my co-authors and I are pleased to announce the publication of our work on the directionality and scanning of narwhals in PLoS ONE:
Koblitz JC, Stilz P, Rasmussen MH, Laidre KL (2016)
Highly Directional Sonar Beam of Narwhals (Monodon monoceros) Measured with a Vertical 16 Hydrophone Array
PLoS ONE 11(11): e0162069. doi:10.1371/journal.pone.0162069
The paper is available as OPEN ACCESS here:
Recordings of narwhal (Monodon monoceros) echolocation signals were made using a linear 16 hydrophone array in the pack ice of Baffin Bay, West Greenland in 2013 at eleven sites. An average -3 dB beam width of 5.0° makes the narwhal click the most
directional biosonar signal reported for any species to date. The beam shows a dorsal-ventral asymmetry with a narrower beam above the beam axis. This may be an evolutionary advantage for toothed whales to reduce echoes from the water surface or sea ice surface.
Source level measurements show narwhal click intensities of up to 222 dB pp re 1 μPa, with a mean apparent source level of 215 dB pp re 1 μPa. During ascents and descents the narwhals perform scanning in the vertical plane with their sonar beam. This study
provides valuable information for reference sonar parameters of narwhals and for the use of acoustic monitoring in the Arctic.
Dr. Jens C. Koblitz
Eichenallee 32 a
Office: +41 (0) 56 55 876 20
Cell: +49 (0) 1512-2236452