Where have all the cuckoos gone? (1 Viewer)

Chris Monk

Well-known member
Where have all the cuckoos gone?


One of our favourite birds may be in terminal decline. Simon Birch investigates
Published: 29 March 2007

If you're planning a trip to the countryside over the coming weeks and are hoping to hear the first cuckoo of spring, be prepared to be disappointed. The bad news is that the bird whose evocative call has traditionally heralded the end of winter, and that has inspired poets and composers for generations, is rapidly disappearing from Britain's hedgerows and woodlands.

What growing numbers of birdwatchers have increasingly suspected has been confirmed in figures released by the British Trust for Ornithology (BTO), which show that cuckoo numbers have plummeted by almost 60 per cent over the past 30 years.

"I've been monitoring the arrival of cuckoos back from their African wintering grounds at the Aylesbury sewage treatment works in Buckinghamshire for almost 40 years," says BTO researcher David Glue. "But two years ago was the first year, that I didn't see or hear a cuckoo at that site and the same thing happened last year. It's very sad that we're losing one of our most charismatic birds."

Graham Madge from the Royal Society for the Protection of Birds is equally concerned. "We have been alarmed for some time about the cuckoo's fall in numbers over the last three decades," he says. "For such a familiar bird to be in so much trouble is extremely worrying." Indeed, such is the crisis in cuckoo numbers that it's expected that the cuckoo will soon be added to the Red List, a register of the UK's most threatened breeding birds.

So just what's causing cuckoo numbers to nosedive so alarmingly? "While there's no easy explanation as to what's going on, the cuckoo's decline is symptomatic of the difficulties that many other birds now face in the UK," says Glue.

One possible factor is the decline of the cuckoo's key host species. The cuckoo is, of course, known as the bird that lays its eggs in the nests of other birds and gets them to raise the young. Although 50 different species of bird are known to have been targeted by cuckoos for this enforced foster-parenting, just three species, the dunnock, meadow pipit and reed warbler, make up over 80 per cent of all foster parents.

However, the numbers of meadow pipits, which in nest in moorland and heaths, have fallen by 40 per cent over the past 30 years. Similarly, dunnocks, which nest in woodland and rural gardens, are down by 40 per cent. Intensive modern farming practices are thought to be responsible for these losses, which have been bad news for other farmland birds such as lapwings and skylarks.

Researchers like David Glue recognise that cuckoo populations, and those of its key foster parents, are declining in tandem. Despite this, "There is no firm evidence to show that they are inextricably linked," says Glue.

The second possible reason behind the disappearance of the cuckoo is a decrease in the number of moths found in the countryside, whose juicy caterpillars are an important source of food for cuckoos returning from warmer shores. "The large black hairy caterpillar of the garden tiger moth is poisonous to all British birds apart from the cuckoo," says Ian Woiwood, principal research scientist at Rothamsted Research in Hertfordshire, Britain's oldest agricultural research station. "Once very common, the numbers of the garden tiger moth have decreased by over 40 per cent in the past 30 years and it's the same for a number of other species of moths."

Woiwood says that our milder and wetter winters could be encouraging the spread of fungi, which are then attacking the overwintering caterpillars. Again, while researchers believe that there is a link between a lack of caterpillars and the decline of the cuckoo, David Glue says that there's a lack of hard evidence linking the two.

Instead, Glue believes that the main reason why the cuckoo is in crisis is to be found not in the UK but thousands of miles away in Africa. "We know that the cuckoo overwinters in East Africa, which is increasingly being hit by drought as a result of climate change and which is making conditions very difficult for both wildlife and people in the region," he says.

Glue points out that there's corroborating evidence for this theory in that other bird species that overwinter in the region, such as sand martins and sedge warblers, are experiencing a similar dramatic decline in numbers, while the marsh warbler and red-backed shrike no longer breed in the UK at all.

So what, if anything, can be done to stop the slide in cuckoo numbers? "The new policy of encouraging wildlife-friendly farming recently introduced by the EU could help improve the habitats of both meadow pipits and dunnock, which in turn would benefit the cuckoo," says Glue.

Much more research is also needed into why cuckoo numbers are falling, and this is where members of the public have a key role to play. "We're asking the public to record when they first heard a cuckoo this spring on the BTO's online bird recording scheme, birdtrack.net, so that we can monitor the arrival and spread of cuckoos across the country," says Glue. Collecting this information is of vital importance for the conservation of the cuckoo, as it allows researchers to build up a picture of what's happening to cuckoo numbers.

Glue used to think that the call of the cuckoo was a welcome harbinger of spring. But now he believes that it's taken on a more pressing role. "The sound of the cuckoo for me is now an ecological alarm bell for the deepening environmental crisis that's happening here in the UK and over in Africa," he says. "It would be a complete tragedy if we were to lose such an important element of the spring soundscape of our gardens and countryside."


* Cuckoos usually arrive in the UK in mid-April

* Female cuckoos lay a single egg in up to 25 other birds' nests each year

* Cuckoo chicks always hatch first and then push the host's egg out of the nest

* The host foster-parents then devote all their efforts to feeding the rapidly growing cuckoo chick

* In flight, the cuckoo resembles a kestrel, making it tricky to identify. The call of the male cuckoo, however, is unmistakeable. If you've never heard one, go to: www.garden-birds.co.uk/Birds/cuckoo.htm#Voice

* To register your first cuckoo of spring go to: www.birdtrack.net

Users who are viewing this thread