Collaborative Research: Does Anti-predator Behavior Modify Indirect Effects of Top Predators?

捕食者可以通过吓跑食草动物和防止过度放牧来使植物受益，这一过程被称为“营养级联”。“生物学家假设每一种捕食者都会产生一种营养级联。例如，老虎会吓跑食草动物，保护它巡逻地区的植物。然而，证据表明，并非所有食草动物对捕食者的恐惧反应一致。相反，在有多种食草动物的生态系统中，每种食草动物都可能避开最不可能逃脱捕食者的区域，而这些区域可能会有所不同。如果是这样的话，那么捕食者可能会引发一系列的营养级联，使任何特定的食草动物最有可能被捕获的植物受益。为了了解捕食者如何通过吓跑食草动物来保护植物，生物学家必须确定每个猎物物种最不可能逃脱的区域或栖息地类型。这种识别需要猎物逃跑策略的知识。这项拟议中的研究将利用华盛顿两种食草动物--骡子和白尾鹿--的逃跑策略来预测灰狼最近的回归对它们栖息地使用的影响。骡鹿行动缓慢，并利用它们的敏捷来逃避捕食者。他们将被期望转移到粗糙的地形，在那里他们的敏捷性是有利的，并避免平坦的地形，逃生需要速度。白尾鹿的速度很快，可以通过冲刺来躲避捕食者;当它们受到狼的惊吓时，它们会避开崎岖的地形，这样它们的速度就被抵消了。因此，狼应该保护生长在平缓地形上的黑尾鹿所吃的植物，以及生长在崎岖地形上的白尾鹿所吃的植物。该项目将通过强调猎物逃逸行为在驱动捕食者如何影响植物和塑造生态系统方面的重要性，改变人们对捕食者生态作用的理解方式。该研究的更广泛影响包括培训两名博士生，建立长期研究狼的生态影响，作为制定保护政策的手段，并启动了一项推广计划，其中包括教师培训、公开讲座和中学课堂视频课程计划。

Predators can benefit plants by scaring away herbivores and preventing overgrazing in a process known as a "trophic cascade." Biologists have assumed that each predator creates one kind of trophic cascade. A tiger, for example, scares herbivores away from and protects plants growing in the area it patrols. Evidence suggests, however, that not all herbivores respond uniformly to the fear of predators. Instead, in ecosystems with multiple herbivores, each one may avoid the area where it is least likely to escape the predator, and these areas might differ. If so, then predators could trigger an array of trophic cascades, benefiting plants eaten by any particular herbivore where it is most likely to be caught. To understand how a predator shields plants by scaring away herbivores, biologists must identify the area, or habitat type, where each prey species is least likely to escape. Such identification requires knowledge of prey escape tactics. The proposed research will use escape tactics of two herbivores in Washington -- mule and white-tailed deer -- to predict changes to their habitat use caused by the recent return of the gray wolf. Mule deer are slow, and use their agility to escape predators. They would be expected to shift to rough terrain where their agility is advantageous, and avoid smooth terrain where escape requires speed. White-tailed deer are fast and escape predators by sprinting away; when frightened by wolves they would be expected to avoid rugged terrain where their speed is neutralized. Consequently, wolves would be expected to protect plants eaten by mule deer that grow on gentle terrain, and plants eaten by white-tailed deer that grow on rugged terrain. This project will change the way that the ecological role of predators is understood, by highlighting the importance of prey escape behavior in driving how predators affect plants and shape ecosystems.The broader impacts of the research include training of two doctoral students, establishment of a long-term study of the ecological impacts of wolves as a means to inform conservation policy, and initiation of an outreach program incorporating teacher training, public lectures, and video lesson plans for secondary school classrooms.