Humpback Calves "Whisper" To Their Moms

Every winter, hundreds of humpback whales migrate long distances from their high latitude feeding grounds in the Arctic and Antarctic to warmer tropical regions to breed and give birth. The newborn calves, which consume over 52 gallons of milk on a daily basis, have only a few months to pack on the body fat needed to survive the long trek back to cooler waters in summer. How the babies signal hunger and avoid predatorsduring these formative months has always been a mystery to scientists.

We know next to nothing about the early life stages of whales in the wild, but they are crucial for the calves’ survival during the long migration to their feeding grounds. These early life stages of wild whales are so elusive because they're an aquatic animal. We can't follow them around all the time to see what they're doing.

To investigate, a team of scientists tracked eight calves using special recorders that captured their movement and ambient sounds. They used temporary tags which they stuck onto the babies’ skin using suction cups. The tags fell off within a day, and were therefore, not harmful to their health.

They learned that instead of bawling loudly like their human counterparts, humpback calves signal their hunger by gently nudging their mothers or uttering soft grunts and squeaks. The moms acknowledge the requests by responding with quiet calls. This is very different from the normally loud and eerie adult whale songs which reverberate across the ocean.

The team believes these quiet conversations help whale mothers keep track of their young in murky waters without being overheard by dangerous eavesdroppers. The scientists speculate that the barely audible conversations also keep mate-seeking males at bay. This allows the females to focus on nurturing the newborns before the tough, 5,000-mile journey back to their feeding grounds in the Antarctic.

The study highlights the importance of keeping the nursery waters shielded from human noise pollution. The scientists assert that activities such as whale watching, shipping and fishing, could mask the quiet communication between the mother and calf, increasing the risk of their separation with potentially fatalconsequences for the baby humpbacks. Given that the population of the majestic mammals, that were on the endangered list until 2016, is finally recovering, it is important to ensure that every one of these precious calves survives.