Digestive tracts were examined from 115 lesser scaup (Aythya affinis) killed by hunters in impoundments managed for crayfish (Procambarus clarkii) production at Indigo Island, Iberville Parish, Louisiana. Plant material (seeds) comprised 99.7% (by dry weight) of the food material during the 1981-82 wintering season and 99.6% during the 1982-83 season. Twenty-three scaup were collected while they were actively feeding; animal material was present in 21 scaup esophagi and plant material was present in 22. Nevertheless, plant material was the major food and comprised 99.0% of the diet. Seeds of Echinochloa colonum and Fimbristylis miliacea were the most important food items and were major species in bottom samples where scaup were collected. Dominant animal foods were snails, amphipod crustacea, and Diptera larvae. Small crayfish were abundant in the impoundments but no crayfish remains were found in scaup digestive tracts.