Seabird research at Cape Shirreff, Livingston Island, Antarctica, 2006/07

Our tenth season of seabird research at Cape Shirreff allowed us to assess trends in penguin population size, as well as inter-annual variation in reproductive success, diet and foraging behavior. The gentoo breeding population has decreased marginally from the previous season and is the lowest population size in the 10 years of census data. The number of diet samples containing fish was the highest ever and comparable to the first six years of the study. Unlike 2005-06, 18% of the gentoo penguin diet samples contained juvenile krill. Fledgling success and fledgling weights were slightly below the nine year means for these parameters at our study site.
The chinstrap penguin breeding population has been declining for the past seven years and is at its lowest size in the 10 years of study. Chinstrap penguins ate mainly Antarctic krill, with a strong component of juvenile krill in their diet samples. Juvenile krill were also plentiful in the chinstrap penguin’s diets in the 1997-98 and 2002-03 seasons. The mean foraging trip duration during chick- rearing was approximately one hour longer than in 2005-06. The data collected, using the PTTs and TDRs, on foraging location and diving behavior should assist us in interpreting the foraging trip data. Fledgling success and chick fledging mass in 2006-07 were higher than both last season and the past 10 year mean.