Population dynamics of breeding mallards in the Great Lakes states / John M. Coluccy, Tina Yerkes, Rebecca Simpson, John W. Simpson, Llwellyn Armstrong, and Jonas Davis.

Includes bibliographical references (pages 1186-1187).

Mallard (Anas platyrhynchos) populations in the United States portion of the Great Lakes region increased through the 1990s
but have since declined. To promote sustainable growth of this population, managers need to understand how perturbation of vital rates will
affect annual population growth rate (k). We developed a stage-based model representing the female mallard population in the Great Lakes
using vital rates generated from a landscape-level study documenting reproductive parameters from 2001 to 2003. We conducted perturbation
analyses (i.e., sensitivity analyses) to identify vital rates that most influence k and variance decomposition analyses to determine the proportion
of variation in k explained by variation in each vital rate. Perturbation analyses indicated that k was most sensitive to changes in nonbreeding
survival, duckling survival, and nest success. Therefore, changes in these vital rates would be expected to result in the greatest Dk. Process
variation in breeding season parameters accounted for 63% of variation in k. Breeding season parameters explaining the most variation were
duckling survival (32%) and nest success (16%). Survival of adult females outside the breeding season accounted for 36% of variation in k.
Harvest derivation, high harvest, and high sensitivity of k to nonbreeding survival for Great Lakes female mallards suggests there is a strong
potential for managing the Great Lakes mallard population via harvest management. Because k was highly sensitive to changes in duckling
survival, we suggest programs that emphasize wetland protection, enhancement, and restoration as a management strategy to improve
population growth for breeding mallards.