Pigeons have a natural hatred for water, strong scented spices and sticky surfaces. If a person wishes to remove troublesome pigeons in a harmless way, methods involving these items may be effective.
Due to their hatred of strong scents, a generous coating of spices on ledges can be a effective pigeon deterrent. Garlic powder, cayenne pepper and cumin are excellent, inexpensive spices to use. A more expensive method is to install sprinklers or motion-activated water systems on pigeon inhabited rooftops. These systems spray the pigeons with water as they land, and when used consistently, pigeons will associate that rooftop with the uncomfortable spray of water and avoid the area. A chemical spray that leaves a sticky film can also be sprayed onto ledges as a tactic to deter pigeons from an area.