Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) flying low over the water. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) in flight over the water. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) banking in flight, revealing its distinctive tail shape. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) pale morph perched on coastal rocks. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) pair of pale morph adults in flight together. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) dark morph adult perched on coastal rocks. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) in flight against coastal cliffs. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) showing aggression towards another adult coming in to land. Shetland Islands, Scotland, UK, July. (non-ex)

Hanne & Jens Eriksen / Arctic skua {Stercorarius parasiticus} dark and light phase, pair on nesting ground, Iceland, June

Hanne & Jens Eriksen / Arctic skua {Stercorarius parasiticus} dark and light phase, pair on nesting ground, Iceland, June

Hanne & Jens Eriksen / Arctic skua {Stercorarius parasiticus} light phase, in flight, Iceland, June

Hanne & Jens Eriksen / Arctic skua {Stercorarius parasiticus} nest with two eggs, Iceland, June

Hanne & Jens Eriksen / Arctic skua {Stercorarius parasiticus} dark phase, landing, Iceland, June

Hanne & Jens Eriksen / Arctic skua {Stercorarius parasiticus} dark phase, in flight, Iceland, June

Hanne & Jens Eriksen / Arctic skua {Stercorarius parasiticus} dark phase, in flight, Iceland, June

Hanne & Jens Eriksen / Arctic skua (Stercorarius parasiticus) in flight, Iceland, June

Sven Zacek / Arctic skua (Stercorarius parasiticus) flying, Norway, Scandinavia

Sven Zacek / Arctic skua (Stercorarius parasiticus) flying, Norway, Scandinavia

Sven Zacek / Arctic skua (Stercorarius parasiticus) flying, Norway, Scandinavia

David Kjaer / Arctic / Parasitic Skua (Stercorarius parasiticus) dark phase, calling, Handa Island, Scotland, June

Wild Wonders of Europe / Liodden / Arctic skua (Stercorarius parasiticus) in flight, Spitsbergen, Svalbard, Norway, June 2009

Steve Knell / Arctic skua {Stercorarius parasiticus} chick on ground, Shetland Islands, Scotland, UK

Mike Read / Arctic skua {Stercorarius parasiticus} juvenile displaying, UK

Mike Read / Arctic skua {Stercorarius parasiticus} juvenile, UK

Tom Vezo / Arctic skua / Jaegar (Stercorarius parasiticus) on nest beside water, Canada

Andrew Parkinson / Arctic skua (Stercorarius parasiticus) perched on cliff top in evening sunlight, Shetland Islands, Scotland, UK, July

Andrew Parkinson / Arctic skua (Stercorarius parasiticus) perched on a cliff top in evening sunlight, Shetland Islands, Scotland, UK, July

Andrew Parkinson / Arctic skua (Stercorarius parasiticus) perched on cliff top in evening sunlight, Shetland Islands, Scotland, UK, July

Andrew Parkinson / Arctic skua (Stercorarius parasiticus) landing on coastal cliffs in evening sunlight, Shetland Islands, Scotland, UK, July

Jasper Doest / Arctic Skua (Stercorarius parasiticus), Svalbard, Norway

Jasper Doest / Arctic Skua (Stercorarius parasiticus) standing on tundra, Svalbard, Norway

Staffan Widstrand / Arctic skua, dark morph {Stercorarius parasiticus} landing on water, Flatanger, Nord-Trondelag, Norway, August

Staffan Widstrand / Arctic skua, dark morph {Stercorarius parasiticus} in flight, turning, Flatanger, Nord-Trondelag, Norway, August

Jasper Doest / Arctic Skua (Stercorarius parasiticus), Svalbard, Norway

Roger Powell / Arctic Skua {Stercorarius parasiticus} about to take off, Varanger, Norway

Graham Eaton / Arctic Skua (Stercorarius parasiticus) flying, Cardigan Bay, Wales, UK, May

Jasper Doest / Arctic Skua (Stercorarius parasiticus) calling, Svalbard, Norway

Jasper Doest / Arctic Skua (Stercorarius parasiticus), Svalbard, Norway

Jouan Rius / Arctic skua (Stercorarius parasiticus) sitting on rock, Shetland Islands, Scotland, UK

Jouan Rius / Arctic skua (Stercorarius parasiticus), Shetland Islands, Scotland, UK

Jouan Rius / Arctic skua (Stercorarius parasiticus), Shetland Islands, Scotland, UK

Roger Powell / Arctic skua (Stercorarius parasiticus) nesting on tundra, Finland

Steve Packham / Arctic skua {Strericoraius parasiticus} on arctic tundra, Svalbard, Norway

Steve Packham / Arctic skua {Stercorarius parasiticus} stretching wing, tundra, Svalbard, Norway

Steve Packham / Arctic skua {Stercorarius parasiticus} on tundra with stone in beak, Svalbard, Norway

Steve Packham / Arctic skua (Stercorarius parasiticus) Svalbard, Norway

Paul Hobson / Arctic skua brown phase {Stercorarius parasiticus} Handa Is, Scotland, UK

Staffan Widstrand / Arctic skua {Stercorarius parasiticus / arcticus} in flight, Norway.

