Biology question (red descriptions)?

One of the changes that happened during the study period was that there was less food available for the finches. how does having less food for the finches caused less beak length over the years?


Possibly having long narrow beaks was ideal for finding and eating the kind of seeds that were available at the start of the study. If conditions change, such as weather patterns or plant diseases, maybe the types of seeds available favored a shorter and wider beak.