Emigration and survival correlate with different precipitation metrics throughout a grassland songbird's annual cycle
Emigration and survival correlate with different precipitation metrics throughout a grassland songbird's annual cycle
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DOI：
10.1002/jwmg.22371
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发表时间：
2023-02-06
影响因子：
2.3
通讯作者：
Boyle，W. Alice
中科院分区：
文献类型：
--
作者：
Silber，Katy M.;Mohankumar，Narmadha M.;Boyle，W. Alice
许多外生因素可能会影响人口统计比率(即出生、死亡、迁徙、迁出)，特别是对候鸟而言，它们必须在整个活动范围和年度周期中适应变化的天气和栖息地。在中大陆草原，干扰(例如，火和放牧)和降水影响草地结构和功能的变化，但我们对降水何时以及为什么与草地物种的生命速率相关知之甚少。我们将探测、存活和迁出的估计与降雨量的先验指标关联起来，以检验可能影响蝗虫麻雀(Ammodramus Avannarum)活动和死亡的替代因素。本种是一种迁徙的鸣鸟，表现出极高的季节内和季节间的扩散速度。2013至2020年间，我们在美国堪萨斯州东北部捕获并重新观察了蚱蜢麻雀，收集了1332只成年雄性蝗虫的捕获历史。我们测试了气候假说的预测，这些假说解释了蝗虫生存和迁徙在整个年度周期中的变化；生存和迁徙都与厄尔尼诺-南方涛动降水指数(ESPI)有关。越冬存活率与ESPI呈正相关，临时迁出与繁殖季节呈曲线相关，ESPI滞后2年，保真度最高的地点与中等降雨量有关。降雨和临时移民之间的关系可能反映了多年天气对植被结构的影响，从而对当地人口统计产生影响。这项研究有力地支持了草原物种通过采取扩散策略来应对高年际变异性的观点，而不是许多经过充分研究的候鸟。此外，研究结果还表明，极端气候现象增加的后果可能不会立即显现，人口方面的后果至少会持续几年。
Many exogenous factors may influence demographic rates (i.e., births, deaths, immigration, emigration), particularly for migratory birds that must cope with variable weather and habitat throughout their range and annual cycle. In midcontinental grasslands, disturbance (e.g., fire and grazing) and precipitation influence variation in grassland structure and function, but we know little about when and why precipitation is associated with grassland species' vital rates. We related estimates of detection, survival, and emigration toa priorisets of precipitation metrics to test the putative alternative factors influencing movement and mortality in grasshopper sparrows (Ammodramus savannarum). This species is a migratory songbird that exhibits exceptionally high rates of within‐season and between‐season dispersal. Between 2013 and 2020, we captured and resighted grasshopper sparrows in northeastern Kansas, USA, compiling capture histories for 1,332 adult males. We tested predictions of climatic hypotheses explaining variation in survival and emigration throughout a grasshopper sparrow's annual cycle; both survival and emigration were associated with the El Niño‐Southern Oscillation precipitation index (ESPI). Survival was positively related with ESPI during winter, and temporary emigration was curvilinearly related to breeding season ESPI lagged 2 years, with the highest site fidelity associated with intermediate rainfall values. The relationship between rainfall and temporary emigration likely reflects the influence of weather over multiple years on vegetation structure with consequent effects on local demography. This study provides compelling support for the idea that grassland species respond to high interannual variability by adopting dispersal strategies unlike those of many well‐studied migrant birds. Furthermore, the results imply that the consequences of increasing climatic extremes may not be immediately apparent, with demographic consequences lasting for at least a few years.