A bird beak is the most important resource it has, and every species has one solely designed for survival. Birds use beaks ...

Over time, natural selection favored finches with sharper, longer beaks. These birds were better equipped to quickly and easily pierce the skin of their booby bird neighbors. Vampire finches still ...

Under these drastically changing conditions, the struggle to survive favored the larger birds with deep, strong beaks for opening the hard seeds. Smaller finches with less-powerful beaks perished.