MEPS 608:279-289 (2019)  -  DOI: https://doi.org/10.3354/meps12827

ABSTRACT: The concept of individual behavioural consistency has received a great deal of attention in the past 2 decades. However, the fitness benefits of being consistent in varying environmental conditions remain poorly explored. Such information is strongly relevant to our understanding of ecological processes, but also for predicting how some individuals and populations cope with environmental changes. We investigated short-term consistency in foraging behaviours of African penguins Spheniscus demersus at population and individual levels on Bird Island (Algoa Bay, South Africa) between 2015 and 2017, and related individual levels of consistency to reproductive outputs. Short-term overall consistency in foraging behaviour across individuals of the same population (population level) was generally moderate, although it was high for bearing (i.e. direction) towards the furthest point of the foraging trip. At the individual level, foraging consistency differed between years and was higher when environmental conditions were less profitable. Females were more flexible in their foraging behaviours than males. Overall, these results suggest that both intrinsic and extrinsic factors are responsible for inter-individual differences in foraging consistency in African penguins. Chicks of parents that were consistent in their foraging trip duration had higher growth rates than those of more flexible individuals when conditions were poor. It is not clear whether penguins adapt their level of short-term consistency at sea to the changing conditions or maintain their strategy across years. However, our results have revealed a reproductive advantage of individual foraging consistency during a year when resources were poor. For the first time, we have identified a potential mechanism to explain why some African penguins may cope better than others during poor environmental conditions.

KEY WORDS: Flexibility · Chick growth · Trip duration · Seabirds