Veasey JS, Metcalfe NB, Houston DC
Ornithology Group, Institute of Biomedical and Life Sciences, University of Glasgow
Anim Behav. 1998 Oct;56(4):883-889. doi: 10.1006/anbe.1998.0880.
A number of theoretical studies have predicted that avian predation risk is mass dependent. Models of bird flight predict that increased mass will reduce flight velocity, making birds more vulnerable to predation. Empirical studies supporting this have demonstrated a significant relationship between mass and routine flight velocity (when birds are not alarmed). Studies investigating the effects of mass upon flight velocity when birds are alarmed, however, tend to show that the mass/velocity relationship is less marked. We found a real difference in the relationship between mass and flight velocity in zebra finches, Taeniopyga guttata, when comparing flights of alarmed and unalarmed birds. Despite the strong mass/routine velocity relationship already shown for zebra finches, mass tended to be a poor predictor of the flight velocity of alarmed birds within the natural weight range of the species. This difference appeared to be partly due to alarmed birds increasing their velocity more when heavy than when light, in comparison to their respective predicted routine flight velocities for their weights. As a result, mass/velocity regression slopes tended to be more shallow for alarmed birds. Consequently, increases in body mass within the natural weight range of a bird, may have less effect on the flight velocities of alarmed birds than they do on routine flight velocities. We therefore recommend caution in the use of weight as a predictor of predation risk in birds without examining its effects upon the flight velocity of alarmed birds. We suggest some explanations for the differences in the mass/velocity relationship between the flights of alarmed and unalarmed birds. Copyright 1998 The Association for the Study of Animal Behaviour.
一些理论研究预测，鸟类被捕食的风险取决于体重。鸟类飞行模型预测，体重增加会降低飞行速度，使鸟类更容易被捕食。支持这一观点的实证研究表明，体重与常规飞行速度（鸟类未受惊时）之间存在显著关系。然而，研究鸟类受惊时体重对飞行速度影响的研究往往表明，体重与速度之间的关系不太明显。在比较受惊和未受惊的斑胸草雀（Taeniopyga guttata）飞行时，我们发现体重与飞行速度之间的关系存在实际差异。尽管斑胸草雀已经显示出强烈的体重/常规速度关系，但在该物种的自然体重范围内，体重往往不能很好地预测受惊鸟类的飞行速度。这种差异似乎部分是由于与各自体重对应的预测常规飞行速度相比，受惊的重鸟比轻鸟在受惊时速度增加得更多。因此，受惊鸟类的体重/速度回归斜率往往更平缓。因此，在鸟类的自然体重范围内，体重增加对受惊鸟类飞行速度的影响可能比对常规飞行速度的影响小。因此，我们建议在未研究体重对受惊鸟类飞行速度的影响之前，谨慎使用体重来预测鸟类被捕食的风险。我们对受惊和未受惊鸟类飞行时体重/速度关系的差异提出了一些解释。版权所有1998动物行为研究协会。
