Galápagos Derailed

Abstract

The same species of Galápagos rail, a 6-inch insectivorous ground bird, has been reported on all eight islands with a highland humid zone. Evidence suggests that the rail colonized Galápagos at roughly the same time as giant tortoises, which evolved into 15 species with life spans of 150 years. So why is there just one species of rail? The question is especially germane given reports of the rail’s “reduced flight ability” (as is true of many island-dwelling rails), which would effectively isolate different island populations. And why has the species survived when so many similar rails have succumbed to human influence on other Pacific islands? The human history of Galápagos helps to answer these questions. Two things have saved the Galápagos rail from extinction: (1) It remains capable of flying between islands, which explains why it failed to differentiate like tortoises. (2) There have been massive efforts to eradicate or control invasive species, restoring habitat for rails to repopulate.