Super Groups of Humpbacks Baffling Researchers
Vast groups of up to 200 humpback whales are gathering to feed thousands of kilometres from their normal feeding grounds.
This unusual behaviour for what are not normally considered to be particularly social animals is baffling scientists.
The common pattern of activity for southern hemisphere humpback whales (Megaptera novaeangliae) is an annual migration from the krill-rich feeding grounds of Antarctica in summer to warm subtropical latitudes in winter to breed and raise their young in small groups of no more than seven individuals. Many seem to spend the majority of their time alone or just with a single calf.
But in recent years sightings of large gatherings of humpbacks have been made off the south-west coast of South Africa. A study just published in Plos One reports 22 instances of humpback 'super groups' witnessed on three research cruises in 2011, 2014, and 2015, backed up by a number of public observations from aircraft of these strange gatherings in the region.
'I've never seen anything like this,' said lead researcher Ken Findlay, from the Cape Peninsula University of Technology in South Africa.
He is now considering what is causing the phenomena. One theory is that the migrating animals just opportunistically came across the krill and whatever else they are gorging on in the area.
Another is that they are reverting to earlier behaviour that was common before more than 90 per cent of the species was killed by whalers during the 19th and early 20th centuries. Recently, and again baffling researchers, the number of southern hemisphere humpbacks has dramatically surged in the past decade.