Berta boreale Calonectris borealis

Large, lumbering shearwater. Diagnostic yellow bill is often visible from quite a long distance. Look for warm pale brown upperparts and clean white belly and underwings. Also note little contrast between the brown head and white throat (compare with distinct capped appearance of Great Shearwater). Lazier wingbeats than other large shearwaters, especially in calm conditions; wings look crooked with wrists pushed forward in flight. Forms mixed flocks with other shearwaters, especially when feeding. Fairly common in warm water in the Atlantic Ocean; increasingly frequent in cooler water, ranging further northward in recent years. Very similar to closely related and recently split Scopoli’s Shearwater. Can be identified with caution, and often by analysis of photographs, by the solidly dark outer part of the underwing.