Antje Chiu Werner (Departamento de Ornitología, Museo de Historia Natural “Javier Prado,” Universidad Nacional Mayor de San Marcos, Lima, Peru) and colleagues have published in the ornithological journal Auk on differences in the at-sea foraging behaviour of male and female Cory's Shearwater Calonectris borealis in relation to nest quality.
The paper’s abstract follows:
“An extended reproductive period and high variability in food resource availability at sea make good quality nest sites particularly important for the survival of pelagic seabird chicks. Despite high philopatry during the early pre-laying period, males compete strongly for nests, making this period a unique opportunity to independently assess the influence of nest-site characteristics and individual quality on the foraging behavior of Cory's Shearwater (Calonectris diomedea borealis) individuals. We found significant differences in the at-sea foraging behavior of males and females at temporal (trip duration) and spatial (foraging areas, trip distance, and trip sinuosity) scales, both of which are greater in females. Furthermore, we suggest that nests of higher quality are deeper and closer to the nest of a conspecific neighbor because both variables were associated with males foraging closer to the colony. Finally, we showed that during the early pre-laying period the influence exerted by nests on males' behavior at sea is independent from the individual's quality. Our study links nest-site features with the at-sea behavior of pelagic male seabirds during a period of nest competition and suggests that nest-site characteristics are important to explain foraging patterns of central-place foraging birds.”
A pair of Corys's Shearwaters, photograph by Paulo Catry
Chiu Werner, A., Paiva, V.H. & Ramos, J.A. 2014. On the “real estate market”: individual quality and the foraging ecology of male Cory's Shearwaters. Auk 131: 265-274.
John Cooper, ACAP Information Officer, 02 May 2014