I either solved the problem, or got lucky and all the big birds left. I took down the seed-hopper feeder (it was empty anyway), and replaced it with a tube seed feeder. The tube feeder has four small perches, and is proportioned for smaller birds. A big bird has to be a contortionist to stand on that little perch and eat seed out of the feeding port right at his feet. After the big birds left, we got a five chickadee morning, all on the feeders at once. That was nice.
