An Owl or Falcon decoy make a very effective bird repellent. These work as a bird deterrent by replicating the look and size of a real bird of prey. Most garden birds will recognise the outline of the falcon or owl decoy as a preditor and scare it sufficiently to keep away at a safe distance. But birds are not totally stupid and after a period of time, they realise that the deterrent predator hasn't moved for a few weeks and so you might need to move the decoy bird to a new position in your garden or allotment once in a while.
One of the most hated of all bird pests are Pigeons (AKA rats with wings). If your question is: Will a decoy Owl or Falcon scare Pigeons away? Unfortunately the answer is not clear cut. For example, we might get a customer who will order a decoy Owl or Falcon and then phone a week later to order more. However, sometimes we get emails with a photograph of a pigeon sitting on the head of the bird deterrent. With pigeons, sometimes a bird repeller works superbly, but at other times it doesn't.
Having said that, of the decoys we sell, the Action Owl with a rotating head gets more consistently positive results with pigeons. It probably has something to do with the movement of the Owl's head in the breeze that acts as a great bird repellent.
All of the decoy repellers are a plastic, hollow, moulded shape with a removable bung in the base that you can fill with sand or soil to give the bird repellent some weight and stability. None are supplied with fixings, but its not too difficult to drill a hole through the plastic and secure the bird decoy with a couple of wood screws to a fence post etc.
Positioning any of the decoy requires a bit of thought. You have to imagine how it will look from a birds eye point of view as it approaches from 100ft in the air. Although you might want to hang the Flying Falcon decoy from a branch of a tree in your garden, when trees are in full leaf during summer, an incoming bird probably won't be able to see it at all. If you can, find a raised location to position the decoy such as on the corner of a garage roof, or on a pole. Or even hanging the deterrent from a washing line!