Britain – and Yorkshire – could act as a ‘Noah’s Ark’ for southern European species endangered by global warming in their own habitats STEPHEN LEWIS reports.

WHEN he was a little boy growing up in southern England, Chris Thomas saw plenty of wild birds and animals. But he never once saw a Little Egret, a kind of small white heron with black legs and yellow feet.

A few years ago, however, when he went back to revisit some of his favourite old haunts, he saw plenty. “All the ditches seemed to have Little Egrets fishing in them,” he says.

A comparative newcomer to the UK, the bird is already common in the estuaries of Devon and Cornwall and along the south and east coasts, according to the RSPB.

Prof Thomas, a conservation biologist at the University of York, says Little Egrets have even been spotted further north on occasion. “And I would expect that we’re going to see them in the Vale of York in the next ten to 20 years,” he says.

That is because the birds, in common with thousands of other European plant and animal species, are gradually but steadily moving northwards as the climate warms.

In Britain alone, more than 80 per cent of all animal species which have been studied – many of them insects – have moved their ranges northwards in the past 25 years. The rates at which they are moving varies, but on average in the last quarter century it has been by between 25 to 75 kms. “That’s quite a lot,” Prof Thomas says.

And it is not only in Europe that this is happening: all over the world, in the northern hemisphere, species are moving northwards or upwards – higher into the cooler hills and mountains – to escape warming.

Prof Thomas and a team of University of York researchers discovered recently that moths living on Mount Kinabalu in Borneo have moved their territories upwards by about 220 feet since 1965 because of changes in climate.

That northward and upward migration will continue as the climate continues to warm this century, Prof Thomas says. And it could have quite profound implications for the kind of animal and plant species that share Yorkshire with us.

The rate of climate change is now faster than at any time for more than 11,500 years. “And we expect that by the middle to the end of this century the climate will be warmer than it has been for at least a million, if not several million, years.”

That means that over time we are likely to lose some northern, mountain, upland species, such as the golden plover and the mountain hare, as they move northwards to escape the warmer weather.

In their place, we will find new, ‘exotic’ species of plants and animals arriving. The Little Egret, for one, but also species such as the golden oriole, the European Bee-eater – which has already been seen on the Humber – and the Essex Skipper butterfly.

New plant species will start to arrive from further south, too – and some plants that at the moment only survive cloistered in our gardens may soon start to “jump over the garden fence” and become established as native species living in the wild, Prof Thomas says.

Crocuses are one example. “With warmer winters they may be able to establish themselves in a wide range of natural habitats such as chalk downs, heathland or moors.”

None of this is new. Over millions of years, as the climate has warmed then cooled, warmed then cooled, plant and animal species have always moved their territories north then south again.

To a human used to the colder Britain of the Ice Age 25,000 years ago, many of the common species we consider native to our shores today would have seemed alien, southern invaders – the oak tree, for example. Instead, there would have been much more heather in Yorkshire, Prof Thomas says, and species now common in more northerly or upland areas – bilberries, lichen, ptarmigan.

None of this is a problem for plant or animal species such as birds, butterflies and other insects which are able to move – to travel northwards or climb higher.

But, in southern Europe, there are a number of species that are effectively trapped – marooned on the tops of mountains or in pockets of habitat from which, for some reason, they can’t escape.

“They are already isolated, and as the environment gets hotter, many of these isolated populations are predicted to die out,” Prof Thomas says.

Among these marooned southern European species are the Iberian Lynx – the world’s rarest and most endangered cat species, Prof Thomas says – the Spanish imperial eagle, the Pyrenean desman (a small, insectivorous mammal) and the Provence chalkhill blue butterfly.

Many of these species, if only they could reach cooler, moister Britain, may well thrive, Prof Thomas says.

Which raises the question: should we give them a helping hand?

In a recent academic paper, he talks of Britain as an ARC – an ‘assisted regional colonisation’ area. But the biblical reference to Noah’s Ark is clear. Britain could become the ideal refuge for these animal asylum seekers, he says.

Take the Iberian Lynx, for an example. It’s main prey is rabbits. “And here we have a country jam-packed full of rabbits,” he says. “Some farmers might appreciate a natural predator of rabbits.”

There are always concerns about introducing new species, he accepts – look at the way rabbits once overran Australia, or how the grey squirrel has pushed the native red squirrel out of much of Britain.

But those kind of problems usually occur when you introduce a new species into an isolated oceanic island, where the native species have no defence against it, or from one continent to another.

Over the course of thousands and millions of years, native British species will have come into contact with the endangered southern European species at one time or another, as wildlife migrated north and then south again in response to a changing climate.

There would be little risk to our native plants and animals from introducing such species therefore, Prof Thomas says. Even the red squirrel is not in danger of becoming extinct – it still flourishes across parts of Europe and Asia.

Britain has had about 2,000 non-native species introduced at one point or another, either deliberately or accidentally, he says.

“And as far as I know, no native species have died out as a direct consequence of this.”

There is a good case for claiming that, if you go back far enough in time, the Iberian Lynx can in one sense be regarded as native to Britain, he says. “It is closely related to a species of lynx that occurred here 150,000 to 200,000 years ago.”

In that, historical sense it is more of a ‘native’ to these shores than the Eurasian lynx – a non-threatened species which once displaced the ancestors of the Iberian lynx here, and which has been considered for re-introduction to Britain.

So should we give these endangered southern European species a helping hand to come and settle in ARC Britain? He’s not saying yes or no, Prof Thomas says. But it is something we should consider.

“Britain could be a refuge for them. If we can save some of these species that would otherwise go extinct – well, that would be a real contribution to world conservation.”

• Species we might see arriving under their own steam

Little Egret
Golden oriole
European bee-eater
Essex Skipper butterfly.

• Species we could save by introducing them here

Iberian Lynx
Spanish imperial eagle
Pyrenean desman
Provence chalkhill butterfly
De Prunner’s ringlet butterfly
Iberian water beetles.