Raising calves in beluga society
A recently published study looks at why belugas take care of each other’s offspring.
“Another calf-switching event!” Exclaims Jaclyn, her eyes fixed on the screen as she expertly maneuvers the drone above the beluga whales, while Marie-Ana and I keep our eyes on it. “Looks like another large female has taken over… which one is mom, I wonder?”
While this idyllic scene unfolds, our small research tower is enveloped by sounds from the herd: mother-calf contact calls can be heard loud and clear, as this is a herd of females and young. The hydrophone is connected to a little speaker that hangs from the railing of our small observation tower, so we have eyes and ears on the belugas.
For two summers, the three of us have been sharing this tower, erected on the tidal flats of Baie Sainte Marguerite, to conduct our respective research projects on endangered St Lawrence beluga whales. Marie-Ana Mikus, my longtime research assistant and collaborator, and I, worked on our “Mom, can you hear me” project to learn about the impacts of underwater vessel noise on mother-calf communication. Jaclyn Aubin was completing her fascinating Master’s work to shed light on beluga allocare – the care of young that are not one’s own – a study that taught us a great deal about beluga society.
It seems appropriate, on this International Woman’s Day, to reflect on the role of females in a species that shares uncanny similarities to our own species. A recent study by Greg O’Corry Crowe and colleagues revealed that, just like humans, belugas form complex communities and social networks of all ages and often both sexes, involving interactions and associations between kin and non-kin. Within these communities various kinds of groupings are possible, including all-male bands and loose matrilineal groups of females, calves and older female offspring. In the manner of fission-fusion societies – which contrast with more stable matrilineal societies such as killer whales or sperm whales – individuals from these loose groups periodically associate with both related and unrelated animals in the larger herd, forming friendships that can last a lifetime.
A lifetime, for a beluga, can be a very long time, as they can live up to 80 years. In fact, they are one of the few cetacean species, along with killer whales and short finned pilot whales, that show menopause, whereby females stop reproducing in their late 30s and early 40s, several decades before the end of their lives. These experienced and knowledgeable post-reproductive females are believed to play a significant role in their communities as helpers, teachers and guides. In killer whales, grandmas improve the survival of their grandoffspring, providing evidence of the grandmother effect in non-humans.
Amongst the fluid comings and goings of a beluga community, the young are often cared for by their mother’s close associates. “I am interested in what is going on with the females,” says Jaclyn excitedly during our joint webinar presentation Who Are Beluga Whales? “During my masters I found that belugas perform allocare, which is really a fancy way to say that they look after each other’s offspring. We were reviewing drone footage to look at these behaviours and we saw that tiny newborn calves as well as great big older juveniles…were spending a lot of time swimming with other females that were in groups with their mothers.” Jaclyn shows us a beautiful image of a newborn calf swimming alongside two females and confesses that she has no idea who these individuals are, a mother and a grandmother, or a mom and an aunt, or even two unrelated individuals that share a common bond in looking after this calf. And indeed earlier evidence from captive animals showed that both related and unrelated belugas can spontaneously lactate and nurse another female’s young with whom they share a close bond. “Watching these drone clips was one of my first experiences seeing the strong bonds that seem to be present within these groups,” Jaclyn adds.
Findings from the research
Her recently published study in the journal Behaviour explores why belugas care for each other’s offspring. Jaclyn and her colleagues tested two hypotheses: the natal attraction, or, in her own words, the “babies are just too darn cute” hypothesis, and the learning-to-parent hypothesis, which assumes that females babysit to learn parental skills.
The study found that neither hypothesis was a likely candidate to explain allocare in the St. Lawrence beluga population. Young females actually did not do much babysitting, and in fact, the calves themselves initiated most allocare bouts, choosing their own caregiver. The authors concluded that kin selection (helping relatives that share your genes, thus fostering the spread of those genes) and reciprocity (you scratch my back, I’ll scratch yours) may explain the prevalence of cooperative care of the young in this species – two hypotheses that are yet to be tested.
But regardless of the evolutionary explanation, something remains clear: in belugas whales, as the saying goes, it takes a community to raise a child…or rather, a calf!
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