Pete Oxford / Finch specimens at the Charles Darwin Research Station, Puerto Ayora, Santa Cruz Island, Galapagos Islands, L to R Top: Large Ground Finch (Geospiza magnirostris), Woodpecker Finch (Cactospiza pallidu...

Tui De Roy / Green warbler finches (Certhidea olivacea) seeking small insects among shoreline boulders. Punta Cevallos, Espanola Island, Galapagos Islands, Ecuador, June.

Tui De Roy / Green warbler finch (Certhidea olivacea) in bracken and Miconia forest. Media Luna, Santa Cruz Highlands, Galapagos Islands, Ecuador, June.

Tui De Roy / Green warbler finch (Certhidea olivacea) foraging for seeds, Gardner Bay, EspanÞola (Hood) Island, Galapagos Islands, Ecuador, June.

Tui De Roy / Green warbler finch (Certhidea olivacea) on fern frond, Media Luna, Santa Cruz Highlands, Galapagos Islands, Ecuador, November.

Tui De Roy / Green warbler finch (Certhidea olivacea) on fern frond, Media Luna, Santa Cruz Highlands, Galapagos Islands, Ecuador, June.

Rolf Nussbaumer / Digital composite of Cardinal, Mockingbird, Green jay, House finch, Pine warbler, Golden-fronted woodpecker, Chipping sparrow, birds landing on Texas prickly pear cactus (Opuntia lindheimeri), Dinero,...

Pete Oxford / Warbler Finch (Certhidea olivacea), Galapagos Islands, Ecuador

Pete Oxford / Warbler Finch (Certhidea olivacea), highlands of Santa Cruz Island, Galapagos Islands, Ecuador

Tui De Roy / Warbler Finch (Certhidea olivacea) endemic small insectivore, one of 13 species of Darwin's Finches, Genovesa Island, Galapagos Islands, Ecuador

Tui De Roy / Warbler Finch (Certhidea olivacea) endemic small insectivore, one of 13 species of Darwin's Finches, Genovesa Island, Galapagos Islands, Ecuador

Tui De Roy / Warbler Finch (Certhidea olivacea) perching on branch, Santa Cruz Island, Galapagos Islands, Ecuador

Paul D Stewart / Two Galapagos Mockingbirds (right, upper from Espanola lower from San Cristobal), three Galapagos finch species (upper left) and Yellow Warbler (gold, lower left), from the collection of the Charles D...

Paul D Stewart / Illustration from page 379, 'Journal of Researches' 2nd Edition 1845 Charles Darwin. The contrasting beaks of four Galapagos finches, three Geospizinae genus and one Certhidea (Warbler finch). Darwin...