I came across a blog post from someone in the Phoenix area about keeping chickens cool in summer. I found the included photos very helpful.
http://tbnranch.com/2011/08/02/keeping-the-chickens-cool-heres-how/
(Won't it be funny if the person who wrote it is a regular here?!!)
Ok, with all this discussion, I have to chime in. I firmly disagree with several things in this article. First and foremost is that we shouldn't pamper our animals this way. It does much more harm than good. Mother Nature has allowed warm-blooded animals to acclimate to their environment without the assistance of us pesky humans for thousands of years. Just look around at all of the animals that not only survive, but thrive in the desert. Coyotes, mountain lions, javelina, hawks, eagles, and then list goes on. Our pets are the same way. An animal who is kept inside all the time will have a far more difficult time handling the heat than those kept outside. They shed their winter furs and molt their winter feathers in exchange for their summer counterparts. We see it in humans every year, too. The countless people rescued off the mountains from heat exhaustion because they don't maintain an active outdoor lifestyle year round. They decide to up and go hiking during summer, and even in the 80s and 90s, many end up in distress. It's all about how you prepare for it.
Not to say there aren't a few reasonable steps to take to ensure an adequate environment, but frozen bottles and misters being changed hourly (like several mentioned doing last summer), is not natural or healthy for anyone. I will agree with their blog in terms of getting rid of the standard watering containers. Ceramic crocks and insulated containers like Gallo's five-gallon bucket are more than adequate to provide clean, cool water all day. You don't need to be changing them out constantly. Likewise, a properly installed system plumbed directly to your water line will provide an endless supply of cool, fresh water for a minimal amount of money, too. No matter how you do it, keep it in the shade for the most benefits.
I think misters and fans are overrated in all but the most extreme heat. Put all that extra water in to maintaining a nice, lush lawn and you will get far more benefits out of it. Below is a quote of a small experiment I did last summer here at my house. The difference in temperatures between my rock and dirt from yard compared to my backyard lawn were just astounding to me. But that brings up another point in the above blog that I disagree with. All of the "ground litter including hay and straw" doesn't "hold in the heat" anymore than it holds in the cold. It acts as an insulator and regulates the temperature more than just barren ground. And a lush grass lawn does not use an excess of water. Properly maintained, it actually uses very little because that insulation the grass provides helps prevent the water from evaporating and allows it to be absorbed in to the ground. Check in to Allan Savory and his desertification theories about this topic!
The only other two things are plenty of shade and a well ventilated coop, just like Jacie mentioned. I'm sure this seems very counterintuitive to many, but commercialism has caused us to stray so far from holistic management in order to sell their products. Joel Salatin and PolyFace Farms have this figured out and all of us should take his advise to heart. Less is really more, far more. Let the animals be the animals the way God intended.
SO, with our discussion early regarding grass, xeriscaping, and temperatures, I decided to do an unscientific test of the various parts of my house. I started by sitting in the backyard and calculated how many sweat droplets appeared on my arm in 60 seconds... I cooled off inside and repeated the procedure out front... Just kidding!!!
What I actually did was to place a digital quick-read meat thermometer in each location and allowed it to sit until the temperature stabilized. I wasn't really surprised the results, but it makes me feel a whole lot better about my setup... And it explains why they prefer sitting in the shaded grass below the slides
Backyard
Shaded Grass: 88*
Sunny Grass: 97*
Shaded Porch with Ceiling Fan: 111*
Inside the Coop: 112*
Front Yard
Shaded Rock: 119*
Sunny Rock: 127*