Darwin's Finches

What are the specific differences between Darwin's Finches?

Charles Darwin categorized the different species of finches based on their eating habits and the shapes and sizes of their beaks. Darwin found 13 different species of the finches but 6 of them are the warblerlike finch, the insect-eating finch, the woodpeckerlike finch, the plant-eating finch, the ground finch, and the cactus-eating finch(biology coloring workbook). The warblerlike finch has the smallest beak in the size and shape (http://www.doc.ic.ac.uk/~kpt/terraquest/galapagos/wildlife/island/finch.html). The insect-eating finch has a very heavy beak that allows the finch to be able to grab insects for food. The next finch out of the six is the woodpeckerlike finch, this finch lives in trees and has a long and narrow beak similar to a woodpeckers so it can drill holes in the tree. This finch has no tongue so it uses a cactus spine to dig out insects. The plant-eating finch also lives in trees but has a beak designed for eating only plants (biology coloring workbook).  Next is the ground finch which there is actually four different kinds of ground finches. The large ground finch is the largest of the ground finches and has a massive bill. The small ground finch has a dainty, short, pointed bill. The medium ground finch is between the small and large finches beaks and the upper mandible is always greater than the depth of the bill. The last ground finch is the sharp beaked or vampire finch which is very similar to the small ground finch but the bill is longer and more curved and this finch feeds off of other birds blood (http://www.galapagosexpeditions.com/islands/darwin-finches.php). The last finch of the six is the cactus-eating finch which feeds off of cactus seeds and uses its beak to crush the seeds and since the seeds are usually soft, their bill is pretty small (biology coloring workbook).