This is an article on a study done in Brazil on animal tears (including macaws and other parrots). They found that birds have tears like humans but the electrolytes in them are more concentrated AND that the environment they evolved to live in makes a difference which tells us that parrots that evolved to live in high humidity environments need it not only for their skin, feathers and respiratory system -as we previously thought- but also for proper eye lubrication!
https://www.msn.com/en-us/news/us/birds ... r-BB17TJi9