Impaired predator evasion in fat blackcaps (Sylvia atricapilla)
Impaired predator evasion in fat blackcaps (Sylvia atricapilla)
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DOI：
10.1098/rspb.1996.0244
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发表时间：
1996-12-22
影响因子：
4.7
通讯作者：
Jakobsson, S
中科院分区：
文献类型：
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作者：
Kullberg, C;Fransson, T;Jakobsson, S
当鸟类受到捕食者的攻击时，起飞能力对生存机会至关重要。最近，理论研究预测，捕食风险降低飞行性能增加与体重。然而，经验数据很少。由于候鸟有时会增加一倍的体重，质量依赖捕食风险可能是特别重要的迁徙育肥。在这里，我们提出了第一个研究起飞能力与迁移脂肪负荷。本文分析了由模拟捕食者攻击引起的笼养黑顶莺（Sylvia atricapilla）的警报起飞飞行的速度和上升角。鸡的脂肪负荷（占无脂肪体重的百分比）范围为1%至59%。发现脂肪负荷的增加影响速度和上升角。从我们的研究结果中，我们计算出，携带60%脂肪负荷的黑顶帽将有32%的上升角和17%的速度比没有携带脂肪负荷的黑顶帽低。即使脂肪负荷对黑头的影响小于在以前的实验研究中所示的其他物种，我们的研究结果表明，迁移所需的大脂肪负荷可能会使他们在捕食的风险增加。
When birds are attacked by predators, take-off ability is crucial for the chance of survival. Recently, theoretical studies have predicted that predation risk in terms of reduced flight performance increases with body mass. However, empirical data are scarce. Because migratory birds sometimes double their body mass, mass dependent predation risk may be especially important during migratory fattening. Here we present the first study of take-off ability in relation to migratory fat load. Alarmed take-off flights of caged blackcaps (Sylvia atricapilla) induced by a simulated predator attack were analysed in terms of velocity and angle of ascent. Fat loads (percentage of fat-free body mass) of the birds ranged from 1% to 59%. An increase in fat load was found to influence both velocity and angle of ascent. From our results we calculated that blackcaps carrying 60% fat loads would have 32% lower angle of ascent and 17% lower velocity than blackcaps carrying no fat load. Even though the effect of fat load on the blackcaps was less than indicated in previous experimental studies of other species, our results suggest that the large fat loads needed for migration probably place them at increased risk of predation.