I have a timneh grey for 4 years. I recently noticed that he is always holding a leg up. I know they do this when they sleep are or relaxed. He is doing it all the time. I looked at the foot and there is nothing on it like a sore or cut. He will eat and drink still loves his almond treats. He still talks and gives screams like normal. He will sit on two legs sometimes but almost all of the time one is held up. Is this behavior normal?
Yes, it is very common for all Parrots to lift one leg when perching. Please remember that with the exception of over-night, those Parrots of the Wild are not standing on their feet for hours at a time during the day.
There are two reason that they lift one leg. One is to offset by shifting between each leg, the time they spend on any one leg (foot). The second is that they only expose one leg to room temperature, which keeping the other close to the body to keep it warmer. When they are warm, you will note that they common have both legs down as the number of exposed legs also allows they to control body temperature. It is not the only method, but it is one that they employ.