What’s the News: Bats have to use twice as much energy to fly when they’re wet as when they’re dry, a new study in Biology Letters found, which may help explain why many bats refrain from flying in heavy rain.
Posts Tagged ‘bats’
How Does Rain Mess With Bat Flight—Thermodynamics or Aerodynamics?
Bats Worth Billions to Agriculture—But They’re Dying Fast
What’s the News: Bats are an economic boon worth approximately $23 billion per year, and possibly up to $54 billion, to U.S. agriculture, a study in today’s issue of Science estimates. Their voracious appetite for insects—a colony of 150 brown bats eats about 1.3 million pesky, crop-chomping bugs each year—means that bats function as effective, and free, natural pesticides.
Storm-Watching Radar Systems Find Another Use: Bat-Tracking
In the realm of meteorology, bats, birds, and insects are usually considered “animalas non grata,” since they create unwanted noise in the Doppler radar readouts used to study storms. But now, thanks to better radar station networking and the sharing of unfiltered data, ecologists have realized that these radar systems can be used as powerful animal tracking tools.
At last week’s American Association for the Advancement of Science meeting, researchers Thomas Kunz, Winifred Frick, and Phillip Chilson explained how Dopplar data can be used by ecologists. They call their new discipline aeroecology.
This melding of meteorology and ecology started with an “Aha!” moment:
“Dr Kunz and I were meeting Dr Chilson about a year ago over breakfast and they kept talking about the ‘QPE’, and finally I asked what it is,” Dr Frick told the meeting. It stands for quantitative precipitation estimator — a numerical method to measure how much rain there is in a storm front. “I paused and said, ‘you can estimate the number of raindrops in a raincloud? Do you think we could estimate the number of bats in a bat cloud?’” To calibrate their experiment, the team took a bat into a chamber where the degree to which it reflects radio waves could be measured. “From those measurements and using radar, we’ve been able to adapt those QPE measurements to a ‘QBE’ – a quantitative bat estimator,” Dr Frick said. [BBC News]
In Borneo, Bats and Plants Form a Peculiar Poop Partnership
Some plants want ample water and sunshine. The plant Nepenthes rafflesiana, however, desires the droppings of Hardwicke’s woolly bats.
The carnivorous plant and the key-sized tiny bat live on the Indonesian island of Borneo, where their unusual arrangement has blossomed. Scientists who placed trackers on the backs of the bats found that they nap away their days nestled in the pitcher of this pitcher plant, and they use it as their personal commode. That’s just fine for the pitcher plant, which doesn’t trap as many bugs as its relatives, but makes up for it by deriving one-third of its nutrients from bat excrement.
“It’s totally unexpected,” said Ulmar Grafe, an associate professor at the Universiti Brunei Darussalam who led the study. “There’s a lot of animal-plant mutualisms, but this one is where the animal gives a nutrient to a plant. Usually it’s the other way around.” [Reuters]
You might think it’d be dangerous for bats to lay around in a plant’s pitcher, where they could plummet into the gooey nectar the plant uses to trap and eat insects. But, in fact, the pitcher is shaped just right so that the bats can’t fall through. Says Grafe:
Devastated Brown Bats Could Earn Endangered Species Protection
The continued onslaught by white nose syndrome against North America’s bats is one of the stories of the year—number 13, in fact, on DISCOVER’s Top 100 of 2010. But some help soon could be on the way in the form of Endangered Species Act protection. Earlier this month, a group of conservationists and scientists filed an emergency petition with the United States Fish and Wildlife Service to list the little brown bat under the act.
Emergency listing for a species does happen, but not very often, says Ann Froschauer, national white-nose syndrome communications leader for FWS. “Given the urgency of white-nose syndrome and recent information about predicted declines in little brown bat populations, the Service is committed to quickly reviewing scientific information, both published and provided by organizations such as these, in assessing the status of little brown bats and other bat species affected by WNS.” [Scientific American]
Listing the bats as endangered could force government action to protect them, including increased funding and the designation of critical habitat.
