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.

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

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

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

John Cancalosi / Greater Roadrunner (Geococcyx californianus) running, Arizona, USA

David Kjaer / Reed warbler (Acrocephalus scirpaceus) with large fledgling Cuckoo (Cuculus canorus) in it's nest, Essex, UK

Pete Cairns / Cuckoo (Cuculus canorus) two males fighting over territory. Cairngorms NP, Scotland, UK.

Pete Cairns / Cuckoo (Cuculus canorus) male flying, Cairngorms NP, Scotland, UK.

Pete Cairns / European Cuckoo {Cuculus canorus} male display posture Cairngorms, Scotland. Spring.

David Kjaer / Juvenile European cuckoo {Cuculus canorus} fed by Reed warbler {Acrocephalus scirpaceus}. Bucks, UK. Cuckoos lay their eggs in the nests of reed warblers and when they hatch, the warbler mother will a...