The Disconnect Between Summer and Winter Monarch Trends for the Eastern Migratory Population: Possible Links to Differing Drivers
The Disconnect Between Summer and Winter Monarch Trends for the Eastern Migratory Population: Possible Links to Differing Drivers
复制标题
东部迁徙人口夏季和冬季君主趋势之间的脱节：不同驱动因素的可能联系
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Eduardo Rendón
中科院分区：
文献类型：
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作者：
L. Ries;D. Taron;Eduardo Rendón
摘要
迁徙帝王蝶东部种群数量的下降已成为人们高度关注的话题，但这完全是基于在越冬群体规模中观察到的模式。人们对迁徙周期其他阶段的人口趋势关注较少。在这里，我们使用三个监测计划对趋势进行分析，其中一个侧重于越冬群体规模，两个侧重于夏季繁殖地。我们发现，自 2008 年以来，冬季蜂群规模急剧下降，令人震惊。然而，两个独立夏季监测项目的种群指数的特点是逐年变化较大，并且随着时间的推移没有统计上可检测到的趋势。尽管夏季和冬季模式不匹配，但这些关键时期之间的年度波动之间仍然存在关联，这表明全年人口动态之间存在联系。此外，未来应该仔细追踪夏季临近结束时出现的经济低迷迹象。我们讨论了这种脱节的两个可能原因：1）较高水平的方差或可能有偏差的抽样可能会削弱任何统计信号，2）秋季迁徙期间的损失可能会导致越冬下降。
ABSTRACT
The decline of the eastern population of the migratory monarch has become a topic of great concern, but has been based entirely on patterns observed in overwinter colony sizes. Less attention has been paid to population trends during other phases of the migratory cycle. Here, we present an analysis of trends using three monitoring programs, one focused on overwinter colony size and two focused on summer breeding grounds. We discovered an alarming steepening in the decline of winter colony size since 2008. However, population indices from two independent summer monitoring programs were characterized by high year-to-year variability and no statistically detectable trends over time. Despite the mismatch in summer and winter patterns, there is still an association between the yearly fluctuations between these key periods, suggesting a link in population dynamics throughout the year. Further, a suggestion of a downturn near the end of the summer time-series should be carefully tracked into the future. We discuss two possible reasons for this disconnect: 1) higher levels of variance or possibly biased sampling could weaken any statistical signal, and 2) losses during fall migration could potentially contribute to overwinter declines.