Sound management of bird populations rests upon an adequate understanding of their population dynamics. Our study evaluated recruitment and population growth rates of 14 American common eider (Somateria mollissima dresseri) colonies from Labrador, Nova Scotia, Quebec, Canada, and Maine, USA, during various periods between 1970 and 2019. We used Pradel mark-recapture models to estimate colony-specific growth rates and the relative contributions of survival and recruitment on growth. We also validated this approach using annual nest counts (~8,000 pairs) conducted between 2003 and 2019 during down harvest operations in 3 colonies located in the Saint Lawrence estuary in Quebec. There was generally a good agreement between estimates derived using the 2 approaches. We considered that capture-recapture data were suitable to estimate population trends of common eiders in other colonies, especially for colonies where accurate nest monitoring is impaired by dense vegetation. The breeding abundance declined at major colonies in Maine and Nova Scotia and increased or was stable in Quebec and Labrador. Female survival contributed the most to population growth, but variation in recruitment among colonies was more important than variation in survival to explain population growth. Management measures should thus strive to maximize local recruitment in colonies with declining populations. The assumption that apparent survival probabilities were homogeneous throughout an individual capture history was violated at several colonies in Quebec and Labrador. Using recaptures and band recoveries, we showed that the lower apparent survival for newly marked individuals compared to females that had been recaptured at least once was caused by a difference in site fidelity rather than true survival. But <1% of recaptured females dispersed to another colony for breeding, indicating that the lower site fidelity could be related to heterogeneity in capture probability among individuals. © 2021 The Wildlife Society.

中文翻译：

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估计美国绒鸭范围内的人口增长和招聘率

鸟类种群的健全管理取决于对其种群动态的充分了解。我们的研究评估了 14 种美国绒毛绒鸭（Somateria mollissimadresseri) 来自拉布拉多、新斯科舍、加拿大魁北克和美国缅因州的殖民地，在 1970 年至 2019 年的不同时期。我们使用 Pradel 标记重新捕获模型来估计特定于殖民地的增长率以及生存和招募对生长的相对贡献。我们还使用 2003 年至 2019 年间在魁北克圣劳伦斯河口的 3 个殖民地的羽绒收获作业期间进行的年度巢穴计数（约 8,000 对）验证了这种方法。使用 2 种方法得出的估计值之间普遍存在很好的一致性。我们认为捕获-重新捕获数据适用于估计其他殖民地普通绒鸭的种群趋势，特别是对于密集植被影响准确巢穴监测的殖民地。缅因州和新斯科舍省的主要殖民地的繁殖丰度下降，而魁北克和拉布拉多的繁殖丰度增加或保持稳定。雌性存活率对种群增长的贡献最大，但在解释种群增长时，殖民地之间招募的变化比存活率的变化更重要。因此，管理措施应努力最大限度地在人口下降的殖民地当地招募。魁北克和拉布拉多的几个殖民地违反了在整个个体捕获历史中表观生存概率是同质的假设。使用重新捕获和带恢复，我们表明，与至少重新捕获一次的雌性相比，新标记的个体的表观存活率较低是由现场保真度而不是真实存活率的差异引起的。但是 < 1% 重新捕获的雌性分散到另一个群体进行繁殖，表明较低的位点保真度可能与个体捕获概率的异质性有关。© 2021 野生动物协会。