There is no exact formula for the number of Hawk Bird Scarers required. Every property, crop, type of bird, feeding habit, climate etc all combine to produce a different set of conditions. Where one Hawk Bird Scarer would be suitable for the domestic back garden or pleasure craft, more would be needed for a large commercial crop. In ideal conditions and when suspended from high trees, two Hawk Bird Scarers have effectively kept 2ha free of any major bird damage. More Hawk Bird Scarers are required if conditions are not ideal.