INTERRELATIONSHIPS BETWEEN BREEDING FREQUENCY, TIMING AND OUTCOME IN KING PENGUINS APTENODYTES-PATAGONICUS - ARE KING PENGUINS BIENNIAL BREEDERS

King Penguin Aptenodytes patagonicus chick growth is interrupted by a winter fast which extends the length of the breeding cycle (laying to chick independence) to 14-16 months, so that continuous annual success ful breeding appears to be impossible. The 3-month laying period impos es further constraints with respect to timing of breeding attempts in relation to the onset of fasting. By the frequent resighting of indivi dually marked birds at Marion Island, we examined the frequency of bre eding and the relationships between timing, outcome and frequency in t he same and in consecutive years. A total of 3101 adult King Penguins were banded between 1984 and 1991, yielding continuous breeding histor ies spanning a maximum of 5 years. Most penguins attempted to breed in consecutive years, although the likelihood of taking a year off incre ased with the number of consecutive attempts. In any one season, about 19% of potentially breeding adults did not breed. Early breeders were more likely to succeed than late breeders and comprised 84% of breedi ng attempts of known timing. Successful birds in one season usually br ed late in the following season, whereas failed attempts were usually followed by an early attempt. Non-breeding was more likely to occur af ter a successful outcome than a failed one, and after a year off 93% o f birds bred early. It is incorrect to refer to the King Penguin as a biennial breeder.