The piercing “crex crex” call of the male corncrake once kept country people awake at night. But its last breeding strongholds are falling silent as this elusive migratory bird teeters on the brink of extinction in Britain.
Despite a successful rescue effort that led to its numbers rallying on the islands of north-west 苏格兰, rising to 1,289 calling males in 2014, the corncrake’s population has since fallen by more than 30%, to just 850 calling birds in Scotland in 2021.
A last-ditch effort to stop the corncrake vanishing is under way, 与 Corncrake Calling project in Scotland encouraging farmers to cut hay meadows later in the year and in a corncrake-friendly way. 在英国, 100 corncrakes are being bred in captivity and released each year to re-establish them in the wild.
The corncrake is an unusual species, a long-distance flying machine that soars through the skies from the Congo before spending all summer on the ground, eating insects and worms and rearing two broods of chicks hidden in long grass.
The male’s repetitive, mechanical-sounding calls – which bequeath the bird its scientific name – once resounded across the land, 日夜. But modern farming, with meadows cut mechanically early and often for silage, has led to corncrakes vanishing from most of Britain over one human lifetime.
Populations have clung on in western Scotland, where traditional crofting gives the birds the insect-rich long grass through the spring and summer it requires.
The species has been revived since 1993, 什么时候 numbers fell to only 480 calling males 在英国. But a steady decline since 2014 is concerning conservationists who fear that there has been less uptake of government payments for corncrake-friendly farming in vital areas.
Jane Shadforth, project manager for Corncrake Calling, an RSPB Scotland project to save the species supported by the National Lottery Heritage Fund, 说: “Most crofters and farmers want to support wildlife and help nature and help the corncrake but they can only do that if they are getting the support they need from the government. They need to make a living and they need to be rewarded for farming in these wildlife-friendly ways.”
在英国, 97 corncrakes were this year bred in captivity by the Pensthorpe Conservation Trust and released on to the Wildfowl and Wetlands Trust (WWT) reserve at Welney in the Fens, as part of a Natural England-funded bid to restore the species that became extinct in England as a regular breeding bird in the 1970s.
Birds have been bred in captivity and released for 16 years to restore wild populations, which is particularly challenging with a migratory species.
“There is no quick fix here,” said Chrissie Kelley, the head of species management at Pensthorpe. “Captive breeding is a huge learning curve and it does take years but I’m really hopeful that the Welney trial is going to show some success. The main aim is to get a self-sustaining population of wild birds.”
Calling males have been heard again on the Ouse Washes around Welney and on the Nene Washes in Cambridgeshire in recent years, with wild birds successfully breeding at both locations. But another attempt to return the species to the Wensum valley in Norfolk has faltered because male returnees from Africa disperse too widely for their calls to be heard by females.
Kelley said a good success rate for releasing a migratory bird is for more than 10% of the birds to return the following year. 为了 97 released birds to produce seven or eight calling males next year would be a “good result”.
“Captive breeding has its place – it can be a sticking plaster – but any reintroduction can only really work alongside habitat management,” said Kelley. “There’s no point releasing birds into habitat that can’t sustain them. These projects are long-term, very expensive and well-managed habitat is what it’s all about in the end.”
在苏格兰, Corncrake Calling is encouraging corncrake-friendly cutting. Traditional cutting from the field-edge inwards traps and kills corncrakes, who will not run or fly across a mown field. But if mowing begins in the centre of a field and works outwards, corncrakes and their chicks run to the safety of long grassy margins at the edge.
RSPB Scotland’s annual survey has found that numbers have declined by more than 30% 自从 2014, but with important regional differences. While the population in the Outer Hebrides has increased by 9.9% 自从 2019, corncrakes on the Inner Hebrides have fallen by 12.2%.
自从 2017, corncrakes have disappeared from Mull and their number plummeted on Islay from 75 到 26. There was better news on Lewis, where numbers increased from 75 到 89 while on South Uist they surged from 68 到 149.
The reasons for these differences are likely to include changes in the uptake of agri-environment schemes. Managing land for corncrakes ideally requires farmers not to cut for silage or hay until 1 September to allow the birds to produce two broods in the long grass.
A government scheme supporting corncrake-friendly farming, the Agri-Environment Climate Scheme, has been crucial in boosting corncrake populations in recent years but its future was in doubt until the Scottish government announced a three-year extension in autumn.
But the climate emergency and more intensive farming in African wintering grounds are also challenging corncrakes. Many of Britain’s other long-distance migrants are also suffering drastic population declines, 包括 turtle dove, swift 和 willow warbler.
“We don’t have the evidence at the moment to understand what might be occurring on that migratory route,” said Shadforth. “But we’re very keen to support the populations we have got in Scotland and enhance these by working with crofters and farmers here.”