Non-consumptive factors affecting foraging patterns in Antarctic penguins: a review and synthesis

• Published in: Polar biology Vol. 35; no. 1; pp. 1 - 13
• Main Authors: Ainley, David G., Ballard, Grant
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-01-2012; Springer; Springer Nature B.V
• Subjects: Analysis; Animal and plant ecology; Animal behavior; Animal migration; Animal, plant and microbial ecology; Aptenodytes forsteri; Aves; Biological and medical sciences; Biomedical and Life Sciences; Ecology; Ecosystem components; Emperor penguin; Food chains (Ecology); Food webs; Foraging behavior; Fundamental and applied biological sciences. Psychology; Life Sciences; Literature reviews; Marine; Marine environment; Marine mammals; Microbiology; Oceanography; Particular ecosystems; Plant Sciences; Predators; Prey; Pygoscelis adeliae; Review; Risk aversion; Sea water ecosystems; Synecology; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Zoology; Antarctic region; PS, Antarctic Ocean; Apex predator; Leopard seal; Emperor penguin; Risk balancing; Predation; Foraging habitat; Killer whale; Predation fear; Adélie penguin; Mesopredator; Aptenodytes forsteri; Risk; Review; Marine environment; Habitat; Polar region; Cetacea; Aves; Apex; Carnivora; Balancing; Pygoscelis adeliae; Foraging behavior; Orcinus orca; Vertebrata; Mammalia; Predator
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-011-1042-x

Recent research has clearly shown that the fear of predation, i.e. aversion to taking risks, among mesopredators or grazers, and not merely flight from an apex predator to avoid predation, is an important aspect of ecosystem structuring. In only a few, though well-documented cases, however, has this been considered in the marine environment. Herein, we review studies that have quantified behavioral responses of Adélie penguins
Pygoscelis adeliae
and emperor penguins
Aptenodytes forsteri
to the direct presence of predators, and question why the penguins avoid entering or exiting the water at night. We also show, through literature review and new analyses of Adélie penguin diving data, that Antarctic penguins are capable of successful prey capture in the dark (defined here as <3.4 lux). Finally, we summarize extensive data on seasonal migration relative to darkness and prey availability. On the basis of our findings, we propose that penguins’ avoidance of foraging at night is due to fear of predation, and not to an inability to operate effectively in darkness. We further propose that, at polar latitudes where darkness is more a seasonal than a year-round, daily feature, this “risk aversion” affects migratory movements in both species, consistent with the “trade-off” hypothesis seen in other marine vertebrates weighing foraging success against predation risk in their choice of foraging habitat. Such non-consumptive, behavioral aspects of species interactions have yet to be considered as important in Southern Ocean food webs, but may help to explain enigmatic movement patterns and choice of foraging grounds in these penguin species.