Spike systems with a variety shapes and sizes are available for use against pigeons, gulls and other birds. Where spike systems are to be installed, the surface must be properly prepared. Remove all dirt, bird droppings, loose and flaking paint, old adhesive, grease and oil. Ensure all surfaces are clean and dry. When installing on stone work a neutral curing silicone adhesive is recommended or when attaching to a wooden surface the spikes may be nailed. Gaps between adjacent rows of spikes or between spikes and back walls should not exceed 65mm for pigeons and 100mm for gulls. Angled wires are more difficult to penetrate and the closer together they are the better the protection. Tips of angled wires should slightly overhang the front edge of the surface to prevent birds from landing.