Cuckoo adult (top) mimics sparrowhawk, giving female time to lay eggs parasitically

Description
English: Images of European Cuckoo. Cuculus canorus, and Sparrowhawk, Accipiter nisus, showing the extent of mimicry.
Date 27 March 2012
Author Chiswick Chap https://commons.wikimedia.org/wiki/User:Chiswick_Chap
Source: https://en.wikipedia.org/wiki/File:European_Cuckoo_Mimics_Sparrowhawk.jpg

The common cuckoo (Cuculus canorus) is a member of the cuckoo order of birds, Cuculiformes, which includes the roadrunners, the anis and the coucals. This species is a widespread summer migrant to Europe and Asia, and winters in Africa. It is a brood parasite, which means it lays eggs in the nests of other bird species, particularly of dunnocks, meadow pipits, and reed warblers. Although its eggs are larger than those of its hosts, the eggs in each type of host nest resemble the host's eggs. The adult too is a mimic, in its case of the sparrowhawk; since that species is a predator, the mimicry gives the female time to lay her eggs without being seen to do so.
Order: Cuculiformes
Family: Cuculidae
Genus: Cuculus
Species: Cuculus canorus Linnaeus, 1758