Espen Bergersen / European shags (Phalacrocorax aristotelis) in courtship display. Hornoya bird cliff, Finnmark, Norway. March.

Markus Varesvuo / Flock of Common shags (Phalacrocorax arostotelis) resting on a cliff, with wind blown snow, Vardo, Norway, March.

Agustin Esmoris / Blue-eyed Cormorant (Phalacrocorax atriceps), Black-browed Albatross (Thalassarche melanophrys), and Rockhopper Penguin (Eudyptes chrysocome) colony, Falkland Islands

Philippe Clement / European shag / common shag (Phalacrocorax aristotelis) perched on rock in sea cliff in spring, Shetland Islands, Scotland, UK, June

Philippe Clement / Two Shags (Phalacrocorax aristotelis) perched on a rock, one flying away, Shetland Islands, Scotland, UK, June.

Ashley Cooper / Pool coloured red from algae that have been fertilized by seabird guano on the Farne Islands, Northumberland, England, UK. July.

Linda Pitkin / Sergeant major (Abudefduf vaigiensis), shoal on wreck of the Kingston, near Shag Rock, Strait of Gubal, Egypt, Red Sea.

Linda Pitkin / Sergeant major (Abudefduf vaigiensis), shoal on wreck of the Kingston, near Shag Rock, Strait of Gubal, Egypt, Red Sea.

Mike Read / Rock shag (Phalacrocorax magellanicus) at nesting colony on cliff face, Saunders Island, Falkland Islands. December.

Roy Mangersnes / Rock shag (Phalacrocorax magellanicus) coming in to the nest with nesting material. Gypsy Cove, Falkland Islands.

Frederique Olivier / Wide angle shot of a Magellan cormorant (Phalacrocorax magellanicus) breeding site, with chicks and adults on nest ledges, Gypsy Cove, Stanley, Falkland Islands.

Frederique Olivier / Two Magellan cormorant (Phalacrocorax magellanicus) chicks preening on a nest ledge, with an adult resting nearby, Gypsy Cove, Stanley, Falkland Islands.