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Fig. 4 | BMC Biology

Fig. 4

From: Hook tool manufacture in New Caledonian crows: behavioural variation and the influence of raw materials

Fig. 4

New Caledonian crows’ method of releasing basic tools in Experiment 2. Place and mode of detachment for the first (left) and second (right) actions of manufacture sequences; for a detailed explanation of colour-coding and terminology, see Fig. 1. The attempted and realised place of detachment is only shown for first actions, as they were the same for all second actions. Tool icons indicate when the basic tool (hooked or non-hooked) was released from the plant stem, and numbers above bars are manufacture sample sizes across subjects. Three manufacture sequences (all by bird EV0) are not shown, as they deviated from the general pattern (two incomplete detachments at the hook shaft with subsequent detachment at the root shaft, and one detachment at the hook shaft followed by a detachment at the root shaft, which was clearly a cut action)

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