Foraging behavior and at-sea distribution of White-Tailed Tropicbirds in tropical ocean.

L F A S Campos,M A Efe,S Bertrand,A B Andrade

doi:10.1590/1519-6984.173578

Abstract

We used miniaturized GPS loggers and site observations to access foraging patterns and nest behaviour of the White-tailed Tropicbird Phaethon lepturus (WTTB), an endangered species at its South Atlantic breeding colony. Dual foraging pattern was observed with alternation between long and short foraging trips. Birds responsible for nest attendance engaged in short foraging trips with mean distance from colony of 25 ± 17 km, total distance covered of 79 ± 65 km and mean duration of 4.02 ± 5.28 hours. Birds flew by dawn and returned before dusk while partners were at sea for long foraging trips that ranged from four to 11 days, with mean maximum distance from colony of 105 ± 47.48 km. Chicks were usually left alone for hours and chick predation by Land Crab Johngartia lagostroma, egg consumption by Goniopsis cruentata and intra-specific competition are suspected to be responsible for high chick mortality rates.

Highlights

Seabirds are adapted to maximize energy intake during their life-history (Bradshaw et al, 2004)
White‐tailed Tropicbird Phaethon lepturus (WTTB) showed a dynamic attendance behavior, where even the parent responsible for staying on the nest leaves for short foraging trips at dawn, returning after a couple of hours or even late afternoon
Our study evidences the existence of great foraging range, a dynamic attendance behavior and dual foraging pattern, consistent with previous studies of the species in other oceans

Summary

Introduction

Seabirds are adapted to maximize energy intake during their life-history (Bradshaw et al, 2004). Seabirds are central place foragers, and the spatial distribution of their foraging effort emerges from a combination of previous experience, local environmental cues and energy demand increased by the necessity to raise offspring (Baylis et al, 2008; Bonadonna et al, 2001). Considering these constraints, seabirds have to make judicious choices of where to forage successfully within a restricted time span (Bonadonna et al, 2001; Kotzerka et al, 2011).

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Results

Conclusion