I saw bluebirds on the suet feeder all of once last spring/summer, but they’ve been all over it this winter. I put a bunch of dried mealworms in the platform feeder and they brawl over them regularly. One bird will sit in the middle of the feeder, not even eating, and run off all comers until a bunch of them mob it and chase it off, and then they go back to a squabbling rotation.
The exception is when they declare a truce after a stormy or bitterly cold day, though unfortunately the lighting then isn’t so great. Once the sun comes out, it’s back to one bluebird at a time.
There hasn’t been much in the way of bitter cold, though - the Bradford pears are starting to bloom, and I hear the indicator cherry tree in DC is showing blooms, so we’re making plans to head down in a week or so. We’re hoping the cold front that’s rolling through briefly this weekend doesn’t kill them off again.