However, this is an experiment with controlled in mallard ducks.
From the accumulation phase experiment found, In nature if a female bird moved into, and began feeding in, a mercury-contaminated area during the reproductive season.
once a bird began ingesting elevated levels of mercury in its diet, it would not take many days before it would deposit high levels of mercury in its eggs.
The level of mercury accumulated in eggs, and the possible harm from the mercury, would depend on how much mercury was in the diet of the female.