Nature & Environment
Bat Echolocation Images Reveal How These Animals View Their World
Catherine Griffin
First Posted: Sep 02, 2015 07:39 AM EDT
Scientists are learning a bit more about bat hunting habits. They've created the first visual images from echolocation to show how these nocturnal creatures sense their world.
Most bats hunt by detecting the movement of flying insects using echolocation. Only a third of all bat species are able to hunt for prey on surfaces. Previous studies, therefore, have concluded that bats must detect prey by sight, smell and sound.
In this latest study, though, the researchers suggest that instead of searching for prey directly, bats intimately learn the layout of a home range-down to the surface of individual leaves and stones. When one of these familiar leaves is covered by an insect, the normal echoes are interrupted and this "acoustic shadow" is a very strong signal to a hunting bat.
More specifically, the common big-eared bat Micronycteris microtis, a neotropiocal species from South and Central America, has been found to use echolocation alone. Scientists have speculated that by hovering beside prey, this species bombards it and the surface on which it rests with short sound waves. By continually changing their angle of scanning, the prey becomes easier to pick out.
In this latest study, the researchers developed a new imaging technique to allow them to enter the bat's world view. They built four acoustic cues into the system, combining the duration and amplitude of echoes with the depth profile of objects and the strength of the shadow cast by insects.
"Using information like X-rays to build pictures is well established in medicine with the use of CT scans and ultrasound, but no one has ever before attempted to create images from sounds generated in ecology," said Elizabeth Clare, one of the researchers, in a news release.
The researchers found that the acoustic cues available to bats to detect motionless prey don't improve greatly if the profile of the insect seems to stand out more. Instead, it seems as if it's important when it comes to the kind of surface on which the insect rests. For example, insects are easier to "see" on slate and smooth leaves rather than on rough bark.
"Our findings also suggest a new phenomenon of acoustic camouflage, where insects are harder to discern on rough surface such as bark and bats compensate for this by focusing their attention on the simpler, mirror-like surfaces in their patch," said Clare.
The findings are published in the journal Molecular Psychiatry.
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First Posted: Sep 02, 2015 07:39 AM EDT
Scientists are learning a bit more about bat hunting habits. They've created the first visual images from echolocation to show how these nocturnal creatures sense their world.
Most bats hunt by detecting the movement of flying insects using echolocation. Only a third of all bat species are able to hunt for prey on surfaces. Previous studies, therefore, have concluded that bats must detect prey by sight, smell and sound.
In this latest study, though, the researchers suggest that instead of searching for prey directly, bats intimately learn the layout of a home range-down to the surface of individual leaves and stones. When one of these familiar leaves is covered by an insect, the normal echoes are interrupted and this "acoustic shadow" is a very strong signal to a hunting bat.
More specifically, the common big-eared bat Micronycteris microtis, a neotropiocal species from South and Central America, has been found to use echolocation alone. Scientists have speculated that by hovering beside prey, this species bombards it and the surface on which it rests with short sound waves. By continually changing their angle of scanning, the prey becomes easier to pick out.
In this latest study, the researchers developed a new imaging technique to allow them to enter the bat's world view. They built four acoustic cues into the system, combining the duration and amplitude of echoes with the depth profile of objects and the strength of the shadow cast by insects.
"Using information like X-rays to build pictures is well established in medicine with the use of CT scans and ultrasound, but no one has ever before attempted to create images from sounds generated in ecology," said Elizabeth Clare, one of the researchers, in a news release.
The researchers found that the acoustic cues available to bats to detect motionless prey don't improve greatly if the profile of the insect seems to stand out more. Instead, it seems as if it's important when it comes to the kind of surface on which the insect rests. For example, insects are easier to "see" on slate and smooth leaves rather than on rough bark.
"Our findings also suggest a new phenomenon of acoustic camouflage, where insects are harder to discern on rough surface such as bark and bats compensate for this by focusing their attention on the simpler, mirror-like surfaces in their patch," said Clare.
The findings are published in the journal Molecular Psychiatry.
Related Stories
Ancient Massive Bat Species from New Zealand Walked on All Fours
Fruit Bats Navigate the Dark with Their Strange, Clicking Wings
For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone