Time activity budgets, foraging habitat quality and behavior of Semipalmated Plovers (Charadrius semipalmatus) were examined during three non-breeding seasons in a large estuarine system in southeastern Georgia, USA. Among the foraging sites available to shorebirds at each tidal stage, non-breeding plovers tracked those with the greatest biomass and density of invertebrate prey. Prey biomass differed according to tidal conditions but was strongly predicted by the salinity, organic content and particle sizes of the sediments. Foraging rates (pecks/ min) and densities (birds/ha) of plovers were both predicted by invertebrate density and biomass. Foraging rates correlated significantly with the rate of defecations, indicating that peck rates were related to intake rates. Foraging rates reached an asymptote of 25 pecks per minute, suggesting an upper limit to the rate of capture unconstrained by digestive bottlenecks. While available, nearly all plovers foraged when on mudflat habitats, while about 33% foraged on salt marsh habitats and 12% foraged on beaches. There was no effect of density of foraging birds on their rate of foraging at mudflats, suggesting that birds were not experiencing intra-specific competition at this productive site.