Variation in predation risk and vole feeding behaviour:: a field test of the risk allocation hypothesis
Variation in predation risk and vole feeding behaviour:: a field test of the risk allocation hypothesis
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DOI：
10.1007/s00442-004-1490-x
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发表时间：
2004-03-01
期刊：
影响因子：
2.7
通讯作者：
Ylönen, H
中科院分区：
文献类型：
--
作者：
Sundell, J;Dudek, D;Ylönen, H
许多被捕食动物在被捕食的风险上经历了时间的变化，因此面临着在对抗捕食者的努力和其他活动（如喂养和繁殖）之间分配时间的问题。我们研究了平衡捕食风险和取食机会的猎物时间分配。捕食风险分配假说预测，动物在低风险情况下应该比在高风险情况下觅食更多，这种差异应该随着攻击率（即低风险和高风险情况之间的差异）和在高风险情况下花费的时间比例的增加而增加。为了验证这些预测，我们使用田鼠（Clethrionomys glareolus）作为猎物和最小鼬鼠（Mustela nivalis nivalis）作为捕食者进行了现场测试。在室外大型围场环境中，对田鼠捕食风险的时间格局和强度进行了控制，并通过记录放弃密度来测量田鼠的觅食努力和斑块利用情况。我们没有观察到由于风险水平的变化或在高风险条件下花费的时间比例的变化而导致喂养努力的任何变化。唯一显著的影响是当攻击率改变时：低攻击率处理的田鼠觅食努力高于高攻击率处理的田鼠。因此，结果不支持捕食风险分配假设，我们质疑该假设在我们的研究系统中的适用性。我们认为，观察到的银行田鼠的摄食行为模式与捕食风险分配假设预测的模式之间的偏差主要是由于田鼠无法准确评估风险水平的变化。然而，我们也强调在室外条件下和具有灵活行为模式的哺乳动物身上测试假设的困难。
Many prey animals experience temporal variation in the risk of predation and therefore face the problem of allocating their time between antipredator efforts and other activities like feeding and breeding. We investigated time allocation of prey animals that balanced predation risk and feeding opportunities. The predation risk allocation hypothesis predicts that animals should forage more in low- than in high-risk situations and that this difference should increase with an increasing attack ratio (i.e. difference between low- and high-risk situations) and proportion of time spent at high risk. To test these predictions we conducted a field test using bank voles (Clethrionomys glareolus) as a prey and the least weasel (Mustela nivalis nivalis) as a predator. The temporal pattern and intensity of predation risk were manipulated in large outdoor enclosures and the foraging effort and patch use of voles were measured by recording giving-up densities. We did not observe any variation in feeding effort due to changes in the level of risk or the proportion of time spent under high-risk conditions. The only significant effect was found when the attack ratio was altered: the foraging effort of voles was higher in the treatment with a low attack ratio than in the treatment with a high attack ratio. Thus the results did not support the predation risk allocation hypothesis and we question the applicability of the hypothesis to our study system. We argue that the deviation between the observed pattern of feeding behaviour of bank voles and that predicted by the predation risk allocation hypothesis was mostly due to the inability of voles to accurately assess the changes in the level of risk. However, we also emphasise the difficulties of testing hypotheses under outdoor conditions and with mammals capable of flexible behavioural patterns.