Egyptian fruit bats point sonar beams on either side of a target, not directly at it

According to researchers at the University of Maryland, Egyptian fruit bats, unlike their American relative the big brown bat, locate objects through a series of tongue clicks directed to either side of their target. Big brown bats locate their fast moving prey—such as mosquitos—by firing sounds from their vocal cords directly at their target. Egyptian bats, on the other hand, fire their sonar beams to either side of the target and automatically calculate the slope. In other words, they find the target’s position through the difference between each sonar beam. In the study published in this week’s Science magazine, researchers in Israel trained the fruit bats to land on a spherical target relying exclusively on echolocation. Echolocation, like sonar, is the process bats use to navigate through the air and target objects. At the UMD lab, high speed infrared cameras recorded the bats movement in flight while the shape and direction of their sonar beam patterns was measured with 20 microphones positioned around the room. The above video shows a slow-motion recording of the bat’s echolocation technique. The scientists say, however, that the fruit bat is sacrificing target-detection for target accuracy: by emitting two sonar beams at a time, the bat is less likely to locate the target altogether. Cynthia Moss, a co-author of the study and researcher at the University of Maryland’s Auditory Neuroethology Lab, says in a press release: “We think that this tradeoff between detecting an object and determining its location is fundamental to any process that involves tracking an object whether done by a bat, a dog or a human, and whether accomplished through hearing, smell or sight.”  Read more: http://www.scientificblogging.com/news_articles/how_bats_indirectly_hit_their_targets Yossi Yovel, Ben Falk, Cynthia F. Moss, Nachum Ulanovsky (2010). Optimal Localization by Pointing Off Axis...

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White-nose syndrome forces cave closings

White-nose syndrome, a mysterious disease that has been killing hundreds of thousands of North American bats since its discovery in 2007, has now forced the U.S. Forest Service to close caves in national forests across the country in an attempt to rein in transmission of the disease. The disease is caused by a cold-loving fungus that infects bats’ faces and wings during the winter months, disrupting their hibernation patterns and causing them to starve to death.  An estimated half a million bats have died from the affliction, and scientists have found piles of dead bats around caves where mortality can be up to 90 percent of a cave’s roosting population. According to a New York Times report: “A Forest Service biologist, Becky Ewing, said an emergency order was issued last week for caves in 20 states from Minnesota to Maine. A second order covering the Forest Service’s 13-state Southern region should be issued this month.” At a briefing for conservation partners in Washington on April 30, scientists and managers from the National Park Service, the Fish and Wildlife Service and the U.S. Geological Survey gave an update about the status of this mysterious disease. Jeremy Coleman of the FWS said that although transmission of the fungus is likely bat-to-bat, they don’t have enough data yet on the fungus, a previously undescribed species of Geomyces.  The FWS had requested a voluntary ban on caving in the affected areas, but does not have the authority to close caves, said Wendy Weber, also of the FWS. Although the Times story quotes representatives of the caving industry who are supportive of the measure, the caving ban stands to affect the livelihood of commercial cavers on forest service lands. At last week’s briefing, several representatives from the caving community expressed their frustration at the level of communication from government agencies, saying they feel “in the dark” about the research and management decisions about WNS. Read more about WNS and a new program being tested to curb bat deaths in this ESA press release. Photo courtesy Nancy Heaslip, New York Department of Environmental...

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