Traditional bat-surveying methods, such as trapping, often over- or under-represent populations, says Bruce Miller. Some bats seem to either fly too high to be trapped often or have supersensitive echolocation skills that help them avoid capture. Others seem to readily fly into nets.
The old way is slower too. "In one or two nights work with the acoustic equipment, you can get data that would take months or years to get with trapsor couldn't get at all," says Miller.
With the voice-recognition technology, scientists can quickly amass data, and for the first time they can detect bats winging above the forest or across open fieldsall without laying a hand on the bats, an important factor when studying at-risk species.
Using the AnaBat, Miller is making some surprising discoveries that call into question decades of research. His data on the prevalence of some species is radically different from traditional data from trapping. Some bat species thought to be in trouble are seemingly ubiquitous. And others that seemed to be everywhere may really be quite rare.
Miller has established a database combining his and his colleagues data with records on bat distribution from published sources and museum data.
Miller is also compiling a library of bat calls for the tropics of the Americas. His current archive includes the vast majority of echolocating bats in Belize. (Some are too "soft-spoken" to monitor with AnaBat.) Regional bat-call libraries are also under way in the U.S. (at the University of New Mexico) and Australia (at Charles Sturt University in New South Wales).
Computer-generated bar graphs, GIS (geographic information system) maps, statistics, and photographs produced from these databases provide a gold mine of evidence for conservationists lobbying to protect certain species or habitats.
"If We Lose the Bats, We May Lose the Tropical Forests"
Why are these winged mammals important? "Bats are the primary seed dispersers," says Miller. "Certain bats, like the short-tailed fruit bat, drop guano containing 40,000 to 50,000 seeds in a night. They pollinate many tropical flowers, [as do] hummingbirds and moths." And myriad insect-eating bats help control pests.
"If we lose the bats, we may lose the tropical forests," predicts Miller. Many trees and plants would not survive without them. Using state-of-the-art technology, Bruce Miller and his colleagues are trying to make sure that doesn't happen.
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