Hello, I noticed my male cockatiel acting different the last two months. He is eating well, drinking water, no watery stools, but he not as active. He is 11 years old, and I think he is mostly or completely blind. He can't seem to see your finger to step up, he doesn't try to get out of the cage anymore, he bites randomly at nothing, we put him in front of the mirror (which he used to love to talk to himself)and he didn't even notice it. Also his dark eyes seem to have a bluish color to them. Is there anything I should so for him and I have 3 other cockatiels, could it be something contagious? Thank you for your help!