Philippe Clement / Arctic skua {Stercorarius parasiticus} Shetland Is, Scotland, UK.

David Kjaer / Arctic / Parastic skua in flight pale phase Scotland {Stercorarius parasticus}

Solvin Zankl / Arctic skua {Sterocorarius parasiticus} pair bringing fish to feed chick, Orkney, Scotland UK

Paul Hobson / Arctic skua male light phase {Stercorarius parasiticus} Handa Is, Scotland, UK

David Kjaer / Arctic skua (dark phase) Handa, Scotland.

Avi Meir/ BIA / Arctic Skua (Stercorarius parasiticus) flying, Eilat, Israel

Winfried Wisniewski / Arctic Skua (Stercorarius parasiticus) dark morph, Varanger, Norway

Sergey Gorshkov / Arctic Fox (Alopex lagopus) with a stolen Long-tailed Jaeger (Stercorarius parasiticus) egg in its mouth, Wrangel Island, Russia

Sergey Gorshkov / Arctic Skua (Stercorarius parasiticus) carrying Wrangel Lemming (Dicrostonyx vinogradovi) prey, Wrangel Island, Russia

Sergey Gorshkov / Snowy Owl (Nyctea scandiaca) chick being attacked by Arctic Skua (Stercorarius parasiticus), Wrangel Island, Russia

Sergey Gorshkov / Snowy Owl (Nyctea scandiaca) chick being attacked by Arctic Skua (Stercorarius parasiticus), Wrangel Island, Russia

Rick Tomlinson / Crew member of Superyacht "Adele" carrying gun, being mobbed by an Arctic skua (Stercorarius parasiticus), Spitsbergen, in Norway's Arctic Circle.

Bryan and Cherry Alexander / Arctic skua (Stercorarius parasiticus) raiding an Eider Duck nest on Eholmen Island. Spitsbergen, Norway, 1993.

Rick Tomlinson / Crew member of Superyacht "Adele" carrying gun, being mobbed by an Arctic skua (Stercorarius parasiticus), Spitsbergen, in Norway's Arctic Circle.

Hanne & Jens Eriksen / Arctic skua stretching wing {Stercorarius parasiticus} Svalbard Norway Alkhornet

David Kjaer / Arctic skua (dark phase) flying (Stercorarius parasiticus) Handa Is Scotland UK

Steve Knell / Arctic skua chick {Stercorarius parasiticus} Shetland Islands Scotland UK

Roger Powell / Arctic skua (Stercorarius parasiticus) female, guarding territory near its nest, Varanger fjord, Finnmark, Norway. June. Endangered.

Jose Luis Gomez de Francisco / Arctic skua {Stercorarius parasiticus} Handa Is, Scotland, UK

Staffan Widstrand / Arctic skua (Stercorarius parasiticus) in flight, Varanger Peninsula, Finnmark, Norway. June.

Staffan Widstrand / Arctic skua (Stercorarius parasiticus) portrait, Varanger Peninsula, Finnmark, Norway. June.

Philippe Clement / Arctic skua (Stercorarius parasiticus) in flight, silhouette against white background. Digitally enhanced silhouette.

Espen Bergersen / Arctic skuas (Stercorarius parasiticus) and Kittiwakes (Rissa tridactyla) flying over sea ice at 81° North. Svalbard, Norway. June.

Espen Bergersen / Three Arctic skuas (Stercorarius parasiticus) chasing Kittiwake (Rissa tridactyla) to steal food. Svalbard, Norway. August.

Espen Bergersen / Three Arctic skuas (Stercorarius parasiticus) chasing Kittiwake (Rissa tridactyla) to steal food. Svalbard, Norway. August. (medium repro only)

Espen Bergersen / Arctic skua (Stercorarius parasiticus) chasing Kittiwake immature (Rissa tridactyla). Svalbard, Norway. August.

Espen Bergersen / Arctic skua (Stercorarius parasiticus) vocalising. Svalbard, Norway. August.

Espen Bergersen / Arctic skua (Stercorarius parasiticus) holding twig in beak. Svalbard, Norway. August.

Espen Bergersen / Arctic skua (Stercorarius parasiticus) spreading wings. Svalbard, Norway. August.

Espen Bergersen / Arctic skuas (Stercorarius parasiticus) vocalising. Svalbard, Norway. August.

Espen Bergersen / Arctic skua (Stercorarius parasiticus) vocalising. Svalbard, Norway. August.

Espen Bergersen / Arctic skua (Stercorarius parasiticus) vocalising. Svalbard, Norway. August.

Pal Hermansen / Arctic skuas (Stercorarius parasiticus) in flight, ready to attack anyone walking too close to their nest nearby Hotellneset, Svalbard archipelago. July.

Robin Chittenden / Arctic skua (Stercorarius parasiticus) flying, Norfolk, UK. August.

Markus Varesvuo / Arctic skua (Stercorarius parasiticus) in flight. Uto, Finland. June.

Erlend Haarberg / Arctic skua (Stercorarius parasiticus), Varanger, Norway, July.