Corvids(鸦类) are known to be remarkably intelligent animals. These birds are good at using tools, can plan ahead, solve puzzles and even hold grudges (怨恨)，Some corvids' brains have really high neuronal densities and a brain region called the nidopallium caudolaterale, or NCL, which is believed to act like our prefrontal cortex- the problem -solving part of the human brain.
Rooks are members of the crow family. Six rooks一Boubou, Bamboo, Bill, Black, Bricole and Baco一were trained to pick up litter after people. They are employees of Puy du Fou park, a history-themed park located in Les Epesses，four hours' drive from Paris ，France.
The idea to train rooks originally came from the park 's falconry(鹰猎) show, during which trained corvids would pick up roses and bring them to a"princess" in a castle. This got Christophe Gaborit, project manager at the park, thinking whether he' d be able lo teach rooks to perform a similar task一like picking up cigarette bulls and other small pieces of trash and putting them in a box.
When the birds placed a piece of trash in a box, their trainer would pull a board to show a delicious snack for them. At last, the rooks started to associate tidying up with food, and were happy to pick up small pieces of trash in order to get rewards. The birds would sometimes try to trick Gaborit and instead of disposing of garbage , would drop pieces of wood into the box.
"We don't want to make them machines ,"the president of the Puy du Fou park , Nicolas de Villiers, said. "They don't play the game if they work too much. "
The birds"work" under supervision of a falconer , who makes sure that people don' t throw garbage around just to watch the rooks pick it up. Instead , Boubou, Bamboo, Bill, Black, Bricole and Baco are there to educate the park visitors about littering. " Nature itself can teach us to take care of the environment," Villiers said.
