Visual and olfactory signals are commonly used by seabirds to locate prey in the horizontal domain but foraging success depends on prey depth and the seabird’s ability to access it. Facilitation by diving seabirds has long been hypothesised as a mechanism to elevate deep prey to regions more accessible to volant seabirds, but this has never been demonstrated empirically. Footage from animal-borne video loggers deployed on African penguins was analysed to establish if volant seabird encounters involved active cuing by seabirds on penguins and, during mutual prey encounters, if interactions were driven by the vertical displacement of prey by penguins. We found a strong inverse relationship between penguin group size, a proxy for visibility, and the time elapsed from the start of penguins' dive bouts to their first encounter with other seabirds. Most mutual prey encounters (7 of 10) involved schooling prey elevated from depths > 33 m by penguins and only pursued by other seabird species once prey was herded into shallow waters. This is likely to enhance foraging efficiency in volant seabird species. As such penguins may be integral to important processes that influence the structure and integrity of marine communities.

all observations from AVRs on African penguinsObservations classified from animal-borne video recorders (AVR) deployed on African penguins at Stony Point, South Africa between 2015 and 2018.Data includes classified behaviours of penguins, intra- and interspecific behaviours and counts, foraging behaviour.upforgrabs_raw.csvdata used in LMM modelsFile contains data used in LMM models to assess influence of African penguin group size on the time elapsed since the start of a dive bout to first encounters with volant seabirds. Fields include penguin ID, bout ID, elapsed (time to encounter), maxconsp (maximum penguin group size in dive bout), initconsp( initial group size (in first 5 min of dive bout) and intermode (flight or surface).upforgrabs_lmm_data.csv