File:Cognitive-Processes-Associated-with-Sequential-Tool-Use-in-New-Caledonian-Crows-pone.0006471.s002.ogv

English: This video shows Pierre's first exposure in Experiment 1 to a two-tool problem (Secondary-Long), which was his second testing trial in total. Correct sequence of actions: use tabletop tool (freely available in the arena) to retrieve the longest tool from the tool-tube (second tool-tube from left; the other three tubes contain medium-length tools); then use this long tool to obtain food reward from food-tube (in front). Observed behaviour: Pierre picks up the tabletop tool and quickly inserts it into the food-tube. He then uses the tabletop tool to probe for the correct, longest tool, but fails to retrieve it, and leaves the testing arena. Shortly thereafter (<1 minute; cut from video), he returns with a twig from his aviary, which he immediately uses to extract the longest tool, which he in turn uses to retrieve the reward from the food-tube.