|
 Scientists studying a common species of these flying mammals found
that the bats, while competing for the juicy insects they call
dinner, make noises that "jam" other bats that are using their
sonar-like echolocation abilities to zero in on prey.
Echolocation - bouncing sound waves off objects - is how bats
navigate in the dark while hunting, enabling them to find and catch
elusive insects zipping through the nighttime air.
Sophisticated video and audio recordings made during experiments in
Arizona and New Mexico involving Mexican free-tailed bats revealed
how they thwarted each other's meal plans.
Just as one bat was within a split second of snatching a moth or
other insect in mid-air, another bat that was also out foraging used
its vocal chords to emit a specialized jamming call to prevent the
first one from making the catch.
 "The bats jam competitors to prevent them from capturing insects so
that the jamming bat has an opportunity to catch the prey,"
biologist Aaron Corcoran of Wake Forest University in North
Carolina, who led the study published in the journal Science, said
on Friday.
"The hunting bat is 86 percent less likely to capture the prey when
it is getting jammed," Corcoran added.
The researchers said this is the first bat species known to use
jamming but it is possible other bats do it as well.
The jamming call has a pitch that rapidly moves up and down,
covering the frequencies used by bats to locate and capture insects,
Corcoran said. The hunting bat simultaneously hears the jamming call
and the echoes from its own echolocation, preventing it from being
able to calculate the bug's position, he added.
"This is nature's version of acoustic warfare," Corcoran said.
[to top of second column] |
The jamming is akin to techniques used in modern aviation warfare.
"I liken it to a pilot jamming the radar of an incoming missile,"
said Wake Forest biologist Bill Conner, another of the researchers.
Battling for bugs is particularly challenging for these bats
considering that they often live in colonies of millions of
individuals all wanting the same kind of meal.
"The jamming call is an oscillation in frequency like the vibrato of
an opera singer. We, of course, cannot normally hear it because it
is too high in frequency. When you lower the frequency into our
range, it sounds somewhat like bird song," Conner said.
The Mexican free-tailed bats, scientific name Tadarida brasiliensis,
are medium-sized bats with brown fur, large ears and a wingspan of
about 11 inches (28 cm) found in the western United States, Mexico,
Central America and northern South America.
This study showed that bat sounds have at least three functions:
echolocation, intraspecies communication and acoustic interference.
The bats are known to make at least 15 different communication calls
for purposes including attracting mates, young bats calling for
their mothers and males fending off other males.
(Reporting by Will Dunham; Editing by Sandra Maler)
[© 2014 Thomson Reuters. All rights
reserved.] Copyright 2014 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
 |
