Influence of environmental variability on breeding effort in a long-lived seabird, the yellow-nosed albatross

The provisioning parameters, breeding success, adult mass, and survival of yellow-nosed albatrosses were studied over 7 successive years at Amsterdam Island, southern Indian Ocean. We examined the ability of this long-lived s eabird to adjust its breeding effort under different environmental conditio ns and the fitness consequences in terms of survival and quality of offspri ng produced. Provisioning rate and adult mass varied extensively between ye ars, and the lo lowest and highest values were associated with sea surface temperature anomalies. When waters around the island were colder, adults we re in good condition and brought large meals at short intervals, whereas wa rmer waters resulted in lower provisioning rates, lower adult mass, and lig hter chicks at fledging. Adult survival and fledging success were not affec ted by sea surface temperature anomalies. Yellow-nosed albatrosses appear t o be unable to adjust their breeding effort every season, and their differe ntial breeding investment probably primarily reflects different levels of f ood availability. Yellow-nosed albatrosses are able to regulate their provi sioning behavior according to the nutritional status of their chick only wh en conditions are favorable. Birds appear to invest primarily in their own future maintenance rather than in provisioning. They have a wide safety mar gin in body mass that limits mortality risks during good years as well as d uring poor years. Hoc-ever, during unfavorable seasons adults continue to p rovision chicks that have a poor prospect of survival to breeding, without additional survival costs for the parents. Favorable seasons therefore have a high value in terms of fitness because of the high quality of the chick produced. We suggest that understanding hew long-lived animals optimize the ir provisioning behavior and lifetime reproduction can only be achieved thr ough studies encompassing several contrasted seasons.