Using Drone‐Derived Imagery to Describe Prey Sharing Behaviors in Two Piscivorous Resident Killer Whale Populations

Abstract

Cooperative foraging occurs across diverse taxa and facilitates prey acquisition and social learning, particularly when prey is shared among group members. In Resident killer whales ( Orcinus orca ater ), prey sharing is central to how individuals acquire salmonid prey, yet current research has relied primarily on boat‐based observations. Using 10 years of drone‐based imagery, we examined prey sharing behaviors in two populations, endangered Southern Resident killer whales (SRKWs) and threatened Northern Resident killer whales (NRKWs). Our goal was to evaluate the utility of drones for documenting prey sharing behaviors and conduct preliminary comparisons between NRKW and SRKWs. We detected 41 NRKW and 52 SRKW predation events, with prey sharing observed in 24 NRKW (59%) and 22 SRKW (42%) events. Drones effectively documented prey sharing at or near the surface, revealing subtle behaviors and allowing us to track the roles of individuals. Initial comparisons revealed that adult female NRKWs shared prey more frequently than adult female SRKWs and shared larger portions of prey. Although preliminary, our findings suggest differences in prey sharing between the populations, possibly reflecting social or ecological differences. Overall, drone‐based methods provide valuable insights into foraging behavior in free‐ranging cetaceans and offer a new approach to investigate cooperative behaviors.

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