JOURNAL OF AVIAN BIOLOGY 34: 170–176, 2003 Inter-annual variability in the breeding performance of seabirds in relation to oceanographic anomalies that affect the Crozet and the Kerguelen sectors of the Southern Ocean Pablo Inchausti, Christophe Guinet, Malik Koudil, Jean-Pierre Durbec, Christophe Barbraud, Henri Weimerskirch, Yves Cherel and Pierre Jouventin Inchausti, P., Guinet C., Koudil M., Durbec, J-P., Barbraud C., Weimerskirch, H., Cherel , Y., Jouventin P. 2003. Inter-annual variability in the breeding performance of seabirds in relation to oceanographic anomalies that affect the Crozet and the Kerguelen sectors of the Southern Ocean. – J. Avian Biol. 34: 170–176. Global warming is expected to increase the frequency and intensity of inter-annual variation in Sea-Surface Temperatures (SST) associated with a latitudinal shift of frontal structures in the Southern Ocean. However, the long-term consequences of these major climatic events on the biotic environment remain poorly understood. We studied the effect of SST anomalies in the southern Indian Ocean on the breeding success of eight seabird species, and found these temperature anomalies to have different effects depending on the foraging habitat of the species. The breeding success of four seabird species foraging mainly south of the Polar Front in Antarctic waters was significantly depressed by warm SST occurring mainly in winter and spring, prior to breeding. Conversely, warm SST anomalies were associated with a higher breeding success for species foraging mainly north of the Polar Front, while no significant effect was found for two species that forage on the Kerguelen plateau. These different responses to changes in the SST were also observed for two closely related species (sooty albatross Phoebetria fusca and light-mantled sooty albatross P. palpebrata ) breeding at Kerguelen. These observations highlight the importance of multi-species long-term monitoring programs for understanding the ecological conse- quences of environmental variability. Our results suggest that the predicted south- ward shift of the Polar Front caused by oceanic warming could lead to an important decrease in the breeding performance of top predator seabirds depending on the location and changes of their foraging habitat in relation the Polar Front. P. Inchausti (correspondence), Laboratoire d’Ecologie, Ecole Normale Superie ´ure, 46 rue d’Ulm Paris 75005, France. E-mail: inchausti@biologie.ens.fr. C. Guinet, Centre d’Etudes Biologiques de Chize ´ , UPR 1934 du Centre National de la Recherche Scientifique, 79360 Villiers en Bois, France. M. Koudil and J.-P. Durbec, Centre d’Oce ´anologie de Marseille, Campus de Luminy, Case 901, F -13288 Marseille Cedex 9, France. C. Barbraud, H. Weimerskirch and Y. Cherel, Centre d’Etudes Biologiques de Chize ´ , UPR 1934 du Centre National de la Recherche Scientifique, 79360 Villiers en Bois, France. P. Jouentin, Centre d’Ecologie Fonctionnelle et Eolutie, UPR 9056 du Centre National de la Recherche Scientifique, Route de Mende, 34 293 Montpellier Cedex 5, France. Inter-annual variability is a characteristic feature of the Southern Ocean, yet the consequences of this variability for the biological processes are poorly understood (SCAR 1992, De La Mare 1997). The warming trend observed in this ocean after the 1950s (Jacka et al. 1984, Smith et al. 1999) would increase the frequency and/or the intensity of extreme events of inter-annual variation in Sea-Surface Temperature (SST) in associa- tion with latitudinal shifts of frontal structures (Moore et al. 1999, SCAR 1992). The SST has been related to the inter-annual variation in the depth of the oceanic mixed winter layer (Waluda et al. 1999) which deter- mines the replenishment of surface waters with nutri- ents originating from deeper waters, thereby partly © JOURNAL OF AVIAN BIOLOGY JOURNAL OF AVIAN BIOLOGY 34:2 (2003) 170