Roaring bats

April 30, 2008

Annemarie Surlykke from the Institute of Biology, SDU, Denmark, and her colleague, Elisabeth Kalko, from the University of Ulm, Germany, studied the echolocation behavior in 11 species of insect-eating tropical bats from Panamá, the findings of which are reported in this weeks’ PLoS ONE.

The researchers used microphone arrays and photographic methods to reconstruct flight paths of the bats in the field when these nocturnal hunters find and capture their insect prey in air using their sonar system. Surlykke and Kalko took this information as a base to estimate the emitted sound intensity and found that bats emit exceptionally loud sounds exceeding 140 dB SPL (at 10 cm from the bat's mouth), which is the highest level reported so far for any animal in air. For comparison, the level at a loud rock concert is 115-120 dB and for humans, the threshold of pain is around 120 dB.

Bats emit their echolocation calls at ultrasonic frequencies, i.e. above the human hearing range. This is necessary to get echoes from small insects, but the draw-back of high frequencies is that they do not carry far in air as they are attenuated faster than low frequencies. By estimating detection range for typical insect prey, Surlykke and Kalko conclude that these extreme intensities are essential for the bats as they serve to counteract attenuation.

This is the first comparative field study of bat echolocation sounds focusing on intensity and the results revealed, very interestingly, that although signal intensities (and frequencies) of bats vary widely, they appear to converge on similar detection ranges, because the bats emitting the highest frequencies were also the bats emitting the highest intensities. Thus, the study illustrates the value of an interdisciplinary approach combining bat biology, ecology, behavioral biology and acoustics.

Citation: Surlykke A, Kalko EKV (2008) Echolocating Bats Cry Out Loud to Detect Their Prey. PLoS ONE 3(4): e2036. doi:10.1371/journal.pone.0002036

Source: Public Library of Science

Related Stories

Recommended for you

Amazon deforestation leaps 16 percent in 2015

November 28, 2015

Illegal logging and clearing of Brazil's Amazon rainforest increased 16 percent in the last year, the government said, in a setback to the aim of stopping destruction of the world's greatest forest by 2030.

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.