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Id | 5044 | ||||||||||||
Family | Cormorants and Shags ~ Skarver ~ Cormoranes (Phalacrocoracidae) | ||||||||||||
Species |
Great Cormorant (Phalacrocorax carbo) Skarv ~ Cormorán Grande ~ Storskarv |
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Subspecies | |||||||||||||
Locality |
Christianshavns vold og voldgrav, Denmark
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Date | 2023-03-10 | ||||||||||||
Sex, Age, Comment |
Third calendar year. A young adult with few white neck plumes. The darkish bill must be an indication of a bird growing older, though it is not mentioned as an aging criteria, where I've looked. I think the sport in Denmark regarding this species is to separate the two subspecies carbo and sinensis. It has been my perception, unqualified?, that most birds were continental sinensis but it appears that the larger part of photos on netfugl.dk have ids to subspecies level and the majority are N Atlantic coastal carbo. How is that possible when the most reliable field mark is the angle of the gular pouch below the eye, and there is an overlap zone where subspecies cannot be determined by this criteria alone. According to studies, birds with an angle of 65 degrees or less are surely carbo and birds showing 73 degrees or more are confirmed sinensis. This gives you an 8 degrees span to base your field-photo decision on. Absolutely unreliable if you ask me. Assuming that many, perhaps depending on which birding generation you belong to, are defaulting their observations to subspecies level without solid support. Using an online measure device I get the angle on this bird fall in overlap or sinensis zone, depending on how I make the measuring. And a correct measurement of course should be made on a bird that has the head completely in the neutral planes perpendicular to the observer. |
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Same bird | |||||||||||||
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