Humpback whale babies can be born on their migratory path, putting them at risk

Humpback whales ( Megaptera novaeangliae) are great travelers found in oceans around the world. “This migratory species travels hundreds [or even thousands] of kilometers from its summer 'feeding grounds' in high latitudes to its winter 'breeding grounds' in warmer lower latitudes,” says the Cosmos website .

Until now, experts believed that calving also took place in breeding grounds, where the warm water temperature would allow the calves to not use too much energy to keep warm and avoid predation by killer whales.

But a study of a humpback whale population that lives off the east coast of Australia and migrates from the cold, food-rich Southern Ocean to a warm, tropical region further north has invalidated this belief. It shows that calves can be born in the cold waters off New Zealand or Tasmania, some 1,500 kilometers further south than previously thought.

The results of this study are detailed in the specialist journal Frontiers in Marine Science .

“Calving along the 'humpback whale route' means these vulnerable calves, which are not yet strong swimmers, have to travel long distances much earlier than if they had been born in the breeding grounds,” Tracey Rogers, a marine ecologist at the University of New South Wales in Australia, told Popular Science .

But above all, the journey exposes them, as well as their mothers, to the dangers of an extremely busy shipping route. “Mothers with newborns swim much more slowly,” the researcher told Cosmos, because the clumsy and easily tired young often rest on their mothers’ backs as they continue their migration north, toward warm, tropical areas.