Darwin’s finches had a common ancestor but now have different types of modified beaks according to their food habits. As the original population of finches increased in size it spreaded out from its centre of origin to exploit new habitats and food sources. After some time it resulted in evolution of a number of populations, each adapted to its particular habitat. Eventually these populations differed from each other sufficiently to become new species. Darwin differentiated thirteen species of finches and grouped them into six main types–

(i) Large ground finches

(ii) Cactus ground finches feeding on cacti

(iii)Vegetarian tree finches

(iv) Insectivorous tree finches

(v) Warbler finches

(vi) Tool-using or Wood pecker finches.