GREAT SHEARWATER Puffinus gravis

GREAT SHEARWATER Puffinus gravis

Greater Shearwater (N America)

L 43–51 cm, WS 100–118 cm.
 

IDENTIFICATION 

Large, heavily built shearwater approaching Cory’s in bulk. Flight strong and powerful, recalling Cory’s with its high, bounding arcs in windier conditions but wingbeats stiffer and wings held straighter, less pressed forward, flexed and bowed, recalling Manx and Yelkouan in this respect. Often follows ships and scavenges. Can be distinguished from Cory’s by dark cap contrasting with white underparts, whitish collar (absent in some), alldark bill (although this is shared with Cory’s of race edwardsii), less extensive dark tip to underwing, band of dark mottling across underwing coverts (hard to see at long range) and different flight action. Darkish belly patch is a good feature when present, but even then can be hard to see unless bird banks right over. Whitish band on uppertail coverts is also present in some Cory’s. Moulting birds often show whitish bands on upperwing across base of secondaries. See also Blackcapped Petrel.

VOICE 

Generally silent at sea, but makes harsh squeals when squabbling over food. 

STATUS/HABITAT 

Locally fairly common but generally uncommon, especially from Scotland northwards. A non-breeding visitor from S Atlantic (spending northern summer mainly in NW Atlantic), mostly occurring in our region during southbound migration in late summer/autumn. Pelagic away from breeding colonies, only coming inshore during strong winds.