They drift back.

The feeding station here got a cake of seed in the bottom I hadn't noticed & we wondered, through the window, why ...
A) Birds were getting fewer.
B) Seed wasn't going down at all.
One day I was inspired told to go out & check it. Result remove caked hard pan in bottom. ... One or two visits. ... Buy new/better(?) feeder.
Seems to have worked, unless the mix of seeds/meal-worms is more acceptable.

On a comical/grammatical note:-
I hope "he" engraves better than he spells.