IF scientists had talked about tagging birds with high-tech satellite trackers 20 years ago – we would have thought they were living in cuckoo land!

But now the idea has taken off– literally.

Five male cuckoos have been fitted with miniature GPS systems as part of a new study to monitor their migration patterns. The tags have soft straps which fit around the bird’s wings like tiny backpacks and weigh just five grams.

Dr Chris Hewson of the British Trust for Ornithology (BTO) which is carrying out the study, hopes it will help shed light on the reasons for their rapid decline. (The south west of England has lost two thirds of its cuckoos since 1995).

“At the moment we don’t know what cuckoos do when they leave Britain – how they move around, where they go and when,” explained Dr Hewson.

“It should show us some of the threats they face. We might even be able to look at where the birds are dying as these tags should last for two to three years.”

The GPS trackers, which cost around £2,000, will communicate their whereabouts via a satellite-based system. Each device will switch on for 10 hours every two days.

Tony Whitehead, regional spokesman for the RSPB, welcomed the study and has been avidly following the birds’ progress on the BTO website.

“It’s a brilliant idea. This is the sort of technology scientists could only dream of 20 years ago,” he says.

“The reasons for the cuckoo’s decline, and why it’s so sharp in the south west, are not entirely clear, but this information will help us target their conservation.

“Part of problem could lie in its habitat overseas – as these birds have to fly further to get places because of expanding desserts.

“There could be many other factors involved, but the first thing we need to know is precisely where they go and what route they take.

“One of the cuckoos is already in France and another in Sussex – you never know one might even pass through Dorset!.”

Cuckoos only spend a quarter of the year from mid-April to mid-July in the UK. The rest of the year it spends in tropical Africa where apparently it has never been heard to sing.

The call of this popular songbird was once a common sound over much of the region, heralding the return of the warmer weather. Nowadays though, you’ll be unlikely to hear a cuckoo anywhere away from the region’s uplands and heaths.

Nicky Hoar of the Dorset Wildlife Trust said the cuckoo (famous for laying its eggs in other birds nests), is clearly still one of the nation’s favourite birds. She said: “We put an appeal on our Facebook page for people to get in touch to let us know if they had heard or seen any cuckoos this year and we were overwhelmed by the response.

“I think it is because the cuckoo is such an iconic bird – its song is so evocative of the start of spring. Anything that can be done to halt its decline is to be welcomed.”

To follow the birds’ progress visit the British Trust for Ornithology website – bto.org.

Factfile

It is traditional to write to The Times when you hear the first cuckoo of spring. Only the male cuckoo calls cuckoo, and as the spring progresses the double-note tends to change: In June I change my tune. Cuckoo spit has nothing to do with cuckoos, but is produced by insects as a protection from predators. The cuckoo’s favourite diet is hairy caterpillars. The word cuckold indicates a betrayed husband, a reflection of the cuckoo’s mating habits. Each season a female will lay between 12 and 22 eggs, all in different nests.