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.

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 attacked.

The species' binomial name is derived from the Latin cuculus (the cuckoo) and canorus (melodious; from canere, meaning "to sing").

The song is written in Middle English, and the first two lines are "Svmer is icumen in / Lhude sing cuccu."

[5] There are four subspecies worldwide:[6] Although the common cuckoo's global population appears to be declining, it is classified of being of least concern by the International Union for Conservation of Nature.

[1] The longest recorded lifespan of a common cuckoo in the United Kingdom is 6 years, 11 months and 2 days.

During the breeding season, common cuckoos often settle on an open perch with drooped wings and raised tail.

[8] All adult males are slate-grey; the grey throat extends well down the bird's breast with a sharp demarcation to the barred underparts.

[7] Grey adult females have a pinkish-buff or buff background to the barring and neck sides, and sometimes small rufous spots on the median and greater coverts and the outer webs of the secondary feathers.

[8] The barred underparts of the common cuckoo resemble those of the Eurasian sparrowhawk, a predator of adult birds.

[10] Other small birds, great tits and blue tits, showed alarm and avoided attending feeders on seeing either (mounted) sparrowhawks or cuckoos; this implies that the cuckoo's hawklike appearance functions as protective mimicry, whether to reduce attacks by hawks or to make brood parasitism easier.

[13] Essentially a bird of open land, the common cuckoo is a widespread summer migrant to Europe and Asia, and winters in Africa.

[7] The common cuckoo has also occurred as a vagrant in countries including Barbados, the United States, Greenland, the Faroe Islands, Iceland, Indonesia, Palau, Seychelles, Taiwan and China.

[14] The common cuckoo's diet consists of insects, with hairy caterpillars, which are distasteful to many birds, being a specialty of preference.

Evidence from mitochondrial DNA analyses suggest that each gente may have multiple independent origins due to parasitism of specific hosts by different ancestors.

[18] A second proposal for the inheritance of this trait is that the genes controlling egg characteristics are carried on autosomes rather than just the W chromosome.

The dunnock's inability to distinguish the eggs suggests that they have not been parasitised for very long, and have not yet evolved defences against it, unlike the redstart.

[2] Research has shown that the female common cuckoo is able to keep its egg inside its body for an extra 24 hours before laying it in a host's nest.

Scientists incubated common cuckoo eggs for 24 hours at the bird's body temperature of 40 °C (104 °F), and examined the embryos, which were found "much more advanced" than those of other species studied.

The idea of 'internal incubation' was first put forward in 1802 and 18th- and 19th-century egg collectors had reported finding that cuckoo embryos were more advanced than those of the host species.

At 14 days old, the common cuckoo chick is about three times the size of an adult Eurasian reed warbler.

The researchers suggested that "the cuckoo needs vocal trickery to stimulate adequate care to compensate for the fact that it presents a visual stimulus of just one gape".

This may reflect a tradeoff—the cuckoo chick benefits from eviction by receiving all the food provided, but faces a cost in being the only one influencing feeding rate.

[38] If the hen cuckoo is out-of-phase with a clutch of Eurasian reed warbler eggs, she will eat them all so that the hosts are forced to start another brood.

Aristotle rejected the claim, observing in his History of Animals that cuckoos do not have the predators' talons or hooked bills.

In England, William Shakespeare alludes to the common cuckoo's association with spring, and with cuckoldry,[44] in the courtly springtime song in his play Love's Labours Lost:[45][46] In Europe, hearing the call of the common cuckoo is regarded as the first harbinger of spring.

"'[49] On Hearing the First Cuckoo in Spring is a symphonic poem from Norway composed for orchestra by Frederick Delius.

Some like a girl who is pretty in the face and some like a girl who is slender in the waist But give me a girl who will wriggle and will twist At the bottom of the belly lies the cuckoo's nest... ...Me darling, says she, I can do no such thing For me mother often told me it was committing sin Me maidenhead to lose and me sex to be abused So have no more to do with me cuckoo's nest[52] One of the tales of the Wise Men of Gotham tells how they built a hedge round a tree in order to trap a cuckoo so that it would always be summer.