Journal article

Publication year: 2017

Pages: 199-212

Journal: Marine Ecology Progress Series

Volume number: 585

ISSN: 0171-8630

eISSN: 1616-1599

Open access status: Green

DOI Link: https://doi.org/10.3354/meps12377

Publisher: Inter-Research Science Publisher

Abstract: 
Predators exploiting tropical pelagic waters characterised by low fluctuations in seasonal temperature and salinity may require different foraging strategies than predators that can rely on persistently productive marine features. Consistent individual differences in foraging strategies have been found in temperate seabirds, but it is unclear whether such foraging specialisation would be beneficial in unpredictable tropical pelagic waters. We examined whether foraging trip characteristics of a tropical seabird were consistent between seasons and within individuals and explored whether seasonal changes could be explained by environmental variables. Ascension frigatebird Fregata aquila trips lasted up to 18 d and covered a total travel distance of up to 7047 km, but adult frigatebirds stayed within a radius of 1150 km of Ascension Island. We found that the 50% utilisation distribution of the population expanded southwestward in the cool season due to individuals performing more and longer trips in a southerly and westerly direction during the cool compared to the hot season. Individual repeatability was low (R < 0.25) for all trip characteristics, and we were unable to explain seasonal changes in time spent at sea using oceano graphic or atmospheric variables. Instead, frigatebird usage per area was almost exclusively determined by distance from the colony, and although individuals spent more time in distant portions of their foraging trips, the amount of time spent per unit area decreased exponentially with in creasing distance from the colony. This study indicates that, in a relatively featureless environment, high individual consistency may not be a beneficial trait for pelagic predators.

Harvard Citation style: Oppel, S., Weber, S., Weber, N., Fox, D., Leat, E., Sim, J., et al. (2017) Seasonal shifts in foraging distribution due to individual flexibility in a tropical pelagic forager, the Ascension frigatebird, Marine Ecology Progress Series, 585, pp. 199-212. https://doi.org/10.3354/meps12377

APA Citation style: Oppel, S., Weber, S., Weber, N., Fox, D., Leat, E., Sim, J., Sommerfeld, J., Bolton, M., Broderick, A., & Godley, B. (2017). Seasonal shifts in foraging distribution due to individual flexibility in a tropical pelagic forager, the Ascension frigatebird. Marine Ecology Progress Series. 585, 199-212. https://doi.org/10.3354/meps12377