Did The Animal Move? A Cross-Wavelet Approach to Qeolocation Data Reveals Year-Round Whereabouts of A Resident Seabird

Abstract

Considerable progress in our understanding of long-distance migration has been achieved thanks to the use of small lightweight geolocator devices (GLS). Errors of geolocation are however important, difficult to estimate, have a complex structure leading to poor precision and accuracy. Thus, the study of short-distance migrants or resident birds remains challenging. Here we aimed at elucidating the sex-specific marine space uses of a resident tropical seabird, the masked booby ( Sula dactylatra ) over the full annual life cycle at the Fernando de Noronha archipelago (Brazil), using GLS and synchronicity analyses between movement and saltwater immersion data. Masked boobies (n = 31) showed a resident behaviour over their entire annual cycle. We inferred from the wavelet analysis that birds traveled way and back from the colony on consecutive trips of short length (~ 2-4 days) and short range (~ 100-300 km) from the east of the colony. Duration and range of trips depended on the sex of the individual and on the time of the year. Trip duration increased gradually from the end of the breeding period to the post-breeding period, probably due to the release of the central-place breeding constraints. During the pre-breeding period, females had farther ranges eastward and spent more time in water than males. Despite inherent limits of light-based geolocation, synchronicity analysis of geolocation data revealed year round whereabouts of the resident tropical masked booby and sex-specific movement behaviour, which could be used more broadly to investigate resident or short-migrants animal movement based on GLS data.