George McCarthy / RF- Tawny owl with moon behind (Strix aluco), UK. (This image may be licensed either as rights managed or royalty free.)

Jack Dykinga / Burrowing owl (Athene cunicularia) female and ten chicks aged a few weeks. Marana, Arizona, USA. May.

Sven Zacek / Ural owl (Strix uralensis) hunting, Tartumaa county, Southern Estonia.

Sven Zacek / Ural owl (Strix uralensis) in flight, hunting, Tartumaa county, Southern Estonia. February.

Sven Zacek / Ural owl (Strix uralensis) nestling, Tartumaa county, Southern Estonia. May.

John Chan / Great horned owl (Bubo virginianus) chicks stretching and flapping their wings, Southern California, USA, May.

John Chan / Great horned owl (Bubo virginianus) chick watching for parents to return with food, Southern California, USA, June.

John Shaw / Western screech owl (Megascops kennicottii) is camouflaged as it looks from a tree cavity. Bosque del Apache National Wildlife Refuge, New Mexico, USA, January.

Jack Dykinga / Burrowing owls (Athene cunicularia) one moving its head - with blurred motion. Marana, Arizona, USA, November.

John Cancalosi / Great horned owl (Bubo virginianus) chick stretching its wings in nest in a Saguaro (Carnegiea gigantea), is groomed by its parent, Sonoran Desert, Arizona, USA, May.

Bernard Castelein / Spotted owlet ( Athena brama), Keoladeo NP, Bharatpur, India

Marie Read / Snowy Owl (Nyctea scandiaca) female perched, Amherst Island, Ontario, Canada, January.

Alan Murphy/ BIA / Great Horned Owl (Bubo virginianus), Texas

Markus Varesvuo / Pygmy owl (Glaucidium passerinum) perched in lichen covered tree. Helsinki, Finland. February.

Karine Aigner / Cuban bare-legged owl (Margarobyas lawrencii) perched, Cienaga de Zapata, Cuba.

Karine Aigner / Cuban bare-legged owl (Margarobyas lawrencii) in nest hole. Cienaga de Zapata, Cuba.

Sven Zacek / Eurasian pygmy owl (Glaucidium passerinum) perched on snow covered branch in evening light. Vorumaa, Southern Estonia. November.

Sven Zacek / Ural owl (Strix uralensis) female on nest, male landing with twig in beak. Tartumaa, Southern Estonia. April.

Sven Zacek / Ural owl (Strix uralensis) male presenting prey to nesting mate. Tartumaa, Southern Estonia. April.

Sven Zacek / Ural owl (Strix uralensis) female feeding at nest on rodent prey presented by mate. Tartumaa, Southern Estonia. April.

Sven Zacek / Ural owl (Strix uralensis) female on the nest with nestling hidden under wing. Tartumaa, Southern Estonia. April.

Sven Zacek / Ural owl (Strix uralensis) female stretching wings whilst perched in Spruce (Picea sp) tree. Tartumaa, Southern Estonia. May.

Sven Zacek / Ural owl (Strix uralensis) female and nestling on nest in tree stump. Tartumaa, Southern Estonia. May.

Sven Zacek / Ural owl (Strix uralensis) female on nest after snowfall. Tartumaa, Southern Estonia. March.

Sven Zacek / Ural owl (Strix uralensis) female on nest in tree stump. Tartumaa, Southern Estonia. April.

Sven Zacek / Ural owl (Strix uralensis) female in flight having taken off from nest, in evening light. Tartumaa, Southern Estonia. May.

Sven Zacek / Ural owl (Strix uralensis) female flying with prey in beak. Flying back to nest in evening light. Tartumaa, Southern Estonia. May.

Sven Zacek / Ural owl (Strix uralensis) perched on Alder (Alnus sp) tree at dusk. Tartumaa, Southern Estonia. April.

Pedro Narra / Little owl (Athene noctua) Sado Estuary, Portugal. June

Jack Dykinga / Burrowing owl (Athene cunicularia) at sunset, standing on one leg, Marana, Sonoran Desert, Arizona, USA. October.

