Heat is a big issue for me here in SoCal too.
I've mentioned before my chief strategies:
- locating your chickens with the best shade possible
- improving shade by extending shade cloth from your roof overhang
- box fans for air circulation
- water-intense fruits & veggies like watermelon, cucumber & berries; you can freeze them too
- block ice to provide cooling; ice in their water as well
I've just figured out another point and that's
planning. I am now printing out 2-week and, when called for,
hourly temperature forecasts for my zip code. If I know what's coming at me I can accumulate ice cubes in bags in my freezers and I can anticipate in advance what days not to be away so I'm not responsive. I can also watch those hourly forecasts to know when to keep an eye on them and water down a portion of the run if necessary.
I also just discovered that an aluminum catering pan is an available and cheap container for my ice blocks. It works for my small flock. A few might be used for larger flocks and runs. It doesn't take up too much of their run space and it's low enough that they can drink the cool water from it or walk through it if they want to cool their feet and ankles.