The cuckoos were caught in June and fitted with the backpack-like devices. All five birds have now made the journey to Africa, but are distributed across an area measuring 3,000km.
The tags switch on automatically once every two days for a 10 hour period. They then send out a radio signal revealing their whereabouts, which is picked up by a satellite.
The tracking team, led by Dr. Chris Hewson, are able to follow the birds from the BTO’s headquarters in Thetford.
The team is interested in finding out how the cuckoos progress on their migration, including where they stop to feed and rest, and how many make it back to England.
The rising temperatures in the UK and Europe mean that cuckoos have to return from their wintering ground to their breeding ground at an ever-earlier time of year.
Cuckoos are a declining species in Britain and the BTO hopes that this study will help to reveal why, by locating where the birds are breeding, if not in Britain.
Unfortunately the programme had its first loss recently as Clement the cuckoo, who took a different route to all other known cuckoos to Africa, and is thought to have passed away just as he started his return to the UK. Hatched from an egg in 2010, Clement never knew his biological parents and was raised by a foster family, successfully undertaking his first migration to Africa in the autumn of that year.
Clement got as far as Congo before starting from home and his journey has added greatly to the store of knowledge about the habits of these extraordinary birds. Next year the BTO plans to track some Scottish and Welsh birds on their winter migrations.