Anyone else been to Sainsbury's at Lower Sydenham and heard the tape recorded bird sounds coming out of the speakers? Outside the main entrance by the trolleys. I can only guess that it's a bird of prey sound to frighten off other birds that may poop on the trolleys.
It's there to protect the birds, actually. They fly in under the roof and get stuck. The recording is of a distress call, so the idea is to keep the birds away from the building.