SHARP – BEAKED FINCH

INTRODUCTION

In the 1832, Darwin left Great Britain in the ship HMS Beagle. Darwin was a naturalist who studied fossils, plants, rocks, and animals. He made a very famous collection in the Galapagos Islands; in those islands he studied plants animals and rocks. He had a particular interest in the fiches he found there. He found 14 species, 13 of them in the Galapagos Islands, and 1 on the Cocos Island. Two examples of these are the Geospiza difficilis whose common name is sharp - beaked finch. This gets its name because of its sharp beak which it uses to peck on other birds skin to extract their blood. The other is the Pinaroloxias inornata whose common name is Cocos Island finch found in the Cocos Island.

SHARP – BEAKED FINCH (Geospiza difficilis)

The sharp – beaked finch is a small bird native of the Galápagos Islands. It has a large and cone-shaped beak that is used to collect a more varied diet of both insects and small seeds. They can take ticks from iguanas and tortoise. Their large beak helps them eat larger seeds. It is specifically found in the Darwin and Wolf Islands. Its natural habitat is located in tropical or subtropical forests. Males are mainly black and females are mostly gray with brown stripes. It has the largest beak of all subspecies of Geospiza difficilis. Generally it looks like a miniature Cactus ground finch.

This bird is known for its unusual diet. It is called the “vampire” finch because it feeds itself with blood of other birds; they peck with their sharp beaks on the bird’s skin until they extract their blood. The finches also feed with their eggs they push it with their beaks and their legs until the egg finally breaks. They also take nectar from Galapagos cactus. The base of their diet consisted of seed and invertebrates.

The sharp beaked finch is an endangered species, it is and endemic specie in a small island. Their diet varies from the high islands to the low islands. The low islands are mostly dry so they feed with seed. In the islands of Wolf and Darwin this species drink blood of seabirds. They peck on the bird’s skin until the blood begins to flow. They like to feed on the eggs of seabirds. They push it so it can crack against rocks. In high islands they prey invertebrates because of their abundance.

Finches reproduce more abundantly and begin laying egg when the precipitation is higher and there is more food. The sharp beaked finch shows its adaptive radiation in how they get their food, for example, in dry places they feed with seed, in more diverse places they can feed with invertebrates. Also, how they use their beaks to take blood out of another bird’s body, their ability to crack eggs with rocks.

There are so many finch species because of natural selection. Natural selection begins because of hereditary variations in a population. Traits are passed down from generation to generation.

COCOS ISLAND FINCH (Pinaraloxias inornata)

The Cocos Island finch is the only Darwin’s finch that is nonnative of the Galapagos Islands. It is endemic of the Cocos Island that is about 360 km south of Costa Rica. It is a finch 12 cm long and a weight of 12.5 g. It has a black curved pointy beak. Males are completely black and females are is brown with many stripes. Younger birds are similar but they have a yellow beak. They can lay up to two eggs which are white with brown spots. It occupies all habitats in Cocos Island. They have several ways to search for food; they look between twigs, branches, leaves and in the ground. They can introduce their beak in the cracks of barks, they extract larvae, they can roll small stones, they can make holes with their beaks in flowers, and they take fruits, they have learn all this to feed themselves, this is a way in which they can show adaptive radiation.

Cocos island

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