Famous (or perhaps infamous) for the female's habit of laying her eggs in the nests of other birds, the Cuckoo is a summer visitor to Europe. The majority arrive in Ireland during April, having travelled from their African wintering grounds. Though still widespread in Ireland, surveys show that the population has been declining, both here and elsewhere in Western Europe.
The song of the male Cuckoo is well known: the oft-repeated “cuck-oo” phrase that gives the species its name. What is less well known to many, however, is the bird's appearance. Around 33cm in length and superficially resembling a dove or hawk, the male is uniform grey on the upper parts and breast, with a black-and-white barred breast, white-tipped grey tail and very long grey wings, which it often droop below its body. The female comes in two different colour forms: they either resemble the males, though with a touch of brown on the breast, or are a striking barred rufous colour overall.
After mating, a female first locates the nest of a suitable host species, usually the same species that raised her as a chick: Meadow Pipits, Dunnocks and Sedge Warblers are the most common “victims”. She picks up an egg in her bill, then lays one of her own it its place; though larger, it is usually a good colour match. She then flies off and usually swallows the stolen egg. Twelve days later, the Cuckoo chick hatches out, and instinctively throws the other eggs and/or chicks over the side of the nest. The “foster parents” never intervene, and feed the young Cuckoo until, before long, it dwarfs them.
Adult Cuckoos depart for Africa again in August. However, the young Cuckoos, who have never seen another of their own kind before, do not leave for another month or so: how they know where to go in Africa remains one of the great mysteries of the natural world.
BirdWatch Ireland is running a special project called “Spring Alive” to keep track of Cuckoos, as well as Swallows and Swifts, this year, and would like to receive as many records of these three migratory species as possible. To report your sightings, call 01 2819878, write to Spring Alive, BirdWatch Ireland, PO Box 12, Greystones, Co Wicklow or, best of all, go to the project website at www.springalive.net and fill in the online form. The website also contains lots of information on Cuckoos, including video clips and recordings of the male's famous song.