flight

Thanks to help from a local macademia grower, Koos Steyn, here in South Africa, we finally got approximately 100 green stink bugs, the most costly pest of macademias, and were able to coax our common slit-faced bat (Nycteris thebaica) to carry a couple of them through  an infrared beam before eating them beyond recognition. In the process we used up nearly all our stink bugs, but on the last shot of the night, after hours of failed efforts, we got a nice photo.  Merlin still isn’t completely satisfied, so we’ll be trying for more.

His next goal is to photograph a Botswanan long-eared bat (Laephotis botswanae) plucking a stink bug off of a macademia branch. This is a real challenge, especially since we still haven’t even been able to catch one of these bats! The nights have been quite cold this whole trip, likely accounting for this failure. But we’ll try our luck again tonight in Koos’ orchard.

 

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