The waters have been well and truly muddied by our own arrival – before Homo sapiens, everything was where it ought to be.
The fact remains that although most organismal translocation is either beneficial or of neutral effect, public perception is that it’s an evil, largely because invasive species ‘seem practically designed to excite public concern’, being most visibly abundant in the most human-modified habitats – that is, those places where they’re most likely to be seen.
Ken Thompson’s book provides a wealth of baseless horror stories. Purple loosestrife, for instance, a European wetland plant introduced into the USA during the 19th century, has since ‘obliterated’ much native flora, and by 2011 was costing an annual US$45million in control costs. But research, as opposed to belief, reveals no evidence that native plant species have dwindled where loosestrife has flourished – loosestrife’s problem is just that it’s too conspicuous for its own good.
Similarly, imported American mink were blamed for the drop in the British otter population, due to their competing for the same food. But their diets actually overlap little: pesticide pollution was responsible for the otter’s decline.
Thompson’s rational, readable treatise, which reveals that about 20 per cent of Britain’s 300 or so ‘native’ species might more accurately be called ‘doubtfully native’, provides useful correctives to storms in media teacups.
WHERE DO CAMELS BELONG? The Story and Science of Invasive Species by Ken Thompson, Profile, £10.99