It is fairly common knowledge that crows and ravens are extraordinarily intelligent animals. They seem to grasp the concept of cause and effect, including a rudimentary understanding of how water displacement works.
When you combine their intelligence with a penchant for training, you have the ingredients to create an exemplary flying trash man. This was discovered by the professional falconer Christophe Gaborit who taught two crows to pick up trash in exchange for food back in the 2000s. Later, Mr Gaborit’s employer the French Puy du Fou themepark, bought into the idea and trained six rooks to pick up smaller pieces of trash around their park in exchange for food.
The birds was initially deployed for 4 days a week and under close supervisor by park authorities. This was done not because they were in doubt about the birds abilities, but to ensure that people don’t litter just to see the birds in action. According to the park however the only purpose of the crows is not just to collect trash but also to educate (read shame) the park goers who litter. Said in another way if even a bird can pick up the trash why can’t you, in the words of the president of Puy du Fou.
“The purpose of the crows … is to educate the people, to open their minds, to think, ‘OK, the birds are able to do something that we are much more able to do than them, so we should do this by ourselves.’President of Puy du Fou
The methods used to train the rooks are neither new nor revolutionary, but it has been used to demonstrate that for example ravens are able to use flexibility in planning for both tool using and bartering rivaling that of great apes. This is also why it is important for people who rehabilitate these birds to provide them with what is known as enrichment. An example of which is regularly presenting them with puzzles that requires the bird to use its own cognitive abilities.