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Alien invasives are the biggest conservation problem, not habitat for bats

My recent column in The Times is on wildlife conservation:

On the day last week that the House of Commons was debating a private member’s bill dealing with bats in churches, conservationists were starting to eliminate rats from the island of South Georgia by dropping poisoned bait from helicopters. Two very different facets of wildlife conservation: the bats stand for preservation of pristine nature from human interference; the rats for active intervention to manage nature in the interests of other wildlife. Which is better value for money?

Bats love roosting in churches, but those who love bats and those who love churches are increasingly at loggerheads. Bat pee has damaged many of the brasses in British churches, and stained or eroded precious medieval monuments and paintings. Expensive restoration work is often undone in a matter of months by micturating bats.

Vicars and church wardens are tearing their hair out, but there is little legally they can do. Excluding bats from a church, or even disturbing them, is forbidden, and building a bespoke bat roost elsewhere rarely works because the bats must choose to leave; they cannot be evicted.

While one arm of government, English Heritage, enforces EU directives to preserve cultural heritage, another, Natural England, enforces a directive that churches may not disturb bat roosts. Both demand the spending of money, which is thus circular. Church wardens complain of officious bullying by amateur and self-trained busybodies from the Bat Conservation Trust, to whom the task of enforcing the bat rules has been delegated by government.

Relishing their role, these amateur bat policemen demanded that work was stopped in one church because of a single dropping, which was probably from a mouse. Elsewhere, they reported a church architect to the police based on the false presumption gathered during a snap inspection that he had ordered work on a roof. In another case, they suggested a monument be wrapped in plastic to protect it.

Most bat species are not rare or declining, but it makes no difference. The whole system wastes money, time and goodwill towards bats (there are huge incentives to eliminate them surreptitiously) while doing very little to help to conserve rare species, and contributing massively to the desecration of our cultural heritage. But it is all highly lucrative for the bat people: building managers must order expensive bat inspections from the bat folk themselves before converting or repairing buildings.

For a tenth of the cost of this system, the active provision of special bat roosts aimed at the rarer species, as a quid pro quo for giving people the right to exclude bats, would achieve more. And therein lies a lesson: active conservation is better than passive preservation.

The bat policy preserves an outdated model of what wildlife conservation is: the passive preservation of a supposedly pristine natural system — though churches designed for worship, not bat roosting, are hardly natural habitats anyway. For better or for worse, human intervention is messing up wildlife all over the world, and active human intervention is necessary to un-mess it.

For example, the demise of the water vole in much of England was caused almost entirely by the spread of the mink, an alien invader from North America, released by people. Protecting river banks from disturbance would do almost nothing to help water voles; eradicating mink would and does make all the difference. Likewise protecting red squirrel habitat achieves little unless alien grey squirrels are removed.

More invasive pests are on the way. A friend recently encountered a raccoon in her hen house, eating her hens. Escaped pet raccoons are beginning to establish themselves in northern England with potentially devastating consequences for native wildlife. Escaped Chinese raccoon-dogs have already ravaged the ground-nesting birds of Finland and are starting to escape here too: why are on earth are they allowed as pets?

Signal crayfish and killer shrimps in rivers, Himalayan balsam and rhododendrons, mitten crabs, ash dieback — wherever you look, the urgent conservation priority in Britain is the eradication of invasive aliens, not the officious preservation of habitats for species doing just fine.

By far the commonest cause of species extinction globally is the spread of invasive alien species. This is especially true on islands. On Gough island in the south Atlantic, sweet little house mice, released by people, feed by gnawing at the flesh of albatross chicks, killing them slowly. Even the demise of the dodo on Mauritius was actually caused by the introduction of alien species — monkeys, rats and pigs — rather than humans themselves.

Of the 190 species of mammal and bird that are known to have become extinct in the past 500 years, all but nine were found exclusively on islands (if you count Australia as an island) and most of the extinctions were caused by the introduction to islands by people of goats, cats, rats, snakes, sparrows and all sorts of pests and parasites. So this month’s ambitious plan to eradicate the remaining rat infestations on South Georgia (two thirds of the island has already been cleared) in order to revive the seabird colonies there, is exactly what conservationists should be doing.

In the Pacific, 34 islands have already been cleared of rats and other invasives. In December the charity Birdlife announced that all the goats and rats had been eradicated from Monuriki, the 100-acre Fijian island where Tom Hanks filmed Castaway. This is good news for the wedge-tailed shearwaters and Fijian crested iguanas that live on the tiny island.

Birdlife recently published a report identifying 25 islands among the 2,500 in the UK Overseas Territories where eradication of invasives should begin. The most crucial include Henderson, a large, uninhabited and almost impossibly remote island 3,000 miles from the nearest continent, where rats are eating 95 per cent of the chicks of breeding Henderson petrels and threatening 54 other species found nowhere else. Getting rid of the rats is the single most valuable thing British conservationists can do to save species. The first attempt failed, but conservationists are trying again.

Just imagine if you took all the money spent on bat surveys in churches and other such futile tick-box conservation bureaucracies and redirected it to active rat eradication on such islands, and to the eradication of the mink, the grey squirrel, the raccoon and other invasives threatening British wildlife. That’s true conservation.

By Matt Ridley | Tagged:  rational-optimist  the-times