How should we consider the theories of science in matters of faith?

Change is measured by taking DNA samples from organisms from the past and today. Genetic mutation is needed to survive. Lets say a bird kept on eating a specific insect. The insect was about to extinct, but then mother nature thought why don't I give this insect a shape of a leaf. The bird couldn't catch the insect easily, because the insect lived in a forest. You know forest have a lot of leafs. So, the bird couldn't tell which one was the insect. The insect lived happily ever after.