Scientists still have high hopes for Kasper's survival, although they haven't heard from him since April 11Scientists are making progress in trying to understand why cuckoo populations are declining, after data from birds tagged last year show where they met their demise.
Three out of five male cuckoos, which were fitted with transmitters last spring, have gone missing in recent days - two close to the Sahara, and one in Spain.
All of the birds were on their return migration to British soil, after departing their winter habitat in Africa's Congo around mid-February.
It is the first time cuckoos have been tagged and observed in such a manner. While it was known numbers of pairing couples in the UK were dramatically falling, little was previously known about where they went and what they got up to in the autumn and winter months.
In fact, records are so out of date that they relied upon just one recovery of a cuckoo in Cameroon - 82 years ago, according to the British Trust for Ornithology (BTO).
Dr Phil Atkinson, head of international research at BTO, said: 'They are African birds really, all the birds got down to Congo and survived and it's only on spring migration that we started to lose birds. 'We lost our first bird, Clement, in Cameroon on the return journey, so we think the crunch time is just before they cross the Sahara.'
Atkinson, quoted in The Sunday Telegraph, said that understanding the most challenging parts of a cuckoo's journey and where they were most likely to die, thanks to the transmitters, provided 'an incredible amount of new and important information'. He suggested that one likely cause of death for the birds was that they were unable to fatten up enough in West Africa before embarking on the arduous leg across the desert.
All of the five birds headed north-west from the Congo to Cameroon, before the difficult leg.
The five male cuckoos that were tagged and followed on their migratory journeys to the Congo, and, for some, back to the UKThe male birds were caught by attracting them to a stuffed female cuckoo by playing a recording of a female's 'bubbling' call.
Lyster, Chris, Clement, Martin and Kasper were all fitted with the transmitter 'backpacks', which each cost £2,000. Worn on their backs, the mini rucksacks are attacked with soft straps around the birds' wings.
All five tagged cuckoos successfully completed the southerly migration to the Congo rainforests late last summer, with each taking remarkably different routes.
While one swept across France and Spain and then shadowed the western coast of Africa, others drifted east over Switzerland and Italy and headed direct to Congo over the Sahara from Libya.
Information gleaned from the project will help to form conservation strategies and initiate action.
source: dailymail
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