A bird feeder provides a feed container extending downwardly, a limited support surface positioned around the feed container at a lower end thereof and having one or more feeding ports, the limited support surface being adapted for supporting a feeding animal in proximity to the one or more feeding ports, a biasing mechanism adapted for supporting the limited support surface at a lower end of the feed container and for allowing a limited amount of vertical movement of the limited support surface, and one or more portal shields affixed to the biasing mechanism and adapted to open and close the feeding ports, wherein the biasing mechanism is further adapted to open and close the feeding ports with the portal shields in response to the limited amount of vertical movement upwardly and downwardly, respectively, of the limited support surface.