Where do wintering cormorants come from? Long-term changes in the geographical origin of a migratory bird on a continental scale

1. Populations of migratory birds often mix to a considerable extent in their wintering areas. Knowledge about the composition of wintering populations is highly relevant in relation to management, not least for species, such as the great cormorant Phalacrocorax carbo sinensis, prone to conflicts with human interests. However, few studies have been able to estimate long-term changes in winter population composition. 2. We use 30 years of ringing and recovery data (1983-2013) from all major breeding populations of cormorants in continental Europe (except the Black Sea region) to estimate partitioning probabilities (i.e. the probabilities of moving to specific wintering areas) using a Bayesian capture-mark-recovery model. Combining these results with information on breeding numbers and reproductive output in a population model, we estimate the size and composition of wintering populations in Europe and North Africa. 3. Partitioning probabilities showed some variation over time, but were s...

1. 候鸟种群在越冬地通常会发生显著的种群混合。明晰越冬种群的组成结构，与物种管理工作息息相关，对于普通鸬鹚（Phalacrocorax carbo sinensis）这类易与人类利益产生冲突的物种而言尤为如此。然而，目前鲜有研究能够对越冬种群组成的长期变化进行估算。
2. 本研究采集了1983年至2013年共计30年的环志与回收数据，涵盖欧洲大陆（黑海区域除外）所有主要鸬鹚繁殖种群，通过贝叶斯标记重捕（Bayesian capture-mark-recovery）模型估算种群分配概率（即迁往特定越冬地的概率）。随后将上述结果与种群模型中的繁殖种群数量及繁殖产出数据相结合，我们得以估算欧洲与北非地区越冬种群的总规模与组成结构。
3. 种群分配概率随时间呈现一定波动，但...