Crows Can Use 'Up To Three Tools' In Correct Sequence Without Training
In the wild, New Caledonian crows use a range of tool types for extracting invertebrate prey from holes and crevices, and in captivity, they have been shown to make, or select, tools to retrieve food rewards. In previous experiments, the Oxford team reported that a crow (named ‘Betty’) was capable of spontaneously inventing new tool designs according to what was required by the tasks. In all these cases, however, objects were used to act on pieces of food.
Using tools to act on non-food objects – for example, to make or retrieve other tools – is considered to be a hallmark of human intelligence, and may have been a crucial step in our evolution. One form of this behaviour, ‘sequential tool use,’ has been observed in a number of non-human primates, and has recently been reported for New Caledonian crows by a research team from Auckland University, New Zealand.
In their new study, the Oxford scientists tested seven captive New Caledonian crows on a range of tasks requiring the use of up to three different tools in a sequence to retrieve food. Five crows successfully used tools in a sequence (four from their very first trial), and four repeatedly solved the most demanding three-tool condition. In this, food was placed at a depth so that it was only reachable with one particular tool, but getting that tool required the use of two other others. The crows had to use a short, available tool to drag in a longer, otherwise out-of-reach tool, and then use that longer tool to retrieve the correct, longest one. They could then use the longest tool to reach for the food morsel.
http://www.sciencedaily.com/releases/2009/08/090805144114.htm
Note: Not from the experiment, just an example of a crow making a hook when he realized a straight wire wouldnt work.
