It is a greyish bird with a slender body, long tail and strong legs. It looks a little bit like a small bird of prey when it flies. The male is dark grey above with a blackish brown tail, spotted and tipped with white and unevenly barred in black. The female is similar but a bit more reddish on the upper breast. It likes to eat hairy caterpillars. It is often found where woods border on to open land.

The common cuckoo does not make a nest of its own, and they do not bring up their own young. Instead, the female lays her eggs in the nests of other birds. Each female cuckoo specialises in just one host species, and lays camouflaged eggs in that bird's nest. For example, a cuckoo which lays its eggs in reed warbler nests will lay eggs that look like those of a reed warbler. When the cuckoo chick hatches it soon grows very fast. It will then push out the other eggs or chicks from the nest.

The cuckoo gets its names because the male Common Cuckoo sings two notes which sound like the word “cu – ckoo”. The female does not make this sound. She has a loud bubbling call.