Stephen Dalton / Orange tip butterfly (Anthocharis cardamines) male in flight amongst Lady's smock or Cuckooflower (Cardamine pratensis),England.

Edwin Giesbers / Orange tip butterfly (Anthocharis cardamines), two females on Cuckooflower (Cardamine pratensis) in marshy grassland, egg visible on stem. April 2009.

Edwin Giesbers / Orange tip butterfly (Anthocharis cardamines) two females on Cuckooflower (Cardamine pratensis). The Netherlands. March.

John Cancalosi / Greater Roadrunner (Geococcyx californianus), sunbathing. Warming itself by erecting feathers to allow sun to strike directly on black skin. Arizona, USA.

Franco Banfi / Cuckoo wrasse (Labrus mixtus) male in front of Red sea fan, (Paramuricea clavata), Stupiste In dive site, Vis Island, Croatia, Adriatic Sea, Mediterranean

Andy Sands / Orange tip butterfly (Anthocaris cardamines) on Cuckoo flower / Lady's smock (Cardamine pratensis), Hertfordshire, England, UK, April - Focus Stacked

Hermann Brehm / Cuckoo (Cuculus canorus) in flight, Germany, April. May

Jack Dykinga / Greater roadrunner (Geococcyx californianus) running to feed brood with Lizard prey in beak. Catalina State Park, Sonoran Desert, Arizona, USA. June.

Phil Savoie / Painted nomad bee (Nomada fucata) male bee with characteristic green eyes, sleeping with jaws locked around grass stem, Monmouthshire, Wales, UK. June

SCOTLAND: The Big Picture / Cuckoo wrasse (Labrus bergylta) and Ballan wrasse (Labrus bergylta) on the wreck of Jayne, Shetland

Andy Rouse / Cuckoo (Cuculus canorus) perched on conifer in habitat. Wales, UK. May

Andy Rouse / Cuckoo (Cuculus canorus) in habitat, Wales, UK, May.

Hermann Brehm / Cuckoo (Cuculus canorus) male, Germany, April.

Jack Dykinga / Greater roadrunner (Geococcyx californianus) with Desert spiny desert lizard (Sceloporus magister) prey, Catalina State Park, Arizona, Sonoran Desert, USA. August.

David Tipling / Common cuckoo (Cuculus canorus) male in flight, Peak District, England, UK. May.

Rolf Nussbaumer / Greater roadrunner (Geococcyx californianus), adult drinking, Rio Grande Valley, South Texas, Texas, USA. June

Bence Mate / Great reed warbler (Acrocephalus arundinaceus) feeding Cuckoo chick (Cuculus canorus) Pusztaszer, Kiskunsagi National Park, Hungary, June.

Bence Mate / DUPLICATE Cuckoos (Cuculus canorus) squabbling, Kiskunsagi National Park, Pusztaszer, Hungary. February.

Claudio Contreras / Greater roadrunner (Geococcyx californianus) with nuptial gift calling mate, Laredo Borderlands, Texas, USA. April

Alex Hyde / Orange tip butterfly egg (Anthocharis cardamines) on Cuckoo flower / Lady's smock (Cardamine pratensis). Peak DIstrict National Park, Derbyshire, UK. May.

Ole Jorgen Liodden / Meadow pipit (Anthus pratensis) feeding young Eurasian cuckoo (Cuculus canorus), Valdres, Norway, July.

Sven Zacek / Common cuckoo (Cuculus canorus) perched in Spruce tree top after sunset, Southern Estonia, June.

Guy Edwardes / 2020VISION / Wild arum / Cuckoo Pint (Arum maculatum) backlit in late eveing sunlight, Collard Hill, Somerset, England, UK. April

Guy Edwardes / 2020VISION / Cuckoo flower / Lady's Smock (Cardamine pratensis), Catcott Lows SWT reserve, Somerset Levels, England, UK, April

David Tipling / 2020VISION / Reed Warbler (Acrocephalus scirpaceus) at nest feeding 12 day Cuckoo chick (Cuculus canorus), Fenland, Norfolk, UK, May

David Tipling / 2020VISION / Cuckoo (Cuculus canorus) 12 day chick in Reed Warbler nest (Acrocephalus scirpaceus) fed by Reed warbler, Fenland, Norfolk, UK, May

David Kjaer / Cuckoo (Cuculus canorus) perched in tree. Buckinghamshire, UK, June.

David Tipling / 2020VISION / 12 day chick of European cuckoo (Cuculus canorus) in Reed warbler's (Acrocephalus scirpaceus) nest, East Anglian Fens, Norfolk, May

David Tipling / 2020VISION / Reed warbler (Acrocephalus scirpaceus) feeding 12 day chick of European cuckoo (Cuculus canorus) in its nest, East Anglian Fens, Norfolk, May. 2020VISION Book Plate.

Steve Nicholls / View up through leaves of Lords and Ladies / Cuckoo-pint (Arum maculatum) Leigh Woods, Bristol, UK, May

Bernard Castelein / Orange Tip Butterfly (Anthocharis cardamines) at rest on Cuckoo-flower (Cardamine pratensis) Wuustwezel, Belgium, April

Bernard Castelein / Orange Tip (Anthocharis cardamines) at rest on Cuckoo-flower (Cardamine pratensis) Wuustwezel, Belgium, April

Bernard Castelein / Cuckoo-flower (Cardamine pratensis) Brasschaat, Belgium, April

Andy Sands / European Cuckoo (Cuculus canorus) female perched on fence post, Isle of Coll, Scotland, UK, June

Hanne & Jens Eriksen / European cuckoo {Cuculus canorus} resting on fence on migration route, UAE, October

Bence Mate / Common cuckoo chick (Cuculus canorus) begging for food from Great reed warbler (Acrocephalus arundinaceus) foster parent, Pusztaszer, Kiskunsagi National Park, Hungary

Bence Mate / Common cuckoo chick (Cuculus canorus) begging for food from Spotted flycatcher (Muscicapa striata) Pusztaszer, Kiskunsagi National Park, Hungary

Stephen Dalton / Hedgesparrow / Dunnock (Prunella modularis)feeding European cuckoo (Cuculus canorus) in oak tree, UK

Andy Sands / European Cuckoo chick (Cuculus canorus) being fed by Reed Warbler on post, West Sussex, England, UK

Laurent Geslin / Vestal cuckoo bee in flight, Europe

Markus Varesvuo / European Cuckoo (Cuculus canorus) male in flight, Kuusamo Finland June