Humpback whales, which were almost hunted to extinction by the mid-20th century, have rebounded spectacularly. Recent observations off the Australian coast indicate that these majestic marine mammals are giving birth further south than previously believed. During her time as a tour guide in 2023, PhD Candidate Ms. McPhee-Frew made a particularly exhilarating discovery. She eventually tracked down a single very young humpback whale, an exciting first in the ongoing study of whale migration patterns.
Historically, scientists thought that humpback whales could only calve to the north of 28 degrees latitude on the U.S. east coast. On the west coast, this dividing line was drawn at 23°N. Documents recently obtained reveal over 200 newborn calve sightings well outside of these boundaries. This increase in sightings is evidence that the migratory behavior of these whales is changing. More than that, they’re continuing to adapt to how environmental conditions change.
The migration of humpback whales typically involves traveling from cold, nutrient-rich southern waters to warmer breeding grounds in the north. They begin their incredible journey ever northward every April and head back south between August and November. Remarkably, some of these neonates have been observed as far south as 43 degrees latitude (PA), which seems improbable at first glance. This encompasses waters off of Tasmania and New Zealand.
Record-Breaking Calf Sightings
The past couple migration seasons have yielded a record high number of observations. About 64% of all live calf sightings happened in the 2023 and 2024 migrations. This dramatic increase in sightings of these whales has caused scientists to reevaluate theories about where humpback whales are known to give birth.
Ms. McPhee-Frew said that citizen scientists were crucial in doing the field work to document these sightings.
“The majority of our data came from citizen science sources — basically, people seeing tiny little whales, very clearly neonates,” – Ms. McPhee-Frew.
She stressed the need to comply with rules that shield these whales in their migratory months.
“We encourage people to enjoy these lovely animals, provided they’re following the rules that are in place for the whales’ protection,” – Ms. McPhee-Frew.
Researchers and citizen scientists whale watchers have joined forces to deepen our understanding of humpback whale migration patterns. This partnership has helped reveal the survival of whale calves.
The Benefits of Warmer Waters
Dr. Olaf Meynecke, a leading cetology researcher, has already indicated a strong willingness to research the ramifications of these discoveries. He believes that warmer waters can significantly benefit mother whales and their calves, which struggle with temperature regulation when they are young.
Humpback whales face fewer predators, such as orcas, in warmer waters, creating a safer environment for calves during their formative weeks. Dr. Meynecke explained that such adaptations may be associated with shifts in habitat and food sources.
“With an expansion of the population and higher stress on food availability during summer feeding, it may be an advantage to give birth further south,” – Dr. Meynecke said.
He further posed a fascinating hypothesis about as-yet-unexplained migratory behavior among females humpback whales.
“Is it that the female is just driven north through some deep either cultural or genetic instinct?” – Dr. Meynecke pondered.
This new investigation into the foraging behaviors of whale mothers could open up a corridor of research exploring the best reproductive strategies for migratory whales.
The Future of Humpback Whale Research
Additionally, researchers are closely watching, and documenting amazing patterns of behavior in humpbacks. This has led to an urgent need for comprehensive research on humpback whale mothers and their calves born during mid-migration. Learning what factors influence their movement and home range choice during this pivotal nesting season could offer key information to help ensure their survival and reproductive success.
Dr. Meynecke expressed his desire for more extensive research in this area:
“Will it return to the same waters where it was born for reproduction?” – Dr. Meynecke queried.
The evolving narrative of humpback whale migration highlights not only the resilience of this species but the importance of ongoing research and conservation efforts. By piecing together their responses to climate change, it will allow scientists to more accurately predict what these magnificent creatures will face in the coming years.
