UK migratory birds 'in freefall' over climate change

There are millions fewer wild birds over Britain than in 1970

British bird lovers will see a very different pattern of species as the climate warms, according to scientists.

They say climate change is bad news for birds, but locally we will see "winners and losers".

Migrants seldom seen on British shores, such as black-winged stilts and bee-eaters, are delighting bird watchers.

But populations of cuckoos are "in freefall" as UK wildlife struggles to cope with multiple pressures.

In nature-depleted Britain, almost half of all bird species are in decline due to a host of pressures - from the loss of meadows, hedgerows and other natural land to climate change and the use of pesticides.

Bee-eaters nested in Norfolk this year and may set up home here

The number of wild birds in Britain has fallen by 73 million since 1970, according to the British Trust for Ornithology, which studies birds in the British Isles.

Head of ringing, Dr Dave Leech, said climate change was a growing pressure, particularly for migratory birds dealing with extreme weather on several continents.

He told BBC News: "Climate change is one of the biggest pressures that all species are facing, but particularly migratory species, because they have to worry about the climate conditions not only where they're breeding, but also where they're wintering and the areas that they're travelling through to get here, which can be thousands of kilometres."

Some birds such as reed warblers are taking advantage of longer, hotter summers by producing more young. Others, such as the Cetti's warbler, which colonised the UK some decades ago, are expanding their range north.

Yet many species, including the cuckoo and the willow warbler, are declining in southern Britain as the climate warms.

Cuckoos are being affected by the changing seasons

Scientists think some birds are having difficulty adjusting their internal clocks to cope with changes in the seasons.

Cuckoos spend their summer in the UK, arriving in April when they can be heard making their distinctive call. They then leave in late June to over-winter in Africa.

Dr Dave Leech said the birds are struggling to make it back over the Sahara because climate change means there's less food for them to fuel up with before they make the crossing, and that their numbers were in "free fall".

"How terrible would it be if future generations never heard a cuckoo, something that was so commonplace in British wildlife before now?" he said.

The number of Cetti's warblers are increasing across Europe

Many other migratory birds leave British shores and travel south around now, with others arriving from northern countries.

For decades, thousands of skilled bird ringers and other volunteers have been collecting data on changes in British bird populations, shedding light on their decline.

Peter has been ringing birds for many years in Gloucestershire. There "will be winners as a result of climate change and losers", he said.

"Future generations might not hear a nightingale or see a cuckoo but there will be other things they see.

"A bee-eater might become a common species for example. And by collecting all this ringing data we can monitor what is going on and mitigate for the human- led climate change that is the major driver behind most of these changes."

Follow Helen on Twitter @hbriggs.

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