English: The Competitive Exclusion Principle states that two species aren't able to coexist at constant population values competing for the same resource. In this example, stage 1 shows a smaller (yellow) species of bird originally foraging for insects across the whole tree. In stage 2, a larger, invasive (red) species of bird is introduced into the environment and competes with the yellow bird for resources. As time goes on, the invasive red species dominates the yellow species in competition for the middle part of the tree and for the more abundant resources, as shown in stage 3. The yellow species then adapts to its new niche and both birds thrive without competition.