Bali, Mauritius, Iceland, Galapagos, Madagascar: these are fine and exotic places, far away from the busy center of things. Yet, no matter how remote they may seem, islands are at the epicenter of the ongoing mass extinction of animal and plant species—one that has every chance, one day, of involving humans not as agents but as victims.
Now, islands are, by definition, geographically isolated: bits of land, large or small, separated from other bits of land by water. That isolation, as David Quammen, quoting biologist Ernst Mayr, remarks, is “the flywheel of evolution”: on islands, species separate and transform markedly. The smaller the island, for complex reasons, the greater the danger of extinction. This formula is one of many elaborated in Robert MacArthur and E. O. Wilson’s theory of island biogeography, which has been highly influential in ecological circles in the five decades since its publication.
Getting from one island to another is fraught with peril as well, as the plight of the leatherback turtle suggests. These sea creatures emerged more than 100 million years ago to occupy a niche in the ecology of what is now the eastern Pacific Ocean. In the last 20 years, biologists estimate, their numbers have fallen by 90 percent. The reasons are many, but, reports a team of researchers from Stanford University, the National Oceanic and Atmospheric Administration, and other institutions, one is the turtle’s migration route from the waters of Costa Rica beyond the Galapagos Islands to small islands in the middle of what is called the South Pacific Gyre. Given worldwide demand for seafood, the area and points all along the turtle’s migration route are being heavily fished by trawler fleets from many nations—and many of the creatures pulled up in their nets are leatherbacks.