As one phase in a black duck research program, a food habits study was carried out in Maine from 1938 to 1946. A total of 605 stomachs were collected. All seasons of the yr. were represented. Data were classified according to the 3 general habitat types used by Maine black ducks. Food habits were found to be influenced by 4 major factors: water levels, food abundance, food preference, and hunting pressure. The economic relationships of black duck food habits were satisfactory. Damage to fishing interests was negligible and crop damage occurred only rarely. The planting of preferred, seasonal foods is recommended on managed breeding marshes in the northeast, provided water levels can be adequately stabilized.