University of Exeter, Stocker Road, Exeter EX4 4PY, UK.
School of Psychological Science, University of Bristol, Bristol, UK.
Biol Lett. 2024 Nov;20(11):20240405. doi: 10.1098/rsbl.2024.0405. Epub 2024 Nov 6.
Weight, though it cannot be seen directly, pervades nearly every aspect of an animal's life. However, the extent to which non-human animals reason about the property of weight remains poorly understood. Recent evidence highlights birds as a promising group for testing this ability: for example, New Caledonian crows can infer the weight of objects after observing their movements in a breeze. Here, we tested for similar weight inference abilities in kea (), a parrot species known for its sophisticated problem-solving skills. Subjects were trained to exchange objects of a target weight (light or heavy) for a food reward. They were then allowed to observe pairs of novel objects (one light and one heavy) hung in front of an electric fan in both an experimental condition (fan on, light object moving) and a control condition (fan off, both objects motionless). The birds were subsequently presented with test trials in which they could use the information from the demonstration to select an object of their target weight. We found that, unlike New Caledonian crows, kea did not perform significantly better on trials in which they observed the objects' movements and discussed our findings within the context of the kea's highly explorative nature.
体重虽然不能直接看到，但它几乎渗透到动物生活的方方面面。然而，非人类动物对体重这一特性进行推理的程度仍知之甚少。最近的证据表明，鸟类是测试这种能力的一个很有前途的群体：例如，新喀里多尼亚乌鸦可以通过观察物体在微风中的运动来推断物体的重量。在这里，我们测试了一种名为啄羊鹦鹉的鹦鹉是否具有类似的体重推断能力，啄羊鹦鹉以其复杂的解决问题的能力而闻名。实验对象被训练用目标重量（轻或重）的物体来换取食物奖励。然后，让它们观察一对挂在电风扇前的新物体（一个轻的和一个重的），在实验条件（风扇开着，轻的物体移动）和控制条件（风扇关着，两个物体都不动）下。然后，给这些鸟进行测试，让它们可以利用演示中的信息来选择目标重量的物体。我们发现，与新喀里多尼亚乌鸦不同，啄羊鹦鹉在观察物体运动的试验中表现并不明显更好，并在啄羊鹦鹉高度探索的本性的背景下讨论了我们的发现。
