Ole Jorgen Liodden / Arctic skua (Stercorarius parasiticus) in flight, Svalbard, Norway, August.

Loic Poidevin / Arctic Skua (Stercorarius parasiticus) calling. Handa Island, Scotland, June.

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) in flight, stealing fish from Arctic Tern (Sterna paradisaea). Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Tern (Sterna paradisaea) in flight chasing Arctic Skua (Stercorarius parasiticus) that has stolen its food. Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) pair stealing fish from Arctic Tern (Sterna paradisaea) Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) pair stealing fish from Arctic Tern (Sterna paradisaea) in flight, Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) pair almost colliding in flight, as they pursue an Arctic Tern (Sterna paradisaea). Shetland Islands, Scotland, UK, July. (non-ex)

Wild Wonders of Europe / de la Lez / Arctic skua (Stercorarius parasiticus) portrait, Bjrndalen, Svalbard, Norway, July 2008

Wild Wonders of Europe / de la Lez / Arctic skua (Stercorarius parasiticus) chick walking, Bjrndalen, Svalbard, Norway, July 2008

Wild Wonders of Europe / de la Lez / Arctic skua (Stercorarius parasiticus) head portrait, Bjrndalen, Svalbard, Norway, July 2008

Wild Wonders of Europe / Liodden / Arctic skua (Stercorarius parasiticus) with wind blowing feathers, Spitsbergen, Svalbard, Norway, June 2009

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

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

David Tipling / Arctic skua (Stercorarius parasiticus) (dark form) Unst, Shetland, Scotland, UK. June

Roger Powell / Arctic skua (Stercoarius parasiticus) sitting on its nest in the tundra.Varanger fjord, Finmark, Norway

Jose B. Ruiz / Arctic skua / Parasitic jaeger (Stercorarius parasiticus) Sletness Reserve, Gamvik, Finnmark, Norway. May.

Jose B. Ruiz / Arctic skua / Parasitic jaeger (stercorarius parasiticus). Con kari loimu. Reserva de sletness. Gamvik. Finnmark. Noruega.

Niall Benvie / Arctic skua (Stercorarius parasiticus) in flight, Iceland, July.

Gerrit Vyn / Parasitic Jaeger (Stercorarius parasiticus) in flight, Yukon Delta National Wildlife Refuge, Alaska, USA June

Gerrit Vyn / Parasitic Jaeger (Stercorarius parasiticus) light morph perched on tundra, Yukon Delta National Wildlife Refuge, Alaska, USA June

Gerrit Vyn / Parasitic Jaeger (Stercorarius parasiticus) light morph perched on tundra, Yukon Delta National Wildlife Refuge, Alaska, USA June

Peter Cairns / Arctic skua (Stercorarius parasiticus) in flight over breeding territory, Svalbard, Norway, August.

Pal Hermansen / Arctic skuas (Stercorarius parasiticus) in flight, mobbing to protect nest, Svalbard, Norway, July.

Pal Hermansen / Arctic skuas (Stercorarius parasiticus) in flight, mobbing to protect nest, Svalbard, Norway, July.

Ole Jorgen Liodden / Parasitic jaeger (Stercorarius parasiticus) in flight in front of mountains, Spitsbergen, Svalbard

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

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus) adult male feeding adult female, Shetland, Scotland, UK, July

Markus Varesvuo / Arctic Skua bathing (Stercorarius parasiticus) Shetland, Scotland, UK, July

Glenn Bartley / Arctic Skua (Stercorarius parasiticus) flying, Manitoba, Canada

Glenn Bartley / Arctic Skua (Stercorarius parasiticus), Manitoba, Canada

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

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

Winfried Wisniewski / Arctic Skua (Stercorarius parasiticus) light morph, Varangerfjord, Norway

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

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

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

Ben Cranke / Arctic skua (Stercorarius parasiticus) Svalbard, Norway. July.

David Tipling / Arctic Tern (Sterna paradisaea) chasing off Arctic Skua (Stercorarius parasiticus) near colony on, Shetland, Scotland, UK, June.

David Tipling / Arctic Skua (Stercorarius parasiticus) chick, Fair Isle, Scotland, UK.

Markus Varesvuo / Arctic skua (Stercorarius parasiticus) in flight, calling, Norway, July

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus) in flight, Norway, August

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus) perched, Norway, July

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus) in flight, Norway, July

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus) dark phase, in flight, Norway June

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus) Eggs , Norway June on ground

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus) dark phase, Norway June

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus) flying, Norway June

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus), Norway June

Pal Hermansen / Arctic skua (Stercorarius parasiticus) in flight, Hotellneset, Svalbard, Norway. July.

Pal Hermansen / Arctic Skua (Stercorarius parasiticus) in flight, Hotellneset, Svalbard, Norway, July.

