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Provedor de dados:  ArchiMer
País:  France
Título:  Fine-scale recognition and use of mesoscale fronts by foraging Cape gannets in the Benguela upwelling region
Autores:  Sabarros, Philippe S.
Gremillet, David
Demarcq, Herve
Moseley, Christina
Pichegru, Lorien
Mullers, Ralf H. E.
Stenseth, Nils C.
Machu, Eric
Data:  2014-09
Ano:  2014
Palavras-chave:  Seabird
Environmental cue
Behavioral shift
Area-restricted search
Feeding activity
Fractal landscape
Oceanographic fronts
Morus capensis
Southern Benguela
South Africa
Resumo:  Oceanic structures such as mesoscale fronts may become hotspots of biological activity through concentration and enrichment processes. These fronts generally attract fish and may therefore be targeted by marine top-predators. In the southern Benguela upwelling system, such fronts might be used as environmental cues by foraging seabirds. In this study we analyzed high-frequency foraging tracks (GPS, 1 s sampling) of Cape gannets Morus capensis from two colonies located on the west and east coast of South Africa in relation to mesoscale fronts detected on daily high-resolution chlorophyll-a maps (MODIS, 1 km). We tested the association of (i) searching behavior and (ii) diving activity of foraging birds with mesoscale fronts. We found that Cape gannets shift from transiting to area-restricted search mode (ARS) at a distance from fronts ranging between 2 and 11 km (median is 6.7 km). This suggests that Cape gannets may be able to sense fronts (smell or vision) or other predators, and that such detection triggers an intensified investigation of their surroundings (i.e. ARS). Also we found that diving probability increases near fronts in 11 out of 20 tracks investigated (55%), suggesting that Cape gannets substantially use fronts for feeding; in the remaining cases (45%), birds may have used other cues for feeding including fishing vessels, particularly for gannets breeding on the west coast. We demonstrated in this study that oceanographic structures such as mesoscale fronts are important environmental cues used by a foraging seabird within the rich waters of an upwelling system. There is now need for further investigations on how Cape gannets actually detect these fronts.
Tipo:  Text
Idioma:  Inglês

Editor:  Pergamon-elsevier Science Ltd
Formato:  application/pdf
Fonte:  Deep-sea Research Part Ii-topical Studies In Oceanography (0967-0645) (Pergamon-elsevier Science Ltd), 2014-09 , Vol. 107 , P. 77-84
Direitos:  2013 Elsevier Ltd. All rights reserved.


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