Rands S A, Cuthill I C
Centre for Behavioural Biology, School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
Proc Biol Sci. 2001 Sep 7;268(1478):1783-90. doi: 10.1098/rspb.2001.1653.
The optimal amount of reserves that a small bird should carry depends upon a number of factors, including the availability of food and environmental predation risk levels. Theory predicts that, if predation risk increases, then a bird should maintain a lower level of reserves. Previous experiments have given mixed results: some have shown reduced reserves and some, increased reserves. However, the birds in these studies may have been interpreting a staged predation event as a period when they were unable to feed rather than a change in predation risk: theory predicts that, if the food supply within the environment is variable, then reserves should be increased. In the present study, we presented blue tits (Parus caeruleus) with a potential predator and compared this response (which could have been potentially confounded by perceived interruption effects) with a response to an actual interruption in the environment during both long and short daytime lengths. During long (but not short) days, the birds responded in line with theoretical predictions by increasing their reserves in response to interruption and reducing them in response to predation. These results are examined in the light of other experimental manipulations and we discuss how well experimental tests have tested the predictions made by theoretical models.
小鸟应携带的最佳储备量取决于多种因素，包括食物的可获取性和环境中的捕食风险水平。理论预测，如果捕食风险增加，那么鸟类应维持较低的储备水平。先前的实验结果不一：一些实验显示储备减少，而另一些则显示储备增加。然而，这些研究中的鸟类可能将 staged 捕食事件理解为它们无法进食的时期，而非捕食风险的变化：理论预测，如果环境中的食物供应不稳定，那么储备应该增加。在本研究中，我们向蓝山雀（Parus caeruleus）展示了一个潜在的捕食者，并将这种反应（可能因感知到的干扰效应而混淆）与在白天长短不同的情况下对环境中实际干扰的反应进行了比较。在长（而非短）日期间，鸟类的反应符合理论预测，即它们会因干扰而增加储备，因捕食而减少储备。我们根据其他实验操作对这些结果进行了检验，并讨论了实验测试在多大程度上验证了理论模型所做的预测。 （注：原文中“staged”可能有误，推测应为“actual”，译文按推测修正后翻译，若有误请根据实际情况调整）
