Mere fear shrinks bird families

                There is a type of bird, song sparrows, which are greatly influenced by predators to the extent that they will raise fewer babies out of mere fear of predator sounds. Scientists researched these birds on a small western island and were able to conclude that birds will lay fewer eggs and be much more jumpy when raising offspring. This is a problem evolutionary wise for the sparrows, with less offspring it leads us to assume that there will eventually be a change in genes to reduce predator anxiety.