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.
Source: Public Library of Science
- Whispering bats are 100 times louder than previously thoughtFri, 12 Dec 2008, 10:50:47 EST
- A new species of predatory bagworm from Panama's tropical forestTue, 29 Jul 2008, 10:07:51 EDT
- Sand fly barcoding in Panama reveals Leishmania strain and its potential controlTue, 6 Apr 2010, 13:38:33 EDT
- Bat researchers no longer flying blind on echolocationSun, 24 Jan 2010, 13:38:48 EST
- 'I can hear a building over there' -- researchers study blind people's ability to echolocateWed, 25 May 2011, 18:03:16 EDT
- Roaring Bats: New Scientific Results Show Bats Emitting More Decibels Than A Rock Concertfrom Science DailyFri, 2 May 2008, 11:28:16 EDT
- Research shows bats emitting more dB than a rock concertfrom Science CentricThu, 1 May 2008, 14:56:06 EDT
- Roaring batsfrom Biology News NetWed, 30 Apr 2008, 19:14:08 EDT
- Bats Screech Louder Than Rock Concertsfrom Live ScienceWed, 30 Apr 2008, 14:50:03 EDT
- Bats can put on the loudest rock concert — everfrom MSNBC: ScienceWed, 30 Apr 2008, 14:49:54 EDT
Latest Science NewsletterGet the latest and most popular science news articles of the week in your Inbox! It's free!
Check out our next project, Biology.Net
From other science news sites
Popular science news articles
- King Richard III found in 'untidy lozenge-shaped grave'
- UEA scientists make breast cancer advance that turns previous thinking on its head
- Cradle turns smartphone into handheld biosensor
- Scientists develop powerful new method for finding therapeutic antibodies
- Detection of the cosmic gamma ray horizon: Measures all the light in the universe since the Big Bang