How would you explain the presence of different species of birds on different islands that are in close proximity to each other?

Evolution by geographic isolation

Explanation:

To explain the presence of different species of birds on different islands that are close in proximity to each other, we use the concept of evolution by means of geographic isolation.

In this type of evolution, the birds originally must have a common ancestor. As at the time when the Islands were joined together, there must have been a prevalent gene flow among the specie.

As the Island drifted apart, the apparent gene flow was cut short and organisms had to evolve and device new evolutionary strategies to survive on their own.

This will lead to formation of new species of organisms now dominating and occupying the different Islands.