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Auteur (up) Sabarros, P.S.; Grémillet, D.; Demarcq, H.; Moseley, C.; Pichegru, L.; Mullers, R.H.E.; Stenseth, N.C.; Machu, E. url  doi
  Titre Fine-scale recognition and use of mesoscale fronts by foraging Cape gannets in the Benguela upwelling region Type Article scientifique
  Année 2014 Publication Revue Abrégée Deep Sea Research Part II: Topical Studies in Oceanography  
  Volume Numéro Pages 77-84  
  Mots-Clés Area-restricted search; Behavioral shift; Environmental cue; Feeding activity; Fractal landscape; Morus capensis; Oceanographic fronts; seabird; South Africa; southern Benguela  
  Résumé 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.  
  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Fronts, Fish and Top Predators Titre de collection Abrégé  
  Volume de collection 107 Numéro de collection Edition  
  ISSN 0967-0645 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1204  
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