• A racoon dog, invasive species in some parts of Europe. (pixabay)Source: pixabay
A blacklist of alien and invasive species is intended to get member states to work together on eradicating or controlling these invaders.
Aisling Irwin

New Scientist
1 Mar 2016 - 3:16 PM  UPDATED 1 Mar 2016 - 3:16 PM

Oblivious to his sterilisation, Judas the raccoon dog treks through the Swedish countryside in search of a lifelong mate. At last he finds one, only for their liaison to end when she is shot. He trudges on, in search of another, but she is killed too. This is his destiny: for he is radio-tagged, and is leading hunters to the last live raccoon dogs remaining in the country.

The Swedish war on the raccoon dog (Nyctereutes procyonoides), a luxuriously furry, short-legged mammal spreading west across Europe, is a rare success in the battle against alien intruders.

Any day now, the European Commission will publish a blacklist of 37 alien invasive plants and animals that require action across the EU under its regulation on invasive alien species, which became law last year.

Member states are obliged to prevent these species entering their countries; to quickly detect and eradicate them if they do invade; and to manage invasions that are already established. Also, purchases of listed species and their commercial breeding and import are illegal, as, of course, are wild releases.

The list will include several species of plants and crayfish, plus the ruddy duck and grey squirrels, nemesis of the red. Key future threats will also be listed, such as the squirrel-like small Asian mongoose and the South American coati, a relative of the raccoon.

Raccoon outlaws

The vast majority of alien species are benign but some become invasive and threaten native biodiversity. Leave it too long and it’s often too late to deal with them, as the case of the raccoon (Procyon lotor) shows.

Already, a million of these creatures infest Germany, feasting on crops and eggs, damaging houses and transmitting diseases humans can catch, such as the raccoon roundworm. Raccoons were introduced there from North America in the last century.

“There’s not much we can do now,” says Marten Winter, coordinator of the German Centre for Integrative Biodiversity Research in Leipzig. Even hunters can’t be bothered nowadays. “Once you have one hat you don’t need more,” he says. “And you can’t eat them because of parasites.”

Raccoons are on the blacklist despite unease in Germany, which doesn’t want to be forced into an expensive and futile campaign against them. However, the Commission says that when a species is already widespread, a member state’s responsibility is to prevent them spreading further rather than eradicate them.

The blacklist is driven by figures showing that invasive species cost Europe at least €12 billion per year in human and animal health costs, decreased crop and fish yields, damage to infrastructure and river navigability, and in harm to protected species. The idea behind the list is to get member states to work together for more effective results, something Francisco José García, an independent biologist from Spain, says is essential.

Spain, too, has an epidemic of free-roaming raccoons, which began when a generation of kids fell in love with one in the film Pocahontas and demanded their own. Many pets ended up in the wild, and since then several regions have been assiduous in launching eradication campaigns, García says.

But in central Spain, where raccoons pose a great threat to migrating birds, crops and plants, the populations are older and larger as the control programmes began too late and lack resources. Various public organisations are working “with an obvious lack of coordination and technical criteria”, García says.

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Non-fussy eaters

Escaped mammal predators can flourish in Europe for several reasons. Rabies, which used to hold mammalian populations in check, has largely gone from Western Europe. Prey in intensively farmed fields is easier for them to spot, and as generalist eaters, they can often survive on urban leftovers too.

And the European single market, which removed regulations that obstruct the free movement of goods and people, generally takes priority over measures aimed at halting the flow of alien species, according to the authors of DAISIE, an invasive species handbook.

In such an environment, acting early and decisively is vital, says P-A Åhlén of the Swedish Association for Hunting and Wildlife Management. When the Swedish government tasked his association with eradicating raccoon dogs and gave him a budget now at €800,000 a year, he swiftly recruited a team of professional hunters.

They erected cameras over an area three times the size of Denmark, trained dogs to sniff out the pests and encouraged the public to report sightings. The raccoon dog population is now so low that they have to recruit their “Judas” animals from outside the country.

But it can be hard to act decisively. For example, the American mink has devastated some ecosystems but divides nations because those with lucrative mink fur farms fear its inclusion in the blacklist. Officially, mink will not be included because the damage they cause has not yet been scientifically assessed.

Divisions over how to treat newcomers are illustrated by the golden jackal (Canis aureus), spreading rapidly from south-eastern Europe and the Caucasus, thanks in part to climate change.

In Hungary, where it attacks sheep and newborn calves, it is regarded as indigenous but is proliferating like an invasive species. The Baltic states, where it was first spotted in 2011, have declared it an alien. Yet in Italy it is protected. It is listed in the European Habitats Directive as an animal whose hunting should be compatible with their survival as a species.

Alien or not?

These contrasts arise largely because in some countries it is thought to have returned after a long absence, whereas others have never seen it before. So, is this slim, wolf-like creature to be welcomed or fought? Legally, the answer lies not in how much damage it causes, but in whether it arrived through human intervention – in which case it is an alien.

A team led by Wieslaw Bogdanovicz, of the Polish Academy of Sciences in Warsaw, revealed last year that Baltic golden jackals are descended from a population that moved there naturally. “We have proved it is not an alien species,” says Bogdanovicz.

As a result, he says, Estonia has reversed its classification as an alien, and Lithuania may do the same.

Because it is indigenous to part of Europe, the golden jackal may never be added to the blacklist, but others inevitably will.

Helen Roy of the Centre for Ecology and Hydrology in Wallingford, UK, and her colleagues have conducted a detailed study of future species threats to Europe that contains likely future additions to the blacklist. She says that over 90 per cent of new arrivals are no trouble. But the value of the blacklist and Roy’s study is that prevention is better than cure.

The 10 biggest living threats to Europe

A team of 43 researchers across Europe has compiled a list of the top 95 invasive species threats to Europe over the next decade. The assessment combines factors such as the likelihood of their arrival and the scale of their impact. Of these, 37 are due to be published on the European Union’s new official blacklist, including the small Asian mongoose. Here are the top 10 invasive threats to Europe over the next decade:

alligator weed Alternantherea philoxeroides

devil firefish Pterois miles

small Asian mongoose Herpestes auropunctatus

common kingsnake Lampropeltis getula

golden mussel Limnoperna fortune

rusty crayfish Orconectes rusticus

northern brown shrimp Penaeus aztecus

western mosquitofish Gambusia affinis

striped eel catfish Plotosus lineatus

This article was originally published in New Scientist© All Rights reserved. Distributed by Tribune Content Agency.