Although winter foods of mallards (Anas platyrhyncos) and wood ducks (Aix sponsa) have been documented in several studies, no such research has been conducted in natural bottomland hardwood forests in eastern Texas. We collected 40 mallards and 38 wood ducks and sampled available foods in eastern Texas during winters 1987-1988 and 1988-89 to study food habits and preferences. Acorns from four oak species comprised >89% and >99% of the diets of mallards and wood ducks, respectively. Nuttall oak (Quercus texana) acorns made up >67% of the diet of each species both years. Program PREFER indicated seeds of deciduous holly (Ilex decidua) and willow oak (Q. phellos) acorns were favored by mallards and wood ducks, respectively; preferences overlapped widely among potential foods, however. Although bottomland systems provide critical habitat for wintering waterfowl, their contributions can be enhanced by applying established silvicultural techniques to encourage desirable oak species.