Wheatear Migration

Hello! I am totally new to bird watching and this is my first post on here. I have been watching wheatears in my garden since May and there were quite a few pairs nesting in the wall along the back of our garden. However since late July, they all seem to have left apart from one male Wheatear who I still see patrolling up and down the wall, chasing away other birds who land near it. Is it possible that the other Wheatears have migrated and left him behind? Thanks