Alloparental feeding in Adélie penguins: why is it uncommon

• Published in: Journal für Ornithologie 2009, Vol.150 (3), p.637-643
• Main Authors: Beaulieu, Michaël, Thierry, Anne-Mathilde, Le Maho, Yvon, Ropert-Coudert, Yan, Ancel, André
• Format: Article
• Language: English
• Subjects: Aptenodytes forsteri; Aptenodytes patagonicus; Biodiversity; Biodiversity and Ecology; Body mass; Breeding sites; Ecology; Environmental Sciences; Fish & Wildlife Biology & Management; Life Sciences; Nests; Original Article; Parental behavior; Populations and Evolution; Pygoscelis adeliae; Zoology
• ISSN: 0021-8375; 2193-7192; 1439-0361; 2193-7206
• DOI: 10.1007/s10336-009-0386-2

We investigated alloparental interactions and conditions which could facilitate or prevent the expression of alloparental behaviours in Adélie penguins (Pygoscelis adeliae), a long-lived seabird which nests in high-density colonies around Antarctica. Observation sessions were carried out during the crèche stage on 48 identified pairs and 50 identified chicks in a 217-nest subcolony. As the season progressed, young were fed less often by their own parents because these were increasingly absent from the breeding site and less responsive to their offspring's solicitations. As a consequence, young and particularly those with a low body mass, coming from a two-chick brood, opted for gradually soliciting more from other adults to obtain food, preferentially those nesting in their direct vicinity. Unsuccessful breeders represented a low and constant part of the adult population and were not specifically solicited by unrelated young. Despite the increasing chick demand, only 4.1% (3 out of 73) of alloparental solicitations resulted in feeding, which is negligible compared to parental feeding. To investigate factors that could trigger the appearance of alloparental care, we carried out comparisons with king (Aptenodytes patagonicus) and emperor penguins (Aptenodytes forsteri) which represent the closest species for which data on alloparental behaviour were available. Our results show different trends to those observed in these species and three factors may explain the low occurrence of alloparental behaviour in Adélie penguins: (1) the low and constant proportion of unsuccessful breeders, (2) the absence of chick selectivity towards unsuccessful breeders, and (3) the late period of chick accessibility for potential alloparents.