Photos: The Glamorous New Species of Papua New Guinea
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Pharmaceutical Hope for the Bats Dying of White Nose Fungus
When we last covered little brown bats it was with big bad news: A study in Science suggested that white nose syndrome could kill enough of the bats to make them regionally extinct in many parts of the United States by 2020. This week, though, brought a glimmer of hope. Scientists at the New York State Department of Health led by Vishnu Chaturvedi say some anti-fungal drugs work against the mysterious fungus causing the bat die-off.
They tested six strains of the novel fungus against drugs already used to treat people and animals such as cats and dogs for ailments ranging from athlete’s foot to life-threatening infections. “We found that two major classes of antifungal drugs have very good activity” against the bat germ, Chaturvedi reported Sunday in Boston at a meeting of the American Society for Microbiology. The drugs include fluconazole, the most widely used antifungal drug, which is sold as Diflucan by Pfizer Inc. and in generic form. Four other drugs also seem highly effective, Chaturvedi said. [AP]
White-Nose Syndrome Threatens Northeast Bats With Extinction
Five years ago, there were six and a half million little brown bats in the Northeastern United States. In 2020, there may be next to none.
This week in Science, a study models the collapse in bat populations brought on by white-nose syndrome, which was first found in 2006 and is seemingly caused by a nasty fungus. Researchers think that bats with the affliction awaken too early from hibernation, messing up their natural cycles and draining their reserves of energy. A team led by Winifred Frick checked the math on bat population decline and found that they could be locally extinct in many parts of the United States by 2020.
The loss of all these bats would be bad for us, not just them, because they like to dine on pesky insects. So far, researchers have little idea how to cure diseased bats or stop the blight from spreading. The U.S. Forest Service last month proposed to close off abandoned mines in several states, hoping to protect the bats who live in them from the disease. For more about the bats, check out Ed Yong’s Not Exactly Rocket Science.
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Image: Al Hicks, NY DEC
Great Minds Think Alike: Bats & Dolphins Evolved Same Gene For Echolocation
Bats and dolphins are two of the most celebrated users of echolocation, employing high-frequency sounds to locate prey, find their way, or to communicate. Now a new set of findings in Current Biology show that not only do the two different kinds of mammals use the same method, they also evolved nearly the exact same molecular means for hearing at high frequencies.
That second part was a surprise, study author Stephen Rossiter says: “It’s common on a morphological scale but it’s assumed not to occur at a DNA level because there are so many different ways to arrive at the same solution” [BBC News]. That is, while it’s quite common for different species to separately evolve similar features—like the tusks of elephants and walruses—it’s quite unlikely that natural selection working in separate species would settle an essentially identical gene and protein for growing tusks, hearing high-frequency sounds, or anything else. Or so the thinking went.
Green vs. Green: Judge Halts Wind Project to Protect Rare Bats
Besides the challenges of integrating variable wind power into an electrical grid built with fossil fuel plants in mind, wind farms also must clear the hurdle of showing that their turbines don’t pose a danger to wildlife. The latter issue has now thrown a wrench into the construction of a $300 million West Virginia wind farm, after a judge ruled it would threaten endangered bats.
U.S. District Judge Roger W. Titus ruled that Chicago-based Invenergy can complete 40 windmills it has begun to install on an Appalachian ridge in Greenbrier County. But he said the company cannot move forward on the $300 million project — slated to have 122 turbines along a 23-mile stretch — without a special permit from the U.S. Fish and Wildlife Service [Washington Post].
With Chirps and Trills, Bats Sing Love’s Sweet Song
Male Brazilian free-tailed bats sing intricate songs to attract females and deter other males using a set syllabic order and syntax, according to a study published in the journal PLoS One. The bats can even add their own creative touches to the croonings.
By examining 400 songs produced by 33 free-tailed bats, researchers found that all the bats produce songs with a common hierarchical structure. “All are constructed from the same four types of syllables and all syllables are combined in the same way to form three types of phrases,” says [lead author Kirsten] Bohn. These phrases can be either chirps, trills or buzzes [BBC News], and the complexity of the songs rival those only of birds and whales, leaving those produced by mice in the dust. The bats may vary their songs to appeal more to females or to convey different sentiments. “Within the broad rules, the bats are quite versatile” [BBC News], Bohn says.
