The food flows from the outside reservoir thru the wire or bars of the cage into the trough on the inside of the cage. The bird eats out of the trough and what the bird drops or rakes out gets caught by the feeder and is sent back thru the bars or wire to the outside of the cage where it is held. All you have to do is slide up the sliding back door and retrieve the left over food hulls, whole seed or pellet and powder into a bucket. Blow off the hulls with a fan or blow dryer, put the whole seed back in the top of the feeder. Or sift out the pellet powder from the whole pellet and put the whole pellet or the crumbles back in the top of the feeder for the birds to finish eating.