Population Dynamics of Breeding Mallards in the Great Lakes States

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.

Population dynamics of mallards breeding in eastern Washington

“…Coinciding with delayed irrigation (i.e., poor wetland conditions) in 2007, we captured fewer females, those captured were of lower body mass ( in 2007 = 954 g; 2006 = 989 g), and they initiated fewer nests relatively later in the nesting season. Additionally, our renest rate was lower than reported for the Prairie Pothole and Great Lakes Regions (Coluccy et al , Arnold et al ). Renesting is most influenced by date of first nest attempt, which is related to body condition (Devries et al , Arnold et al ).…”

“…Our estimate of breeding incidence (53%) in eastern Washington is considerably lower than values from the Prairie Parkland region of Canada (89%; Devries et al ); Ontario, Canada (96%; Hoekman et al a ); and the Great Lakes Region of the United States (84%; Coluccy et al ). Our overall estimate of breeding incidence is lower than that for first‐year females characterized as being in poor condition in the Prairie Parkland Region (60%; Devries et al ).…”

“…Each time step in the model began at the start of the breeding season (Mar 29). We calculated annual population growth (λ) assuming no emigration or immigration, a stable age distribution, density independence, and invariant vital rates (Caswell , Coluccy et al ). Probability distributions for each parameter were defined by estimated mean and empirical variation (Hoekman et al , Coluccy et al ).…”

Survival and habitat selection of wood duck ducklings

“…Patterns in habitat selection were consistent with previous research that identified use of woody or dense vegetative cover (McGilvrey , Sousa and Farmer , Smith and Flake , Granfors and Flake , Davis et al ). Brood and duckling survival may limit recruitment at our northern study area and additional data collection is required to support life‐cycle analysis (Coluccy et al , Davis et al ).…”

Full Issue

“…For species with precocial young, survival from hatching to fledging is a key factor influencing recruitment (Wisdom and Mills 1997, Hoekman et al 2002, Coluccy et al 2008). Prior to fledging, precocial young have relatively limited mobility compared with adults; thus, their survival is influenced by the landscape that was selected by adults during nesting Ratti 1992a, Krapu et al 2000).…”