When he first thought about the plan, says Professor Chris Thomas, “my immediate reaction was that it’s crazy”. Moving a species into an area where it doesn’t belong has long been regarded as unacceptable and not only by scientists such as Thomas, a conservation biologist at York University.
However, because of climate change our conservation practices are out of date, he says. We must learn to love invasive species — and bring in more of them. Britain must become a latter-day Noah’s Ark or ARC (assisted regional colonisation) area. “If we took in a high number of international species we would be making a big contribution to tackling climate change,” Thomas says. “We could hold our heads high with pride.”
Has he gone mad? Is he suggesting we stock our fields and woodlands with lions, koalas and polar bears? Not quite — only species from Europe and possibly north Africa would be imported. As it happens he’s not the only conservationist to come out with this message — leading experts around the world are saying the same — but he’s steeled for vigorous criticism.
No wonder. Look what happened to native British red squirrels after the American grey squirrel was brought over here. Or consider the problems in Australia after the introduction of cane toads, which have few predators and teem like a biblical plague.
Nor are the difficulties restricted to animals. Japanese knotweed was introduced into British gardens in the 19th century. It flourished. Eradicating it has become an extraordinarily expensive problem for unhappy gardeners as well as builders needing to clear it from their sites. But a warming planet changes everything.
“Most of our existing conservation activity tends to be about keeping things as they are, or turning the clock back. But that is no longer an option,” says Thomas.
Research published in Nature, the scientific journal, last year showed that species need to move about 420 metres a year, on average, to remain within the climate they’re used to. That’s more than a metre a day — quite a dash for plants — and about 10 times faster than species moved to keep pace with climate change at the end of the last ice age.
Some species can move themselves. Only last week a novel type of European tick was reported to have turned up in Britain. “But the species that are really threatened are mostly the ones restricted to rare and isolated areas,” says Thomas. “If they were going to move, they would have done so by now.”
A case in point is the Iberian lynx, once common throughout Spain and Portugal, but now endangered as a result of lost habitat, poaching, road accidents and disease in its main food source, wild rabbit. It also hunts small deer. This would be a splendid candidate for assisted migration to Britain.
Other potential immigrants from southern Europe include a rare eagle, a butterfly and a beetle (see panel at the end of the article).
A vast number of species, possibly hundreds of thousands, are predicted to die out as a result of climate change. Britain can’t take them all, but we can draw up a shortlist, Thomas says: “If we want things to perish, we should make that decision knowingly. But there is a huge interest in biodiversity. We should at least ask the question: is there anywhere else on Earth they don’t currently live where they could in the future survive? Conservation agencies should stop shying away from this.”
As many as 40% of known extinctions resulted directly from the introduction of alien species, he concedes. After placental mammals arrived in Australia, many native species could not survive. The same happened with flightless birds in Madagascar.
Not a single species in Britain appears to have died out as a result of invasive species. It seems that this country is quite well able to establish new things at low risk. Indeed, the vast majority of species in Britain arrived in the past 11,000 years and we were connected by land to Europe until about 8,000 years ago.
However, even if non-native species from Europe could be expected not to cause extinctions here, there would be doubts about a wider migration. “This is not about moving things from one continent to another,” says Thomas. “We wouldn’t move polar bears to Antarctica because they’d eat all the penguins.
“But after the convention on biodiversity was drawn up at Rio in 1992, each [representative] went home with the task of reducing species loss in their own country. With climate change we need to think at a larger scale. For instance, what kind of managed change would be most desirable at the European scale?”
Such schemes have been tried elsewhere. In the past 15 years Australian conservationists have relocated some species with the result that three native mammals — the woylie, quenda and tammar wallaby — have been removed from the threatened list.
Others have sought to replace extinct species with latter-day equivalents to serve a similar “job” ecologically. Thus, nonnative tortoises are being introduced to Round Island in the Indian Ocean to stand in for extinct native tortoises.
When species are reintroduced into an area where they were found previously, conservationists frequently raid gene pools from elsewhere. Over recent decades red kites have been successfully reintroduced across parts of Britain using birds from Spain, Sweden and Germany, says Iain Yoxall, a wildlife ranger with the Forestry Commission in the northwest.
“Now the populations in southern Europe are in rapid decline, while ours is becoming a potential lifeline. In time we may see birds being taken from the UK,” he says.
Professor Ben Minteer is an ecological ethicist at Arizona State University. He says there’s a widely held philosophical objection to the very idea of human intervention. “The fact that ‘we’ are doing this rather than the populations themselves is sometimes regarded as another example of human arrogance toward wild species and the environment more generally,” he says.
Sometimes reintroductions can have an adverse effect on established species. Wolves were reintroduced to America’s Yellowstone national park to reduce the numbers of elk, which were damaging the forest. Nobody predicted the fall in coyote numbers — and probably few regret it.
Whatever conservationists do, Thomas points out, others will continue to move species for forestry, horticulture, agriculture, the pet trade and biomedical purposes, or by accident.
Indeed, some of us are moving endangered species to safety without even thinking about it, says Alastair Culham of Reading University. He gives the example of cyclamen species that grow wild in the Mediterranean but are likely to become extinct as conditions there get warmer and drier. “Human intervention has already started, albeit unintentionally, as cyclamen is becoming a common plant in many people’s gardens [here],” he says.
In time we may come to regard them as native. “Some of the rare poppies and cornflowers that are really threatened,” says Thomas, “almost certainly arrived here as arable weeds. They’re not native. I don’t see the logic in putting money into protecting species like that and not welcoming other international species.”
Take the rhododendron, reviled by woodland managers all over the country. “Most of what we have in Britain originates in the Spanish peninsula,” says Thomas. “The subspecies there is isolated in moist micro habitats and they’re expecting droughts. So it’s likely they will go extinct — and if it survives at all, it will be in the British Isles. It has been moved here and clearly likes it.
“I think we just have to get used to it. If we regarded it as a native, we could enjoy it as one of our flowering glories.”
Most at risk:
The most endangered cat in the world, it lives in the Iberian peninsula. Its main prey, rabbit, is abundant in southern Britain.
Spanish imperial eagle
An extremely rare eagle native to Spain and Portugal. Also eats rabbit.
Provence chalkhill blue
A butterfly found in northern Spain, southern France and northern Italy. At serious risk of extinction from climate change. Its host plants already grow in southern England.
Iberian water beetles
Many of the 120 water beetle species native to the Iberian peninsula that live in streams in mountain ranges are under threat from increased droughts.
Semi-aquatic insect-eating mammal that lives in streams in the Pyrenees. Could be suited to western Britain.
1403 words. First published 3 April 2011. © Times Newspapers Ltd.