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Cleasby IR, Wakefield ED, Bodey TW, Davies RD, Patrick SC, Newton J, Votier SC, Bearhop S, Hamer KC
Sexual segregation in a wide-ranging marine predator is a consequence of habitat selection
Sexual segregation is common among marine species, yet its causes and consequences remain poorly understood. Using a multifaceted approach that combined data on movements, diving behaviour, stable isotopes and oceanography, Cleasby and co-authors found that over three consecutive years, sexual segregation in northern gannets Morus bassanus at a large colony on Bass Rock, UK was driven largely by habitat segregation across a tidal mixing front. Male gannets typically foraged in mixed, inshore waters characterized by higher primary productivity, whereas females forged more in offshore stratified waters. In addition, differences in habitat usage were reflected in differences in sex-specific dive depths and profiles, indicating that males and females adapt their diving behaviour to the environment in which they forage.