How to capture fish in a school? Effect of successive predator attacks on seabird feeding success

1. Prey aggregations, such as fish schools, attract numerous predators. This typically leads to the formation of multi-specific groups of predators. These aggregations can be seen both as a place of increased competition and as a place of possible facilitation between predators. Consequently, the functional role of such predator-prey aggregation is uncertain, and its effect on individual feeding success is virtually unknown. 2. Using underwater film footages of different predators feeding on fish schools during the sardine run in South Africa, we directly measured the in-situ feeding success of individual Cape gannets Morus capensis in different foraging situations. 3. We determined the types of Cape gannet attacks (direct plunge dive or plunge dive followed by underwater pursuit) and we measured the occurrences and timing of attacks from the different species (mostly Cape gannets and long-beaked common dolphins Delphinus capensis). We also estimated the size of the targeted fish school...