Study reveals curiously human-like social ties among beluga whales
Belugas appear to embrace the idea of a chosen family.
In the Arctic, beluga whales live, hunt, and migrate together. Pods range from just a few whales to hundreds. Within those groups, scientists have discovered a surprising social network.
Just like many humans find themselves surrounded by friends more often than family, beluga whales branch outside of their relatives when they socialize.
In fact, beluga whales' social relationships are predominantly with either non-family members or distant relatives, biologists report in a new study — the first to analyze group dynamics and kinship in beluga whales.
The finding challenges previous beliefs about social ties among belugas, Delphinapterus leucas. Researchers previously believed these cetaceans were more likely to bond around their maternal lineages.
The researchers observed wild belugas in 10 locations across the Arctic, with the help of partnerships with Native communities, lead study author Gregory O'Corry-Crowe tells Inverse.
"Sometimes you just need to sit and observe these animals in the wild," says O'Corry-Crowe, a professor at Florida Atlantic University.
In addition to observation, the team took samples of the whales for genetic analysis, to determine which whales were related to one another. They also fitted some whales with satellite tags.
"Putting these three approaches together gave us a uniquely in-depth view of beluga whale societies," O'Corry-Crowe says.
The findings were published on July 10 in the journal Scientific Reports.
Family ties — Many social animals, including orcas and African elephants, bond with animals they're closely related to. Until now, researchers believed the same would be true for beluga whales.
"I think the finding that, in most cases, beluga whale social groups are predominantly composed of either distant relatives or non-kin was a surprise," O'Corry-Crowe says.
Known for their bulbous foreheads and lively noises, belugas talk to each other through a series of clicks, chirps, and whistles. Each year, the whales travel south when Arctic ice forms, and return poleward in the spring to feed. They eat salmon, herring, shrimp, crabs, and mollusks.
O'Corry-Crowe has spent years studying beluga whales' population structure, movement patterns, and habitat use. "But I’ve always wondered how their societies are organized and function," he says. So he and his team set out to answer that question.
While the new research provides the first evidence of abundant non-familial relationships, researchers aren't yet sure how widespread beluga social networks are. An individual whale may have quite an extensive social life, with "both kin and non-kin, brief and long-term affiliations, old and young, males and females," O'Corry-Crowe says. In other words, they may exist in a relationship structure much like ours.
While these findings are novel, animal friendships may be more common than we think.
The classic understanding of social species suggests that hanging around close relatives benefits the group. Animals can call on close kin for help rearing offspring, for instance. However, the beluga research suggests there may be reasons why an animal would benefit from a relationship with an unrelated individual.
"It likely comes down to how beneficial that relationship, in terms of cooperation, for example, is to both individuals," O'Corry-Crowe says. "This is where we now need to go with research in this field."
Abstract: Evolutionary explanations for mammalian sociality typically center on inclusive-fitness benefits of associating and cooperating with close kin, or close maternal kin as in some whale societies, including killer and sperm whales. Their matrilineal structure has strongly influenced the thinking about social structure in less well-studied cetaceans, including beluga whales. In a cross-sectional study of group structure and kinship we found that belugas formed a limited number of distinct group types, consistently observed across populations and habitats. Certain behaviours were associated with group type, but group membership was often dynamic. MtDNA-microsatellite profiling combined with relatedness and network analysis revealed, contrary to predictions, that most social groupings were not predominantly organized around close maternal relatives. They comprised both kin and non-kin, many group members were paternal rather than maternal relatives, and unrelated adult males often traveled together. The evolutionary mechanisms that shape beluga societies are likely complex; fitness benefits may be achieved through reciprocity, mutualism and kin selection. At the largest scales these societies are communities comprising all ages and both sexes where multiple social learning pathways involving kin and non-kin can foster the emergence of cultures. We explore the implications of these findings for species management and the evolution of menopause.