Estimates of demographic parameters for lesser snow geese Anser caerulescens caerulescens have become critical to understand ecosystem change in northern Canada. Exponential increase in abundance has produced hyperdensities of these herbivores that can affect Arctic ecosystem stability through intense foraging. Increased and sustained marking of individually-identifiable lesser snow geese over their breeding distribution now permits joint estimation of local vital rates and movement probabilities among widely scattered subpopulations. We used multi-state models, including an unobservable state, with live captures from 5 subpopulations and dead recoveries to estimate annual probabilities of 1) survival, 2) capture, 3) reported mortality and 4) movement to other subpopulations, as well as derived estimates for probabilities of site fidelity and harvest. Our dataset included 144 719 captures of 139 177 lesser snow geese marked with metal legbands, from 2006 to 2015, of which 5542 were recaptured near breeding sites and 9709 were recovered dead in North America. The best model supported variation in survival by subpopulation and age, with additive effects of subpopulation, age and sex on movement probability. Male breeding dispersal was greater than by females, and juvenile geese were more likely to move than adults. Strong northeastward geographic asymmetry in the probability of breeding movement was consistent with an eastward shift in wintering distribution observed in hunter recoveries. Mean annual survival ranged from 0.79 to 0.94 for adults, and 0.16 to 0.47 for juvenile geese, with a strong negative relationship between regional adult and juvenile survival. Harvest probabilities were all ≤ 0.03 for adult and ≤ 0.06 for juvenile geese, suggesting little influence from direct anthropogenic exploitation. Metrics for subpopulation persistence and contributions of each to the metapopulation suggested declines in all but one subpopulation, and a declining Midcontinent population overall. Our study highlights the importance of all subpopulation demographic parameters as modulators of persistence at both local and range-wide population dynamics.

中文翻译：

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亚种群对迁徙北极食草动物繁殖种群的贡献：生存、繁殖力和不对称扩散

小雪雁Anser caerulescens caerulescens的人口统计参数估计已成为了解加拿大北部生态系统变化的关键。丰度的指数增加导致这些食草动物的高密度，可以通过强烈的觅食影响北极生态系统的稳定性。在其繁殖分布上增加和持续标记可单独识别的小雪雁现在允许联合估计广泛分散的亚种群之间的局部生命率和移动概率。我们使用多状态模型，包括一个不可观察状态，从 5 个亚群的活捕获和死亡恢复来估计 1) 生存、2) 捕获、3) 报告的死亡率和 4) 移动到其他亚群的年度概率，以及导出的估计场地保真度和收获的概率。我们的数据集包括从 2006 年到 2015 年捕获的 139 177 只带有金属腿带的小雪雁的 144 719 次捕获，其中 5542 只在繁殖地附近被重新捕获，9709 只在北美被发现死亡。最好的模型支持亚群和年龄的生存变化，亚群、年龄和性别对运动概率的累加效应。雄性的繁殖扩散大于雌性，幼鹅比成年鹅更容易移动。繁殖运动概率的强烈的东北方向地理不对称与在猎人恢复中观察到的越冬分布向东移动一致。成年鹅的平均年存活率为 0.79 至 0.94，幼鹅为 0.16 至 0.47，区域成年和幼鹅存活率之间存在强烈的负相关关系。成年鹅的收获概率均≤0.03，幼鹅的收获概率均≤0.06，表明直接人为开发的影响很小。亚群持续性和每个亚群对综合群的贡献的指标表明，除一个亚群外，所有亚群均出现下降，中大陆人口总体呈下降趋势。我们的研究强调了所有亚群人口统计参数作为局部和范围内人口动态持久性调节剂的重要性。