Jack Dykinga / Burrowing owl (Athene cunicularia) with head turned to one side, Marana, Sonoran Desert, Arizona, USA. October.

Donald M. Jones / Great Gray Owl (Strix nebulosa), Yaak, Montana

Ann & Steve Toon / Spotted eagle owl (Bubo africanus) subadult at nigh by water, Zimanga private game reserve, KwaZulu-Natal, South Africa, September

Chase Dekker / Great Gray Owl (Strix nebulosa), Grand Teton National Park, Wyoming

Jack Dykinga / Burrowing owl (Athene cunicularia), two huddled together. Marana, Pima County, Arizona, USA.

David Allemand / Snowy owl (Bubo scandiacus) female landing in the snow, Quebec, Canada, March.

David Allemand / Snowy owl (Bubo scandiacus) Female landing in the snow, Quebec, Canada

Felis Images / Spotted owlets (Athene brama) group of juveniles, Tamil Nadu, India.

Michael Quinton / Northern Hawk Owl (Surnia ulula) pair at nest, Alaska

Michael Quinton / Northern Hawk Owl (Surnia ulula) peering from nest, Alaska

Michael Quinton / Northern Hawk Owl (Surnia ulula) parent with chicks at nest, Alaska

Benjamin Olson / Great Gray Owl (Strix nebulosa), Sax-Zim Bog, Minnesota

Dave Bevan / Slow motion clip of a Tawny owl (Strix aluco) leaving nest site in hollow tree, Carmarthenshire, Wales, UK, April.

Nick Saunders/ BIA / Boreal Owl (Aegolius funereus) chicks, Saskatchewan, Canada

Guy Edwardes / Snowy owl (Bubo scandiacus) walking on ground in snow, one foot raised, Ontario, Canada, January.

Ralf Kistowski/ BIA / Long-eared Owl (Asio otus), North Rhine-Westphalia, Germany

Michael Milicia/ BIA / Great Gray Owl (Strix nebulosa) flying, Quebec, Canada

Rosl Roessner/ BIA / Burrowing Owl (Athene cunicularia) pair, Florida

Markus Varesvuo / Snowy owl (Bubo scandiaca) female face close up, Canada February

Markus Varesvuo / Snowy owl (Bubo scandiaca) female sitting among snow covered vegetation on ground, Canada February

Markus Varesvuo / Hawk owl (Surnia ulula) takingn off from powder snow, possibly with prey in talons, Kuusamo Finland February

Sven Zacek / Great grey owl (Strix nebulosa) perched on dead umbellifer plant, winter, Finland, February.

Markus Varesvuo / Snowy owl (Bubo scandiaca) female, with lights behind, Canada, February.

Juergen & Christine Sohns / Eurasian Eagle-Owl (Bubo bubo) in forest in winter, Zdarske Vrchy, Bohemian-Moravian Highlands, Czech Republic

Neil Aldridge / Portrait of an adult Spotted eagle owl (Bubo africanus) Table Mountain National Park, South Africa.

Bence Mate / Two Burrowing owls (Athene cunicularia) fledgling with adult about to take off, Pantanal, Brazil.

Bence Mate / Burrowing owl (Athene cunicularia) fledgling with head on side, Pantanal, Brazil. November.

Michel Poinsignon / Eurasian pygmy Owl (Glaucidium passerinum) perched on conifer branch, Vosges Mountains, France, June.

Wim van den Heever / Pearl-Spotted Owl (Glaucidium perlatum) perched on a branch. Okavango Delta Botswana

Donald M. Jones / Mountain Pygmy-Owl (Glaucidium gnoma), western Montana

Ben Hall / Eagle owl (Bubo bubo) in flight through forest, backlit at dawn, Czech Republic, November. Captive.

Ben Hall / Eurasian eagle owl (Bubo bubo) flying low over snow covered grouns with trees in background, Czech Republic, February. Captive.

Gerrit Vyn / Great horned owls (Bubo virginianus) roosting in an abandoned barn. Idaho, USA. February.

