Calonectris's a genus of seabirds. It comprises three large shearwaters. There're 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're thought to be more closely related to the shearwaters than to the other petrels. The taxonomy of this group's the cause of some debate, and it's only recently that the Cape Verde Shearwater has been split fr… (More on Calonectris)