The Common Cuckoo is 32-34 centimetres (13-13 in) long from bill to tail (with a tail of 13-15 centimetres (5.1-5.9 in) and a wingspan of 55-60 centimetres (22-24 in). The legs are short. It is greyish with a slender body and long tail and can be mistaken for a falcon in flight, where the wingbeats are regular. During the breeding season, Common Cuckoos often settle on an open perch with drooped wings and raised tail. There is a rufous colour morph, which occurs occasionally in adult females but more often in juveniles. All adult males are slate-grey; the grey throat extends well down the bird's breast with a sharp demarcation to the barred underparts. The iris, orbital ring, the base of the bill and feet are yellow. 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. Rufous morph adult females have reddish-brown upperparts with dark grey or black bars. The black upperpart bars are narrower than the rufous bars, as opposed to rufous juvenile birds, where the black bars are broader


Habitat and Distribution

Essentially a bird of open land, the Common Cuckoo is a widespread summer migrant to Europe and Asia, and winters in Africa. Birds arrive in Europe in April and leave in September. The Common Cuckoo has also occurred as a vagrant in countries including Barbados, the United States of America, Greenland, the Faroe Islands, Iceland, Indonesia, Palau, Seychelles, Taiwan and China.


Feeding

The Common Cuckoo's diet consists of insects, with hairy caterpillars, which are distasteful to many birds, being a specialty of preference. It also occasionally eats eggs and chicks.


Breeding

The Common Cuckoo is a brood parasite; it lays its eggs in the nests of other birds. At the appropriate moment, the hen cuckoo flies down to the host's nest, pushes one egg out of the nest, lays an egg and flies off. The whole process takes about 10 seconds. A female may visit up to 50 nests during a breeding season. Common Cuckoos first breed at two years old. More than 100 host species have been recorded: Meadow Pipit, Dunnock and Eurasian Reed Warbler are the most common hosts in northern Europe; Garden Warbler, Meadow Pipit, Pied Wagtail and European Robin in central Europe; Brambling and Common Redstart in Finland; and Great Reed Warbler in Hungary.


Calls and Songs

The male's call, goo-ko, is usually given from an open perch. During the breeding season the male typically gives this call with intervals of 1-1.5 seconds, in groups of 10-20 with a rest of a few seconds between groups. The female has a loud bubbling call. The song starts as a descending minor third early in the year in April, and the interval gets wider, through a major third to a fourth as the season progresses, and in June the cuckoo `forgets its tune` and may make other calls such as ascending intervals. Also the cuckoo seems to have a form of absolute pitch as it tends to sing in the key of C.