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Cuckoos are well known for their distinctive spring-time calls and their cunning or lazy behaviour, depending on your point of view.

Females lay one egg into up to 25 nests each year, and the unsuspecting 'host' birds devote all their attention to raising the cuckoo chicks which hatch first and then push the other eggs out of the nest.

Cuckoos are usually first heard in mid-April, but bad weather in the Mediterranean, their stop-over point en route from Southern Africa, will delay them and other migratory birds.

Since the early 1980s, the abundance of cuckoos has been falling, and in the last 10 years Wales has seen a dramatic decline of about 50%.

The sexes are similar in appearance - sleek, blue-grey with dark and white striped underparts - but females have a slight brown tinge across their breast.

Cuckoos can be seen in a variety of settings. If a female is fostered by a reed warbler, for example, then she will return to wetlands where she will lay her own eggs in reed warbler nests.

Their host species also live in moorland, woodland and farmland and females will return to the relevant habitat to continue the family tradition.