Going Native

The global transportation of goods has a long history. As we have moved around the planet so we have transported with us many different plants and animals, introducing them to new regions. Some have been taken unwittingly, stowing away on ships, in timber or in foodstuffs; others have been deliberately introduced to remind us of home.

Within the UK we have seen countless examples where introduced species have gone on to become a problem within the wider countryside; American mink, signal crayfish and Japanese knotweed all spring to mind. There are, however, many instances where an introduced species has simply filled a vacant niche and established itself without having any impact on other species. One of the most interesting aspects of the debate about these introduced species has been the extent to which something is considered native or introduced. Some of the creatures that were deliberately introduced many centuries ago are considered as natives, while recent colonists arriving unaided are sometimes treated as unwelcome invaders.

Our own perceptions of particular species cloud the debate and we even see conservation practitioners arguing with each other about whether or not a species should be controlled. The ruddy duck privides a good example. This species was introduced to Britain by the Wildfowl and Wetlands Trust in the 1950s, when individuals escaped from Slimbridge. An expanding population saw individuals move into Europe, where they came into contact with the related white-headed duck, a globally-threatened species. The solution seemed simple enough, cull the ruddy ducks to save the white-headed duck, but there was stiff opposition from many quarters, including from birdwatchers who liked seeing these birds here in Britain. The West Midlands Bird Club, for which the ruddy duck was a special species, even managed to smuggle a subtle image of the species into their new logo once the ducks profile switched to that of unwanted alien.

For other species the problem comes from uncertainty over whether it is native or not. Our slowly expanding eagle owl population almost certainly stems from aviary escapes and deliberate releases. There is, however, a very small possibility that an Eagle Owl from elsewhere in Europe might reach our shores. This uncertainty is used by some as an argument against culling the pairs breeding here now, even though some bird carry the jesses that reveal their captive origins. You might wonder if it really matters; you might even argue that it is better to accept that our activities will result in introductions and that conservation money is better spent elsewhere. Perhaps the most pragmatic solution would be to remove definitely introduced species as soon as they appear, accepting that other species may be too well established now to manage effectively.

Them ruddy ducks!

Conservation can be a brutal business and there are times when sensible, sound and necessary actions require practitioners to implement uncomfortable management options. Nowhere has this been more evident than in the case of the Ruddy Duck. This North American species was first introduced to Britain over half a century ago. Originally held within waterfowl collections, the duck escaped and became established as a breeding species more widely across Britain. By the start of 2000 there were estimated to be some 6,000 Ruddy Ducks living wild in Britain.

The main problem with these ducks was that they did not remain here but instead ranged more widely across Europe and, from the early 1990s, they began to turn up in Spain. Spain is home to the White-headed Duck, a species that is very closely related to the Ruddy Duck and one that has been developing naturally because it is reproductively isolated from its cousin over the water. The newly arrived Ruddy Ducks were found to hybridise with the native White-headed Ducks. If this were allowed to continue then in all likelihood it would lead to the extinction of the White-headed Duck.

Following a great deal of research work, and many discussions, a decision was taken to eradicate the population of Ruddy Ducks living in Britain. Not everyone welcomed this process and there has been a fair amount of bad feeling in some quarters. In some cases the arguments against eradication have been well-intentioned and well-researched; in others they have been ill-informed. The process, however, looks as if it is nearing its end; the latest count suggests that there could be as few as 200 Ruddy Duck left, with many of these associated with traditional sites towards which the eradication work will remain targeted into 2011.

It is a shame that conservation practitioners have been forced to take this action. It is, after all, a consequence of human activities that the Ruddy Duck was brought to Britain in the first place. It is our fault that it escaped and our fault that its presence threatens another species. I know that some readers might argue that if the two ‘species’ can interbreed then they are not really two different species. Such an argument is an oversimplification, since it fails to understand that without our naïve meddling these two species would have remained reproductively isolated because of their geographical separation. Over time they would have become further isolated, as mating behaviours diverged and genetic compatibility declined.

That conservation practitioners must sometimes eradicate a species from an area into which it has been introduced, is never an easy option. It is a sad consequence of the wider damage we humans continue to inflict upon the world.