The breeding biology and factors affecting reproductive success in rockhopper penguins Eudyptes chrysocme at Macquarie Island

Adult mass changes, egg morphometrics, chick growth rates, fledging masses, reproductive success and reasons for reproductive failure were examined in rockhopper penguins at Macquarie Island from 1993/ 1994 to 1995/1996. Mean arrival masses, growth rates of chicks and fledging masses exhibited inter-annual variability, while egg morphometrics, hatching success (68.0±6.0%) and reproductive success (47.3±8.3%) were constant between years. Reproductive failures occurred primarily during incubation, with the majority of eggs lost to great skuas. Logistic regressions revealed that no variable significantly explained hatching success, and only in 1994/1995 was fledging success significantly correlated with the position of nest in the colony (those in the centre were more successful than those on the periphery). Reproductive success during this study was relatively high, and therefore an assessment during poor years would be instructive, particularly in relation to aspects of the penguins’ foraging ecology.