D. the number of mates on the island
their appearance changes cause different birds breeding together can make an impact of how the bird looks
Over long periods of time, living things have gradually altered as the conditions around them change. A species' strongest traits are passed from one generation to the next. This is what evolution is, the process of gradual change.
Sounds like ADD (<span>Attention-Deficit Disorder).</span>
By eating plants and other animals, because they obtain their carbon from food.