Plasticity in the foraging behavior of male Southern Rockhopper Penguins (Eudyptes chrysocome) during incubation in the Falkland/Malvinas Islands

Klemens Pütz,Norman Ratcliffe,Sabrina Harris,Andrea Raya Rey,Sally Poncet,Bernhard Lüthi

doi:10.1007/s00300-018-2320-7

Abstract

Environmental changes often affect the persistence of species or populations at different spatial and temporal scales. Thus, species must either adapt to these changes or experience negative impacts at the individual or population levels. Southern Rockhopper Penguins Eudyptes chrysocome are distributed throughout the Southern Ocean and have experienced substantial declines in the past which were linked to various anthropogenic and environmental factors. The aim of this study was to investigate the foraging behavior of male Southern Rockhopper Penguins at Berkeley Sound, East Falkland, Falkland/Malvinas Islands, during incubation, a period at-sea which is crucial for replenishing body condition between two extended fasting periods ashore. Thus, birds are forced to forage efficiently during that time to balance their energy demands. We linked their at-sea distribution and foraging behavior to satellite-derived sea surface temperatures and temperature-depth profiles which were recorded by devices attached to the birds. While Southern Rockhopper Penguins usually travel several hundreds of km out into the open sea on multiple-day trips during incubation, we found in our study that most birds foraged close inshore, less than 9 km away from their colony, and regularly returned to their breeding site. We propose that this behavior occurred in response to the close proximity of the 8 °C SST isotherm and the vertical stratification of the waters therein. Also, while usually feeding pelagically in open waters, there are strong indications that Southern Rockhopper Penguins performed benthic or, at least, near-bottom dives to catch their prey during these short trips. The consequences of this behavioral plasticity in response to variations in sea temperatures and inferred prey availability are discussed, especially with regard to predicted global climate change.

Highlights

Environmental changes often negatively affect the persistence of populations or species (Stenseth et al 2002; Walther et al 2002)
In 2012 and 2013, all SRP equipped with Global Positioning System-Loggers (GPS)-Loggers foraged less than 9 km away from their breeding site within the Berkeley Sound, while the 8 °C isotherm was either further to the west (2012) or very close (2013) to the breeding site
The breeding cycle of SRP is well established throughout its distributional range (Williams 1995; Pütz et al 2013)

Summary

Introduction

Environmental changes often negatively affect the persistence of populations or species (Stenseth et al 2002; Walther et al 2002). Southwest Atlantic Ocean, less prominent and can lead to massive blooms of gelatinous zooplankton and depress populations of copepods (Sabatini and Martos 2002) This influences the plankton community structure by changing the timing of recruitment and the population growth which in turn affects the trophic chain it generates. Even these “slight” temperature modifications have a bottom-up effect on the entire trophic chain, affecting top predators’ foraging areas and diet (e.g., Garcia-Godos and Goya 2006; Grémillet and Boulinier 2009; Masello et al 2010; Baylis et al 2012; Lescroël et al 2014). Multi-year studies on the behavior of a predator can elucidate alterations in the marine environment utilized

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