From cradle to early grave:: juvenile mortality in European shags Phalacrocorax aristotelis results from inadequate development of foraging proficiency
From cradle to early grave:: juvenile mortality in European shags Phalacrocorax aristotelis results from inadequate development of foraging proficiency
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DOI：
10.1098/rsbl.2007.0157
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发表时间：
2007-08-22
期刊：
影响因子：
3.3
通讯作者：
Wanless, S.
中科院分区：
文献类型：
--
作者：
Daunt, F.;Afanasyev, V.;Wanless, S.
在大多数长寿的动物物种中，幼年动物的生存能力不如成年动物。一个潜在的机制是低劣的觅食技能，但需要纵向研究，以下青少年觅食的发展来测试这一点。我们使用小型化的活动记录仪记录每日觅食时间的少年和成年欧洲shags Phalacrocorax aristotelis从羽翼未丰到次年春天。幼鸟在雏鸟40天后就独立于父母。它们通过比成虫长约3 h d（-1）的觅食时间来弥补觅食能力差的不足，直到11月初受到日照长度的限制。此后，青少年觅食时间跟踪缩短日长到冬至时，觅食时间的两个年龄组收敛，并继续跟踪日长，直到2月初。只有少数个体在隆冬前死亡，死亡率在1月至2月达到峰值，青少年（包括一些研究鸟）的死亡率是成年人的五倍。在他们生命的最后两周，青少年表现出明显的下降觅食时间与个人变得奄奄一息。我们的研究结果提供了令人信服的证据表明，青少年弥补觅食能力差，增加觅食时间，一个策略，是有限的白天长度导致冬季死亡率高。
In most long-lived animal species, juveniles survive less well than adults. A potential mechanism is inferior foraging skills but longitudinal studies that follow the development of juvenile foraging are needed to test this. We used miniaturized activity loggers to record daily foraging times of juvenile and adult European shags Phalacrocorax aristotelis from fledging to the following spring. Juveniles became independent from their parents 40 days post-fledging. They compensated for poor foraging proficiency by foraging for approximately 3 h d(-1) longer than adults until constrained by day length in early November. Thereafter, juvenile foraging time tracked shortening day length up to the winter solstice, when foraging time of the two age classes converged and continued to track day length until early February. Few individuals died until midwinter and mortality peaked in January-February, with juvenile mortality (including some of the study birds) five times that of adults. In their last two weeks of life, juveniles showed a marked decline in foraging time consistent with individuals becoming moribund. Our results provide compelling evidence that juveniles compensate for poor foraging proficiency by increasing foraging time, a strategy that is limited by day length resulting in high winter mortality.