Berlin - The European cuckoo could be sticking to its migration schedule in defiance of global warming at its own peril, according to German bird experts.

The birds, which spend the European winter in Africa, return in mid-April each year to lay their eggs in the nests of much smaller birds just as they are starting their own broods.

The Sueddeutsche Zeitung reported Thursday that while the cuckoo was sticking to its normal time of arrival, its "hosts" among the reed warblers and dunnocks were breeding earlier.

Bird expert Wolfgang Fiedler told the newspaper said there had as yet been no detailed research into the effects of global warming on the European cuckoo, also known as the common cuckoo.

He added, however, that the global warming theory provided a plausible explanation for the observed decline by 25 per cent in the number of cuckoos in Germany over the past decade. (dpa )