This 3 September 2018 video says about itself:
These birds are trained for a job. These six rooks pick up trash at a theme park in Les Epesses, France. They bring the trash to a container that dispenses a food reward. This gives a new, positive spin to the expression “bird brain”.
Ornithologist Robert Mulvihill said that parrots and some songbirds, like rooks and crows, have “really high neuronal densities for their size.” These creatures may be small, but they have an outsized intellect. The whole process is still fundamentally a foraging behavior but a bit more complex.
Read more here.