The survival of sea birds affected by ocean cycles

In a general context of climate change, researchers at the Centre d'écologie fonctionnelle et évolutive (CNRS/Université de Montpellier/Université Paul Valery/EPHE-PSL) and their international partners revealed the impact of ocean cycles, such as the Pacific decadal oscillation and El Niño, on the survival of the Nazca booby, a species found on the Galapagos Islands. Their research, which shows for the first time that long cycles (spanning several decades) directly affect the survival of adult populations, appears in the May edition of Ecology , and may later be expanded to other sea birds. Several ocean cycles, such as the El Niño phenomenon, occur in the Pacific ocean and have climatic repercussions around the globe (e.g. intense rains in South America, mild winters in Canada, etc. However El Niño (with a periodic oscillation of 2 to 7 years) is not the only natural and cyclical variation observed in the Pacific: the Pacific decadal oscillation (PDO) is a variation in surface water temperatures which causes significant changes in sardine and anchovy population sizes due to upwelling, a process in which nutrient-rich deep ocean water rises to the surface. In this study, researchers evaluated the impact of El Niño and the PDO on the survival of the Nazca booby, a tropical sea bird which nests in the Galapagos Islands and has a life expectancy of 15 years. This bird is a good model for the study of the effects of climate change on birds because it consumes resources (sardines, in particular) which are directly affected by climate variations.