Answer:
It can change physical features of bird so that they can access certain food sources.
Step-by-step explanation:
An example of this would be the finches of the galapagos islands. Some finches over many generations formed longer and thinner beaks to be able to reach seeds from tight areas. Other finches developed a sharp point at the end of their beaks in order to crack nuts. There are many others with a wide variety of features.