Top-Fill Hummingbird Feeder with Float Valve Base Closure Mechanism Having a Foam/Frame Float

A top-fill hummingbird feeder is provided having a nectar container with a liquid flow opening at a lower end and a removable cap at an upper end, a feeding basin positioned below the nectar container, and a sealing mechanism associated with the liquid flow opening and the feeding basin. The sealing mechanism includes a bottle seal assembly configured for removable coupling with a base of the feeding basin, and a float valve captured by said bottle seal assembly to prevent rotation thereof while allowing the float valve to move upwardly and downwardly with changing nectar levels in the feeding basin. The float valve includes a float having a frame with a buoyant member mounted thereon, the buoyant member being made of a closed-cell foam.