We collected venous blood samples from 83 apparently healthy Mottled Ducks (Anas fulvigula) July 2012–August 2013 on the Texas, US, Gulf Coast and measured blood gas, electrolyte, biochemical, and hematologic parameters. Age, sex, body condition score, capture year, capture type, and time of day had significant statistical, but not clinically relevant, effects on several analytes. Ducks caught by rocket net had findings consistent with greater stress compared with hand-caught ducks. These analyte data for healthy free-living Mottled Ducks may be useful in the assessment of Mottled Duck population health and in the management and treatment of individual ducks affected by environmental stressors.