-Clean off area where Pigeons are nesting with power washer or hose.
(There are soap additives for the power washer also to assist with the cleaning process.
-Apply bleach to cleaned off areas.
-Attach Bird Spikes to area with adhesive that comes with the spikes, exterior liquid nails or screw them into the surface.
-Spiked Mending Plates also are a good option and are very inexpensive.
-For alcoves where the Pigeons nest, like inside and under roof tiles, block areas off with Hardware Cloth better known as chicken wire by wadding it up and wedging it in the alcove or screwing it to the home.
Pigeons are disease, germ and bacteria infested birds, you MUST make sure to wear gloves and a mask when cleaning off their feces.
Keep on top of this or they will keep coming back again and again!