Dan Eatherley is a writer, filmmaker, and environmental consultant. He has made natural history documentaries for the BBC, National Geographic, and the Discovery Channel, and worked as an assistant producer on two landmark BBC series hosted by David Attenborough. He has also published more than one hundred popular science and environmental articles. He currently resides in Exeter, England. His new book, entitled Invasive Aliens, explores the past, present and future of non-native plants, animals and other organisms in Britain’s countryside


An extract from Invasive Aliens:

Taking a stroll through Hampstead Heath one chilly autumnal morning, I was struck by just how much around me wasn’t ‘natural’ in the sense of representing native British fauna and flora.

The most obvious example was the resident flock of a hundred or so rose-ringed parakeets with their frequent shrill calls. Then there were the grey squirrels, mandarin ducks, Canada geese, alpine newts and marsh frogs, to say nothing of the crayfish and carp in the ponds or the horse chestnuts, rhododendrons and laurels growing amidst the native oak trees.

I could have gone to pretty much any park in Britain and seen the same things, and far more besides. And it’s not just parks: our rivers, lakes and streams; our forests and farmland; our estuaries and coastal waters; our homes and gardens; even our own bodies; all host a wealth of introduced species.