A bird arriving in Japan in late spring, when males give the familiar cuckoo call.
The belly has fine, pale barring.
In field experiments in Britain, reed warblers treated the female cuckoo’s chuckle much like a hawk call. The alarm drew the birds’ attention toward protecting themselves and away from their clutch, and they were less likely to reject a foreign egg.
By contrast, the male cuckoo’s “cuck-oo” call drew no more attention than the call of a harmless dove. The female’s hawk-like call can therefore change how a host responds at its nest, helping the cuckoo’s egg remain there. Both reed warblers and tits became more vigilant after female cuckoo and hawk calls than after male cuckoo or dove calls. Female cuckoos often give the chuckle after parasitizing a clutch.
IUCN Red List · Least Concern (LC) · Global species-level assessment
The 2024 global IUCN Red List assessment lists the Common Cuckoo as Least Concern (LC) and its population trend as stable. It estimates 34.6–54.4 million mature individuals. The global estimate is derived from European population information, and the assessment notes the species’ very large range.