Department of Biology, Tufts University, Medford, Massachusetts, United States of America.
Manomet, Plymouth, Massachusetts, United States of America.
PLoS One. 2019 Sep 6;14(9):e0222232. doi: 10.1371/journal.pone.0222232. eCollection 2019.
We analyzed data from across five decades of passerine bird banding at Manomet in Plymouth, Massachusetts, USA. This included 172,609 captures during spring migration and 253,265 during fall migration, from 1969 to 2015. Migration counts are prone to large interannual variation and trends are often difficult to interpret, but have the advantage of sampling many breeding populations in a single locale. We employed a Bayesian state-space modeling approach to estimate patterns in abundance over time while accounting for observation error, and a hierarchical clustering method to identify species groups with similar trends over time. Although continent-wide there has been an overall decrease in landbird populations over the past 40 years, we found a variety of patterns in abundance over time. Consistent with other studies, we found an overall decline in numbers of birds in the aggregate, with most species showing significant net declines in migratory cohort size in spring, fall, or both (49/73 species evaluated). Other species, however, exhibited different patterns, including abundance increases (10 species). Even among increasing and declining species, the specific trends varied in shape over time, forming seven distinct clusters in fall and ten in spring. The remaining species followed largely independent and irregular pathways. Overall, life-history traits (dependence on open habitat, nesting on or near the ground, migratory strategy, human commensal, spruce budworm specialists) did a poor job of predicting species groupings of abundance patterns in both spring and fall, but median date of passage was a good predictor of abundance trends during spring (but not fall) migration. This suggests that some species with very similar patterns of abundance were unlikely to be responding to the same environmental forces. Changes in abundance at this banding station were generally consistent with BBS trend data for the same geographic region.
我们分析了美国马萨诸塞州朴次茅斯曼尼托鸟类学研究站 50 多年来雀形目鸟类的环志数据。这些数据包括 1969 年至 2015 年春季迁徙期间的 172609 次捕获和秋季迁徙期间的 253265 次捕获。迁徙计数容易受到年际变化的影响，趋势通常难以解释，但具有在单个地点对多个繁殖种群进行采样的优势。我们采用贝叶斯状态空间建模方法来估计随时间变化的丰度模式，同时考虑观测误差，并采用层次聚类方法来识别随时间具有相似趋势的物种组。尽管在过去的 40 年里，整个大陆的陆鸟种群总体上呈下降趋势，但我们发现随时间的丰度模式多种多样。与其他研究一致，我们发现鸟类总数总体上呈下降趋势，大多数物种在春季、秋季或两者兼有的迁徙群体数量都出现了显著的净下降（73 种评估物种中有 49 种）。然而，其他物种表现出不同的模式，包括数量增加（10 种）。即使在增加和减少的物种中，具体趋势随时间变化，在秋季形成七个不同的聚类，在春季形成十个聚类。其余物种则遵循大致独立和不规则的路径。总的来说，生活史特征（对开阔栖息地的依赖、在地面或附近筑巢、迁徙策略、与人类共生、云杉卷叶蛾专家）在春季和秋季都不能很好地预测丰度模式的物种分组，但通过中位数日期的变化可以很好地预测春季迁徙期间的丰度趋势（但秋季迁徙期间不行）。这表明，一些具有非常相似丰度模式的物种不太可能对相同的环境压力做出反应。这个环志站的丰度变化与同一地理区域的 BBS 趋势数据基本一致。
