The type of food available in an environment affects the natural selection of birds with certain types of beaks. Birds with beak shapes that are better suited for the available food will survive and reproduce more often. Birds that eat seeds tend to have short, thick beaks to crack hard shells.Birds that eat nectar have long, slender beaks for reaching deep into flowers.If food changes, like a drought that reduces soft seeds, birds with beaks adapted for harder seeds may become more common.This is an example of evolution by natural selection, like what Darwin observed with finches in the Galápagos Islands.