Konrad Lorenz Forschungsstelle, Grünau im Almtal, Austria.
Anim Cogn. 2012 Jan;15(1):73-82. doi: 10.1007/s10071-011-0434-1. Epub 2011 Jul 13.
Recently, two corvid species, food-caching ravens and non-caching jackdaws, have been tested in an exclusion performance (EP) task. While the ravens chose by exclusion, the jackdaws did not. Thus, foraging behaviour may affect EP abilities. To investigate this possibility, another food-caching corvid species, the carrion crow (Corvus corone corone), was tested in the same exclusion task. We hid food under one of two cups and subsequently lifted either both cups, or the baited or the un-baited cup. The crows were significantly above chance when both cups were lifted or when only the baited cup was lifted. When the empty cup was lifted, we found considerable inter-individual variation, with some birds having a significant preference for the un-baited but manipulated cup. In a follow-up task, we always provided the birds with the full information about the food location, but manipulated in which order they saw the hiding or the removal of food. Interestingly, they strongly preferred the cup which was manipulated last, even if it did not contain any food. Therefore, we repeated the first experiment but controlled for the movement of the cups. In this case, more crows found the food reliably in the un-baited condition. We conclude that carrion crows are able to choose by exclusion, but local enhancement has a strong influence on their performance and may overshadow potential inferential abilities. However, these findings support the hypothesis that caching might be a key to exclusion in corvids.
最近，两种鸦科动物，即食腐乌鸦和非食腐寒鸦，在排除表现（EP）任务中进行了测试。虽然乌鸦通过排除选择了食物，但寒鸦没有。因此，觅食行为可能会影响 EP 能力。为了研究这种可能性，另一种食腐鸦科动物——欧亚红松鼠，在相同的排除任务中进行了测试。我们将食物藏在两个杯子中的一个下面，然后提起两个杯子，或者提起诱饵杯子或非诱饵杯子。当提起两个杯子或只提起诱饵杯子时，乌鸦的表现明显超过了随机水平。当提起空杯子时，我们发现个体之间存在相当大的差异，有些鸟对未诱饵但被操纵的杯子有明显的偏好。在后续的任务中，我们总是为鸟类提供有关食物位置的完整信息，但操纵它们看到食物隐藏或取出的顺序。有趣的是，即使杯子里没有食物，它们也强烈偏好最后被操纵的杯子。因此，我们重复了第一个实验，但控制了杯子的移动。在这种情况下，更多的乌鸦在非诱饵条件下可靠地找到了食物。我们的结论是，欧亚红松鼠能够通过排除选择，但局部增强对它们的表现有很大的影响，可能会掩盖潜在的推断能力。然而，这些发现支持了这样一种假设，即食腐可能是鸦科动物排除的关键。
