The Red-gartered Coot Fulica armillata, is a common herbivorous water bird in coastal wetlands of the southern Neotropical region. Microhistological analyses of feces collected at the coastal wetland of Punta Teatinos (north central Chile; ~29ºS), show that this coot feeds predominantly on Stuckenia pectinata, the most abundant submerged macrophyte at this area. The foraging behavior of F. armillata is discussed in regard with its ecological role as a primary consumer on coastal wetlands.