David J. Hoffman Jon D. Klimstra Katherine R. Stebbins Gary H. Heinz 2009 To determine how quickly breeding birds would have to feed in a mercury-contaminated area before harmful concentrations of mercury, as methylmercury, built up in their eggs, we fed female mallards (<i>Anas platyrhynchos</i>) a control diet or diets containing 0.5, 1, 2, 4, or 8 &mu;g/g mercury (on what was close to a dry weight basis) as methylmercury chloride for 23 d. After 18 d on their respective mercury diets, the eggs of mallards fed 0.5, 1, 2, 4, or 8 &mu;g/g mercury contained 97.8, 86.0, 89.9, 88.9, and 85.9%, respectively, of the peak concentrations reached after 23 d. Depending on the dietary concentration of mercury, no more than approximately a week may be required for harmful concentrations (0.5&ndash;0.8 &mu;g/g, wet weight) to be excreted into eggs. application/pdf en Society of Environmental Toxicology and Chemistry Rapid increases in mercury concentrations in the eggs of mallards fed methylmercury article