We weighed hunter-killed mallards (Anas platyrhynchos; n = 4,747) during the 2005, 2008, and 2009 hunting seasons in Manitoba, Minnesota, North Dakota, Saskatchewan, and South Dakota to examine effects of hunting pressure on body mass. Our final model indicated that main effects describing age, hunting pressure, hunting method, season, relative harvest date, and selected interactions were influential in predicting mass of drake mallards during fall. Body mass of hatch-year and after-hatch-year drake mallards harvested in low hunting pressure jurisdictions was 4.3% and 2.5% greater, respectively, than those harvested in high hunting pressure jurisdictions. Body mass of drake mallards from low hunting pressure jurisdictions was 12.1% greater for birds that were harvested using pass or jump shooting hunting methods than those that were harvested by hunters using decoys over dry agricultural fields. When possible, managers should consider disturbance during planning stages of attracting mallards, and not rely upon dry agricultural fields as foraging resources for mallards unless a positive energy balance can be achieved. Finally, studies examining physiological condition of waterfowl must account for collection technique. © 2012 The Wildlife Society.