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Killer whales battle the din of tourist boats

April 29, 2004

Killer whales off the US west coast are struggling to make themselves heard over the noise of tourist traffic. As the fleet of whale-watching boats has swelled over the past decade, the length of the animals’ calls has increased in an effort to beat the engine noise.

Members of killer whale (Orcinus orca) groups make characteristic calls to each other over distances of several kilometres. In the presence of boats these calls are around 15% longer than when boats are absent, report A. Rus Hoelzel and colleagues in a Brief Communication in the April 29, 2004 Nature. The authors detected no such effect in whale calls recorded between 1989 and 1992. As the number of whale-watching boats increased fivefold during the 1990s—whales are now tracked by around 22 boats each day—this suggests that there is a critical threshold of background noise above which the whales take action to counteract the din.

Abstract © 2004 Nature

“Whale-call response to masking boat noise” Andrew D. Foote, Richard W. Osborne, A. Rus Hoelzel, Nature, April 29, 2004

Rus Hoelzel, University of Durham, UK