'Southern' Shearwaters Ardenna sg Thyellodroma & Neonectris

Subgenera Thyellodroma and Neonectris


Genus Ardenna

Subgenus Thyellodroma

Two species:

  • Wedge-tailed Shearwater Ardenna pacifica, two subspecies in Indian and Pacific Ocean
    • A. p. pacifica
    • A. p. chlororyncha
  • Buller’s Shearwater Ardenna bulleri

Genus Ardenna

Subgenus Neonectris

Two species:

  • Sooty Shearwater Ardenna grisea
  • Short-tailed Shearwater Ardenna tenuirostris

Evolution and taxonomy

After the establishing of the genus Puffinus Mathews & Iredale (1915) proposed a division of Puffinus into several different genera of which some got the status of subgenus in a later stage. The species treated on this page are presently assigned to Ardenna but have been subdivided in two subgenera: Thyellodroma for bulleri and pacifica that are rather similar in behaviour and osteology and Neonectris for grisea and tenuirostris for smilar reasons. Recent evolutionary and genetic research shows that these species, together with A. creatopa, A. carneipes, A. gravis, belong to a lineage that splitted from the ancient shearwaters after the splitting off of Calonectris (Penhallurick & Wink 2004). This research also proves that bulleri and pacifica form a distinct clade within Ardenna. Within pacifica two subspecies are recognized, nominate pacifica and chlororyncha. This division is not widely adopted.

Distribution

A. grisea and A. tenuirostris both breed in the New Zealand/South Australia region with an outpost of grisea at the Falklands and southern Chile. Outside the breeding season tenuirostris moves northward into the Pacific and makes an eight-shaped journey past the Aleutians and Japan. Grisea does the same but part of the population moves into the Atlantic ocean and flies past eastern North America.
A. bulleri is an endemic of islands off New Zelands's North Island, but moves north throughout the Pacific. A. pacifica is widespread in the Pacific and Indian Ocean and breeds on many islands. Subspecies pacifica breeds on Norfolk Island, the Kermadecs and Kandavu, Fiji. Chlororyncha breeds in the rest of the rest of the distribution

Bill length (various sources)

Species
A. pacifica
A. pacifica
A. bulleri

A. grisea
A. tenuirostris

Male               Female
41.0 - 43.8      39.4 - 43.1
34.8 - 44.4 (unsexed)
40.4 - 45.0      40.7 - 43.1

40.0 - 47.0      38.0 - 47.0
29.4 - 35.2      29.1 - 34.2

Osteology


Wedge-tailed Shearwater
Ardenna pacifica chlororyncha. Brisbane, Australia
Culmen: 35.2 mm; total: 82.7 mm, unsexed adult

Buller’s Shearwater
Ardenna bulleri. Cape Farewell, South Island, New Zealand
Culmen: 39.1 mm; total: 88.0 mm, unsexed adult

Sooty Shearwater
Ardenna grisea. Carter's Beach, South Island, New Zealand
Culmen: 41.6 mm; total: 99.9 mm, adult male

Short-tailed Shearwater Ardenna tenuirostris. New South Wales, Australia
Culmen: 30.8 mm; total: 82.

References