Large ground finch

The large ground finch (Geospiza magnirostris) is a species of bird in the genus Geospiza. One of Darwin's finches, it is now placed in the tanager family Thraupidae and was formerly in the Emberizidae. It is the largest species of Darwin's finch.

The large ground finch weighs about 27-39 g, and its length ranges slightly 15-16 cm. It is the largest species of Darwin's finch both in total size and size of beak.

The feather and bill colors vary between males and females. The adult male is mostly black, with slightly browner wings and tail; the cloaca is white-streaked; the eyes are dark brown. It also has blackish legs. The tail is relatively short. An adult female has browner feathers compared to a male, sometimes with yellow-brown or grey outer edges; scaled patterns are found going up the body; most parts of the torso and the head are streaked with brown and pale yellow shades.

It has a large beak, having a thick base of lower mandibles and curved culmen. It allows the bird to feed on large seeds and insects, but also to crack and consume nuts. Thanks to its versatile beak, the large ground finch often has a variety of food supplies. Moreover, the shape of the bill gives the finch slower and lower-pitched sounds and more nasal calls. Similar to other male finches, the beak changes color in relation to different periods: it's black during the breeding season, but turns amber outside the period.