The king penguin Aptenodytes patagonicus, a non-nesting bird which selects its breeding habitat
Publication Type: |
Journal Article |
Year of Publication: |
2001 |
Authors: |
J. Briew, P. Jouventin |
Publication/Journal: |
Ibis |
Keywords: |
aptenodytes, aptenodytes patagonicus, aves, breeding, king penguin, nesting, reproduction |
Abstract:
Birds are expected to choose their breeding sites according to ‘ideal’ distribution models (Fretwell & Lucas 1970), so that their reproductive output is maximized (Cody 1985). However, studies of breeding habitat selection hitherto conducted on birds have only concerned true
nesting species, that is, species that incubate their eggs in a nest or in a nesting cup dug in the ground.
In the two species of the genus Aptenadytes, breeders neither use nor build nests, incubating their egg on their feet and walking in the colony during incubation or chickbrooding. King Penguins A. patagonicus usually breed on beaches along flat coasts, at the mouths of small rivers on subantarctic islands (Stonehouse 1960, Barrat 1976). However, conditions can become extreme at these places, because of storms, flooding from rivers etc. Breeders and large chicks could move to safer areas in the colony after such events, but, because of aggression from neighbours, which defend their breeding spots against intruders (Stonehouse 1960), breeders never move more than a few metres from their laying places (Stonehouse 1960, Barrat 1976, Lengagne et al. 1999). The level of aggression is highest in the centre of the colony (Cote 2000). This suggests heterogeneity of the habitat within colonies and competition for breeding places, whose location should be
a strong determinant of breeding success in this non-nesting and mobile species.
Despite this, no study has so far examined whether King Penguins actively prefer particular areas within the colony. However, Barrat (1976) wrote that individuals attempted to return to their previous breeding place each season: yet, they often find their previous breeding site occupied by earlier breeders (Stonehouse 1960, Barrat 1976). Cote (2000) found that the earliest breeders tended to occupy the centre. Although his results suggest that King Penguins perform habitat selection, Cote (2000) did not show that breeders actively preferred central places, and did not check whether the latter were more suitable for breeding than peripheral spots, although he did not exclude the possibility. The aim of this long-term study on a King Penguin colony was (i) to determine whether the breeding habitat is homogeneous in a colony and (ii) to determine whether individuals choose their breeding places, and if so, on what criteria. We also looked for a relationship between habitat selection, laying date, and reproductive performance in King Penguins.