The fear of urban chickens run amok seems strong in those who oppose the idea of allowing chickens within city limits.
While I'd like to think that all urban chicken farmers are conscientious enough to care for their flocks for the full life cycle (from egg to bones), the law of averages means at least some chickens will either be evicted (on purpose) or escape (on accident) from their coops and become feral.
Miami, Florida, is a good place to look to see what happens when chickens escape to live on the streets. It's estimated there's over 10,000 feral chickens within city limits, and things finally got so bad that the city government had to step in and do something about it.
Starting in April 2003, the city of Miami deployed the Chicken Busters -- a team of Code Enforcement officers, Firefighters and others -- to round up loose chickens from all around Miami.
How do they do it? Well, "to catch a chicken, you have to think like a chicken."
And the team must be awfully good at thinking like chooks: the Chicken Busters have captured over 6,400 chickens so far and in the process raised over $10,000 for charity.
This MiamiHerald.com video tells their story nicely:
Now, who you gonna call? Just be careful not to cross the streams :^)