of the tree-finches one species is vegetarian , with a parrot-like beak seemingly fitted to its diet of buds and fruits the next three species are closely a like differing primarily in body size and in the size of their beaks , presumably scaled to the size of the insects they take . A fifth species eats insects in man grave swamps the sixth species of tree finch is one of the most remarkable birds in the world . like a woodpecker, it climbs tree trunks in search of insects which it excavates from the bark with its chisel-shaped beak. While its beak approaches a woodpecker’s in shape it has not evolved the long tongue with which a woodpecker probes insects from crannies instead , this tree-finch solver the problem in another way: it carries about a cactus spine or small twig which it pokes into cracks, dropping the stick to size any insect that emerges. This astonishing practice is one of the few recorded cases of the use of tools by any animal other than man of the apes