Newcastle, Australia – It turns out humpback whales’ epic migrations to tropical waters aren’t as essential as we thought for giving birth. Calves can be born as far south as Tasmania or New Zealand, 1,500km further south than previously known.

Researchers say these results overturn long-held beliefs about humpback migration. To protect these unexpected baby whales, awareness of expanded calving areas must improve.

“Hundreds of humpback calves were born well outside the established breeding grounds,” said Dr Tracey Rogers of the University of New South Wales. “Giving birth along the ‘humpback highway’ means these vulnerable calves, who are not yet strong swimmers, are required to swim long distances much earlier in life.”

“Alongside my studies, I work as a marine guide,” said Jane McPhee-Frew, PhD candidate at the University of New South Wales. “In July 2023, during a whale-watching tour, I encountered a mum and calf at the mouth of Newcastle Harbor — the busiest shipping port in Eastern Australia. The calf was tiny, obviously brand new.”

Inspired by the sighting, researchers combined citizen science observations, government surveys, and stranding reports. They identified 209 records of newborn calves — 11 births, 41 strandings, and 168 live observations. Of 118 cases with travel direction noted, whales were continuing north after delivery.

“Humpback whale populations undertake extensive long-distance migrations,” said Dr Adelaide Dedden of the National Parks and Wildlife Service. “They rely heavily on body reserves from Antarctic krill to support the journey and reproduction.”

The southernmost calf was at Port Arthur, Tasmania. Most observations occurred after 2016, two-thirds in 2023 or 2024. Older texts show similar behavior before the population crashed due to hunting.

“I think it’s very likely that this pattern has always existed,” said McPhee-Frew. “The Eastern Australia humpback population narrowly escaped extinction. With good policies built on good science, we can have excellent outcomes.”

Migration is costly and dangerous. While this study doesn’t explain why whales migrate when they can give birth further south, conservation concerns remain. Some calves were injured. Scientists call for expanded protections, awareness campaigns, and further research.

“This study was based on opportunistic observations,” McPhee-Frew noted. “We can only document what we see.”

“Perhaps there are things happening in our ocean that we are yet to find out,” added Dr Vanessa Pirotta of Macquarie University.

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