Hi, I have two birds that I bought recently and they are really off colour, they are very listless and just stand or sit about all day, they don't appear to be eating as their crops are empty at night but they are drinking. They have lost a lot of weight and the worst one's breathing seems a bit rattly and her comb is very pale and floppy. All the other birds I bought seem fine, I have had them for about Ten days, could it just be stress or something more sinistar