Trackers Reveal Secrets of Cuckoo Migratory Patterns
May 7, 2012

Trackers Reveal Secrets of Cuckoo Migratory Patterns

The first pair of five male cuckoos that were fitted with tracking devices by UK scientists last spring returned to England over the weekend, bringing with them new data about their annual migratory patterns.

According to Roya Nikkhah of the Telegraph, the five birds were captured by British Trust for Ornithology (BTO) scientists in Norfolk last May, fitted with satellite-tagged units, and then released back into the wild. Their journey was then monitored as they travelled to Africa last fall and then returned this spring.

After travelling some 10,000 miles, one of the two returning birds, named Lyster, was spotted by Dr. Phil Atkinson, the head of international research at the BTO, at the Norfolk Broads last Tuesday -- just 10 miles from where he had been found and tagged, according to Nikkhah.

"We saw him flying past, you can see the wire antenna poking out, so it was definitely him," Dr. Atkinson said. "It´s fantastic -- we know where he´s been, we know the routes he´s taken, and now he´s back in the Broads.”

All five of the birds reached the Congo successfully, though one -- named Clement -- was "lost“¦ in Cameroon on the return journey," Dr. Atkinson told BBC Nature Science Reporter Victoria Gill. A second bird named Chris joined Lyster in returning to London this week. One other bird, Martin, is missing and presumed dead, and the team lost contact with the fifth, Kasper, somewhere over northern Africa.

The goal of the research was to attempt to discover why decreasing numbers of cuckoos make their way back to the UK each year, according to the Telegraph. The summertime population of the birds was nearly halved from 1995 to 2010, and the BTO used the approximately $3,200 tracking units, which fit around the cuckoos' wings like miniature backpacks, to determine the cause of that population decline.

"These birds move into west Africa, they fatten up as much as they can - enough to fuel their Saharan crossing. And if they're not able to do that, I think that's going to be a real pinch point in terms of mortality," Dr. Atkinson told Gill.

"That's where we need to focus our research effort and conservation action," he added. "As we have seen in the five cuckoos, timing is really important and this may be crucial in determining whether a bird undertakes a migration successfully or not."