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Reliable estimates of breeding‐ground demographic rates are needed to develop effective conservation strategies for mallard (Anas platyrhynchos) breeding habitat in eastern North America. We radiomarked 224 female mallards in an agricultural landscape in southern Ontario, Canada, during 1997–2000. At each of 4 sites, 1 during each year, we estimated survival of adult females, breeding incidence, nesting effort, clutch size, nesting habitat use, nest survival, and hen success. We also examined the influence of nest age, date, and habitat on nest survival and the influence of date and female age on survival of adult females. Almost all females remaining on site were observed to initiate ≥ 1 nest (x̄ = 0.97, range = 0.95–0.98), we detected a mean of 2.07 (1.80–2.36) nests per female each season, and full clutch size averaged 9.56 (9.1–10.0). For most sites, females nested in grassland and hay land more than expected relative to habitat abundance, nested in wetlands and woody habitats in proportion to abundance, and avoided cropland and developed areas. Survival of adult females from 25 March to 15 July averaged 0.75 (0.65–0.84). Estimates from our best model showed relatively uniform survival across the breeding season, with the exception of large decreases for 2 sites during the peak of the onset of hay cutting. Nest survival averaged 0.13 (0.11–0.15). Our best model supported increasing survival with nest age but did not include variation relative to habitat or date, except in hay land. Nest survival in hay land was high relative to other habitats early in the nesting season, but declined sharply with the onset of hay cutting. Hen success averaged 0.37 (0.25–0.46). Because estimated nest survival varied little among sites and habitats and because suitable nesting habitat appeared abundant, we suggest that upland habitat conservation will accrue only limited demographic benefits. Incentives to alter hay‐cutting practices may decrease mortality of nests and nesting females, but we believe such incentives are unlikely to be cost efficient and that experiments would be needed to reliably assess benefits.

Population dynamics of mallards (Anas platyrhynchos) in eastern North America likely differ relative to the midcontinent population, but independent management has been hampered by lack of data. We used data from radiomarked females from 4 sites in southern Ontario and 1 site in New Brunswick during 1992–2000 to assess demographic performance during the breeding season and to inform regional management strategies. For each site, we estimated recruitment of female young to 30 days posthatch per breeding female and projected the finite rate of population growth Λ, assuming annual survival typical of the region. We constructed a matrix population model for females and conducted perturbation analyses (i.e., analytic sensitivities and elasticities) to predict response of Λ to change in vital rates. Excluding 1 site, we estimated mean recruitment of 0.89 (range= 0.79–0.98). At 1 site, duckling survival approaching zero resulted in extremely low estimated recruitment (0.08). Perturbation analyses indicated that Λ was highly sensitive to changes in nest survival and nonbreeding survival and moderately sensitive to changes in survival of breeding females. Recruitment for most of our sites was >2 times the mean for the Prairie Pothole Region of Canada and likely was sufficient to maintain populations despite relatively high hunting kill in the region. Despite high sensitivity of Λ to nest survival, intensive management to increase nest survival likely would be inefficient because of uniform nest survival among habitats and low nest densities. Because recruitment levels were generally high but densities of breeding pairs low, we recommend protection, enhancement, and restoration of wetlands to maintain and increase habitat suitability for breeding mallards as likely the most cost‐efficient management strategy to benefit populations. Relatively high hunting kill and high sensitivity of Λ to nonbreeding survival imply that harvest is important to regional population dynamics and suggest the potential effectiveness of adaptive harvest management.

Survival of young is poorly understood, but important to fitness and demographics for many birds. Estimates of duckling survival and the factors influencing it are essential to guiding regional breeding management for ducks. We estimated daily and 30-day duckling survival for Mallards (Anas platyrhynchos) at one of four sites each year during 1997–2000 in southern Ontario, Canada. We examined effects of site-year, brood age, female age, and hatching date on survival. Our best model supported additive effects of site-year, brood age, and hatching date. The odds of daily survival were 8.8 times (95% CI: 4.2–18.5) higher for older (>7 days) relative to younger (≤7 days) ducklings and 1.7 times (0.9–3.1) higher for early-hatched (before 1 June) relative to late-hatched (1 June or later) ducklings. When controlling for differences in hatching date, we did not find support for an influence of female age. Mean 30-day duckling survival across sites was 0.40 (range 0.07–0.50). Extremely low survival at one site appeared to be associated with poor wetland conditions. Our results suggested directional selection for early nesting, and we predicted that early nests made a disproportionately large contribution (61%) to recruitment to 30 days posthatching. We recommend management emphasis on protection, enhancement, and restoration of seasonal wetlands to prevent declines in duckling survival. Factores que Afectan la Supervivencia de Anas platyrhynchos en el Sur de Ontario Resumen. La supervivencia de los juveniles permanece poco entendida, aunque es importante para la adecuación biológica y la demografía de muchas aves. Las estimaciones de supervivencia de los juveniles de patos y los factores que la influencian son esenciales para guiar estrategias regionales de manejo reproductivo en patos. Estimamos la supervivencia diaria y a los 30 días de los juveniles de Anas platyrhynchos en un sitio por año para un total de cuatro sitios entre 1997–2000 en el sur de Ontario, Canadá. Estimamos los efectos de sitio-año, edad de la nidada, edad de la hembra y fecha de eclosión sobre la supervivencia. Nuestro mejor modelo respaldó efectos aditivos de sitio-año, edad de la nidada y fecha de eclosión. La supervivencia diaria fue 8.8 veces (95% IC: 4.2–18.5) mayor para juveniles de mayor edad (>7 días) en comparación con juveniles de menor edad (≤7 días) y 1.7 veces (0.9–3.1) mayor para juveniles que eclosionaron tempranamente (antes del 1 de Junio) en comparación con juveniles que eclosionaron tardíamente (durante o después del 1 de Junio). Cuando controlamos por diferencias en la fecha de eclosión, no encontramos evidencia de una influencia de la edad de la hembra. La supervivencia media, considerando todos los sitios, de los juveniles a los 30 días fue de 0.40 (rango 0.07–0.50). La supervivencia extremadamente baja que registramos en uno de los sitios parece estar asociada con las malas condiciones del humedal. Nuestros resultados sugirieron una selección direccional hacia la nidificación temprana, y predijimos que los nidos tempranos representaron una contribución desproporcionadamente grande (61%) al reclutamiento luego de 30 días de eclosión. Recomendamos que el manejo ponga énfasis en la protección, mejoramiento y restauración de humedales estacionales para prevenir una disminución en la supervivencia de los juveniles de patos.

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