A new study could provide answers to the worrying decline in one of the UK's best-known birds.

Almost three-quarters of the UK's cuckoo population has been lost over the last 25 years, and now the British Trust for Ornithology (BTO) has fitted 10 cuckoos with miniscule satellite tags in a bid to follow them back to their wintering grounds in Central Africa - and, it is hoped, work out what is causing their decline.

The study has already identified important migration routes via stopover sites in northern Italy and southern Spain, and the precise wintering locations in the Congo rainforest.

Mortality of Cuckoos taking the route via Spain has been linked to population decline within the UK, and scientists at the BTO are now hoping to ascertain the relative importance of conditions in the UK and southern Europe in contributing to a successful crossing of the Sahara.

Dr Chris Hewson, lead scientist on the project at the BTO, said the project was 'incredibly exciting'.

"We are looking to find out where our cuckoos go during the winter, how they get there and how survival during migration contributes 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 get to their wintering grounds? Or are conditions in southern Europe, where the cuckoo make final preparations to cross the Sahara, more important?"

Follow your favourite birds as they undertake their long journeys south at www.bto.org/cuckoos.