Chick-provisioning strategies used by king penguins to adapt to a multiseasonal breeding cycle
Résumé
Parental provisioning strategies are central to life history theory, as one of the main components that adults can adjust to maximize their fitness. In altricial species, newly born young rely entirely on parents for food. Provisioning strategies are thus crucial for offspring survival and growth, but they may also have major consequences for parental lifetime reproductive success, especially in long-lived species. We investigated provisioning strategies in an offshore seabird, the king penguin, Aptenodytes patagonicus, through the number of times parents return to the colony to feed their chick, using a pluriannual database on more than 800 microtagged penguins. King penguin chick rearing can be divided into three periods: (1) from thermal emancipation to the onset of winter, (2) winter and (3) from the end of winter to fledging. Overall, we found that the number of feeding visits was larger for males, as well as for older and larger individuals. The timing of the winter low-provisioning period (15 Maye1 September; shorter than previously described) did not vary according to sex, age or breeding timing.We found four different parental strategies during the winter period, from complete absence to regular foraging trips, which led to different breeding success rates. These four strategies were observed in the 6 study years, and in both sexes, although in different proportions. They were not explained by individuals' age, and individuals were not consistent across years, the decision to follow a strategy probably reflecting the trade-off between the bird's current condition and its environment.