It is natural for birds to have particular colors, just as some people have black eyes and hair, while others have blue eyes and yellow hair.

But I can tell you one thing about that.

Look at this Sparrow.

All the colors it shows are _in_ the feathers, whose various markings are due to certain substances called 'pigments,' which filter into the feathers, and there set in various patterns.

The feathers are painted inside by Nature, and the colors show through.