Great Cormorant Phalacrocorax Carbo In Flight. Royalty-Free Stock Photo

The great cormorant is a large black bird, but there is a wide variation in size in the species wide range. It has a longish tail and yellow throat-patch. Adults have white patches on the thighs and on the throat in the breeding season. In European waters it can be distinguished from the common shag by its larger size, heavier build, thicker bill, lack of a crest and plumage without any green tinge. In eastern North America, it is similarly larger and bulkier than double-crested cormorant, and the latter species has more yellow on the throat and bill and lack the white thigh patches frequently seen on great cormorants. Great cormorants are mostly silent, but they make various guttural noises at their breeding colonies.