The Influence of Population Growth and Wind on Vagrancy in a North American Passerine
The Influence of Population Growth and Wind on Vagrancy in a North American Passerine
复制标题
种群增长和风对北美雀形目鸟类迁徙的影响
作者：
Lucinda C. Zawadzki;R. Veit;L. Manne
随着气候变化对鸟类生存的威胁，了解候鸟迁徙的原因变得越来越重要。流浪可以通过扩大其地理范围来保护人口免受环境变化的影响。为了剖析流浪的潜在原因，我们分析了北美东海岸流浪灰喉捕蝇鸟（Myiarchus cinerascenas）的发生情况以及其核心繁殖范围内的种群增长数据，以测试流浪在多大程度上是由种群增长和有探索新地方倾向的幼鸟的产生所驱动的。我们还通过分析北美天气天气图，测试了流浪与盛行风漂移的关系。我们的分析旨在量化哪些因素对到达北美东海岸的灰喉捕蝇鸟数量的年际变化影响最大。我们获得了来自“北美鸟类”的候鸟记录，来自北美鸟类繁殖调查（BBS）的种群数据，来自监测鸟类生产力和生存（MAPS）数据库的繁殖成功数据，以及来自NOAA NCEP北美区域再分析数据库的天气天气图。我们发现，在BBS数据的索引中，流浪的主要原因是繁殖种群规模的增加。此外，我们还发现了繁殖范围内幼鱼的年产量以及北美地区空气环流的三种措施的显著影响。我们的模型表明了种群增长的重要作用，以及繁殖成功和主导气流对流浪发生率的额外影响。数年的高繁殖成功率将大量灰喉捕蝇鸟带到东部，当天气条件特别有利时，这一数量会增加。
Understanding the causes of vagrancy among migratory bird species is of increasing importance as climate change threatens species' survival. Vagrancy may serve to safeguard populations from environmental change through expansion of their geographic ranges. To dissect underlying causes of vagrancy, we analysed data on occurrence of vagrant Ash-throated Flycatchers Myiarchus cinerascens to the east coast of North America and population growth within their core breeding range, to test to what extent vagrancy is driven by population growth and the production of young that have a proclivity to explore new places. We also tested to what extent vagrancy is related to drift by prevailing winds, through analysis of synoptic weather maps of North America. Our analyses aimed to quantify which factors most strongly influence interannual variation in the number of Ash-throated Flycatchers reaching the east coast of North America. We obtained records of vagrants from ‘North American Birds’, population data from the North American Breeding Bird Survey (BBS), reproductive success from Monitoring Avian Productivity and Survivorship (MAPS) databases, and synoptic weather maps from the NOAA NCEP North American Regional Reanalysis database. We found that vagrancy was predominantly explained by the growing breeding population size as indexed by BBS data. In addition, we found significant effects of annual production of young within the breeding range, as well as three measures of air circulation across North America. Our models indicated an important role of population growth, with additional effects of reproductive success and predominant airflow affecting the incidence of vagrancy. Years of high reproductive success bring larger numbers of Ash-throated Flycatchers to the east, and this number is enhanced when weather conditions are especially favourable.