Philippine Deforestation

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© 2002 (Photograph by P. Heideman)

The common Asian ghost bat is one of 48 species of insect-eating bats in the Philippines but is the only one that also eats frogs and lizards. Katydids are among their usual prey.

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Common Asian Ghost Bat
Megaderma spasma

Most kinds of bats in the Philippines—48 species—feed on insects, although one does so with a twist. Insectivorous bats are almost certainly the most economically valuable mammals in the Philippines (as they are in most countries) because of the immense service they provide by consuming crop pests. A thousand bats in an attic—a fairly common occurrence—almost certainly consume at least 50,000 insects every night; when these are moths that feed on corn or rice, the savings to the farmers can be substantial. Since colonies of bats in caves often number 10,000 to 100,000, and the caves in which they live number in the tens of thousands, it is evident that the beneficial impact can be huge. And, of course, if the bats are feeding on mosquitoes, we should be more grateful still.
Two facts about bats are worth mentioning. First, the very negative attitudes toward bats in the United States and Europe is not shared by most Asians, including many Filipinos who view them as symbols of good luck. We know many people who not only tolerate but welcome bats in their houses. Second, and perhaps related to the first, the disease that is most feared in bats in the United States—rabies—has never been found in bats in the Philippines, despite repeated medical surveys. In the Philippines, rabies has been found almost exclusively in domestic dogs and cats.
The common Asian ghost bat (Megaderma spasma) is a little animal with a wingspan of only a foot or so. Nevertheless, it eats only the largest insects——cicadas, crickets, cockroaches, katydids, and large beetles and moths. The bats catch their preynot by using their sonar system (as most insectivorous bats do), but by listening with their huge ears for insects crawling noisily through the leaves or chirping to attract mates. Swooping down on the hapless, lovelorn insects, the bats put a permanent end to their reproductive efforts. There are, frogs and lizards that make similarly inspired noises— and so, once in a while, the ghost bat catches and eats tiny frogs and lizards, the only bat in the Philippines—and one of only two in Asia—that does so.

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