Beaked whales echolocate on prey

TLDR

Beaked whales are poorly understood, known mainly from strandings, and their acoustic behavior is of concern because they mass strand during naval sonar exercises. The study aims to provide definitive data on normal vocalizations of beaked whales to support acoustic monitoring that could mitigate harmful exposure from intense sounds. Researchers deployed a non‑invasive acoustic recording tag on four beaked whales to capture high‑frequency clicks during deep dives. The tagged whales clicked only below 200 m, down to 1267 m, emitting numerous short, directional ultrasonic clicks (<20 kHz) and producing prey echoes—providing the first direct evidence of wild toothed‑whale echolocation and indicating source levels of 200–220 dB re 1 µPa at 1 m.

Abstract

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 ording 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 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 microPa 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.