Two of the five cuckoos being tracked by British researchers on their migration back to Africa have started to cross the Sahara desert, it became clear yesterday.
Ornithologists from the British Trust for Ornithology are watching apprehensively as cuckoos Clement and Kasper, both caught and fitted with satellite transmitters in Norfolk in May, attempt to get over the biggest obstacle between Britain and their West African wintering grounds.
There is no shade and virtually no food for refuelling in their flight of more than 1,000 miles across the desert, which is thought to be one of the major sources of mortality for many migrant birds.
Clement, the first cuckoo to reach North Africa, three days ago after a flight through Spain, has pushed on from the Atlas mountains and has headed south-west to a spot near the borders of Algeria and Mauritania.
Kasper, who flew down the length of Italy and crossed the Mediterranean two days ago, is in a position further east, near the borders of Algeria and Niger.
Two more of the birds, named Martin and Chris, are still in Italy, while the fifth, Lyster, is still in the Norfolk Broads, where he was caught in May.
The birds are being tracked because cuckoos, like some other migrants, are rapidly declining in Britain. An accurate knowledge of where they go may enable conservation action to be taken to help them.