Szostek K Lesley, Schaub Michael, Becker Peter H
Institute of Avian Research "Vogelwarte Helgoland", An der Vogelwarte 21, Wilhelmshaven, D-26386, Germany.
Swiss Ornithological Institute, Sempach, CH-6204, Switzerland.
J Anim Ecol. 2014 Sep;83(5):1015-24. doi: 10.1111/1365-2656.12206. Epub 2014 Mar 14.
Immigration is a major demographic factor shaping population dynamics. However, due to methodological difficulties, the extent of immigration and factors affecting immigration are insufficiently studied. This is also true for seabird colonies. We estimated annual immigration based on a long-term study of a colony of common terns Sterna hirundo marked with transponders, using a Bayesian integrated population model that links colony size and productivity with individual life histories. Strong annual fluctuations in the number of immigrants were found. To identify whether colony-specific covariates influenced immigration, we related the number of immigrants to various proxy variables for breeding site quality, specifically colony size, productivity, number of local subadults and local recruits. Numbers of local recruits and local subadults showed strong positive correlations with number of immigrants. We found that variation in immigration rate had strongly contributed to variation in colony growth rate, more so than variation in local recruitment or adult survival. Collectively, results suggest that immigration strongly affects colony growth rate, that the driving force behind immigration is natal dispersal and that immigrants were attracted by local recruits.
移民是塑造人口动态的一个主要人口因素。然而，由于方法上的困难，移民的程度以及影响移民的因素尚未得到充分研究。海鸟繁殖地的情况也是如此。我们基于对一群用应答器标记的普通燕鸥（Sterna hirundo）进行的长期研究，使用一个将繁殖地规模和生产力与个体生活史联系起来的贝叶斯综合种群模型，估计了年度移民情况。我们发现移民数量存在强烈的年度波动。为了确定特定繁殖地的协变量是否影响移民，我们将移民数量与各种代表繁殖地质量的替代变量相关联，具体包括繁殖地规模、生产力、当地亚成体数量和当地新加入者数量。当地新加入者数量和当地亚成体数量与移民数量呈现出强烈的正相关。我们发现移民率的变化对繁殖地增长率的变化有很大贡献，其影响程度超过了当地新加入者数量或成年个体存活率的变化。总体而言，结果表明移民对繁殖地增长率有强烈影响，移民背后的驱动力是出生后的扩散，并且移民受到当地新加入者的吸引。
