Humpback whales are forming massive (and unusual) 'super-groups'

A new report out of PLOS reveals that humpback whales are congregating in very large (relatively speaking) super-groups near South Africa, in some cases comprising pods as large as 200 whales. These large whale collectives are said to be engaging in feeding behavior, something that itself is unusual for the species, as it typically feeds on Antarctic krill in the southern polar region.

Humpback whales are creatures of habit, tending to feed during certain times in cold waters and breed during other times in warmer waters. Their migration patterns partly dependent on ocean temperatures, and their typical congregations are small. Data on these migration patterns, and feeding and breeding habits, go back decades.

Lately, though, researchers have noticed that humpback whales are collecting together in larger than typical numbers in pods with between 20 and 200 whales. Together (loosely so), these whales are engaging in feeding behavior in regions near South Africa where they would typically be engaging in breeding behaviors. Researchers have observed these large feeding pods in the October/November months in 2011, 2014, and 2015.

According to the new report, no one is sure why these whales are forming such large numbers and why they're deviating from their typical feeding habits. The report states the whales in these super-groups tend to be only about five body lengths away from their nearest whale neighbor, and that they're engaging in 'repetitive diving behavior' indicative of feeding. All signs point toward some large scale prey being present in the region, though researchers haven't been able to sample for it out of fear of entangling the whales in the sampling gear.