The cuckoo’s astonishing journey from the Dales to Africa could hold the clue to why the bird’s numbers are in freefall.
DAVID Peckham doesn’t look much of a mover. But while arguably not as graceful in action as his near footballing namesake, the bird’s seasonal feat of athleticism and sheer stamina is just as impressive as any curling free kick into the top corner.
After a summer spent in the woods of the Yorkshire Dales National Park, the cuckoo – given his tongue-in-cheek name by schoolchildren as part of a national competition – embarks on a 4,000-mile journey that takes him across the English Channel, over Germany and into northern Italy.
There Peckham prepares for an epic flight across one of the most inhospitable environments known to man, or bird – the Sahara Desert.
“The most remarkable thing is that Peckham does this last leg of the journey, which takes two-and-a-half days, without stopping,” says Dr Chris Hewson of the British Trust for Ornithology (BTO).
“The cuckoo doesn’t look the strongest flyer, and it’s certainly not as graceful as a bird like the swift, but the more we know about its migrating habits, the more impressive it becomes.”
Hewson and his team of experts have spent the last few months keenly tracking Peckham’s progress to his winter home as part of a project set up to discover why the cuckoo is in danger of disappearing from the UK’s skies.
Numbers across Britain have halved over the last quarter of a century, with England’s cuckoo population plunging by a worrying two-thirds.
For the past five years, the signals of 50 cuckoos have been helping researchers from the BTO gather information about what happens to them when they leave our shores.
Each bird carries a tiny lightweight satellite tracking device as they make their journey from breeding grounds in the UK to Africa. The trust hopes it will help to solve the riddle of why the cuckoo population has dwindled so dramatically over recent decades.
Peckham is one of the lucky ones. Another Yorkshire cuckoo – named Vigilamus by staff at RAF Fylingdales who helped with his tagging – is missing, presumed dead, after arriving back on the North York Moors in blizzard conditions.
“We haven’t heard from his tag since April,” Hewson says grimly. “At the time the outside temperature was the equivalent of about minus five degrees, not good for a bird that spends most of the time in the tropics.” Others have come a cropper at the claws of local predators such as goshawks.
There was some concern over the whereabouts of Peckham, too. Having left Yorkshire towards the end of June, the cuckoo flew 300 miles to Great Yarmouth in the space of a couple of days. A few days later the tracking device showed him in the Netherlands, then on the banks of the Rhine in Germany, before arriving in the Po Valley of Italy.
The same stopover site Peckham had used last year, the fact that the bird stayed a month longer this time sparked concerns that something was amiss, before data showed he was finally back on the move.
The theory is that he was making the most of this water-rich oasis in an otherwise bone dry southern Europe ahead of the mammoth flight over the Sahara. In other words, Peckham was psyching himself up.
Researchers also know that in 2015 the region suffered a severe drought which might have moved Peckham on early. Only time will tell what is a normal departure date for him.
“It’s fantastic because you can virtually watch their migrations in real time,” says Chris Hewson. “The tags recharge themselves for 48 hours and are then on for 10 hours, sending back data via satellite.
“We’ve seen a cuckoo trying to get from France to Spain being caught in an airstream and blown 50 miles off the coast of Algeria before battling back to the mountains above Madrid.
“With Peckham we discovered that he had set off over the Sahara in daytime, when previously we had thought they started that journey at night. Once he got to Africa it was pretty much desert all the way until he made it the 2,000 miles or so south of the Sahara, flying at around 3omph and not stopping.”
Last pinpointed in the northern tip of Cameroon, he’s expected to end up in the same place he spent last winter, the country of Gabon on the Atlantic coast of central Africa. Drawn by the equatorial climate, the fact that 85 per cent of the land is covered by rainforest provides the ideal habitat.
There Hewson says he will have chimpanzees and gorillas for company.Yet Peckham’s final destination, one common to many of the cuckoos that come to Britain for the summer, along with the Congo Basin, could be a key reason why we’re seeing fewer of them.
Up to now, Africa has presented a major gap in our knowledge about land use and how it affects birds. The fact that 2.1 billion birds migrate from Europe to the continent each year means it’s important to find out more about what happens to them there and why fewer are making it back to Britain the following spring.
Changes in land use are thought to be the biggest factor, with the cuckoo facing loss of habitat as sections of rainforest are cleared to make way for palm oil plantations.
The Gabonese government wants to turn the country into Africa’s largest producer of palm oil and this deforestation is believed to be a major cause of the declines seen in around 70 per cent of the long-distant migrant bird species that winter in sub-Saharan Africa.
Intriguingly, cuckoos migrate to Africa on two established routes, one via Italy, the other Spain. The BTO project has shown that the latter group survive less well, with areas of the UK which are home to this section of the cuckoo population, the Midlands and the South, seeing steeper declines.
Hewson says the choice of which route to take is thought to be down to genetics. But it’s the first time that differences in mortality have been attributed to differences in migration route. Quite simply, the route that a cuckoo takes to get to its African wintering grounds could mean the difference between life and death.
Migrant birds like the cuckoo fuel their migratory flights by storing fat in their bodies. It seems that those feeding up in the western part of the Mediterranean might be finding this harder to do than those in the east, possibly as a result of summer droughts in Spain. This has reduced the abundance of the high-energy invertebrates that the cuckoos need to fuel their desert crossing.
The British Trust for Ornithology project has already gleaned a huge amount of previously unknown information about the habits of the cuckoo, whose arrival traditionally heralds the beginning of Spring. It’s hoped it will also play a part in the species’ protection.
“The more we know, the better,” says Chris Hewson. “And the more we know about what the cuckoo gets up to, the more remarkable you realise it is.”
The secret life of the cuckoo
Long considered to be a herald of Spring, Britons once erected walls to try to keep the cuckoos from migrating, believing they took the good weather with them.
The British Trust for Ornithology project discovered that cuckoos leave the UK much earlier than we previously thought, with more than half of the tagged birds starting their migration journey by the end of June.
It also found that cuckoos arrive in Britain towards the end of April and beginning of May. This means that cuckoos like Peckham spend roughly 47 per cent of their time in Africa, 38 per cent spent on migration and just 15 per cent in Britain.
Stopover sites are vitally important fuelling areas for the birds, areas rich in food which allow them to fatten up for the long journey ahead.
Many of the tagged cuckoos have spent time near the River Po in Italy, confirming this is a very important fattening site for British cuckoos which allows them to cross the Mediterranean Sea.
To find out more about the cuckoo tracking project visit www.bto.org.