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

Abstract

Background The 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. Methods In 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). Results White-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. Discussion 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.

Genetic structuring among colonies of a pantropical seabird: Implication for subspecies validation and conservation

“…None of the tracked birds crossed the equator and reached the southern Atlantic Ocean. Campos, Andrade, Bertrand, and Efe (2018) and Santos, Campos, and Efe (2019) tracked the movement of white‐tailed tropicbirds ( P. l. ascensionis ) during chick‐rearing from Fernando de Noronha archipelago and showed that long foraging trips reached an average distance from the breeding colony of 105 ± 48 km. This reinforces the hypothesis of a lack of connectivity between northern and southern populations of the Atlantic Ocean.…”

Foraging Ecology of Red-Billed Tropicbirds on Saba, Caribbean Netherlands, during Early Chick-Rearing

“…We programmed GPS devices to record a location every 3 min, after which they were waterproofed with heat-shrink tubing. We deployed tags only on adults with chicks younger than 21 d, following Santos et al (2019), and in most cases only on one adult of a given nest. In one case we deployed tags on both adults of a given nest.…”

“…Seabirds have mainly been tracked in studies from mid- and higher-latitude regions, but fewer studies have been conducted in sub-tropical and tropical areas. Some studies exist that have tracked Tropicbirds (family Phaethontidae) using miniaturised GPS technology (see Sommerfeld & Hennicke 2010, Soanes et al 2016, Diop et al 2018, Santos et al 2019). Most recently, Madden et al (2022) combined GPS tracking, environmental variables and diet samples to determine the feeding ecology and foraging strategies of Red-billed Tropicbirds (hereafter Tropicbirds) nesting on St. Eustatius in the Lesser Antilles.…”