Both of these feeders are sold as "squirrel proof" and so they have been, for almost fifteen years, in five (more or less?) different houses before this one. Although the dome shaped one was once conquered by a Very Tall Squirrel who could hold onto the center pole with his hind feet, s t r e t c h down across the dome, and reach inside with his front feet to stuff his cheeks.
This guy has simply managed to push the dome up its sliding post and slip underneath, holding it partly up with his body.
I have never hung the tube one where it would have a standing place below it until now. Clinging to its outsides does not seem to give the flexibility needed to reach into the tube through beak shaped openings.
These squirrels are highly motivated and quite fat. Maybe I need to switch the feeders. (The squirrels have already destroyed my third (tube-type) feeder by simply ripping the bottom out of it.)