Snow Petrel

Genus Pagodroma

Two species of dubious status:

  • Lesser Snow Petrel P. nivea (P. nivea minor)
  • Greater Snow Petrel P. confusa (P. nivea major)

Evolution and taxonomy

According to Penhallurick & Wink (2004) the ancestors of Pagodroma and Thalassoica seem to have diverged ca. 16 My ago). The splitting of this branch occurred about 13.2 My ago and produced Pagodroma and Thalassoica. Nunn & Stanley (1998) suggest a third divergence from this branch that led to Daption as well. There is still debate and confusion about the taxonomic status of the two forms: nivea (or nivea minor) and confusa (or nivea major) : subspecies or true species. The two forms are supposed to have developed after being forced into two separated refugia during the last glaciation, but after recolonization the continent now hybridizing in mixed colonies in eastern Antarctica (Onley & Scofield 2007). They are to be distinguished by their size (and behaviour) and do not to overlap in measurements.

Distribution

P. nivea: Balleny I. P. confusa: Antatarctic conitent and many off shore islands and islands of the Antarctic Sea.

Behaviour

The flight of the snow petrel is erratic and buoyant and frequently changing direction with rapid shallow wingbeats and and infrequent glides. It maneuvres well among icebergs. Its feeding behaviour is mainly dipping, surface-seizing and surface diving. Like the other medium sized and smaller fulmars Snow Petrels are poor walkers and breed on ledges and under overhanging rocks or in small caves.

Osteology

The bill is black, with whitish 'spots' at the gape. The short nostrils point a little bit upwards

Snow Petrel Pagodroma confusa or P. nivea major, Ardery Island 1) Culmen: 22.0 mm, total: 76.1 mm; unsexed adult

  • Skull
  • Flight apparatus
  • Pelvis and legs
  • Vertebrae and ribs

1) Courtesy of Jeroen Creuwels and Jan Andries van Franeker

References