What is the most likely reason for the specialization of these below-given finches?

Finches are birds that are related to the passenger pigeons. Many people think that finches are parrots, but they are not. Most finches around the world have rounded beaks. Most of the time these finches eat seeds. However, there are differences to what birds will eat based on where they are located.

Birds like any other animal will not starve itself to death. Instead, it will locate food that it could eat even though the food is not ideal or what it is used to. In the Galapagos Islands, the finches eat different things and as a result their beaks change shape to match the food that they are beginning to eat on a regular basis.

Therefore expect to see different beak shapes among the finches on the Galapagos Islands.