Netting seems by far the most effective method to keep pigeons and other birds from resting on buildings. Truth is that many pigeons get trapped in the nets and badly injure themselves or die a slow and agonising death virtually undetected by anyone. Luckily there are groups and people like Sidney Barret who highlight the plight of the pigeons and who want the netting reviewed as a method and periodically checked for weaknesses that allow birds to get entangled and trapped in the first place.
Visit other pages mentioned during the interview:
Facebook page: Ban bird netting on buildings
Facebook page: Pigeon protection and rescue action group