The reason why your peony parrot keeps opening its mouth to pant may be caused by a variety of reasons. Here are some possible causes and suggestions:

Excessive temperature: Parrots are sensitive to temperature, and excessive ambient temperature may cause pant. Make sure the birdcage is placed in a temperature-friendly environment and away from direct sunlight and overheated areas.

Respiratory problems: Respiratory infections, airsacculitis, or other respiratory conditions may cause wheezing. Watch your parrot for other unusual symptoms, such as coughing, difficulty breathing, or a runny nose. If symptoms persist or worsen, it is recommended to consult a veterinarian for diagnosis and treatment.

Nervous or anxious: Your parrot may pant when nervous, anxious, or uncomfortable. Check the environment for stressors and try to provide a quiet, stable environment.

Exercise or overheating: Panting may be a normal physiological response if your parrot has just performed strenuous exercise or is overheated. Allow the parrot to rest and provide adequate water.