Why is my budgie quiet, docile, and has diarrhea only at night?
I've never hard of having diarrhea only at night, usually birds that are ill or affected by something will be ill or affected at all times, and show other signs of illness such as listless behavior during the day, not wanting to eat or drink, weight loss, etc. A change in diet or too many treats can sometimes cause loose stools as well, so making sure he's on a balanced diet and removing any extra snacks for a few days may help.
At night, when it's dark, birds tend to become very quiet and docile, so this could be why he is allowing you to touch him at these times. Placing a night light if he seems scared or is easily startled, or covering the cage at night can help him to sleep better, and it's best not to handle him so that he can rest if he needs it.
I would just keep an eye on him, and if the diarrhea continues even during the day, he shows other signs of illness, or he has any new symptoms, then try to convince your parents to take him to a vet.
Updated on September 23rd, 2025