Mallard (Anas platyrhynchos) populations in the lower Mississippi Alluvial Valley (LMAV), USA, historically averaged 1.6 million and represented the largest concentrations of wintering mallards in North America. Effective management of this wintering population requires current information on use of habitats. Accordingly, we employed radiotelemetry techniques to assess proportional use of habitats by female mallards during winters 2004-2005 and 2005-2006. We divided winters into 4 time periods defined by hunting seasons (FIRST, SPLIT, SECOND, and POST) and recorded diurnal and nocturnal locations. We examined variations in proportional use of habitats and use of areas closed to hunting due to effects of age (immature or ad), winter (2004-2005 or 2005-2006), time period (SECOND or POST), individual female, and all potential interactions of these effects, using locations recorded during the latter 2 time periods. We found that diurnal and nocturnal proportional use of habitats varied inconsistently among time periods and winters. Mean proportional use of forested wetlands ranged from 0.475 to 0.816 and from 0.428 to 0.764 during diurnal and nocturnal sampling periods, respectively. Diurnal proportional use of areas closed to hunting varied inconsistently among time periods and winters. Mean proportional use of areas closed to hunting ranged from 0.183 to 0.423 during diurnal sampling periods. Nocturnal use of areas closed to hunting varied inconsistently among female ages and time periods and among female ages and winters. Mean proportional use of areas closed to hunting ranged from 0.211 to 0.445 during nocturnal sampling periods. Our research suggests that forested wetlands in the LMAV provide important wintering habitats for female mallards; continued restoration and establishment of these habitats should benefit female mallards.