A Matrix Population Model for Mottled Ducks (Anas fulvigula) of the Western Gulf Coast

Abstract

Abstract According to three surveys performed annually since the mid-late 1980s, the Anas fulvigula (Mottled Duck) population in Texas has declined substantially. Factors contributing to the observed trend are not well understood. Assessing the relative influence of vital rates on the population growth-rate is necessary to make management and conservation decisions regarding Mottled Ducks. We gathered estimates and associated variance estimates for vital rates of Mottled Ducks on the western Gulf Coast. We constructed a matrix population-model based on female vital rates and assumed birth-pulse reproduction, and parameterized it with a pre-breeding census. We calculated mean and standard error estimates for composite vital rates such as population growth rate (λ), fertility, and recruitment using 1000 iterations of the model. We also performed 20 meta-iterations of the population model to obtain mean coefficient of determination (r2) values for the linear regression of each vital rate and composite rates ...