Leave them alone

I'll agree, pigeons can be messy. But they're birds just like robins and even bald eagles. They just happen to be grey and don't have very good PR. That doesn't make their lives any less valuable, though. I'm sure you don't classify living things by how "pretty" or "non-messy" they are. If you did, then you would have to "rid the neighborhood" of children (very messy) and all housepets that aren't purebreds.

And to answer your question, no, the city does not provide any assistance to private homeowners who want to kill wild animals on their property, and neither does the homeowner's association. And ridding the neighborhood of these birds by using poison is a terribly inhumane way of dealing with them. Not only do these peaceful creatures (they are close relatives of doves) die an agonizing death which can last almost three days, but poison is indiscriminate. While you're poisoning pigeons, you are killing all other birds like robins, sparrows and finches. You also risk poisoning your own or a neighbor's housepet, as dogs and cats prey on birds who are weakened by poison. Animals who have been poisoned suffer terrible pain and convultions for hour after hour. It is not quick and painless.

There are a few things you can do on your own, though. Place screen and other barriers (like nails or bricks) onto or into any area where the pigeons like to congregate. If they don't have a flat surface or ledge on which to sit, they'll go somewhere else.

You can also try an owl or hawk decoy to scare them away, although I think they're onto this one.

Good luck!