Palacín Carlos, Alonso Juan C, Martín Carlos A, Alonso Javier A
Museo Nacional de Ciencias Naturales-CSIC, C/ José Gutiérrez Abascal 2, E-28006, Madrid, Spain.
Departamento de Zoología y Antropología Física, Facultad de Biología, Universidad Complutense, E-28040, Madrid, Spain.
Conserv Biol. 2017 Feb;31(1):106-115. doi: 10.1111/cobi.12758. Epub 2016 Aug 27.
Many bird populations have recently changed their migratory behavior in response to alterations of the environment. We collected data over 16 years on male Great Bustards (Otis tarda), a species showing a partial migratory pattern (sedentary and migratory birds coexisting in the same breeding groups). We conducted population counts and radio tracked 180 individuals to examine differences in survival rates between migratory and sedentary individuals and evaluate possible effects of these differences on the migratory pattern of the population. Overall, 65% of individuals migrated and 35% did not. The average distance between breeding and postbreeding areas of migrant individuals was 89.9 km, and the longest average movement of sedentary males was 3.8 km. Breeding group and migration distance had no effect on survival. However, mortality of migrants was 2.4 to 3.5 times higher than mortality of sedentary birds. For marked males, collision with power lines was the main cause of death from unnatural causes (37.6% of all deaths), and migratory birds died in collisions with power lines more frequently than sedentary birds (21.3% vs 6.3%). The percentage of sedentary individuals increased from 17% in 1997 to 45% in 2012. These results were consistent with data collected from radio-tracked individuals: The proportion of migratory individuals decreased from 86% in 1997-1999 to 44% in 2006-2010. The observed decrease in the migratory tendency was not related to climatic changes (temperatures did not change over the study period) or improvements in habitat quality (dry cereal farmland area decreased in the main study area). Our findings suggest that human-induced mortality during migration may be an important factor shaping the migration patterns of species inhabiting humanized landscapes.
最近，许多鸟类种群因环境变化而改变了它们的迁徙行为。我们在16年的时间里收集了雄性大鸨（Otis tarda）的数据，该物种呈现出部分迁徙模式（在同一繁殖群体中，留鸟和候鸟共存）。我们进行了种群数量统计，并对180只个体进行无线电追踪，以研究候鸟和留鸟在存活率上的差异，并评估这些差异对种群迁徙模式可能产生的影响。总体而言，65%的个体迁徙，35%的个体不迁徙。迁徙个体繁殖地和繁殖后区域之间的平均距离为89.9公里，留鸟雄性最长的平均移动距离为3.8公里。繁殖群体和迁徙距离对存活率没有影响。然而，候鸟的死亡率比留鸟高2.4至3.5倍。对于有标记的雄性个体，与电线碰撞是自然原因以外死亡的主要原因（占所有死亡的37.6%），候鸟死于与电线碰撞的频率高于留鸟（21.3%对6.3%）。留鸟个体的比例从1997年的17%增加到2012年的45%。这些结果与从无线电追踪个体收集的数据一致：迁徙个体的比例从1997 - 1999年的86%下降到2006 - 2010年的44%。观察到的迁徙倾向下降与气候变化（研究期间温度没有变化）或栖息地质量改善（主要研究区域的旱作谷物农田面积减少）无关。我们的研究结果表明，迁徙过程中人为导致的死亡率可能是塑造栖息在人类化景观中物种迁徙模式的一个重要因素。
