The Hodge Oct 2020: Countering Invasive Species

Country Matters

Himalayan Balsam

By The Hodge

‘Policemen, like red squirrels, must be protected.’

Joe Orton, Loot, 1967.

Last month we looked briefly at what measures could be taken to help the reintroduction of extinct or nearly extinct species in this country and there is room for much more discussion on this subject. But that should be for another time because I also promised to look at the other side of the coin – invasive species not native to these islands and what should be or could be done to eradicate them.

When discussing how to increase the numbers and range of the red squirrel, I pretty much said that any action would rely on the removal of the destructive and disease-carrying American grey squirrel, now endemic throughout much of the UK. In the 1950s, there was a positive incentive programme for gamekeepers and shooters to kill as many greys as possible. By presenting the tails of dead grey squirrels at police stations, countrymen were rewarded with a shilling (5p) per tail and many thousands were killed. This was a government incentive but was dropped long before the grey was eradicated, and numbers quickly grew and expanded again.

However, a similar planned programme was more effective against the large South American rodent, the Coypu, in the 1960s. Their population was much smaller, and they were confined to an area of East Anglia, but the elimination was eventually successful.

Another American import is today a pest and inhabits the waterways around here as well as elsewhere. That is the American signal crayfish. This is an aggressive species, larger than our native white-clawed crayfish and the American bruiser kills the smaller native whenever they come into contact. The signal also destroys many smaller fish and other aquatic creatures that inhabit the same streams and lakes that take its fancy. If you don’t believe me that they are rife in this area, keep your eyes peeled when walking near water. Even if you don’t see them in the water, you can often see the remains on the banks where water birds such as gulls have sourced a tasty meal.

But invasive pests are not confined to mammals and crustaceans. The aggressive Asian hornet makes the common wasp look like a little softie. It has been found nesting here in the UK, including here in Gloucestershire, and authorities want to hear from anyone identifying one or more so that pest controllers can find and destroy any nests before their queens take flight and establish new colonies the following year.

Plants too can be destructive – just consider the damage done by Japanese Knotweed. Much more common round here is the pretty – that’s why gardeners were attracted to bring them home from abroad – but pestilent Himalayan balsam or ‘policemen’s helmets’. They are an annual that thrives close to water. A tall plant (up to around 5 feet or more), they have multiple pink flowers not entirely dissimilar to snapdragons. The Himalayan balsam has a cunning trick to help colonise large areas, in that as the flowers fade, they spread their seeds by ‘spitting’ them over some distance so that a single plant can be responsible for a veritable forest the following year, several yards across. They grow so densely that other plants are excluded from their ever expanding territories. They are, quite simply, a pest that takes over entire areas.

Official guidance is to cut them down before they seed but not just to leave them where they fall but to carefully bag them up until they die and then burn them, ensuring that seeds don’t ‘escape’. Unfortunately, landowners, councils and trusts and other authorities seem to make little effort to control this invasive plant and it thrives en masse around the Cotswold Water Park. Hopefully, those responsible for such areas might wake up to the need to control this menace before we’re engulfed by it.

From Spanish slugs to American bullfrogs, there are heaps more immigrants which have taken over parts of the country to the detriment of the environment or native species. As the world becomes smaller, so we have to find ways of ensuring that such invaders do not cause too much damage or find ways to control or eliminate them.

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