Raptors avoid the confusion effect by targeting fixed points in dense aerial prey aggregations

• Published in: Nature communications Vol. 13; no. 1; pp. 4778 - 13
• Main Authors: Brighton, Caroline H., Kloepper, Laura N., Harding, Christian D., Larkman, Lucy, McGowan, Kathryn, Zusi, Lillias, Taylor, Graham K.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23.08.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 631/158/853; 631/158/856; 631/601/1332; 631/601/18; Algorithms; Animals; Behavior; Biology; Birds of prey; Buteo swainsoni; Collision dynamics; Collision mortality; Confusion; Decoupling; Hawks; Humanities and Social Sciences; multidisciplinary; Predators; Predatory Behavior; Prey; Raptors; Schools; Science; Science (multidisciplinary); Steering; Swarming; Tadarida brasiliensis; Target acquisition
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-32354-5

Collective behaviours are widely assumed to confuse predators, but empirical support for a confusion effect is often lacking, and its importance must depend on the predator’s targeting mechanism. Here we show that Swainson’s Hawks Buteo swainsoni and other raptors attacking swarming Mexican Free-tailed Bats Tadarida brasiliensis steer by turning towards a fixed point in space within the swarm, rather than by using closed-loop pursuit of any one individual. Any prey with which the predator is on a collision course will appear to remain on a constant bearing, so target selection emerges naturally from the geometry of a collision. Our results show how predators can simplify the demands on their sensory system by decoupling steering from target acquisition when capturing prey from a dense swarm. We anticipate that the same tactic will be used against flocks and schools across a wide range of taxa, in which case a confusion effect is paradoxically more likely to occur in attacks on sparse groups, for which steering and target acquisition cannot be decoupled. Flocking, schooling, and swarming prey are thought to benefit from a confusion effect. However, here the authors show that hawks attacking swarming bats avoid confusion by steering towards a fixed point in the swarm instead of targeting any one individual.