Cuckoo Bird is a slim, rakish bird with a superficial similarity to a small falcon, with pointed wings and a long roundi tail. However, Cuckoo Bird has a distinctive silhouette in flight as it beats its wings rapidly below the body withoi gliding at all. When perched and calling, it typically droops the long wingtips below the body. It has a small rounded head and a small thin bill, and is uniformly grey on the head, breast and upperpart; and white on the belly with regular fine black band Rufous, or 'hepatic', morphs - occurring only in tl" female - are rusty-red barred with black and with i white belly barred with black.
Cuckoo Bird is found in a very wide range of habitats, typically in wooded areas, scrub, open country with hedges and scattered trees, reedbeds and wetland margins. All it requires are song perches and any of the 100 different possible host species that have been recorded as being 'nest-parasitized'.
The song of Cuckoo Bird is widely recognized and gives the bird its name in many languages. Given by the male in the breeding season, from a perch and also in flight to advertise his occupancy of territory, it is a disyllabic "HAK-koo HAK-koo HAK-koo.,." the first syllable being higher pitched than the second. This is repeated in long sequences, sometimes at night, and in Britain is typically heard from the birds' arrival in April until June. A variant is also sung, in which the first syllable is repeated two or three times, as in "hak-hak-hak-koo", and it is not uncommon to hear a songster with what sounds like a sore throat, emitting a strangled croak instead of the full note. Females have a bright liquid bubbling call, not dissimilar to the Little Grebe's call and lasting for a couple of seconds. Another call is a harsh "gowk", often repeated, and juveniles can be noisy with a piercing "chiz-chiz-chiz".