Stressful conditions experienced by endangered Egyptian vultures on African wintering areas
Stressful conditions experienced by endangered Egyptian vultures on African wintering areas
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濒临灭绝的埃及秃鹰在非洲越冬地区所经历的压力条件
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
J. Donázar
中科院分区：
文献类型：
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作者：
M. Carrete;G. Bortolotti;J. Sánchez‐Zapata;A. Delgado;A. Cortés;J. Grande;J. Donázar
在欧洲繁殖的鸟类中，在萨赫勒地区越冬的鸟类持续严重减少。长期数据表明，萨赫勒过渡区初级生产力的变化显著影响许多物种的生存，这种关系可能是由营养资源的可用性介导的。然而，这种关系背后的生理，激素和行为反应仍然未被探索。我们提出了一个潜在的解释，在冬季的流行条件的重要性，以了解种群生态和迁徙物种的当前趋势。我们测量了生长在非洲和欧洲的埃及秃鹫Neophron nopterus羽毛中的皮质酮水平，显示了鸟类在越冬期间所面临的条件如何导致随着时间的推移释放更多的皮质酮，而不是当这些个体在夏季时。这种模式与家域大小差异一致（c。非洲是欧洲的33倍）。我们认为，随着埃及秃鹫在萨赫勒地区的越冬栖息地在最近一段时间已经退化，粮食供应也减少了。冬季皮质酮增加，随之而来的运动活动增加，例如，食物搜索行为，通常可能是适应性的。然而，如果扩散区的条件不好，扩大活动范围可能是徒劳的，更高的皮质酮水平的成本，包括增强活动的能量消耗，可能会造成重大的权衡。这些生理反应可能是其他欧洲trans-Saharan候鸟的特征，这些候鸟经历了显著的人口下降。
Among European breeding birds, those wintering in the Sahel region have undergone a sustained and severe decline. Long‐term data show that variation in primary production of the Sahelian staging area significantly affects survival of many species, a relationship probably mediated by trophic resource availability. However, the physiological, hormonal and behavioural responses underlying this relationship remain unexplored. We present a potential explanation for the importance of prevailing conditions during winter to understand the population ecology and current trends of migratory species. We measured corticosterone levels in feathers of Egyptian vultures Neophron percnopterus grown in Africa and Europe, showing how conditions faced by birds during wintering periods result in the release of more corticosterone over time than when those individuals were on their summering grounds. This pattern was concordant with home‐range size differences (c. 33 times larger in Africa than in Europe). We suggest that as wintering habitat of Egyptian vultures in the Sahel region has degraded during recent times, food availability has also been reduced. An increase in corticosterone during winter with a consequent increase in locomotor activity, for example, food searching behaviour, may normally be adaptive. However, enlarging home ranges could be futile if conditions are not better in the dispersal area, and costs of the higher corticosterone level, including energy expenditure from enhanced activity, may pose a significant trade‐off. These physiological responses may be characteristic of other European trans‐Saharan migrant birds that have undergone significant population declines.