Gerrit Vyn / Snowy Owl (Bubo scandiacus) fluffing feathers, this image was taken during a massive increase in the range and population of snowy owls. Boundary Bay, Canada. March.

Sven Zacek / Ural owl (Strix uralensis) perching on an Apsen tree during the blue hour of dawn, Tartumaa, Estonia, April.

Sven Zacek / Low angle shot of Ural owl (Strix uralensis) female returning to its nest at night. Southern Estonia, May.

Sven Zacek / Ural owl (Strix uralensis) chick trying to climb an aspen tree with its beak, talons and wings, Southern Estonia. June.

Sven Zacek / Ural owl (Strix uralensis) chick trying to climb an aspen tree with its beak, talons and wings, Southern Estonia. June.

Sven Zacek / Ural owl (Strix uralensis) female feeding her young with part of a pellet it has regurgitated. Estonia, May.

Sven Zacek / Female Ural owl (Strix uralensis) flying over a clear-cut area, Southern Estonia, May.

Sven Zacek / Male Ural owl (Strix uralensis) flying to nest to feed female, Southern Estonia, March.

George Sanker / Barred owl (Strix varia) stretching wings, Corkscrew Swamp Audubon Sanctuary, Florida, USA, March.

Jack Dykinga / Great horned owl (Bubo virginianus) chicks in nest in Saguaro cactus (Carnegiea gigantea) at sunset, Santa Catalina Mountains, Arizona, USA, May.

Jack Dykinga / Great horned owl (Bubo virginianus) chicks nesting in saguaro cactus (Carnegiea gigantea), near Oracle, Sonoran Desert, Arizona, USA, May.

Jack Dykinga / Great horned owl (Bubo virginianus) chick nesting in Saguaro cactus (Carnegiea gigantea), Santa Catalina Mountains, Arizona, USA, May.

Todd Mintz / Great horned owlet (Bubo virginianus) talons Regina, Saskatchewan, Canada. June 2013.

Ole Jorgen Liodden / Eurasian eagle-owl (Bubo bubo) in flight, Norway, July.

Ole Jorgen Liodden / Great grey owl (Strix nebulosa lapponica) in flight, close up, Finland, March.

Ole Jorgen Liodden / Great grey owl (Strix nebulosa lapponica) hunting in flight, Lapland, Finland, March.

Alan Murphy / Great Gray Owl (Strix nebulosa) face, Alaska

Alan Murphy / Barred Owl (Strix varia), Texas

Alan Murphy / Barred Owl (Strix varia), Texas

Alan Murphy / Eastern Screech Owl (Megascops asio), Texas

Alan Murphy / Western Screech Owl (Megascops kennicottii), New Mexico

Alan Murphy / Snowy Owl (Nyctea scandiaca) male flying, Ontario, Canada

Alan Murphy / Snowy Owl (Nyctea scandiaca) male flying, Ontario, Canada

Donald M. Jones / Mountain Pygmy-Owl (Glaucidium gnoma) with mouse prey, western Montana. Sequence 1 of 2

Donald M. Jones / Great Gray Owl (Strix nebulosa) hunting, North America

Donald M. Jones / Great Gray Owl (Strix nebulosa) hunting, North America

Donald M. Jones / Burrowing Owl (Athene cunicularia) owlet greeting parent, Montana

Donald M. Jones / Burrowing Owl (Athene cunicularia) owlets at burrow with one stretching, Montana

Donald M. Jones / Burrowing Owl (Athene cunicularia) parent and owlet at burrow, Montana

Markus Varesvuo / Pharaoh eagle owl (Bubo ascalaphus) on sand, Morocco, March.

Jussi Murtosaari / Snowy owl (Bubo scandiacus) Alajarvi, Etela-Pohjanmaa / Southern Ostrobothnia, Finland

Andy Rouse / Little owl (Athene noctua) on old wheel, UK, April.

Ron Bielefeld / Burrowing Owl (Athene cunicularia) juvenile, Florida