Additional file 3: Movie 2. of Hook tool manufacture in New Caledonian crows: behavioural variation and the influence of raw materials

Behavioural actions of hooked stick tool manufacture – Modifications. Scene 1, processing the tool by stripping bark. Methods of bending the tool shaft: Scene 2, trapping the tool under the foot and bending the tool shaft with the bill; Scene 3, holding the tool in the bill and pressing the tool shaft against a firm substrate; and Scene 4, inserting the tool into a hole and pulling the tool shaft sideways by bill. (MP4 20519 kb)