Group foraging increases foraging efficiency in a piscivorous diver, the African penguin

Abstract

Marine piscivores have evolved a variety of morphological and behavioural adaptations, including group foraging, to optimize foraging efficiency when targeting shoaling fish. For penguins that are known to associate at sea and feed on these prey resources, there is nonetheless a lack of empirical evidence to support improved foraging efficiency when foraging with conspecifics. We examined the hunting strategies and foraging performance of breeding African penguins equipped with animal-borne video recorders. Individuals pursued both solitary as well as schooling pelagic fish, and demonstrated independent as well as group foraging behaviour. The most profitable foraging involved herding of fish schools upwards during the ascent phase of a dive where most catches constituted depolarized fish. Catch-per-unit-effort was significantly improved when targeting fish schools as opposed to single fish, especially when foraging in groups. In contrast to more generalist penguin species, African penguins appear to have evolved specialist hunting strategies closely linked to their primary reliance on schooling pelagic fish. The specialist nature of the observed hunting strategies further limits the survival potential of this species if Allee effects reduce group size-related foraging efficiency. This is likely to be exacerbated by diminishing fish stocks due to resource competition and environmental change.

Local forage fish abundance influences foraging effort and offspring condition in an endangered marine predator

“…Improvements in high-resolution multibeam sonar (e.g. Brierley & Cox, 2015) and in tracking technology, not least the continued miniaturisation of animalborne cameras and accelerometers, will help to clarify how individuals differ in prey capture and energy expenditure in response to changing prey abundance and availability in future (Elliott, Vaillant, Kato, Speakman, & Ropert-Coudert, 2012;McInnes et al, 2017).…”

Peer Review #2 of "Lateralization (handedness) in Magellanic penguins (v0.1)"

“…Penguins often forage in groups, although they also forage alone (Berlincourt & Arnould 2014;Gómez-Laich, Yoda & Quintana 2018;Jehl 1974;McInnes et al 2017;Sutton, Hoskins & Arnould 2015;Wilson & Wilson 1990). We expected lateralization of individuals but not in the population.…”

At sea vocal repertoire of a foraging seabird

“…As a consequence, species from all seabird orders commonly gather at sites where prey resources are concentrated, most often in multi-species associations (Siegfried et al 1975, Hoffman et al 1981, Harrison et al 1991, Camphuysen and Webb 1999, Clua and Grosvalet 2001. In this context, individuals may benefit from group foraging (Ryan et al 2012, Lett et al 2014, Thiebault et al 2015, McInnes et al 2017) and use both visual and acoustic cues (Thiebault et al 2014b(Thiebault et al , 2016. Despite numerous descriptions of seabird aggregations (mainly from boat observations), studies addressing the mechanisms involved in their social interactions at sea have long been constrained by technical limitations.…”

“…As a consequence, tracked individuals are often considered moving alone in the seascape. It is only recently that studies quantifying seabirds interactions at sea have gained impetus thanks to the miniaturisation of image recording devices in particular (Berlincourt and Arnould 2014, McInnes et al 2017. Although visual observation of in-situ foraging seabirds have greatly improved interpretation of remote movement data, the study of their vocal communication at sea has only very recently started (Thiebault et al 2016, Choi et al 2017.…”