A stochastic population model of mid-continental mallards

We developed a simulation model that integrates infonnation on factors affecting the population dynamics of mallards in the mid-continental region of the United States. In the model we vary age, body mass, and reproductive and molt status of simulated females. Females use several types of nesting and foraging habitat in 15 geographic areas. Deterministic and stochastic events cause mortality or attribute changes on a daily basis, depending on current attributes, habitat, area, calendar date, wetland conditions, temperature, and various mortality agents. Because the model encompasses the entire year, it can be used to examine cross-seasonal effects. A simulated increase in nest success from 0.14 to 0.17 changed the annual rate of population growth from -6% to -1 %. A simulated 75% reduction in lead poisoning changed the rate from -6% to -3%.