Population dynamics of mallards breeding in eastern Washington

Abstract

Variation in regional population trends for mallards breeding in the western United States indicates that additional research into factors that influence demographics could contribute to management and understanding the population demographics of mallards across North America. We estimated breeding incidence and adult female, nest, and brood survival in eastern Washington in 2006 and 2007 by monitoring female mallards with radio telemetry and tested how those parameters were influenced by study year (2006 vs. 2007), landscape type (agricultural vs. natural), and age (second year [SY] vs. after second year [ASY]). We also investigated the effects of female body condition and capture date on breeding incidence, and nest initiation date and hatch date on nest and brood survival, respectively. We included population parameters in a stage‐based demographic model and conducted a perturbation analysis to identify which vital rates were most influential on population growth rate (λ). Adult female survival was best modeled with a constant weekly survival rate (0.994, SE = 0.003). Breeding incidence differed between years and was higher for birds in better body condition. Nest survival was higher for ASY females (0.276, SE = 0.118) than SY females (0.066, SE = 0.052), and higher on publicly managed lands (0.383, SE = 0.212) than agricultural (0.114, SE = 0.058) landscapes. Brood survival was best modeled with a constant rate for the 7‐week monitoring period (0.50, SE = 0.155). The single variable having the greatest influence on λ was non‐breeding season survival, but the combination of parameters from the breeding grounds explained a greater percent of the variance in λ. Mallard population growth rate was most sensitive to changes in non‐breeding survival, nest success, brood survival, and breeding incidence. Future management decisions should focus on activities that improve these vital rates if managers want to increase the production of mallards in eastern Washington. © 2016 The Wildlife Society.

Breeding Ecology of Mottled Ducks: A Review

“…That decision may be influenced by environmental conditions on the breeding grounds, such as habitat suitability, weather, and food availability, because females must accumulate the resources necessary for egg production and successful incubation (Sedinger and Alisauskas 2014). For example, mallards in relatively poor body condition were less likely to breed than those in better body condition and initiated nests later in the season (Devries et al 2008, Dugger et al 2016). Body condition in turn is influenced by environmental conditions that affect food availability.…”

Age of the breeders, but not territory quality, explains hatching sex ratio in booted eagles

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Relative Importance of Vital Rates to Population Dynamics of Wood Ducks

“…Nest success was high on the SRS but was consistent with estimates from other nest-box studies (Bellrose and Holm 1994). Nest success of many ground-nesting ducks like mallards is much lower than wood ducks (e.g., 0.13-0.16; Hoekman et al 2002, Dugger et al 2016. Nest success (64%) of wood ducks using natural cavities in Illinois, USA, was generally lower than that of nest boxes, but in floodplains nest success in natural cavities was similar to that of nest boxes (Ryan et al 1998).…”

“…For midcontinent mallards, demographic parameters on breeding areas such as nest success, duckling survival, and adult female survival were most important to λ (Hoekman et al 2002). However, in addition to breeding parameters, nonbreeding survival of female mallards in other populations was also important to λ; therefore, management emphasized activities to improve breeding parameters and nonbreeding survival (Coluccy et al 2008, Dugger et al 2016. Mallards are not unique in this respect, and managers often must act on multiple vital rates to influence λ (Taylor et al 2012).…”