A theme park in France has established a and environmentally-friendly way of keeping its free of litter. It has selected and trained six "intelligent" rooks to pick up and keep the park clean. Rooks are of the crow family and are up to 47cm in . The clever birds will be put to work at the Puy du Fou theme park in the of France. They have been trained to pick up cigarette , paper and other things people throw on the ground. The birds pick up the litter and deposit it into a trash can, which then delivers some bird feed as a . The more litter the birds put in the trash can, the food they get.
The of the theme park, Nicolas de Villiers, explained the of using the crows to the AFP news agency. He said there were reasons for deploying the crows. He said: "The goal is not just to clean up, the visitors are generally to keep things clean, but also to demonstrate that nature can teach us to take care of the ." Crows are highly sociable and intelligent birds. Some biologists say they are as smart as a seven-year-old child. Mr De Villiers said: "In an affectionate, supportive atmosphere, they like to communicate with humans and establish a through play." The crows are workers and can fill a bucket with rubbish in than 45 minutes