The remarkable diversity of beak forms amongst Darwin’s finches allows each species to feed in a specialised way (7). With its curved, powerful beak, the large-tree finch is capable of biting through the bark of twigs, exposing adult insects and larvae such as caterpillars, which are then consumed (4). While invertebrates form the major part of its diet, this species will also consume fruit, especially during the dry season (4).
Darwin’s finches usually breed during the hot and wet season when food is most abundant. Monogamous, lifelong breeding pairs are common, although mate changes and breeding with more than one partner have also been observed. Breeding pairs maintain small territories, in which they construct a small dome-shaped nest with an entrance hole in the side. Generally a clutch of three eggs is laid, which are incubated by the female for about twelve days, and the young brooded for a further two weeks before leaving the nest. The short-eared owl (Asio flammeus), frequently preys on the nestlings and juvenile Darwin’s finches, while adults are occasionally taken by Galapagos hawks (Buteo galapagoensis) and lava herons (Butorides sundevalli) (2).