TY - JOUR
T1 - Survival in king penguins Aptenodytes patagonicus
T2 - Temporal and sex-specific effects of environmental variability
AU - Olsson, Olof
AU - Van der Jeugd, Henk P.
N1 - Funding Information:
Acknowledgements We thank D. Stokes, NCEP/National Weather Service/NOAA, for help with obtaining SST data, P. Anker-Neilssen, E. Soglo and J. Bonnedahl for assistance in the field, the British Antarctic Survey and the Swedish Antarctic Research Programme for logistic support. H.J. was supported by a grant from the Swedish Foundation for International Cooperation in Research and Higher Education (STINT) while in Oxford.
PY - 2002
Y1 - 2002
N2 - We investigated annual adult survival rates of king penguins Aptenodytes patagonicus breeding at South Georgia during 6 years in relation to age/breeding experience, sex, and food availability. During the first 3 years of the study, when food availability was good, survival was 97.7% for experienced breeders, which confirmed the very high survival rates observed in penguins in general. In these years survival did not differ between the sexes, presumably because parental investment is shared equally between the sexes, and the sexual dimorphism is small in king penguins. Survival was lower for young, first-time breeders (83.0%). In experienced birds the annual survival rate decreased to 68-82% following a catastrophic year when food availability was extremely low. We address the question how parents balance their current investment in offspring against their chances to reproduce in the future. We argue that the high mortality rate among breeding individuals after the year of food stress provides support for previous suggestions that the response to increased costs in seabirds might be complex to predict and does not always follow intuitive expectations according to general life-history theory. We also found that females survived significantly less well than males following the bad year. We explain this result as follows: the male-biased sex ratio (56:44) that we observed in our study colony clearly does not result from lower female survival during normal conditions. An already existing skewed sex ratio forces males to delay the onset of breeding because of a lack of breeding partners. This in turn causes breeding females to be, on average, younger and less experienced than males and to have lower survival following a year of food shortage. In this study survival was linked with food availability and we suggest that this was connected to climatic/oceanographic features, such as the position of the Antarctic Polar Front Zone. We could, however, not verify this by anomalies in sea surface temperature data.
AB - We investigated annual adult survival rates of king penguins Aptenodytes patagonicus breeding at South Georgia during 6 years in relation to age/breeding experience, sex, and food availability. During the first 3 years of the study, when food availability was good, survival was 97.7% for experienced breeders, which confirmed the very high survival rates observed in penguins in general. In these years survival did not differ between the sexes, presumably because parental investment is shared equally between the sexes, and the sexual dimorphism is small in king penguins. Survival was lower for young, first-time breeders (83.0%). In experienced birds the annual survival rate decreased to 68-82% following a catastrophic year when food availability was extremely low. We address the question how parents balance their current investment in offspring against their chances to reproduce in the future. We argue that the high mortality rate among breeding individuals after the year of food stress provides support for previous suggestions that the response to increased costs in seabirds might be complex to predict and does not always follow intuitive expectations according to general life-history theory. We also found that females survived significantly less well than males following the bad year. We explain this result as follows: the male-biased sex ratio (56:44) that we observed in our study colony clearly does not result from lower female survival during normal conditions. An already existing skewed sex ratio forces males to delay the onset of breeding because of a lack of breeding partners. This in turn causes breeding females to be, on average, younger and less experienced than males and to have lower survival following a year of food shortage. In this study survival was linked with food availability and we suggest that this was connected to climatic/oceanographic features, such as the position of the Antarctic Polar Front Zone. We could, however, not verify this by anomalies in sea surface temperature data.
KW - Breeding experience
KW - Cost of reproduction
KW - Life history
KW - Sex ratio
KW - Survival
UR - https://www.scopus.com/pages/publications/0036928936
U2 - 10.1007/s00442-002-0985-6
DO - 10.1007/s00442-002-0985-6
M3 - Article
AN - SCOPUS:0036928936
SN - 0029-8549
VL - 132
SP - 509
EP - 516
JO - Oecologia
JF - Oecologia
IS - 4
ER -