Sex-specific effects of wind on the flight decisions of a sexually dimorphic soaring bird

• Published in: Journal of Animal Ecology
• Main Authors: Clay, Thomas A., Joo, Rocio, Weimerskirch, Henri, Phillips, Richard A., Den Ouden, Olivier, Basille, Mathieu, Clusella-Trullas, Susana, Assink, Jelle D., Patrick, Samantha C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley & Sons Ltd. 2021
• Subjects: Biologging (Animal radio tracking); Foraging behavior in animals; Hidden Markov models; Movement ecology; Niche specialization; Optimization; Sexual segregation; Wandering albatross; Wandering Albatross
• Online Access: http://hdl.handle.net/10019.1/121192; https://doi.org/10.1111/1365-2656.13267

CITATION: Clay, T. A. et al. 2020. Sex-specific effects of wind on the flight decisions of a sexually dimorphic soaring bird. Journal of Animal Ecology, 00:1–13, doi:10.1111/1365-2656.13267. The original publication is available at https://besjournals.onlinelibrary.wiley.com/journal/13652656 In a highly dynamic airspace, flying animals are predicted to adjust foraging behaviour to variable wind conditions to minimize movement costs. Sexual size dimorphism is widespread in wild animal populations, and for large soaring birds which rely on favourable winds for energy-efficient flight, differences in morphology, wing loading and associated flight capabilities may lead males and females to respond differently to wind. However, the interaction between wind and sex has not been comprehensively tested. We investigated, in a large sexually dimorphic seabird which predominantly uses dynamic soaring flight, whether flight decisions are modulated to variation in winds over extended foraging trips, and whether males and females differ. Using GPS loggers we tracked 385 incubation foraging trips of wandering albatrossesDiomedea exulans, for which males arec. 20% larger than females, from two major populations (Crozet and South Georgia). Hidden Markov models were used to characterize behavioural states-directed flight, area-restricted search (ARS) and resting-and model the probability of transitioning between states in response to wind speed and relative direction, and sex. Wind speed and relative direction were important predictors of state transitioning. Birds were much more likely to take off (i.e. switch from rest to flight) in stronger headwinds, and as wind speeds increased, to be in directed flight rather than ARS. Males from Crozet but not South Georgia experienced stronger winds than females, and males from both populations were more likely to take-off in windier conditions. Albatrosses appear to deploy an energy-saving strategy by modulating taking-off, their most energetically expensive behaviour, to favourable ...