Dear Marman list members We have just had the following article pulished in Journal of Experimental Biology "Echolocation in sympatric Peale's dolphins (Lagenorhynchus australis) and Commerson's dolphins (Cephalorhynchus commersonii) producing narrow-band high-frequency clicks" Abstract: An increasing number of smaller odontocetes have recently been shown to produce stereotyped narrow-band high-frequency (NBHF) echolocation clicks. Click source parameters of NBHF clicks are very similar, and it is unclear whether the sonars of individual NBHF species are adapted to specific habitats or the presence of other NBHF species. Here, we test whether sympatric NBHF species sharing the same habitat show similar adaptations in their echolocation clicks and whether their clicks display signs of character displacement. Wide-band sound recordings were obtained with a six-element hydrophone array from wild Peale's (Lagenorhynchus australis) and Commerson's (Cephalorhynchus commersonii) dolphins off the Falkland Islands. The centroid frequency was different between Commerson's (133±2 kHz) and Peale's (129±3 kHz) dolphins. The r.m.s. bandwidth was 12±3 kHz for both species. The source level was higher for Peale's dolphin (185±6 dB re 1 *Pa p.-p.) than for Commerson's (177±5 dB re 1 * Pa p.-p.). The mean directivity indexes were 25 dB for both species. The relatively low source levels in combination with the high directivity index may be an adaptation to reduce clutter when foraging in a coastal environment. We conclude that the small species-specific shifts in distribution of centroid frequencies around 130 kHz may reflect character displacement in otherwise-stereotyped NBHF clicks. Key words: acoustic species separation, acoustics, character displacement, clutter adaptation, static acoustic monitoring, sympatric species. You are welsome to request a copy of the paper by sending an email to me or find it here: http://www.marinebioacoustics.com/pub.html You may find a review of the article in Inside JEB on http://jeb.biologists.org/cgi/content/full/213/11/iii?maxtoshow=&hits=20&RES... Drawing is from the review in Inside JEB Best regards, Line Line A. Kyhn Ph.D. student, Ms. Science, National Environmental Research Institute, Aarhus University Frederiksborgvej 399, DK- 4000 Roskilde Phone: +45 46301952 Mail: lky@dmu.dk Home page: http://www.biology.au.dk/line.kyhn.cv.da Act - don't react