29 April 2004
Whale-watchers: In for the killer
'Whale watching' is a growing leisure activity in the coastal waters of Washington state, most famously around San Juan Island. The main attraction is the orca or killer whale. In the past ten years whale numbers have fallen, coinciding with a sharp increase in whale-watching, and orcas were recently identified by the Washington Department of Fish and Wildlife as a vulnerable species. Groups of orcas are typically followed by a fleet of 20 boats, raising the possibility that boat noise might hasten the whales' decline by interfering with their communication signals. But it looks like the whales can handle this challenge. Long-term monitoring of vocal behaviour of orcas off San Juan Island suggests that they have overcome interference from background noise by switching to longer call durations.
Environment: Whale-call response to masking
boat noise
ANDREW D. FOOTE, RICHARD W. OSBORNE & A. RUS HOELZEL
Nature 428, 910 (2004); doi:10.1038/428910a
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