Observed overlooking a lake at Fairburn Ings yesterday. The photos give a good overview of underside and back of cormorant.
No interactions present.
The angle of the gular pouch on the two birds shown here is considerably less than 90 degrees (approximately 54 degrees for the left hand bird, and 48 degrees for the right hand immature bird according to my rough measurement off the screen with a protractor).
If attempting to measure the gular pouch angle to identify the race of (Great) Cormorants, it is important to differentiate between the angle of the gular pouch, and the (usually) larger angle of the facial skin. The gular pouch angle is only the lower part of the facial skin up to the line of the gape.
See the Ardea paper by Newson et al. here: http://ardeajournal.natuurinfo.nl/ardeapdf/a92-003-009.pdf
P. c. carbo = 38-72 degrees
P. c. sinensis = 65-111 degrees
The original ID (to species level) is obviously correct though!
Yes i only know cormorants to species level, just uploaded the photos to help identify the birds for fellow wildlife & conservation students, (and amateurs) as it shows the bird clearly in each photograph for ID features!
In most species identification to the level of subspecies/race is very difficult, and can often only be confirmed if the birds are caught and meaurements taken in the hand.
It is an interesting challenge for those who already experienced, and can sometimes help to provide interesting information on changes in distribution of certain species (such as the spread of continental Cormorants into the UK, which seems to have been at least partly responsible for the spread of breeding colonies into inland parts of the UK).
Like the determination of the sex and precise age of individuals, it is not really something that most people want/need to worry about though!
Ok Roy, that is a fair point, i guess from the fact people are trying to identify to supspecies on this particular photo must mean its a good one ;)
As you can probably tell from the fact that subspecies ID of Cormorants relies on the measurement of the precise angle of the throat pouch (and even there there is some overlap) - unless the bird is 'in the hand' so that other measurements can be taken), it is only possible to even attempt subspecies ID if the photo is good and from the correct angle!
As I said, it doesn't matter to most people (but hopefully you'll let us off!).
Lat/Lng: 53.7406, -1.3195
OS grid ref: SE449273