Female sperm whales hold the newborn calf above water until it can swim on its own
Project CETI
A sperm whale giving birth has been assisted by 10 other females in her social unit – the first time such an event has ever been observed in non-primates.
In July 2023, scientists who have been monitoring a group of sperm whales in the Caribbean since 2005 noticed that all 11 females in the group had gathered near the surface. By chance, the researchers had drones in the air and were able to observe and record the event.
Shortly afterwards, the flukes of a calf started emerging from its mother. The delivery took place over the next half hour, during which the other females coordinated themselves into a highly synchronised formation to protect the mother and newborn.
As soon as the calf was born, the female whales gathered around and took turns making sure that it was kept lifted at the surface so it could breathe and had time for its flukes to fully unfurl. In the first few hours, newborn sperm whales aren’t buoyant and cannot stay at the surface on their own, so such assistance is thought to be critical to prevent calves from drowning.
“This is the first evidence of birth assistance in non-primates,” says team member Shane Gero at Project CETI in New York.
He says such complex behaviour was once thought to be exclusive to humans, and has only recently been seen in non-human primates.
“Sperm whale society is driven by strong female leadership in which knowledge is shared across generations of females,” says Gero. “It is fascinating to see the intergenerational support from the grandmother to her labouring daughter, and the support from the other, unrelated females.”
When short-finned pilot whales arrived about 18 minutes after the birth, the team observed clear defensive responses from the adult female sperm whales.
The newborn sperm whale emerges from the water post birth (bottom right) and is supported by adult females
Project CETI
“They consistently positioned at least one adult between the newborn and the pilot whales, including from below,” says team member Giovanni Petri at Northeastern University London. “On multiple occasions, adults opened their jaws and jerked their heads toward approaching pilot whales. In one instance, a pilot whale rammed into the nose of the adult female closest to the newborn at high speed. The sperm whales also changed direction when pilot whales swam directly in front of the cluster.”
The researchers had deployed underwater audio recording equipment to monitor the sperm whales’ calls as part of a separate study.
“On the acoustic side, what we found is striking,” says Petri. “We detected statistically significant shifts in the overall vocal style at key moments: the onset of labour and the first interactions with pilot whales.”
These shifts were well beyond the normal variation seen in the unit’s everyday socialising, he says. Once the critical moments around the birth had passed, the group’s vocal style returned to baseline.
The combination of the acoustics and the observations allowed the researchers to “connect what these animals do with what they say”, says Petri.
Gero says the team hasn’t yet been able to determine the calf’s sex. “We’re hoping to see the newborn in the field in the next few months, in which case we would give it a name. But we know it has survived the critical first year of its life in which calf mortality is very high.”
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