Variations of behaviour of Carrion Crows Corvus corone using automobiles as nutcrackers
Variations of behaviour of Carrion Crows Corvus corone using automobiles as nutcrackers
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DOI：
10.3838/jjo.44.21
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发表时间：
1995-04
期刊：
影响因子：
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通讯作者：
Yoshiaki Nihei
中科院分区：
文献类型：
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作者：
Yoshiaki Nihei
我们调查了腐肉乌鸦Corvus corone的奇怪行为，它们利用汽车来敲开核桃。一个典型的行为序列是：一只乌鸦把一个核桃放在交通信号灯停下来的汽车前面;然后汽车从核桃上碾过，乌鸦吃核桃的碎片。在21个月的观察期内，经常看到这种行为，并详细记录了43次。研究发现，这种行为由几个变量组成：获取核桃的程序、核桃的状态、在路上放置核桃的方式、一天中的时间、地点、周围是否有其他乌鸦、在放弃之前等待多久、乌鸦是否试图改变核桃的位置以及乌鸦吃核桃的方式。对这些变量的分析表明，乌鸦的用车行为不是偶然的，而是系统的。乌鸦有时会把核桃从离地面10多米的地方扔下来敲碎，但有些核桃太硬了，这种方法很难敲碎。我们认为，使用汽车的行为是一种替代发明，以打破核桃太硬，或核桃覆盖果肉。综上所述，我们认为食腐乌鸦的用车行为是故意的行为
We investigated the curious behaviour of Carrion Crows Corvus corone that make use of automobiles to crack walnuts. A typical sequence of the behaviour is : a crow puts a walnut in front of the automobile that is stopped by a traffic signal ; then the car run over the walnut and the crow eats the fragements of the walnut. This behaviour was frequently seen during the 21 months of the observation period and 43 occurrences of these were recorded in detail. The behaviour is found to consist of several variables : the procedure to get walnuts, the state of walnuts, the way to set walnuts on the road, time of the day, places, whether there are other crows around, how long to wait before abandoning, whether the crow tries to change the position of the walnuts, and the way the crow eats the cracked walnuts. The analyses of these variables suggest that the car-using behaviour of the crows is not accidental but rather systematic. Crows sometimes drop walnuts from more than 10 meters above the ground to crack them but some walnuts are too hard to crack by this method. We suggest the car-using behaviour is an alternative invention to crack walnuts that are too hard, or walnuts covered with pulp. Taken together, we consider the car-using beheviour of Carrion Crows to be intentional behaviour