Matt Palmer, writing for The Nature of Cities:
Family narratives and history books are full of stories about about the hard times that waves of human immigrants found in their new homes. Non-human immigrants – often referred to as exotic, introduced, or non-native species – have received a similarly cold welcome in most places. But the movement of plants and animals across the planet is both ancient and inevitable. It is also increasingly difficult to control. We face choices about which movements to resist and which to allow or perhaps even encourage. We also have the opportunity to plan as well as we can to get the most from our changing ecosystems.