FIGURE 8.6 Tool-using animals (a) New Caledonian crows quickly learned to raise the water level in a tube and nab a floating worm by dropping stones into the water (Bird & Emery, 2009). Other crows have used twigs to probe for insects, and bent strips of metal to reach food. (b) One male chimpanzee in Sweden’s Furuvik Zoo was observed every morning collecting stones into a neat little pile. Later in the day, he used them as ammunition to pelt visitors (Osvath, 2009).
Chris Bird & Nathan Emery
Mathias Osvath
Mathias Osvath