When I first saw a flock of cormorants on the North Basin cove, an experienced birder told me that it included both Double-crested and Pelagic Cormorants. I couldn’t tell the difference. The other day I saw one of each not far from one another, and so I put together the above collage to help me distinguish between them.
The pelagic is smaller, but that isn’t much help unless you see them next to each other. The key is in the head, around the beak. The pelagic beak is thinner, generally dark, and evenly colored. This bird has deep orange or red facial skin at the base of the lower mandible, under the eye. In breeding plumage it has a head crest of black feathers, and a distinct white patch on its lower flanks.
The double-crested bill is thicker, a lighter color, and with darker vertical stripes or dots. It has dark orange facial skin not only below but also above the eye. When in breeding plumage, the double-crested has a pair of grayish/white feather tufts on its head that it can raise or lower at will. It does not develop a white patch.
In full regalia the double-crested is a spectacular looking bird (“Blue Eyes,” Apr 17 2019). I’ve not yet seen a Pelagic Cormorant in full breeding plumage with raised head crest. The double-crested are far more common here.