Whilst some are easy to distinguish, others look very similar. There are also some hybrids, adding to the confusion. They are divided into 3 groups, ground finches, vegetarian finches and warbler finches. Despite the name they are not related to true finches and, apart from the Cocos finch, are only found on the Galapagos Islands. The most important distinguishing feature is the beak, its size and shape being adapted to different feeding habits.
Ground finches have black feathers, though females have slightly lighter brown plumage. They have conical-shaped pale pink or yellow bills which change to black in the breeding season. They feed mostly on seeds, supplemented by flowers, buds, young leaves and insects. The different species vary in size.
Vegetarian finches are the largest. They are mainly black with a white belly. The bill is short and broad. As with the ground finches, the usually pale beak turns black in the breeding season. It’s found on 8 of the islands and feeds on buds, flowers, leaves and fruit, usually in trees but sometimes foraging on the ground.
The warbler finches are the smallest, around 10cm. This group includes woodpecker and mangrove finches as well as warbler finches. Their plumage is grey or brown. The warbler finch has a small, thin and pointed beak, while mangrove and woodpecker finches have broad and long beaks, also quite pointed. These last 2 finches have been known to use a twig or thorn in their beaks to scrape insects out of crevices. As with the other species of Darwin’s finches, the bill is pale for most of the year, turning black in the mating season.
Darwin’s finches are found on most of the islands though some species are only found on certain islands.