I have a canary who initially spent the day resting on one leg, but lately he does not do this anymore and spends the day spreading his wings as if he were going to fly. It looks like a bat. What could happen to him?

Canaries have various forms of communication. On the one hand, she has her songs, but also her body. Sometimes when they only stand on one leg like yours, it means they are relaxed and calm. This is a good sign that should be interpreted as a welfare issue. However, as you say, when they open their wings, it can be the opposite. It is very likely that he is stressed or even showing signs of aggression. You need to be careful and watch. It is true that sometimes this type of behavior also occurs when animals’ body temperature rises and they try to bring the temperature down by cooling it down in this way, but in your interpretation it cannot be ruled out that this is the case. is due to anxiety. It’s best if you try to acclimatize the environment and keep it as calm as possible. Avoid shouting and noise around you and make sure the temperature is adequate. This will help you. In any case, if this does not improve, go to your veterinarian to properly diagnose what may be going on.