Survival of rockhopper penguins in times of global climate change

Abstract

ABSTRACT Anthropogenic changes in the marine environment and global climate change have led to population declines in several seabird species worldwide. Rockhopper penguins (Eudyptes chrysocome and Eudyptes moseleyi) have experienced a dramatic population decline, potentially linked to increasing sea surface temperatures (SST). Among Southern Ocean diving seabirds, rockhopper penguins typically occupy a low trophic level, and might therefore be expected to mirror climate‐driven bottom‐up changes to the food web sensitively and on a short time scale. Using passive integrated transponders, survival rates of adults in a colony of southern rockhopper penguins (E. chrysocome) on the Falkland Islands were monitored over five consecutive years. Mean annual survival rates were in the range 84 to 96%. These values are high compared with other crested penguin species and reflect the generally good conditions during the study period, when low SST prevailed. However, survival rates were lower in 2010, corresponding to very cold conditions. Curve fits showed a best‐fit quadratic relationship between average SST anomaly and survival rates for the present data, as well as for a data set including two additional years from a different study at Staten Island. Results of this study suggest that rockhopper penguins survive best at SSTs that are lower than the average of the last four decades. In accordance with previously observed rockhopper penguin population declines, the present data suggest that rockhopper penguins are highly sensitive to changes in SST and their effects on the food web, a worrying perspective in times of global climate change. It seems likely that these changes could, in the long term, also affect population trends of other seabird species with similar ecological preferences. The most promising conservation approach should aim at enhancing ecosystem resilience, mainly by reducing industrial fishing and oil exploitation. This would allow the currently over‐exploited fish and squid stocks to recover, offering larger food resources to seabirds and other vertebrate species. Copyright © 2013 John Wiley & Sons, Ltd.