The mangrove finch mainly feeds upon adult insects, grubs and spiders, which are obtained by foraging through the leaf litter, or by using its powerful beak to prise off bark from dead wood. As an alternative, particularly when food is scarce, this species employs a more ingenious method of feeding. Like the woodpecker finch (Camarhynchus pallidus), this species is known to use cactus spines and twigs to prise out inaccessible grubs from tree hollows and cavities (2).
The mangrove finch normally breeds throughout the hot, wet season, commencing in December or January and lasting until May (5). Darwin’s finches usually form monogamous, lifelong breeding pairs, although mate changes and breeding with more than one partner have also been observed. 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 (3).