It is a fact that few people know or appreciate: Fully one-fourth of all mammal species, the animal classification for everything from humans to cows and whales and elephants, are blessed with the ability to fly.
All of those flying mammals, as it happens, are bats. Of the slightly more than 4,000 known mammal species in the world, 1,000 of them are bat species.
“Bats are the only mammals that have conquered the third dimension and learned how to fly,” said Bill Stanley, the mammal collection manager at the Field Museum of Natural History.
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The subject of a new exhibit at the Field Museum, bats are celebrated for being some of the most useful creatures on Earth, even though they are popularly maligned and misunderstood as a cheap Halloween prop and horror movie mainstay.
The attention also comes at a time that bats are becoming endangered throughout the U.S., a situation some people might erroneously believe is a good thing.
Having collected bats for more than 100 years, the museum has one of the largest, most valued bat collections: more than 40,000 specimens representing more than 800 species. Scientists use the collection to study everything about bats, from the sounds they make and what they eat to the parasites that live in their fur and bacteria that live in their waste.
“It’s too bad most people don’t like bats very much,” said Stanley. “They are amazing animals, ones that have adapted to special niches probably more than just about any other mammal. We would live in a pretty miserable world without them.”
If it weren’t for bats, the world would be overrun with insect pests, Stanley said. Whole environments would be degraded in other ways, because many different flowers and plants depend on bats for pollination or distribution of their seeds.
In the United States alone, 40 percent of bat species are threatened or endangered, and in other parts of the world they are becoming extinct.
For many people, the extinction of bats might seem like good news. Their nocturnal habits and their remarkably diverse but often grotesque facial features (used as models for gargoyle sculptors in medieval times) have given bats a bad reputation.
The Field Museum exhibit, “Masters of the Night: The True Story of Bats,” tries to change that reputation. The exhibit, which is visiting museums around the country, runs through Sept. 4.
Though they are often mistakenly thought to be rodents, bats have more kinship with humans than to mice.
“A bat wing is really very similar to a human hand,” said Stanley.
The bats’ lifestyle is what is working against their survival in a world being overrun by humans. To be swift and agile flyers, bats must eat prodigiously for energy, but also must digest and cycle out (excrete) what they eat within a half hour or so to minimize body weight.
But bat guano (excrement) is so highly valued by humans, it has in some cases caused the extinction of some bat species. Nitrogen-rich, the guano is mined for fertilizer.
“Bats build up stores of fat to nourish them while they hibernate,” Stanley said. “But when miners invade their caves, they wake them up, which causes them to burn up more of this stored energy than they can afford to lose. Once the miners leave, the entire bat colony can be doomed to extinction for lack of energy to survive the rest of the hibernating season.”
“Scientists are finding all kinds of unique bacteria and other organisms in bat poop,” said Stanley. “This is stuff that looks like its going to be invaluable for a whole bunch of things, like for detoxifying industrial wastes, improving detergents, making antibiotics and gasohol.”
“The world would be a far more uncomfortable place without bats,” Stanley said.
And, apparently, without their waste, possibly a less promising one.