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Why We Need Bats All the Time—Not Just on Halloween


National Science Foundation
Created: October 31, 2012 Last Updated: November 1, 2012
Related articles: Science » Inspiring Discoveries
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A leaf-nosed bat from the New World. The purpose of the leaf structure on the bat's face is not known for sure, but it may be important for echolocation. (Brock Fenton)

A leaf-nosed bat from the New World. The purpose of the leaf structure on the bat's face is not known for sure, but it may be important for echolocation. (Brock Fenton)

The sight of bats hanging upside down in creepy caves or fleeing in fluttery flocks from their subterranean haunts at dusk like “bats out of hell” may spook even the most rational, otherwise unflappable observer.

Nevertheless, on every day (and night) but Halloween, these much maligned creatures of the night should be loved, not feared. Why? Because, contrary to popular belief, bats do not attack people; bats do not tangle in people’s hair; and even vampire bats are not true vampires. (Vampire bats lick blood but do not suck blood.)

What’s more, unbeknownst to most people, bats make important contributions to ecology, the economy and even to the search for new technologies.

Important Ecological Roles

The buds of this flower—a Pseudobombax ellipticum—open explosively at night and are primarily pollinated by bats. (Brock Fenten)

The buds of this flower—a Pseudobombax ellipticum—open explosively at night and are primarily pollinated by bats. (Brock Fenten)

Bats, which live on all continents except Antarctica, are essential members of many types of ecosystems, ranging from rain forests to deserts. By fulfilling their ecological roles, bats promote biodiversity and support the health of their ecosystems.

The ecological roles of bats include pollinating and dispersing the seeds of hundreds of species of plants. For example, bats serve as major pollinators of many types of cacti that open their flowers only at night, when bats are active. In addition, bats eat copious quantities of insects and other arthropods. On a typical night, a bat consumes the equivalent of its own body weight in these creatures.

Economic Value

As bats fulfill their ecological roles, they provide many economically important services. For example, bats serve as essential pollinators for various types of commercially-valuable crops, including bananas, mangoes, and guavas. In addition, bats consume many crop-eating insects and thereby reduce farmers’ need for pesticides.

All told, according to a 2011 study published in Science, insect consumption by bats reduces the pesticide bill of the agriculture industry in the United States by roughly $22.9 billion per year on average. Another study, partially funded by the National Science Foundation (NSF), calculated the average annual value of Brazilian free-tailed bats as pest control for cotton production in eight counties of south-central Texas at about $741,000.

Inspiration for High-Tech Innovations

Bats offer much to the field of biomimetics, which is the science of modeling cutting-edge technologies based on natural forms. After all, the development of sonar for ships and ultrasound was partly inspired by bat echolocation. Echolocation is the navigation system used by most bats to find and follow their quick-moving insect prey at night, sometimes via daring aerial dogfights and speedy chases—all without crashing into trees, buildings or other obstructions.

Here’s how bat echolocation works: A bat emits a structured high frequency sound, usually beyond the range of human hearing, which bounces off surrounding objects and then returns echoes to the bat. By comparing the delay and structure of the echoes to those of the original sound, a bat can calculate its own distance from the objects and determine size and shape of those objects and thereby construct a three-dimensional map of its environment.

Even though a bat’s brain is only peanut-sized, bat echolocation is so sensitive that a bat flying 25 miles per hour in complete darkness would recognize differences in echo delays of less than a microsecond, allowing the bat to distinguish even a junebug from an underlying leaf, according to Universal Sense: How Hearing Shapes the Mind, which was authored by neuroscientist Seth S. Horowitz, whose earlier work was funded by NSF.

How do bats stay focused on sonar echoes from their target prey without being overwhelmed by the cacophony of echoes from other objects? That question is answered by an NSF video about recent research on bat echolocation.

Another bat trait that provides potential grist for future application is the flying ability of bats, which are the only mammals that can fly on their own power. The aerodynamic repertoire of bats, which includes changing flight direction by turning 180 degrees within just three wing beats while flying at full tilt, would be the envy of any fighter pilot, said Horowitz.

Bats are such nimble flyers because of the dexterity of their wings, which—unlike insect and bird wings—are structured to fold during flight, similar to the way that a human hand folds. Also, their wings are draped by stretchy skin and are powered by special muscles. Ongoing research about the structure of bat wings and the mechanics of bat flight may ultimately lead to the development of technologies that improve the maneuverability of airplanes.

See the wonders of bat flight in a Science Nation video that describes an NSF-funded project.

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