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Video: Kirsten Bohn, et al. The slowed-down video shows a male bat singing while performing a wing-flapping display for roosting females.
Radar May Keep Bats Away From Wind Turbines’ Blades
Wind power may prove to be a promising source of clean energy, but it can also be deadly to bats. Not only can the animals be sliced by the blades of wind turbines, but the sudden drop in air pressure around the turbines can also cause bats’ lungs to explode. An electromagnetic field emitted near the turbines, however, may help bats steer clear of them, according to a new study published in the Public Library of Science One.
Bat casualties near wind turbines have proven to be significant: In 2004, over the course of six weeks, roughly 1,764 and 2,900 bats were killed at two wind farms in Pennsylvania and West Virginia, respectively [LiveScience]. If wind power continues to become increasingly prevalent, so too might the turbines become a growing threat to bat populations. “Given the growing number of wind turbines worldwide, this is going to be an increasing problem, no question about that,” said [co-author] Paul Racey [LiveScience].
The Original Bat-Signals: Bats Can Recognize Individual Voices
Scientists have long been impressed with bats’ echolocation calls, the brief bursts of sound that bounce off surrounding objects and allow the bats to navigate in the dark. But now researchers have found a new level of sophistication in those cries. A new study of greater mouse-eared bats proves that bats can distinguish between the calls of different individual bats. Researchers say this could explain how they remain in a group when flying at high speeds in darkness, and how they avoid interference with one another’s echo-location calls [The Guardian].
In the study, published in the journal PLoS Computational Biology, lead researcher Yossi Yovel played the recordings of bat cries back to his test subjects. “Each bat was assigned two others it had to distinguish between,” Dr Yovel explained. “So we trained bat A on a platform, playing a sound from bat B on one side and from bat C on the other. He had crawl to where the ‘correct’ sound was coming from” [BBC News]. For a correct answer, the bat was rewarded with a mealworm.
Scientists Glean Secrets of Flight From Birds, Bats, and Bugs
Researchers have learned the universal secret behind the graceful, aerial turns executed by everything from insects to cockatoos. And it’s a surprisingly simple process: To turn left, all a bird has to do is flap its right wing a little bit harder than the left wing. To end the turn, the bird simply returns to flapping its wings in unison [Discovery News]. Researchers hope to duplicate the simple set of motions to create more nimble and acrobatic flying robots.
Though the dynamics probably can’t work at large scales — building-sized robotic birds won’t ever be as agile as a swallow — they could be harnessed in small drones used by explorers or the military. Compared to the average hummingbird or fruit fly, such craft are now clumsy and unstable. “The results will inform all future research into maneuvering flight in animals and biomimetic flying robots” [Wired], wrote biomechanicist Bret Tobalske in a commentary.
Space Heaters in Caves Could Protect Bats From Mysterious Disease
With the cause of a rampantly deadly bat illness still unknown, biologists have no solution to the problem but have proposed at least a quick fix that may be able to slow it down. At least half a million bats throughout the northeast United States have died from white-nose syndrome (WNS), a fungal infection that was first observed only two years ago. The fungus is thought to grow on bats’ facial skin and flight membranes, possibly causing them to starve. No one knows where the fungus came from, or if it is what is directly killing the bats. But in caves where it has been observed, bats have suffered morality rates ranging from 75 to 100 percent [Scientific American]. With the cause of the fungus not yet determined, researchers worry about the fate of bats, which play an important role in controlling the populations of insects that can damage wheat, apples and dozens of other crops [AP].
While it won’t solve the problem, a temporary stop-gap is now being considered that would place battery-operated heated boxes inside bats’ hibernation caves, and may give the animals the energy they need to fight off, or at least survive, the fungal infections [Scientific American]. The idea is based on the fact that the bats with WNS appear emaciated, as if they’ve starved to death during their winter hibernation; researchers theorize that afflicted bats rouse from hibernation more often than normal bats and thus burn more fat to stay warm [AP]. When they temporarily stir, the bats’ body temperature and metabolism spike.
