Droll Yankees® YCPW-180 Whipper Sunflower Bird Feeder, 4-PortThe Whipper features four seed ports with individual weight sensitive perches. Curved perch design encourages cardinals and small songbirds to eat, but prevents squirrels from feeding. Hungry birds will adapt as best they can to the conditions in order to survive and larger birds will sometimes hang onto the collapsed perch and continue to feed. It is uncomfortable for them and difficult so it discourages them but might not be the ultimate