I don't understand how the city can force anyone to take care of a nuiscance WILDLIFE problem.
It happens frequently right in St. Louis, as I have been involved with some of these situations. The only wildlife service I provide in St. Louis (or any of Missouri) is dealing with bats. When animal control is called to get a bat from a residence, it is reported to the department of public health. After the 2nd call to the same residence, the owners are
required to have the bat problem resolved. On the 3rd call, the residents can and often are
evicted from their home by DPH for safety reasons.
Illinois DPH forced a local building owner to evict all renters from their second story apartments in an older brick structure (business building on a main street). Bats were getting into the living quarters every night for a 5 day period. The owner had me inspect the building and I provided an estimate for a complete bat-proofing and exclusion program, which she refused. DPH called me and wanted to know why I wasn't taking care of the problem. I told them she was not going to pay for the service, and they shut her down the next day.
Some people think these measures (by the states) are too harsh, but the DPH is responsible for human safety, and when people are in a dangerous situation they will take whatever measures necessary to protect the residents. A local school (Shelbyville, IL) was recently shut down for several days due to bats inside the ceiling areas (300 to 500 bats). There was a chance of Histoplasmosis spores possibly being airborne through the ventilation system.
Regarding the pigeon issue, if outside city limits I would give the owner a bid for shooting (reasonably priced), one for trapping (considerably higher), and netting or other roost inhibitor installation (extremely costly). If the mayor can't prove this is a serious health issue, the owner should tell the city board that he will pay for the least expensive method, and if the city wants a complete exclusion program, fork out the money for the difference.
BTW..... shooting or trapping will NOT provide a solution unless followed up with exclusion work. The favorable conditions that attracted these pigeons will also attract "replacement" pigeons to the same location.