A bright red Cardinal had a confrontation with a picture window for 45 minutes as it hammered its beak against the glass and I determined that the bird had probably mistaken its own reflection for that of a rival that it was trying to attack. This suggests that if you feel the urge to fight others, you're probably mad about something in yourself, and you need to realize that it's best not to hurt yourself or drive yourself crazy in an effort to chase away an illusion that is a distorted representation of a real thing. Jon York 2019