Many thanks to an eagle eyed Seamus Enright and an 'Anon' contributor for sending in comments about the Cormorant photograph from David Hill, published the 26th October: http://nibirds.blogspot.co.uk/2012/10/bird-news-friday-26th-october.html
The nominate sub-species of Cormorant, carbo, breeds in Britain and Ireland. The continental sub-species sinensis is a known migrant and has bred recently in Britain as its range seems to be expanding. The yellow-orange area of skin at the base of the lower mandible, the
gular pouch, is generally a different
shape in the two subspecies and this angle of the gular pouch is regarded by most as a reliable character for
assigning the majority of birds to a particular subspecies. The angle is much greater in sinensis.
The pictures of the bird previously published and taken by David (below) were at Blanketnook, Co. Donegal. In the pictures below, it can clearly be seen that the gular angle is quite wide and sweeps back.
Paul Kelly (Irish Bird Images - http://www.irishbirdimages.com/ ) has, below, an excellent photograph of a carbo and a sinensis together at Tacumshin last month. The sinensis bird is the one to the right and the contrast in the gular angle is clear in this photograph:
Chasing a 'sinensis' Cormorant is probably low on many birders to do lists. However a little more knowledge or awareness can make our hobby more interesting. Please feel free to comment or indeed correct us on the above. Many thanks again to Seamus and 'Anon'. Also remember, there is probably Northern Ireland's first Double-crested Cormorant somewhere out there......