You said it! Really messy especially since I filled 3 feeders on the new contraption I got from Costco.
Bird Feeder Station with Baffle (costco.com)
Fortunately my mess doesn't seem to bother anybody - it's out of sight of neighbors - the pine tree blocks the view. But today the birds were pretty loud and there were dozens.
I probably put out about 12 cups of seeds and didn't fill them all the way. The squirrels can only get the seeds from the older container I hung on one of the top arms and they got tired and went away after awhile.
But, the mess will mulch itself into the yard by spring and I will move the feeder further out into my field for spring and summer.