A port assembly for mounting within an opening of a mounting structure, such as a feed port assembly for mounting within a bird feeder opening. The port assembly includes a feed port having a port plate with a port opening therethrough aligned with the housing opening to enable access to the bird feed within the housing. The port plate includes a flange engageable with the housing wall. Disposed within the interior of the housing is an anchor having a pair of clamping feet in engagement with the inwardly facing housing wall whereby the anchor is movable with respect to the feed port to clamp the wall between the feed port flange and the clamping feet of the anchor.