Age-dependent diet choice in an avian top predator
Age-dependent diet choice in an avian top predator
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DOI：
10.1098/rspb.2005.3353
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发表时间：
2006-03
期刊：
影响因子：
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通讯作者：
C. Rutz;M. Whittingham;I. Newton
中科院分区：
文献类型：
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作者：
C. Rutz;M. Whittingham;I. Newton
鸟类的繁殖表现依赖于鸟类，这可以说是鸟类学中记录最多的现象之一。与年龄相关的趋势的存在对生活史理论有重大影响，但这些模式的近因仍然知之甚少。有人提出，年轻个体的繁殖表现不佳可能反映了缺乏觅食技能。我们调查了这种可能性，在一个中等大小，强大的猛禽-北方苍鹰鹰Accipiter generator。雄性苍鹰负责为雌性和后代提供食物。我们假设，年轻的男性可能会普遍表现出不良的繁殖性能，甚至延迟繁殖，因为他们缺乏有效狩猎的经验，特别是，他们的主要鸟类猎物，野鸽鸽。我们的研究利用了一个罕见的“自然实验”，城市人口的扩张阶段，种内干扰可以忽略不计，许多年轻的男性成功繁殖。这使我们能够在更大样本的年轻个体中研究觅食技能的改善，并且在比通常可能的更可控的条件下。使用数据从单独确定的男性育种者，我们表明，与我们的假设相一致，在饮食中的鸽子的比例显着增加与男性年龄，至少在生命的前三年。其他研究表明，生产力的平行增加，以及鸽子丰富的饮食对育雏大小和雏鸟状况的积极影响，强调了这种猎物物种对苍鹰的潜在健身相关性。我们的研究结果表明，觅食生态学和生殖性能的年龄依赖模式之间的因果关系。此外，据我们所知，我们的研究是第一次证明，繁殖者的猎物选择，这可能反映了个人的狩猎技能，是年龄依赖于猛禽。
Age-dependent breeding performance is arguably one of the best-documented phenomena in ornithology. The existence of age-related trends has major implications for life-history theory, but the proximate reasons for these patterns remain poorly understood. It has been proposed that poor breeding performance of young individuals might reflect lack of foraging skills. We investigated this possibility in a medium-sized, powerful raptor—the northern goshawk Accipiter gentilis. Male goshawks are responsible for providing their females and their offspring with food. We hypothesized that young males may generally show poor breeding performance or even delay breeding, because they lack the experience to hunt efficiently—especially, their principal avian prey, the feral pigeon Columba livia. Our study exploited a rare ‘natural experiment’, the expansion phase of an urban population, where intraspecific interference was negligible and many young males bred successfully. This enabled us to examine the improvement of foraging skills in a larger sample of young individuals, and in more controlled conditions than usually possible. Using data from individually identified male breeders, we show that, consistent with our hypothesis, the proportion of pigeons in the diet increased significantly with male age, for at least the first three years of life. Other studies have shown a parallel increase in productivity, and a positive effect of a pigeon-rich diet on brood size and nestling condition, stressing the potential fitness relevance of this prey species for goshawks. Our results suggest a causal link between patterns of age-dependence in foraging ecology and reproductive performance. Furthermore, our study is, to our knowledge, the first demonstration that prey choice of breeders, which might reflect individual hunting skills, is age-dependent in a raptor.