Call for wildlife security force to keep native species safe

A wildlife security service should be set up to stop invasive alien species of animals and plants getting a hold in Britain, the Government was told yesterday.

A wildlife security service should be set up to stop invasive alien species of animals and plants getting a hold in Britain, the Government was told yesterday.

Detailed policies should be developed to prevent the introduction of harmful exotic species which – like the Japanese knotweed or the American mink – can wreak havoc on native wildlife and their habitats, and damage the economy, according to a broad-based group of wildlife experts.

Preventing the arrival of harmful new species will be more effective than trying to contain, control or eradicate them after they are established, says the report of the non-native species working group.

The group was set up by the Government to address growing concerns, in a world of ever-expanding trade and international travel, over what happens when a species is introduced into an ecosystem where it does not naturally occur.

The result can be wildlife and even economic catastrophe. The brown tree snake of Indonesia, introduced to the Pacific island of Guam in the 1940s, had by the 1970s wiped out Guam's native forest birds. The Nile perch, introduced to Lake Victoria in 1954, has now driven to extinction more than 200 fish species that were unique to the African lake, through predation and competition for food.

The World Conservation Union says the introduction of non-native species is the biggest cause of wildlife extinctions around the world, after the destruction of habitat.

In Britain, the native red squirrel has been driven out of most of England by the grey squirrel, introduced from North America in the late 19th century; the native water vole has been similarly wiped out by the American mink, brought over 70 years ago to stock fur farms; and the native white-clawed crayfish of our limestone and chalk streams has been badly affected by the arrival of its US cousin, the signal crayfish.

Perhaps even more directly troublesome have been plants. Japanese knotweed, imported by the horticultural trade, has spread across Britain in the past 40 years and dominates the habitats it invades with a dense mass of foliage and canes that shuts out other plants.

It can grow through Tarmac and even the floors of houses, appears to have no natural enemies and is difficult and expensive to control. Rhododendrons, introduced in the 19th century, can cause similar difficulties.

More recently, non-native aquatic plants such as Australian swamp stonecrop and New Zealand pigmyweed have caused similar problems.

The report accepts that only a small number of alien species become invasive pests. A surprising amount of familiar British wildlife is in the strict sense of the term non-native, including flowers such as the poppy, birds such as the mandarin duck and mammals such as the rabbit (which was introduced by the Romans); many are perfectly benign.

The report says one group should be designated to take charge of the threat of alien species, raise awareness of the dangers, develop codes of conduct for those involved such as the gardening industry, and establish adequate monitoring and surveillance arrangements.

Elliot Morley, the minister for Nature Protection, welcomed the report and promised a government response this summer.

Yesterday Plantlife, a wildflower conservation charity, joined forces with gardening trade and consumer organisations – the Garden Centre Association, Gardening Which?, the Horticultural Trade Association, the Ornamental Aquatic Trade Association and the Royal Horticultural Society – to express support for the report.

"We are aware of the role that horticulture can play in both contributing to and alleviating this problem," they said.

The predators

American mink (Mustela vison)

These were first brought to Britain in the 1930s to stock fur farms. As the farms spread in the late 1940s and 1950s some escaped, and in 1957 they bred in the wild (in Devon) for the first time. Since then they have spread across the country, filling a niche in the ecosystem for an aquatic carnivore, and they have now wiped out more than 90 per cent of Britain's water voles. Some naturalists would like to try to eliminate them but the job would cost millions and take years, and such a national eradication campaign appears unlikely.

Japanese knotweed (Fallopia japonica)

This was deliberately imported by the gardening trade, but was probably released into the countryside accidentally. It is now among the most troublesome of pests in many parts of the country because it can rapidly colonise a site and squeeze out everything else – such as bluebells in a bluebell wood. Hard to eradicate, it can also increase flood risk by causing riverbank erosion.

New Zealand flatworm (Arthurdendyus triangulatus)

This is a predator of the earthworms that keep our soil in good condition and are a source of food for many animals and birds. It was first sighted in Northern Ireland in 1963, probably having arrived in the root-ball of a plant, and is now widespread in Ulster, Scotland and northern England. It can greatly reduce the population of earthworms.