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. The latter are usually named as
petrels, although they are thought to be more closely related to the shearwaters than to the other
petrels.