Recent research has unveiled that humpback whales give birth while migrating and continue their journey shortly after, challenging previous assumptions about their calving habits. These predictions have been recently verified by detailed observations. Importantly, the majority of the live calf sightings occurred after 2016, with two-thirds of all observations made in 2023 or 2024. These results come as a relief, suggesting that these colossal creatures are more surprisingly adaptive. They’re able to travel very long distances soon after calving.
New Insights from Migration Surveys
That fresh perspective is fueled by data shared with them from New Zealand’s Department of Conservation. They’ve done extensive migration surveys as part of the Cook Strait Whale Project. These aerial surveys captured powerful documentation of humpback whales calving along their migration route. Australian state wildlife departments have been instrumental in supporting the research. Specifically, through their citizen science efforts, they’ve published information about whale strandings going back to 1991.
The database includes 209 records of newborn humpback whale calves. This counts 11 confirmed births, 41 strandings, and 168 live observations. This data is the representation of at least 169 separate calves, an impressive jump in the number of calves seen in recent years, if not even more.
“I think it’s very likely that this pattern has always existed, but the low number of whales obscured it from view,” – McPhee-Frew
The study’s most surprising find was the northernmost birth ever reported—as far north as possible—in Kaikoura, New Zealand. This finding means that calves can now be born as far south as Tasmania or New Zealand. That’s 1,500 kilometers south of where we knew it to be!
Continued Migration After Birth
Perhaps the most shocking discovery was that humpback whales do not stop migrating after they have given birth. They still fly over temperate waters in Australia and New Zealand. It’s this kind of behavior that helps us understand how difficult newborn calves have it. Because they are less adept swimmers at this age, they need to swim much farther than calves born in official breeding grounds.
Dr. Tracey Rogers emphasized the risks associated with this migration pattern:
“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 than if they were born in the breeding grounds.”
The Eastern Australia Humpback Whale population now estimates between 30,000 and 50,000 individuals. This is nothing short of astounding considering the historic lows brought on by decimation through hunting.
Observational Trends and Future Research
Dr. Vanessa Pirotta remarked on the observational nature of the data:
“We can only document what we see.”
Dr. McPhee-Frew commented on the possibility of more northern sightings being influenced by heightened whale-watching activities or increased sharing on social media platforms.
“It might appear that we see more [calves] the further north we go, or that we have seen more over time,” – McPhee-Frew
She cautioned against drawing definitive conclusions based on current observations alone:
“But we can’t stretch the interpretations too far.”
The importance of these finds can’t be over emphasized. Scientists believe there are other, even more mysterious factors at work puzzling their behavior and migration patterns.
“Perhaps there are things happening in our ocean that we are yet to find out,” – Dr. Vanessa Pirotta