British scientists track cuckoos' journey

Scientists from the British Trust for Ornithology have tracked the migration routes of five British cuckoos, using tiny satellite-tracking tags, BBC reports.

The team caught and tagged the birds in June and fitted them with trackers, which fitted like miniature backpacks.
All five birds have now reached Africa.

Having started their journeys from the same breeding ground in East Anglia, the birds are now distributed across 3,000km (1,860 miles) of the continent.

Their tags automatically switch on once every two days for 10 hours. They send off a radio signal revealing their whereabouts, which is picked up by a satellite.

The cuckoo-tracking team, led by the BTO's Chris Hewson, is able to follow the birds from the comfort of the trust's headquarters in Thetford.

"We can log on to their website and download the most recent messages from each of the tags and download that onto a map," Dr Hewson explained to BBC Nature. "So we can get an almost live picture of where the birds are."

Four of the birds have already crossed the Sahara; two are in southern Chad, one is in northern Nigeria and the fourth one is in Burkina Faso. One cuckoo is lagging slightly behind the rest and has made it as far as Morocco.

"He was last seen about 20km outside Casablanca," said Dr Hewson

"The bird that has travelled furthest, Chris, has already flown almost 5,000km to Chad. We're expecting him to go further than that - possibly as far as 6-7,000km."

Crossing the Sahara is one of the major sources of mortality for many migrants, so the team is relieved that almost all the birds have made it safely across the desert.

The team wants to find out what environments the birds rely on and where they stop off to feed along the way.

"Migratory birds don't just have a breeding area and a wintering area, they also have staging posts where they spend different amounts of time," said Dr Hewson.

"Because Britain and Europe as a whole is getting warmer, they need to get back earlier and earlier to their breeding grounds.

"If we don't know exactly where they are, we won't know where the bottlenecks are that might be preventing the cuckoos from getting back to Brtain.

"So we're particularly interested in where the birds are fattening up before the final journey to Britain."