Birds have a hard time in cold weather, because their body temperatures are higher than those of humans They provide warmth and insulation against colder temperatures. Many birds grow extra feathers in the months leading up to colder weather, so that they'll stay warmer when temperatures drop.
This might help,the presence of hydrochloric acid creates an acidic environment within the stomach that is needed to convert pepsinogen to pepsin. Mucus that is produced by the epithelial cells of the stomach help protect the lining of the stomach from the corrosive hydrochloric acid and pepsin.
They make their food furing photosynthesis
