Roger Powell / Small flock of Brent Geese (Branta bernicla) in flight..Texel Island, The Netherlands, Europe

Roger Powell / Eurasian lynx (Lynx lynx) walking through snow. Captive, Bavarian Forest National Park, Bavaria, Germany. February.

Roger Powell / Rear view of Ruff (Philomachus pugnax) in full display at the lek. Varanger, Finmark, Norway, May.

Roger Powell / Satellite male Ruff (Philomachus pugnax) in full display at the lek. Varanger, Finmark, Norway, May.

Roger Powell / Pair of Montagu's harriers (Circus pygargus) undertaking a courtship food pass, Castro Verde, Alentejo, Portugal, April.

Roger Powell / Little owl (Athene noctua) perched on a fence post, stretching its wings, Castro Verde, Alentejo, Portugal, April.

Roger Powell / Little owl (Athene noctua) perched on a fence post, ruffling its feathers, Castro Verde, Alentejo, Portugal, April.

Roger Powell / Spanish imperial eagle (Aquila adalberti) perched on a rock and stretching its wings, Castro Verde, Alentejo, Portugal, April.

Roger Powell / Five Cattle egrets (Bubulcus ibis) in flight, Castro Verde, Alentejo, Portugal, April.

Roger Powell / Cattle egret (Bubulcus ibis) perched on the back of a sheep, with another on the ground, Castro Verde, Alentejo, Portugal, April.

Roger Powell / Two Buzzards (Buteo buteo) fighting over food in snow, Dransfeld, Hannover, Germany, January

Roger Powell / Carrion Crow (Corvus corone) tweaking the wing of a Buzzard (Buteo buteo) to try to get it to move off the food, Dransfeld, Hannover, Germany, January

Roger Powell / Pair of European Bee-eater (Merops apiaster) on a bank above their nest hole in front of flowers. Note regurgitated pellets of insect remains. Alentejo, Portugal, April.

Roger Powell / European Bee-eater (Merops apiaster) with a bee landing on a branch by its mate. Alentejo, Portugal, May.

Roger Powell / European Bee-eater (Merops apiaster) courting a female by offering her a Small Copper butterfly (Lycaena phlaeas). Alentejo, Portugal, April.

Roger Powell / Cattle egret (Bubulcus ibis) in flight carrying a large stick to its nest, Guerreiro, Castro Verde, Alentejo, Portugal, May

Roger Powell / Cattle egret (Bubulcus ibis) in flight, Guerreiro, Castro Verde, Alentejo, Portugal, May

Roger Powell / Stone curlew (Burhinus oedicnemus) approaching nest of two eggs, Guerreiro, Castro Verde, Alentejo, Portugal, April

Roger Powell / Short-eared owl (Asio flammeus) hunting, pouncing on prey, Prestwick Carr, Northumberland, UK. December

Roger Powell / Little Bustard (Tetrax tetrax) male display, jumping on the lekking ground, Guerreiro, Castro Verde, Portugal, April

Roger Powell / Lesser black-backed gull (Larus fuscus) on cliff with Little Skellig gannetry in the background, Great Skellig island, Co Kerry, Ireland, June 2011

Roger Powell / Kingfishers (Alcedo atthis) engaged in threat display to warn tresspassing rival. Castro Verde, Alentejo, Portugal, April.

Roger Powell / Kingfisher (Alcedo atthis) territorial display to warn rivals. Castro Verde, Alentejo, Portugal, April.

Roger Powell / Ruff (Philomachus pugnax) male showing off his ruff in a courtship display behaviour. Varanger, Norway, June.

Roger Powell / Ruff (Philomachus pugnax) male in full display. This was the dominant male at the lek. Varanger, Norway, June.

Roger Powell / Two male Ruff (Philomachus pugnax) of different colour types competitively displaying at a lek in the background. Varanger, Norway, June.

Roger Powell / Ruff (Philomachus pugnax) male displaying to attract the attention of a Reeve (female) nearby, Varanger plateau, Arctic Norway. June

Roger Powell / Three male Ruffs (Philomachus pugnax) preparing to display on the communal lekking ground, Varanger plateau, arctic Norway. June

Roger Powell / Arctic Tern (Sterna paradisaea) preening tail feathers, Varanger Fjord, Arctic Norway. June

Roger Powell / Stone Curlew (Burhinus oedicnemus) pair walking through a flower meadow, Castro Verde, Portugal, April

Roger Powell / Red-legged Partridge (Alectoris rufa) portrait of male perched on a prominent boulder & calling over territory. Castro Verde, Portugal, April

Roger Powell / Little Bustard (Tetrax tetrax) male perched on a favourite stone, and calling at lek, Castro Verde, Portugal, April

Roger Powell / Great Bustard (Otis tarda) male in partial display as he walks through the communal lek, Castro Verde, Portugal, April

Roger Powell / Male Common Quail (Coturnix coturnix) perched on a boulder surveying its display area Castro Verde, Portugal, April

Roger Powell / Two Redshank (Tringa totanus) walking along the tideline, Boulmer, Northumberland, UK

Roger Powell / Bar-tailed godwit (Limosa lapponica) in winter plumage, extracting a Lugworm from a deep hole at low tide, Boulmer, Northumberland, UK

Roger Powell / Young male Sparrowhawk perched on plastic feeder in suburban garden, hunting for small garden birds. Northumberland, UK.

Roger Powell / Ringed Plover {Charadrius hiaticula} preening after bathing, Lochan, Glen Kingie, West-Inverness, Scotland, UK

Roger Powell / Dunlin {Calidris alpina} sunbathing / warming itself on heated river gravel, Glen Kingie, West-Inverness, Scotland, UK

Roger Powell / Black Guillemot {Cepphus grylle} with Sandeel fish in beak trying to entice a female to his nest site, Caithness, Scotland, UK

Roger Powell / Hoopoe {Upupa epops} male calling and displaying above nest site, Castelo Branco, Portugal

Roger Powell / Hoopoe {Upupa epops} male displaying on roof, Castelo Branco, Portugal

Roger Powell / European nuthatch {Sitta europaea} with bark in beak whilst searching for grubs on surface of tree trunk, Northumberland, UK

Roger Powell / Rainbow Lorikeets (Trichoglossus haematodus) courtship preening. Victoria, Australia

Roger Powell / Rainbow Lorikeets (Trichoglossus haematodus) courtship preening. Victoria, Australia

Roger Powell / Two Bearded vulture (Gypaetus barbatus). Immature male engaged in early courtship display with an adult female. Valle de Puertolas, Spanish Pyrenees

Roger Powell / Bearded vulture (Gypaetus barbatus) adult flying with a thigh bone clasped in its feet, ready to drop and smash it for the marrow. Valle de Puertolas, Spanish Pyrenees

Roger Powell / Two Bearded vulture (Gypaetus barbatus). Immature male engaged in early courtship display with an adult female, Valle de Puertolas, Aragon, Spanish Pyrenees