Influence of oceanographic structures on foraging strategies: Macaroni penguins at Crozet Islands.

John Y.P Arnould,Alice Della Penna,Timothée Poupart,Charles-André Bost,Francesco D’Ovidio,Cecile Bon

doi:10.1186/s40462-015-0057-2

Abstract

BackgroundIn the open ocean, eddies and associated structures (fronts, filaments) have strong influences on the foraging activities of top-predators through the enhancement and the distribution of marine productivity, zooplankton and fish communities. Investigating how central place foragers, such as penguins, find and use these physical structures is crucial to better understanding their at-sea distribution. In the present study, we compared the travel heading and speed of the world’s most abundant penguin, the Macaroni penguin (Eudyptes chrysolophus), with the distribution of surface physical structures (large-scale fronts, eddies and filaments).ResultsThe study was performed during December 2012 in the Crozet Archipelago (46.42° S; 51.86° E), South Indian Ocean. Six males at incubation stage were equipped with GPS loggers to get their trajectories. We used Eulerian and Lagrangian methods to locate large-scale fronts, mesoscale eddies (10–100 km) and part of the sub-mesoscale structures (<10 km, filaments) at the surface of the ocean. By comparing the positions of birds and these structures, we show that Macaroni penguins: i) target the sub Antarctic Front; ii) increase their foraging activity within a highly dynamic area, composed of eddy fields and filamentary structures; and iii) travel in the same direction as the predominant currents.ConclusionsWe show that penguins adjust their travel speed and movement during their whole trips in relation with the oceanographic structures visited. At a large scale, we hypothesize that Macaroni penguins target the sub Antarctic Front to find profitable patches of their main prey. At finer scale, Macaroni penguin may adopt a horizontal drifting behavior in strong currents, which could be a way to minimize costs of displacement.

Highlights

In the open ocean, eddies and associated structures have strong influences on the foraging activities of top-predators through the enhancement and the distribution of marine productivity, zooplankton and fish communities
We attempted to answer the following questions: i) do Macaroni penguins adjust their spatial movements with the regional circulation of currents?; and ii) how do they adjust their foraging behavior within meso- and sub-mesoscale structures? We address these questions by investigating the relationships between the spatial behavior of penguins and: i) the presence of persistent, large-scale frontal structures; ii) the occurrence of eddies and filamentary structures; and iii) the adjustment of their travel speed with the encountered currents
Data from one GPS were lost due to technical failure and six tracks were analyzed in the present study

Summary

Introduction

Eddies and associated structures (fronts, filaments) have strong influences on the foraging activities of top-predators through the enhancement and the distribution of marine productivity, zooplankton and fish communities. We compared the travel heading and speed of the world’s most abundant penguin, the Macaroni penguin (Eudyptes chrysolophus), with the distribution of surface physical structures (large-scale fronts, eddies and filaments). Bon et al Movement Ecology (2015) 3:32 non-flying, diving predators are highly constrained in their foraging range because of their low travelling speed and high cost of transport. It might be expected, that oceanic penguins should target sub-meso and mesocale structures during their at-sea activities to maximise their foraging efficiency [10]. We investigated the at-sea foraging movements of the Macaroni penguin (Eudyptes chrysolophus) in a highly dynamic marine environment: the waters around the Crozet Archipelago in the South Indian Ocean. The Crozet Archipelago is a breeding stronghold for the species [19]

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