pigeons
ah - they are three-state pigeons - on Ground, on Wire, Elsewhere/Car.
Theatregoers passing by on the ground cause pigeons to transition between Ground and Wire
IT bloke looking at wire causes them to transition from Wire to Elsewhere/Car
IT bloke no-longer looking at wire means they return from Elsewhere/Car to sit on Wire
Presumably if left alone long enough, the pigeons will undergo a spontaneous return to their Ground state; the Wire state being only metastable.
Biting the hand that feeds IT
