Scientists researching whale strandings have hit on a new theory that social disruption prior to strandings might be the cause, rather than following sick family members to a shallow beach.
A whale specialist with both the University of Auckland and the University of Oregon in the United States, Scott Baker, says genetic testing has found 120 pilot whales which stranded on Stewart Island were not all closely related.
Nursing calves were stranded well away from their mothers, on whom they would have been dependent.
Professor Baker says it may be that whale strandings are caused by competition to catch prey and social disruption prior to strandings as well as whales finding themselves in unfamiliar and disorienting territory.
He says research on whale behaviour in New Zealand shows whales gather offshore in a large group and then smaller pods break off and head to shore quite deliberately.