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Population Dynamics of Breeding Mallards in the Great Lakes States |
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| Authors: | JOHN M COLUCCY TINA YERKES REBECCA SIMPSON JOHN W SIMPSON LLWELLYN ARMSTRONG JONAS DAVIS |
| Institution: | 1. Ducks Unlimited Incorporated, 1220 Eisenhower Place, Ann Arbor, MI 48108, USA;2. Ducks Unlimited Incorporated, 1220 Eisenhower Place, Ann Arbor, MI 48108, USA
Livingston County Drain Commissioner, 2300 East Grand River Avenue, Suite 105, Howell, MI 48843, USA;3. Ducks Unlimited Incorporated, 1220 Eisenhower Place, Ann Arbor, MI 48108, USA ASTI Environmental, 10448 Citation Drive, Brighton, MI 48116, USA;4. Ducks Unlimited Canada, Oak Hammock Marsh Conservation Centre, P.O. Box 1160, Stonewall, MB R0C 2Z0, Canada;5. Ducks Unlimited Incorporated, 34 Defense Street, Suite 200, Annapolis, MD 21401, USA Ducks Unlimited Incorporated, 2550 North Diers Avenue, Suite L, Grand Island, NE 68803, USA |
| Abstract: | Abstract: 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 (Λ). 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 Λ and variance decomposition analyses to determine the proportion of variation in Λ explained by variation in each vital rate. Perturbation analyses indicated that Λ 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 ΔΛ. Process variation in breeding season parameters accounted for 63% of variation in Λ. 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 Λ. Harvest derivation, high harvest, and high sensitivity of Λ 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 Λ 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. |
| Keywords: | Anas platyrhynchos demographics Great Lakes states management perturbation analyses population dynamics population growth variance decomposition vital rates |