How interesting!
The jays arrived at my feeder on January 1. I was very happy. Today is January 8th. They arrive early in the morning and stay at the feeder all day. They scared away all the small birds. I'm no longer happy that they eat all the food!
They are bigger and they bully the small birds. They are clever though.
I don't know for sure, but I think the jay here is single.
I have 4 birds flying in, sometimes 5.