Terry Whittaker / Light phase Arctic skua (Stercorarius parasiticus) calling, Jokulsarlon, Vatnajokull Glacier, Iceland, July.

Roland Seitre / Sculpture of Skua egg (Stercorarius parasiticus) 'Eggin i Gledivik?' by Siguraur Guamundsson, ?34 giant granite eggs along the coast? at Djupivogur, Iceland, June 2011.

Jussi Murtosaari / Arctic skua (Stercorarius parasiticus) in flight, Norway, June.

Jussi Murtosaari / Arctic skua (Stercorarius parasiticus) light and dark forms, Norway, June.

Roger Powell / Dark phase male Arctic Skua (Sterocorarius parasiticus) shuffling feathers after preening. Varanger, Finmark, Norway, May.

Roger Powell / Pair of Arctic Skuas (Stercorarius parasiticus) dark phase male and light phase female. Varanger, Finmark, Norway

Roger Powell / Male dark phase Arctic Skua (Stercorarius parasiticus) courtship feeding light phase female. Varanger, Finmark, Norway, May.

Christophe Courteau / Arctic skua (Stercorarius parasiticus) with fish prey, Spitzbergen, Svalbad, Norway, June.

Christophe Courteau / Arctic skua (Stercorarius parasiticus) stealing a fish from a Kittiwake (Rissa tridactyla), Spitzbergen, Svalbad, Norway, June.

Christophe Courteau / Arctic skua (Stercorarius parasiticus) stealing a fish from a Kittiwake (Rissa tridactyla), Spitzbergen, Svalbad, Norway, June.

Christophe Courteau / Arctic skua (Stercorarius parasiticus) in flight, Spitzbergen, Svalbad, Norway, June.

Ralph Martin / Arctic Skua (Stercorarius parasiticus), Baden-Wurttemberg, Germany

Ralph Martin / Arctic Skua (Stercorarius parasiticus), Baden-Wurttemberg, Germany

Glenn Bartley / Arctic Skua (Stercorarius parasiticus), Manitoba, Canada

Glenn Bartley / Arctic Skua (Stercorarius parasiticus), Manitoba, Canada

Alan Murphy / Arctic Skua (Stercorarius parasiticus) flying, Alaska

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

Staffan Widstrand / Arctic skua (Stercorarius parasiticus) calling, Svalbard Norway, July

Staffan Widstrand / Arctic skua (Stercorarius arcticus) profile portrait, Svalbard Norway July

Staffan Widstrand / Arctic skua (Stercorarius arcticus) profile portrait, Svalbard Norway July

Erlend Haarberg / Arctic skua (Stercorarius parasiticus) with beak wide open, Varanger, Finnmark, Norway, June

Markus Varesvuo / Arctic skua (Stercorarius parasiticus) head portrait, Norway, July

Markus Varesvuo / Arctic skua (Stercorarius parasiticus) portrait, Norway, July

Paul Hobson / Arctic Skua (Stercorarius parasiticus) plumage in light phase. Svalbard, June.

Markus Varesvuo / Arctic Skua (Stercorarius parasiticus) in flight. Norway, July. Magic Moments book plate, page 116.

Roger Powell / Light Phase Arctic Skua (Stercorarius parasiticus)calling, Varanger Fjord, Arctic Norway. June

Roger Powell / Light Phase Arctic Skua (Stercorarius parasiticus) portrait standing on moss, Varanger Fjord, Arctic Norway. June

Roger Powell / Light Phase Arctic Skua (Stercorarius parasiticus) taking off, flying towards photographer, Varanger Fjord, Arctic Norway. June

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

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

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) calling from a lichen covered stone wall. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) flying close to the shore. Shetland Islands, Scotland, UK, July. (non-ex)

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

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) looking skywards for any signs of danger. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) A pale morph adult perched on the ground during a rain shower. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) adult on open moorland during heavy rain. Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) A pale morph flying low among coastal rocks. Shetland Islands, Scotland, UK, July. (non-ex)

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

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) adult prepares to take flight from a lichen covered wall. Shetland Islands, Scotland, UK, July (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) in flight, stealing fish from Arctic Tern (Sterna paradisaea) Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) pair in flight, stealing fish from Arctic Tern (Sterna paradisaea). Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) stealing fish from Arctic Tern (Sterna paradisaea) in flight, Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) stealing fish from Arctic Tern (Sterna paradisaea) in flight, Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) pair stealing fish from Arctic Tern (Sterna paradisaea) in flight, Shetland Islands, Scotland, UK, July. (non-ex)

Andrew Parkinson / Arctic Skua (Stercorarius parasiticus) taking off from coastal rocks. Shetland Islands, Scotland, UK, July. (non-ex)