Regarding Perchie's concerns about licensing -- I know a chicken license sounds kind of ridiculous, but we're proposing a one-time "Food Producing Animals" (up to 8 hens and two dwarf dairy goats) license as an alternative to Denver's current crazy, bureaucratic, expensive permitting process. Right now if you want even a couple of hens you have to get a permit from both Animal Control and Zoning. The process takes 2-3 months and costs between $150-$250 for the first year, with a $50-$150 annual renewal. So, compared to that, a one-time $20 Animal Control "license" (with no vaccinations required) seems like a good deal.
And thanks to Eileen for her overestimation of my abilities to craft legislation, but I did not singlehandedly draft Denver's proposed ordinance. It was written in cooperation with the Director of Animal Care & Control plus staff from Community Planning & Development, the Department of Environmental Health, the City Attorney's Office, and City Council. We spent a lot of time reviewing successful ordinances in other cities, and talking to staff in those cities (primarily Seattle, Portland, Los Angeles, Chicago, New York, Fort Collins, Longmont, Colorado Springs, and Littleton). The proposed ordinance was passed unanimously through Denver's Planning Board, and received the support of the Mayor's Sustainable Food Policy Council.
All that being said, the proposed ordinance is still in draft form. We're considering scrapping the minimum space requirements for shelters (seeing as how so many other cities don't have them, and it's hard to come up with a good definition given all the possible variations with nighttime/daytime shelter options) and instead instituting language that the shelter must be "adequate to safely contain the animals." This does not seem to be an unreasonable statement. Along with the Animal Control license, future chicken owners would get a packet of information that includes suggested "best practices," including what I always instruct students in my chicken keeping classes -- more space is always better (in my opinion, anyway). Decide the maximum amount of space you can dedicate to your chickens, and give it to them.