You see, trying to remove pigeons from an area just doesn't work. Poisoning them simply creates vacancies for pigeons from the surrounding area to fill. If the ledges, nooks, and crannies on buildings are ramped, obstructed, screened, or blocked off, pigeons won't be able to nest or roost there. If palm trees are kept trimmed and pet and other food made unavailable, the birds would become scarcer in that area. Of course, keep in mind that pigeons are a lot of fun for people and many want them around.
Pigeons are often the only nonhuman life in some otherwise bleak urban landscapes.
Killing the birds is similar to bailing out a boat without fixing the hole in the bottom. Kill some birds, others take their place. What a horrible travesty that is. Judging from the calls I get from shocked, saddened, or infuriated customers, tenants, or neighbors in effected areas, I estimate that hundreds of thousands of birds are brutally murdered in the Phoenix metro area every year. If left alone, the pigeon population limits itself to whatever the nesting sites will support.