These are cormorants – the birds that swim underwater to catch fish. I fell in love with cormorants reading Ping as a little boy (on the mighty Yangtse, boat-dwellers put rings around their necks and train them to retrieve fish), and was lucky enough to grow up in an area where cormorants and their cousins, anhingas, were relatively populous. You could see them sunning on the side of the road, drying out before another dive.
I always liked the design of their necks and beaks – sort of Art Nouveau curves, as if they’d been designed by Aubrey Beardsley.
This image, drawn by Bob Hines, comes from the U. S. Fish and Wildlife Service.