A clutch of cuckoos are to be fitted with hi-tech satellite tags in mini backpacks in an attempt to track their movements – and help save the bird from extinction.

Eastern Daily Press: Picture: Phil Atkinson/BTOPicture: Phil Atkinson/BTO (Image: Archant)

The Thetford-based British Trust for Ornithology (BTO) is hoping to monitor the birds' movements from the shores of Britain to their wintering grounds in central Africa.

Over the past 25 years, the cuckoo population has declined by 75pc – leading the BTO to investigate why the species is disappearing.

Its study has already identified important migration routes via stopover sites in northern Italy and southern Spain, as well as the bird's precise wintering locations in the Congo rainforest.

The mortality of cuckoos while taking flight to Spain has already been identified as one of the reasons for its decline.

However BTO scientists know now is how successful cuckoos are at making it to and from Africa in different summers.

They also want to know how relatively important are conditions in the United Kingdom and southern Europe in contributing to a successful crossing of the mighty Sahara.

Dr Chris Hewson, lead scientist on the project at the BTO, said: 'This has been an incredibly exciting project identifying, for the first time, where our cuckoos go for the winter, how they get there and how survival during migration appears to be contributing to their population decline.

'But we now need to delve a little deeper to see exactly how they interact with their environments along the way.

'In a wet, cold summer here in the UK, are our cuckoos less likely to successfully get to their wintering grounds? Or, are conditions in southern Europe, where the cuckoos make final preparations to cross the Sahara, more important?

'These are the kind of the questions we would like answers for.'

The birds were tagged at sites in Suffolk, Sherwood Forest, Thetford Forest, the Knepp Estate in Sussex and the New Forest.

The birds have been given names: Sherwood, Robinson, Knepp, Raymond, Lambert, Carlton II, Sylvester, Thomas, Cameron and Bowie.

The birds' progress can be tracked online by visiting www.bto.org/cuckoos