I believe that this species in 500 years will have much darker tones in its legs, beak and feathers compared to what we see today. This is due to the extreme contamination that will be in the future. (Seas with dirtier waters, full of oil and air full of impurities that will stain their feathers). Green feathers represent a poison because in 500 years food will be scarce and we will eat whatever. Therefore, to adapt and protect themselves, they will develop that poison.