Do spikes keep birds off buildings?
In some cases spikes can be very effective in keeping birds from landing on ledges and other surfaces. Spikes are meant to deter larger birds like pigeons. They are not as effective for sparrows. Spikes fail if the target bird has already selected an area to build its nest. Instead of giving up the newly spiked area, the birds will simply drop fresh nesting materials on the spikes until the points of the spikes are no longer a factor.
