Dissertation Research: Thirteen-Lined Ground Squirrel Antipredator Vigilance

9701137 Leger研究动物在面临被捕食者吃掉的风险时的决策能力，可以揭示动物评估最佳权衡的复杂过程。 最佳权衡的一个简单例子是动物面临两个冲突的选择，例如，觅食与扫描捕食者（反捕食者警惕）。 觅食减少饥饿的风险，而反捕食者警惕减少捕食风险。 动物无法在不遭受另一种严重风险的情况下最大限度地从一种中获益。 一个最佳的权衡是动物的选择是联合最大的喂养和antipredator警惕。 决策是本研究的基础框架。 一个非常普遍的观察是，一个群体的规模增加，猎物动物的警惕性下降。 这种警觉性的降低可能导致动物有更多的时间进食，并可能成为社会性进化的重要力量。 虽然视觉障碍是许多猎物环境中常见的情境变量，但这一变量并没有得到太多的实证关注。 十三行地松鼠是大平原上的穴居啮齿动物。 它们被鸟类、陆生哺乳动物和爬行动物（如蛇）捕食。 研究表明，只有当它们的远距离（大于20米）、横向视野被遮挡时，十三线地松鼠才会提高对捕食者的警惕性。 考虑到有多少动物捕食这些地松鼠，这是相当令人惊讶的，他们不作出反应，提高警惕时，他们的'开销'的看法是阻碍。 为了验证关于反捕食者警惕和视觉障碍的假设，13线地松鼠被允许在有机玻璃盒内进食，这些有机玻璃盒不同地阻挡了松鼠的视野，并检测到接近的威胁。 这是一个重要的测试，因为地松鼠反捕食者的警惕行为表明，他们不认为某些位置的视觉障碍是重要的。 因此，即使不提高警惕，地松鼠也应该能够像没有视觉障碍时一样，在“头顶”视觉障碍的情况下发现捕食者的攻击。

9701137 Leger Studies of the decision-making capabilities of animals while they are under the risk of being eaten by predators can reveal the complex process by which animals evaluate optimal trade-offs. A simple example of an optimal trade-off is where an animal is faced with two conflicting choices, e.g., foraging versus scanning for predators (antipredator vigilance). Foraging reduces starvation risk while antipredator vigilance reduces predation risk. The animal is unable to maximize the benefit from one without incurring serious risk from the other. An optimal trade-off is where the animal's choice is the joint maximum of both feeding and antipredator vigilance. Decision-making is the framework within which this research is based. A very common observation is that a group size increases, prey animal vigilance decreases. This decrease in vigilance could result in the animal having more time to feed and could be a significant force in the evolution of sociality. Although visual obstruction is a common contextual variable in many prey animals' environment, this variable has not been given much empirical attention. Thirteen-lined ground squirrels are burrowing rodents that occur across the Great Plains. They are preyed upon by birds, terrestrial mammals, and reptiles such as snakes. It has been shown that thirteen-lined ground squirrels increase their antipredator vigilance only when their long-range (greater than 20m), lateral field of view is obstructed. Considering how many animals prey upon these ground squirrels, it is quite surprising that they do not react with increased vigilance when their 'overhead' view is obstructed. To test hypotheses about antipredator vigilance and visual obstruction, thirteen-lined ground squirrels are allowed to feed inside plexiglass boxes that differentially obstruct the squirrels' filled of view, and detect the approaching threat. This is an important test since ground squirrel antipredator vigilance behavior indicates that they do not co nsider certain positions of visual obstruction to be important. Therefore, even without increasing their vigilance, ground squirrels should be able to detect predator attacks with 'overhead' visual obstruction as when there is no visual obstruction.