The raptor cage! This is one of the first things that I see when I drive in to work at the Metro Transfer Station (working with my art grant at the city dump gleaning for art materials). Like probably all "dumping grounds" everywhere, Recology's Transfer Station has its share of nuisance birds coming in to eat from the rotting piles of food scraps. I met the falconer, Chris, yesterday, who is contracted to bring in his birds a few days a week.
He brings two falcons and two hawks, allowing one of them at a time to "work the area." He has them fully trained to respond to the "treats" that he carries in his pockets, which allows him to let them fly free over the area, thus scaring off the crows (some gulls, etc.) They do not attack the crows, but merely scare them off by their presence. The crows seem to be incredibly intelligent, knowing which days Chris and his birds are on the job.