Although Rocky's screaming is greatly diminished from what he was doing a few months ago (luckily, or I might be in a padded room somewhere...), he still occasionally will scream for no discernible reason. Actually, as far as I could tell, he no longer wanted to be on Stella's cage, and decided to let me know that before climbing down and improving his own situation. He might have been upset that he didn't find any treats in her foraging bucket, having removed them earlier in the evening. Maybe he just didn't want me to make a video of him.
The video does not capture how loud the screaming is, but it gives an idea. Why, Rock, why?