Answer:
When two different species having similar ancestors evolve to become different is called divergent evolution.
Birds belonging to different species might all share a common ancestor are also based on divergent evolution. Animals undergo divergent evolution for several reasons such as enviornmental changes and existance or absence of predators.
Some animals or birds adapt according to enviornmental changes for their survival and presence of predators affect the evolution of animals or birds to protect themselves from predators.
For example: Galapogas finches undergo divergent evolution in which they have same ancestors but radiates into different species such as medium ground finches, woodpecker finch, and mangrove finch.