Foraging habitat choice of White-tailed Tropicbirds revealed by fine-scale GPS tracking and remote sensing.

Carlos D Santos,Márcio A Efe,Leila F.A.S Campos

doi:10.7717/peerj.6261

Abstract

BackgroundThe introduction of animal tracking technology has rapidly advanced our understanding of seabird foraging ecology. Tracking data is particularly powerful when combined with oceanographic information derived from satellite remote sensing, allowing insights into the functional mechanisms of marine ecosystems. While this framework has been used extensively over the last two decades, there are still vast ocean regions and many seabird species for which information is scarce, particularly in tropical oceans.MethodsIn this study we tracked the movement at high GPS recording frequency of 15 White-tailed Tropicbirds (Phaethon lepturus) during chick-rearing from a colony in Fernando de Noronha (offshore of Northeast Brazil). Flight behaviours of travelling and searching for food were derived from GPS data and examined in relation to satellite-sensed oceanographic variables (sea surface temperature, turbidity and chlorophyll-a concentration).ResultsWhite-tailed Tropicbirds showed marked preference for clear and warm sea surface waters, which are indicative of low primary productivity but are likely the best habitat for preying upon flying fish.DiscussionThese findings are consistent with previous studies showing that foraging habitat choices of tropical seabirds may not be driven by primary productivity, as has been widely shown for non-tropical species.

Highlights

The way how pelagic seabirds move across the vastness of the open ocean have fascinated generations of scientists, but only recently have technological developments provided the tools to uncover that mystery
We found that White-tailed Tropicbirds searching for food in oligotrophic waters during breeding show preference for areas with higher sea surface temperature (SST) and lower turbidity (Fig. 2), while no influence of chlorophyll-a was observed (Table 1)
These patterns match with general predictions of habitat use by seabirds breeding in tropical oceanic islands, where the sea is largely unproductive and food resources are unpredictable (Weimerskirch, 2007)

Summary

Introduction

The way how pelagic seabirds move across the vastness of the open ocean have fascinated generations of scientists, but only recently have technological developments provided the tools to uncover that mystery. Tracking devices have become indispensable tools to study the behaviour of seabirds at-sea. Foraging habitat choice of White-tailed Tropicbirds revealed by finescale GPS tracking and remote sensing. Tracks of marine animals and oceanographic variables derived from satellite imagery provide exceptional opportunities to understand the functional mechanisms of marine ecosystems (Wakefield, Phillips & Matthiopoulos, 2009). Tracking data is powerful when combined with oceanographic information derived from satellite remote sensing, allowing insights into the functional mechanisms of marine ecosystems. While this framework has been used extensively over the last two decades, there are still vast ocean regions and many seabird species for which information is scarce, in tropical oceans. These findings are consistent with previous studies showing that foraging habitat choices of tropical seabirds may not be driven by primary productivity, as has been widely shown for non-tropical species

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