Pigeons naturally eat grain and seeds off the ground and are attracted by speckly surfaces.
Remove or cover such lures as speckled table cloths or linoleum. They can't tell a model from the real thing, as both sit motionless all day. Neither can pigeons, and they are instinctively terrified of owls. Set your model on the balcony rail and change its attitude or position every day or so to mimic live behavior. To add to the effect, you can get a model owl that blinks its eyes or flaps its wings or a recording of a screech owl or barn owl's call from The Audubon Society and play it out a balcony window on a tape recorder.