Simon Littlejohn / Bonelli's eagle chicks (Aquila fasciata) in nest pecking each other, aged one week, Andalusia , Spain, May.

Ben Cranke / King Penguins (Aptenodytes patagonicus) approached by an Antarctic Fur Seal (Arctocephalus gazella). A few pecks from the penguins caused the seal to retreat. Southern elephant seal (Mirounga leonina)...

Markus Varesvuo / Black woodpecker (Dryocopus martius) male perched on tree trunk, trees covered in hoar frost. Kuusamo, Northern Ostrobothnia, Finland. February. Commended in the Birds in the Environment Category of t...

Kerstin Hinze / Male Black woodpecker (Dryocopus martius) drilling a hole in a tree, hunting for insects, Bavarian Forest National Park, Bavaria, Germany, February.

Sven Zacek / Black woodpecker (Dryocopus martius) excavating nest hole. Valgamaa, Southern Estonia. April.

Philippe Clement / Territorial Common raven (Corvus corax) on cliff top, tearing out vegetation, Eshaness, Northmavine, Shetland Islands, Scotland, UK, May.

Dave Bevan / Juvenile Herring gull (Larus argentatus) pecking a suckling Grey seal (Halichoerus grypus) pup, Norfolk, England, UK. December.

Fred Olivier / Chinstrap penguin (Pygoscelis antarcticus) adding a stick to its nest and fighting with a neighbouring pair, Aitcho Island, South Shetland Islands.

Ole Jorgen Liodden / Arctic tern (Sterna paridisea) mobbing, Arctic fox (Alopex lagopus) in Spitsbergen, Svalbard, Norway, July.

Erlend Haarberg / Three-toed woodpecker (Picoides tridactylus) on tree trunk, Sarek National Park, Laponia World Heritage Site, Lapland, Sweden, September.

Matthew Maran / Mute swans (Cygnus olor) Highgate Ponds, Hampstead Heath, London, UK, February.

Erlend Haarberg / Spotted redshank (Tringa erythropus), two males fighting in snow. Pasvik, Norway. May.

David Tipling / Black woodpecker (Dryocopus martius) male pecking on snowy tree trunk. Kuusamo, Finland. January.

Simon Littlejohn / Two Bonelli's eagle (Aquila fasciata) chicks in the nest, pecking each other, Andalusia, Spain, June.

Simon Littlejohn / Griffon vulture (Gyps vulvus) chick pecking parent, trying to get attention, Andalusia, Spain, June.

Doug Perrine / Laysan albatross (Phoebastria immutabilis) attacking unrelated chick to keep it away from its own nesting area. Sand Island, Midway Atoll National Wildlife Refuge, Papahanaumokuakea Marine National Mo...

Doug Wechsler / Eastern tiger swallowtail (Papilio glaucus) and Peck's skipper butterfly (Polites peckius) on swamp milkweed (Asclepias incarnata) French Creek State Park, Pennsylvania, USA. July.

John Chan / Great horned owl (Bubo viginianus) pecking its mate, Bolsa Chica Ecological Reserve, Southern California, USA.

Ismaele Tortella / Cormorant chick (Phalacrocorax carbo) pecking at a Northern gannet (Morus bassanus) in breeding colony, competing for space, northern Norway, July.

George Sanker / Pileated woodpecker (Dryocopus pileatus) feeding, on tree trunk. Acadia National Park, Maine, USA. February.

Fred Olivier / Yellow-billed oxpecker (Buphagus africanus) pecking parasites on a Giraffe (Giraffa camelopardalis), Serengeti National Park, Tanzania.

John Chan / Horned lark (Eremophila alpestris) predating a caterpillar, Southern Califoria, USA, June.

John Chan / Horned lark (Eremophila alpestris) predating a caterpillar, Southern Califoria, USA, June.

John Chan / Cooper's hawk (Accipiter cooperii) nestling pecking sibling, Southern California, USA, June.

Marie Read / Yellow-bellied Sapsucker (Sphyrapicus varius), male drumming, long exposure, New York, USA, April.

John Chan / Great blue herons (Ardea herodias) courting, bill dueling and bill snapping, Southern California, USA, March.

John Chan / Juvenile Western gulls (Larus occidentalis) attacking an Elegant tern (Thalasseus elegans) with a broken wing, Southern California, USA, April.

John Chan / Western gulls (Larus occidentalis) attacking an Elegant tern (Thalasseus elegans) with a broken wing, attempts to take flight, Southern California, USA, April.

John Chan / Western gulls (Larus occidentalis) attacking an Elegant tern (Thalasseus elegans) with a broken wing, attempts to take flight, Southern California, USA, April.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) brooding chick aged 1-3 weeks on feet. Atka Bay, Antarctica. August.

Kerstin Hinze / Slow motion clip of a male Black woodpecker (Dryocopus martius) drilling a hole in a tree, hunting for insects, Bavarian Forest National Park, Bavaria, Germany, February.

Kerstin Hinze / Slow motion clip of a male Black woodpecker (Dryocopus martius) drilling a hole in a tree, hunting for insects, Bavarian Forest National Park, Bavaria, Germany, February.

Kerstin Hinze / Slow motion clip of a male Black woodpecker (Dryocopus martius) drilling a hole in a tree, hunting for insects, Bavarian Forest National Park, Bavaria, Germany, February.

Kerstin Hinze / Slow motion clip of a male Black woodpecker (Dryocopus martius) drilling a hole in a tree, hunting for insects, Bavarian Forest National Park, Bavaria, Germany, February.

Tui De Roy / Nazca booby (Sula granti), male pinning another male down during fight. Genovesa Island, Galapagos. Sequence 4/6.

Tui De Roy / Blue-footed booby (Sula nebouxii) with chick. Santa Cruz Island, Galapagos.

John Chan / Great horned owl (Bubo virginianus) fledglings waiting for parents to return with food, one pecking the other, Bolsa Chica Ecological Reserve, California, USA, June.

Konrad Wothe / Male Black woodpecker (Dryocopus martius) drumming on tree trunk, Bavaria, Germany, April.

Konrad Wothe / Male Black woodpecker (Dryocopus martius) drumming on tree trunk before flying off, Bavaria, Germany, April.

Konrad Wothe / Male Black woodpecker (Dryocopus martius) preening and drumming on tree trunk, Bavaria, Germany, April.

Konrad Wothe / Male Great spotted woodpecker (Dendrocopos major) drumming and stretching wings, Bavaria, Germany, March.

Konrad Wothe / Male Great spotted woodpecker (Dendrocopos major) stretching wings and drumming on a tree trunk, Bavaria, Germany, March.

Konrad Wothe / Male Great spotted woodpecker (Dendrocopos major) preening and drumming on a tree trunk, Bavaria, Germany, March.

Robin Chittenden / Golden-olive woodpecker (Colaptes rubiginosus) in tree. Trinidad and Tobago.

Staffan Widstrand / Great spotted woodpecker (Dendrocopos major) on tree trunk, Kalvtrask, Vasterbotten, Sweden. December.

Loic Poidevin / Black-headed gull (Chroicocephalus ridibundus), two fighting at nest. Marais Breton, Vendee, Pays-de-la-Loire, France. May.

Loic Poidevin / Black-headed gull (Chroicocephalus ridibundus), two fighting at nest. Marais Breton, Vendee, Pays-de-la-Loire, France. May.

Nick Garbutt / Grey-necked woodrail (Aramides cajanea) opportunistically pecks at the remains of a fish caught by a Yacare caiman. Backwater of the Cuiaba River, northern Pantanal, Mato Grosso, Brazil.