Shearwaters form a group of tubenoses with more or less torpedo-shaped bodies and mostly rather long and slender bills. They vary in size from the large ‘big-gull-sized’ Cory’s Shearwater to the small Little Shearwater, hardly bigger than a Starling (Sturnus sp.). Most shearwaters breed on the Southern Hemisphere, but there are several tropical and Northern Hemisphere breeders. Shearwaters are very migratory and many species cross the Equator yearly. Therefore dead shearwaters can be found on almost all beaches on the globe.
As a group the shearwaters diverged from the primitive tubenose stock about 15 mya. Since then Calonectris was the first split (13.8 to 9 mya) and subsequently the group of the larger 'Southern Hemisphere' shearwaters of the genus Ardenna and and a group that presently contains the smaller so called 'northern' shearwaters belonging to the genus Puffinus, comprising the group of the Manx Shearwaters, the lherminieri- and assimilis-tribes. The latter called so because their evolutionary origin is supposedly lying in the Northern Hemisphere. Some 'northern' species recolonized the Southern Hemisphere. Notes on the evolution can be found on the species pages.
Until recently the shearwaters were devided in two genera Calonectris and Puffinus, but based on dna-analysis Penhallurick and Wink (2004) have proposed a splitting of the shearwaters into three genera: Calonectris for the large shearwaters of the Northern Atlantic, the Mediterranean and the waters around Japan, Ardenna for a group of large Southern Hemisphere breeders and Puffinus for the smaller shearwaters such as the Manx' group, Audubon's and Little Shearwaters. This new taxonomy is now widely accepted, but not by all and is stil subject of discussion.
The evolution and taxonomy of the shearwater groups and genera is treated in the respective chapters.
- Ardenna subgenus Thyellodroma
- Ardenna subgenus Neonectris
- Ardenna subgenus Ardenna
- Ardenna subgenus Hemipuffinus
- Manx' Puffinus
- Lesser and small Puffinus