Green Warbler-Finch (Certhidea olivacea)

With its remarkably warbler-like appearance and behaviour (3), it is not surprising that, during his famous visit to the Galapagos, Charles Darwin erroneously classified this species (2) (4). It was only following investigations of Darwin's specimen collection by John Gould, that the warbler finch was discovered to be one of thirteen species of finch endemic to the Galapagos, which would later become known as Darwin's finches. Each of Darwin's finches has evolved a distinct beak shape in order to exploit different food sources (2). The warbler finch possesses a thin, probing bill, finer than that of the other species, which is ideal for feeding on small insects (5). The plumage of the warbler finch is unremarkable, with uniform dull, olive-grey feathers found in both sexes (4). Although recent studies indicate that there are in fact two separate species of warbler finch, the green warbler finch (Certhidea olivacea) and the grey warbler finch (Certhidea fusca), they are assessed together as a single species, Certhidea olivacea,on the 2008 IUCN Red List. Despite having little difference in appearance, they are genetically distinct and occupy different islands in the Galapagos (6).

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