Kill one unwanted species and another arises

IN THE HIERARCHY of conservationists’ concerns, animals often seem to trump plants. For example, feral rats that live on islands after having been introduced accidentally by passing ships are excoriated because of the damage they do to local wildlife. More than 100 island-based animals have been exterminated or are imperilled by these rodents—birds being at particular risk through loss of eggs and nestlings. The effects of the interlopers on the local flora are, however, less well investigated.Rats’ main source of nutrition being seeds and fruit, this is a surprising omission. But it has been rectified in part by a project undertaken by Ana Miller-ter Kuile of the University of California, Santa Barbara. The object of Ms Miller-ter Kuile’s attention was Palmyra, an atoll that is one of the most remote specks of land in the Pacific Ocean. And, as she describes in , by focusing on the atoll’s plants she showed just how extensive an effect rats can have on an isolated island’s ecology. She also showed, though, that restoring matters to the status quo ante bellum is not as easy as might be hoped.