P. gravis then migrates to the North Atlantic during the winter, reaching noth-east Canada and sometimes reaching as far north as Greenland. Migration to the breeding grounds involves a flight east, past Britain and Iberia, than turning south to reach their Southern Hemisphere breeding grounds. Colouring is unique with a combination of pale underparts with a poorly defined dark patch on the belly. White bands of plumage occur across the uppertail-coverts and also across the hindneck, emphasizing the Greater Shearwaters strongly capped appearance. Upperparts are dark gray-brown to black with light feather edgings to give a scaled appearance.
Flight feathers have black upper- and undersurfaces.
The tubenosed bill is long, thin, and black. The legs are pink to grey with webbed feet, and eyes are brown. Chicks have bluish-grey down and juveniles are similar to adults but greyer with paler fringes to feathers to give less scaled appearance. There is no sexual dimorphism in terms of size or colour between males and females. Food Habits Greater Shearwaters feed in groups where aggressive intraspecific feeding competition is evident through lashing with bills and wings.