Someone told me about rubbing chalk around the feeder so I unhooked it tonight and scrubbed the bottom and insides of the feeder with children's sidewalk chalk.
I also used the moat idea today Hazel and it seemed to help a bit but a few still found their way into the ceramic circle.
I made a spare bottom with the last batch of feeders and I think I will ulimately glue a bottom to this new feeder. Unfortunately, that would mean my feeder wouldn't be out there for a couple days until the glue dries.
If the feeder's not out for a couple days, would the orioles still come back?