Buzzes and High-Frequency Clicks Recorded from Narwhals (Monodon monoceros) at Their Wintering Ground

摘要

High-frequency broadband clicks were recorded from narwhals (Monodon monoceros) off the Uummannaq region, Northwest Greenland, in April 2012 and 2013 while whales were on their wintering grounds in Baffin Bay. Recordings were made on eight different days directly from the pack ice edge or through holes drilled in pack ice floes at approximately 71 degrees N and between 54 degrees to 60 degrees W. Recordings were conducted using a single hydrophone along with a recording system with a sampling frequency of 500 kHz and an Acousonde (TM) 3B with a sampling frequency of 250 kHz. The energy in the high-frequency narwhal clicks extended up to 200 kHz. Buzzes with inter-click intervals (ICI) down to 3.2 ms were also recorded; however, no whistles were obtained. This is the first time the whole bandwidth of narwhal echolocation clicks has been reported and the first case for which buzzes have been recorded from narwhals at their wintering ground. These data may have implications for conservation, management, and acoustic monitoring techniques in light of ongoing and expected significant increases in anthropogenic sound (e.g., seismic exploration, shipping) in the Arctic.