Cooper Nathan W, Yanco Scott W, Rushing Clark S, Sillett T Scott, Marra Peter P
Migratory Bird Center, Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC 20008, USA.
School for Environment and Sustainability, University of Michigan, Ann Arbor, MI 48109, USA; Center for Biodiversity and Global Change, Yale University, New Haven, CT 06511, USA; Department of Integrative Biology, University of Colorado Denver, Denver, CO 80204, USA.
Curr Biol. 2024 Nov 4;34(21):5097-5103.e3. doi: 10.1016/j.cub.2024.09.015. Epub 2024 Oct 4.
Identifying the processes that limit populations is a foundational objective of ecology and an urgent need for conservation. For migratory animals, researchers must study individuals throughout their annual cycles to determine how environmental conditions limit demographic rates within each period of the annual cycle and also between periods through carry-over effects and seasonal interactions. Our poor understanding of the rates and causes of avian migration mortality hinders the identification of limiting factors and the reversal of widespread avian population declines. Here, we implement new methods to estimate apparent survival (hereafter survival) during migration directly from automated telemetry data in Kirtland's Warblers (Setophaga kirtlandii) and indirectly from mark-recapture data in Black-throated Blue Warblers (S. caerulescens). Previous experimental and observational studies of our focal species and other migratory songbirds have shown strong effects of Caribbean precipitation and habitat quality on food availability, body condition, migration timing, natal dispersal, range dynamics, reproductive success, and annual survival. Building on this research, we test the hypotheses that environmental conditions during the non-breeding period affect subsequent survival during spring migration and breeding. We found that reduced precipitation and environmental productivity in the non-breeding period strongly influenced survival in both species, primarily by reducing survival during spring migration. Our results indicate that climate-driven environmental conditions can carry over to affect survival in subsequent periods and thus likely play an important role in year-round population dynamics. These lethal carry-over effects may be widespread and are likely magnified by intensifying climate change.
识别限制种群数量的过程是生态学的一个基本目标，也是保护工作的迫切需求。对于迁徙动物来说，研究人员必须在其整个年度周期内对个体进行研究，以确定环境条件如何在年度周期的每个阶段以及不同阶段之间通过遗留效应和季节性相互作用来限制种群统计学率。我们对鸟类迁徙死亡率的速率和原因了解不足，这阻碍了对限制因素的识别以及扭转鸟类种群普遍下降的趋势。在这里，我们采用新方法直接从基尔特兰莺（Setophaga kirtlandii）的自动遥测数据中估计迁徙期间的表观存活率（以下简称存活率），并间接从黑喉蓝莺（S. caerulescens）的标记重捕数据中进行估计。之前对我们所关注的物种以及其他迁徙鸣禽的实验和观察研究表明，加勒比地区的降水和栖息地质量对食物供应、身体状况、迁徙时间、出生扩散、分布动态、繁殖成功率和年度存活率有显著影响。基于这项研究，我们检验了以下假设：非繁殖期的环境条件会影响春季迁徙和繁殖期间的后续存活率。我们发现，非繁殖期降水减少和环境生产力下降对这两个物种的存活率都有强烈影响，主要是通过降低春季迁徙期间的存活率。我们的结果表明，气候驱动的环境条件可以延续到后续时期影响存活率，因此可能在全年的种群动态中发挥重要作用。这些致命的遗留效应可能很普遍，并且可能因气候变化加剧而被放大。
