The Development of Orientation Mechanisms in Birds

对候鸟和其他动物定向行为的研究在很大程度上依赖定向笼作为分析动物方向选择的手段。 对于鸟类来说，这些通常是圆形笼子，记录动物跳跃或扑动的方向。 此类研究结果的完整性显然取决于研究人员至少了解并常常控制鸟类所受到的刺激的能力。 由于其他物种的感知世界通常与我们自己的感知世界明显不同，因此研究人员必须非常小心，以确保他们的实验对象对感兴趣的刺激做出反应。 候鸟已被证明可以利用偏振天光的图案来确定方向。 这是人类几乎不敏感的视觉刺激，脊椎动物感知偏振光的生理机制尚不清楚。 此外，在技术上不可能精确模拟晴朗天空的偏振光图案。 艾布尔博士迄今为止的实验表明，偏振天光可能主要参与几种候鸟定向能力的发展和表现。 这些事实使得详细检查鸟类对偏振天光的反应变得极其重要：它们对刺激的哪些具体方面做出反应，以及它们如何使用这些信息作为指南针？ 了解这些事情将有助于实验者产生最佳的测试刺激和设备，并将确保鸟类的方向不是基于测试情况的​​某些未知方面的人为因素。

Studies of the orientation behavior of migratory birds and other kinds of animals rely heavily on orientation cages as the means of assaying the animal's choice of direction. In the case of birds, these are usually circular cages in which the direction of the animal's hopping or fluttering is recorded. The integrity of the results of such studies obviously depends upon the researcher's ability at least to know, and often to control, the stimuli to which the birds are exposed. Because the perceptual world of other species often differs markedly from our own, researchers must be extremely careful to be certain that their experimental subjects are responding to the stimuli of interest. Migratory birds have been shown to use patterns of polarized skylight for orientation. This is a visual stimulus to which human beings are barely sensitive, and the physiological mechanism by which vertebrates perceive polarized light is unknown. In addition, it is technically impossible to simulate precisely the polarized-light pattern of the clear sky. Dr. Able's experiments to date suggest that polarized skylight may be centrally involved in the development and performance of orientation in several species of migratory birds. These facts make it extremely important to examine in detail the birds' response to polarized skylight: To what specific aspects of the stimulus are they responding, and how do they use the information as a compass? Knowing these things will help experimenters produce an optimal testing stimulus and apparatus, and will ensure that the birds' orientation is not an artifact based on some unknown aspect of the testing situation.