Bluebird looks oddly fierce.
I have been very happy with my Droll Yankees X1B Blue Seed Saver feeder. The bluebirds consider it their own special feeder and dominate it when they are around. “Blue things are us!”
Blue jays do not fit under the dome so they can’t stuff their faces with all the dough and fly off to hide it.
What to feed bluebirds in fall and winter? I use this recipe for Zick Dough, Improved and many species of birds LOVE it, including the bluebirds. (It makes them fierce!)
Here is more info at Sialis.org on Suet recipes for bluebirds and other birds.
Bluebirds generally prefer homemade over storebought suet mixes. Keep your feeder clean, and only stock it with fresh food.