Shearwater - AbsoluteAstronomy.com

Shearwaters are medium-sized long-winged seabird

Seabird

Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

s. There are more than 30 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

of shearwaters, a few larger ones in the genus Calonectris
Calonectris
Calonectris is a genus of seabirds. It comprises three large shearwaters. There are two other shearwater genera. Puffinus, which comprises about twenty small to medium-sized shearwaters, and Procellaria with another four large species...

and many smaller species in the genus Puffinus
Puffinus
Puffinus is a genus of seabirds in the order Procellariiformes. It comprises about 20 small to medium-sized shearwaters. There are two other shearwater genera: Calonectris, which comprises three large shearwaters, and Procellaria with another four large species...

. The Procellaria
Procellaria
Procellaria is a genus of southern ocean long-winged seabirds related to prions and a member of the Procellariiformes order.-Taxonomy:Procellaria is a member of the family Procellariidae and the order procellariiformes. As members of Procellariiformes, they share certain characteristics. First they...

petrel

Petrel

Petrels are tube-nosed seabirds in the bird order Procellariiformes. The common name does not indicate relationship beyond that point, as "petrels" occur in three of the four families within that group...

s and Bulweria

Bulweria

Bulweria is a genus of seabirds in the family Procellariidae named after English naturalist James Bulwer. The genus has two living species, Bulwer's Petrel and Jouanin's Petrel...

were believed to belong to this group, but are only distantly related based on more recent studies, while the Pseudobulweria
Pseudobulweria
Pseudobulweria is a genus of seabirds in the family Procellariidae. They have long been retained with the gadfly petrel genus Pterodroma despite morphological differences. mtDNA cytochrome b sequence analysis has confirmed the split out of Pterodroma and places the genus closer to shearwaters...

and Lugensa "petrels" are more closely related (Bretagnolle et al., 1998; Nunn & Stanley, 1998).