Timing of King Penguin Breeding at Marion Island

Abstract

King Penguins Aptenodytes patagonicus breed in a circumpolar distribution, with 31% of the world population occurring at Marion Island in the Prince Edward Island group (46'53'S, 37'54%) (Adams & Klages 1987). The breeding cycle of the King Penguin is unique among penguins in taking more than one year to complete (Stonehouse 1960; Barrat 1976; Weimerskirch et al. 1992). Because the timing of breeding of individual penguins is influenced by the outcome of their previous breeding attempt (Stonehouse 1960; Barrat 1976; Weimerskirch et al. 1992), there is a considerable spread in the dates over which egg laying occurs. Chicks are subject to a winter period when they receive little or no food, and since late-hatched smaller chicks are less likely to survive this period (Stonehouse 1960; Barrat 1976; Cherel et al. 1987), timing of breeding events will affect chick survival and ultimately population growth. Of the three localities that have been examined previously, Heard Island (5305'S, 73'30'E) and Possession Island (46'301S, 52301E) in the southern Indian Ocean have egg laying periods extending over three months, from late-November to midFebruary (Barrat 1976; Weimerskirch et al. 1992; van den Hoff et al. 1993). However, at most southerly situated South Georgia (54S, 37'W), in the south Atlantic, egg laying was observed over four and a half months (Stonehouse 1960). In this paper we document the timing of reproductive events at Marion Island, a previously unstudied locality.