Abramsky Z, Strauss E, Subach A, Riechman A, Kotler B P
Department of Life Science, Ben-Gurion University of the Negev, 84105, Beer Sheva, Israel.
Mitrani Center for Desert Ecology, Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, 84993, Sede Boqer, Israel.
Oecologia. 1996 Feb;105(3):313-319. doi: 10.1007/BF00328733.
Predation plays an important role in ecological communities by affecting prey behavior such as foraging and by physical removal of individual prey. In regard to foraging, animals such as desert rodents often balance conflicting demands for food and safety. This has been studied in the field by indirectly manipulating predatory risk through the alteration of cues associated with increased risk such as cover or illumination. It has also been studied by directly manipulating the presence of predators in aviaries. Here, we report on experiments in which we directly manipulated actual predatory risk to desert rodents in the field. We conducted a series of experiments in the field using a trained barn owl (Tyto alba) to investigate how two species of coexisting gerbils (Gerbillus allenbyi and G. pyramidum) respond to various cues of predatory risk in their natural environment. The gerbils responded to risk of predation, in the form of owl flights and owl hunger calls, by reducing their activity in the risky plot relative to the control plot. The strongest response was to owl flights and the weakest to recorded hunger calls of owls. Furthermore, when risk of predation was relatively high, as in the case with barn owl flights, both gerbil species mostly limited their activity to the safer bush microhabitat. The response of the gerbils to risk of predation disappeared very quickly following removal of the treatment, and the gerbils returned to normal levels of activity within the same night. The gerbils did not respond to experimental cues (alarm clock), the presence of the investigators, the presence of a quiet owl, and recorded "white noise". Using trained barn owls, we were able to effectively manipulate actual risk of predation to gerbils in natural habitats and to quantify how gerbils alter their behavior in order to balance conflicting demands of food and safety. The method allows assessment of aspects of behavior, population interactions, and community characteristics involving predation in natural habitats.
捕食在生态群落中起着重要作用，它会影响猎物的行为，如觅食行为，还会通过物理方式消灭个体猎物。关于觅食，沙漠啮齿动物等动物常常要在食物需求和安全需求之间进行权衡。在野外，人们通过间接改变与风险增加相关的线索（如遮蔽物或光照）来操控捕食风险，对这一现象进行了研究。人们还通过在鸟舍中直接操控捕食者的存在进行了研究。在此，我们报告了在野外直接操控沙漠啮齿动物实际捕食风险的实验。我们在野外进行了一系列实验，利用一只经过训练的仓鸮（Tyto alba）来研究两种共存的沙鼠（Alleni沙鼠和pyramidum沙鼠）如何应对自然环境中各种捕食风险线索。沙鼠会对以鸮飞行和鸮饥饿叫声形式存在的捕食风险做出反应，相对于对照区域，它们会减少在危险区域的活动。最强的反应是对鸮飞行的反应，最弱的是对录制的鸮饥饿叫声的反应。此外，当捕食风险相对较高时，如仓鸮飞行的情况，两种沙鼠大多将活动限制在更安全的灌木丛微生境中。在去除处理因素后，沙鼠对捕食风险的反应很快消失，并且在同一晚内沙鼠的活动水平就恢复到了正常水平。沙鼠对实验线索（闹钟）、研究人员的存在、安静的鸮的存在以及录制的“白噪音”均无反应。利用经过训练的仓鸮，我们能够在自然栖息地有效操控沙鼠实际面临的捕食风险，并量化沙鼠如何改变其行为以平衡食物和安全的相互冲突的需求。该方法能够评估自然栖息地中涉及捕食的行为、种群相互作用和群落特征等方面。
