From: "Peter T. Madsen" <[EMAIL PROTECTED]> Subject: Beaked whale biosonar paper Date: Sat, 18 Sep 2004 14:27:02 -0400
Please be informed that a paper entitled "Beaked whales echolocate on prey" by Johnson et al. has recently been published in Proceedings of the Royal Society Letters. See abstract below. Requests for reprints can be directed to: Mark Johnson [EMAIL PROTECTED] or Peter Tyack [EMAIL PROTECTED] Please do not reply directly to this message. Best regards, Peter T. Madsen Woods Hole Oceanographic Institution Beaked whales echolocate on prey Mark Johnson 1*, Peter T. Madsen 1, Walter M. X. Zimmer 2, Natacha Aguilar de Soto 3 and Peter L. Tyack 1 1 Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA 2 NATO Undersea Research Center, viale San Bartolomeo 400, 19138 La Spezia, Italy 3 La Laguna University, Tenerife, Canary Islands, Spain * Author for correspondence ([EMAIL PROTECTED]). Beaked whales (Cetacea: Ziphiidea) of the genera Ziphius and Mesoplodon are so difficult to study that they are mostly known from strandings. How these elusive toothed whales use and react to sound is of concern because they mass strand during naval sonar exercises. A new non-invasive acoustic recording tag was attached to four beaked whales (two Mesoplodon densirostris and two Ziphius cavirostris) and recorded high-frequency clicks during deep dives. The tagged whales only clicked at depths below 200 m, down to a maximum depth of 1267 m. Both species produced a large number of short, directional, ultrasonic clicks with no significant energy below 20 kHz. The tags recorded echoes from prey items; to our knowledge, a first for any animal echolocating in the wild. As far as we are aware, these echoes provide the first direct evidence on how free-ranging toothed whales use echolocation in foraging. The strength of these echoes suggests that the source level of Mesoplodon clicks is in the range of 200�220 dB re 1 _Pa at 1 m. This paper presents conclusive data on the normal vocalizations of these beaked whale species, which may enable acoustic monitoring to mitigate exposure to sounds intense enough to harm them.
