A theme park in France is set to deploy six "intelligent" birds to pick up rubbish and spruce up the grounds.
The rooks at the Puy du Fou theme park in the west of the country have been taught to collect cigarette ends and other small bits of rubbish.
They then deposit the litter into a small box which will deliver some bird food as a reward for their hard work.
The first feathery cleaners have already been put to work, with the rest set to join them on Monday.
Nicolas de Villiers, the head of the park, told AFP news agency that it was not just about keeping the area clean.
"The goal is not just to clear up, because the visitors are generally careful to keep things clean".
It was also about showing "that nature itself can teach us to take care of the environment".
He added that the rooks, which are a member of the crow family that also includes ravens and jackdaws, are "particularly intelligent" and "like to communicate with humans and establish a relationship through play".
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This is not the first time that birds have displayed their intelligence. Earlier this year, scientists created a vending machine that showed the crow's ability to solve problems.
The machine required a particular size of paper token to release a treat.
Scientists found that the crows could remember the right size of paper, and they even trimmed bigger pieces until they could fit into the machine.