Shaping of hooks in new Caledonian crows
Shaping of hooks in new Caledonian crows
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DOI：
10.1126/science.1073433
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发表时间：
2002-08-09
期刊：
影响因子：
56.9
通讯作者：
Kacelnik, A
中科院分区：
文献类型：
--
作者：
Weir, AAS;Chappell, J;Kacelnik, A
许多动物使用工具，但它们对物理力或因果关系的理解尚不清楚（1，2）。灵长类动物被认为是最多才多艺和最复杂的工具使用者，但对新喀里多尼亚乌鸦（Corvus moneduloides）的观察（3-5）提出了这样一种可能性，即这些鸟类可能在与工具相关的认知能力方面与非人类灵长类动物相媲美。我们在这里报告一个实验，灵感来自于观察到一只被捕获的雌性自发地将一根直铁丝弯成钩子，并成功地用它从垂直管道中提起装有食物的水桶（图1A）。这发生在一个实验的第五次试验中，乌鸦必须在钩状和直线之间做出选择，并且只有在钩状线被另一个受试者（男性）移除之后。这些动物之前有使用该装置的经验，但它们之前唯一的柔性材料经验是在本实验前一年用柔性管道清洁器自由操作1小时，并且它们不熟悉电线。为了研究这一观察结果的重要性，我们进行了几次新的试验，其中我们放置了一根直的花园电线（直径0.8mm，长90 mm），并且不干预，直到任一只鸟获得食物（有效试验）或将金属丝不可挽回地落入管中（无效试验）。在10次有效试验中（穿插7次无效试验），雌性弯曲钢丝并用其取回食物9次，雄性用直钢丝取回食物1次（7次）。为了使金属丝弯曲，她首先将金属丝的一端楔入胶带中（可在管的底部和包含装置的塑料托盘的侧面周围获得），或者将金属丝放在距离食物3米的位置，在那里没有胶带。然后，她将另一端与她的喙垂直地拉动（见电影S1），导致弯曲，角度为74 30（平均SE）（见图1B的单个工具形状）。她在每次试验开始后35 8 s开始弯曲导丝，并在6 2 s后使用产生的钩。在所有情况下，除了一个，她尝试了直丝（15 4秒），然后才开始使钩。在所有有效的试验中，鸟检索的食物在2分钟内。因此，至少有一个我们的鸟是能够新的工具修改的特定任务。在野外，新喀里多尼亚乌鸦使用不同的技术制作至少两种钩工具（3，4），但我们的雌性乌鸦使用的方法是
Many animals use tools, but their understanding of physical forces or causal relations is unclear (1, 2). Primates are considered the most versatile and complex tool users, but observations of New Caledonian crows (Corvus moneduloides)(3–5) raise the possibility that these birds may rival nonhuman primates in tool-related cognitive capabilities. We report here an experiment inspired by the observation that a captive female spontaneously bent a piece of straight wire into a hook and successfully used it to lift a bucket containing food from a vertical pipe (Fig. 1A). This occurred on the fifth trial of an experiment in which the crows had to choose between a hooked and a straight wire and only after the hooked wire had been removed by the other subject (a male). The animals had prior experience with the apparatus, but their only previous experience with pliant material was 1 hour of free manipulation with flexible pipe-cleaners a year before this experiment, and they were not familiar with wire (6).To investigate the importance of this observation, we conducted several new trials in which we placed a single straight piece of garden wire (0.8 mm in diameter, 90 mm long) on top of the tube and did not intervene until either of the birds obtained the food (a valid trial) or dropped the wire irretrievably into the tube (an invalid trial). Out of 10 valid trials (interspersed with seven invalid ones), the female bent the wire and used it to retrieve the food nine times, and the male retrieved the food once with the straight wire (7). To bend the wire, she first wedged one end of it in sticky tape (available around the bottom of the tube and the side of the plastic tray containing the apparatus) or held it in her feet at a location 3 m from the food, where there was no tape. She then pulled the other end orthogonally with her beak (see Movie S1), resulting in a bend with an angle of 74 30 (mean SE)(see Fig. 1B for individual tool shapes). She started to bend the wire 35 8 s after the start of each trial and used the resulting hook 6 2 s later. In all cases but one, she tried with the straight wire (for 15 4 s) before starting to make the hook. In all valid trials, the birds retrieved the food within 2 min. Thus, at least one of our birds is capable of novel tool modification for a specific task. In the wild, New Caledonian crows make at least two sorts of hook tools using distinct techniques (3, 4), but the method used by our female crow is