Decoding Killer Whale Friendships with Drones

Known as “southern residents,” this killer whale pod inhabits the coastal waters of the northeastern Pacific, off the coasts of Washington state and British Columbia. The closely studied population of around 80 individuals has been the subject of an annual census since 1976. Since every individual in the pod is known and can be identified by its distinctive markings, the population was an ideal candidate for the study on social interactions.

Southern residents live in a society divided into matrilineal social groups. These small groups are made up of individuals that share a recent maternal ancestor and therefore represent family lineages. Those lineages with the most genetic links to each other come together to form larger, relatively stable social groups that share the same vocal dialect. In the southern resident population alone, there are three different dialects and several maternal lines.

Due to this “family” configuration, the majority of associations within the population are dictated by lineage, which means that individuals observed together are generally related matrilineally. An association takes place when two individuals swim in proximity to one another, while an interaction is a social behaviour that has a positive or negative impact on the quality of the bond maintained by two individuals.

The researchers first documented the synchronized ascent to the surface and simultaneous breathing of two individuals. This behaviour is important because it can promote cooperation as well as the maintenance of social relationships. They subsequently noted all physical contacts between individuals (with the exception of aggressive behaviours and those related to maternal care), as they often indicate a strong bond between two individuals and may also contribute to reconciliation following aggressive interactions. These two social interactions generally indicate peaceful relationships and can therefore help determine which groups of individuals are the most social.

By analyzing the occurrences of these two interactions in all individuals of the same social group, the researchers concluded that killer whales mostly tend to touch or breathe concurrently with other individuals of their age and/or sex. Just like at a family gathering, youngsters play together while parents mingle amongst themselves. The researchers also noted that interactions were mostly concentrated in two specific groups: juveniles and females. These groups are believed to represent the core of social networks and the ones that maintain the most bonds.

How did the research team manage to capture these fleeting moments of interaction? Using drones, the team tracked the killer whale population from above and managed to collect several hours of video footage. This is the first time that this population was studied using drones. The images therefore provide an unprecedented perspective on the social lives of these animals. However, this perspective remains limited to interactions occurring near the surface, as drone cameras cannot penetrate deeper, darker waters.

Physical interactions and contact between cetaceans are still poorly understood, but there appears to be no general rule. Sperm whales organize themselves into complex matriarchal societies, humpback whales produce extraordinary songs whose exact function is unknown, porpoises engage in collaborative hunting… And, in St. Lawrence belugas, the existence of allomaternal care and contact calls has been documented. And unlike killer whales, it is the males that are the most “touchy-feely”! “They depend on alliances to reproduce. It is in their best interest to invest time into developing their relationships and their skills,” explains Robert Michaud, director of the Group for Research and Education on Marine Mammals (GREMM). According to Michaud, the use of drones is set to revolutionize our knowledge of whales. “This is only a guess, but I believe the majority of social interactions in belugas takes place near the surface,” he hypothesizes. “I think they go to the depths to orient themselves, to listen, to feed… but not to socialize.” Thus, by carefully analyzing data obtained from the skies, we may be able to draw a fairly accurate portrait of the social lives of St. Lawrence belugas as well as killer whales in the Pacific.