Good hardy chicken breeds?

[hartlover]

I live in a desert. Summers here reach 115 F and winters can reach 30 F at night. My family is looking for good survivor chickens because we keep loosing them to the heat, mysterious illnesses, and dogs (sometimes our own).
Mainly, they are for egg production purposes. (Family is a little squeamish about the meat idea)

What we need is,

-High egg production (preferably 5+ a week)
-Extreme heat and cold tolerant
-Foraging skills (we would like them to get most of their own food. Mostly what they eat here is weeds with the occasional insect because it's so dry and irrigation is currently out of our reach.)
-Disease resistant
-Capable of fending for itself. (knowing when to run and when to not take bull from our chasing 10 pound poodle mix)

What we've had,

Barred rocks: Most susceptible to heat breed that we've had. They only laid less than half of the number that we had. They can peck each-others butts to the point that they kill each other when they are confined.

White leghorn: The most egg productive for sure. They are so flighty that they fly over the fence into the back where the boxers make short work of them. One of them would dive under things and get herself stuck, thus she's the only one that's still alive. This same one got broody, twice, If you'd believe it.

Andalusian: Even more flighty than the leghorn. Egg production was almost as good, although not as big. They would explore until they got lost or stuck.

Red Star: Our favorite so far. They are the most friendly. Egg production is impressive (more than andalusion, less then the leghorn) They slowly died off one by one from some sort of illness.

Rhode island red: They are our newest batch (the pet club employee said they were red stars) They are over 7 months old and have yet to lay eggs. They are terrified of our single little leghorn that is half their size, including the big surprise rooster. (there were two but one was killed by the neighbor's husky.) One recently died from illness. She was very slow and weak, felt like she weighed an ounce, and had scabs all over her face and comb.

Currently interested in,
Speckled sussex
Welsummer
Easter eggers
Possibly the dark cornish

Is there any I haven't mentioned that could help?

 

[Michael OShay]

I would suggest Black Australorps. I've raised them for years (along with dozens of other breeds and hybrids) and they are extremely hardy. I've raised them in CA where summer temperatures frequently reached 117-118 F (123 F once), and in northern Kansas where temperatures dropped to 30 F below zero one winter, and in both climate extremes, they came through like troopers. In addition, they are calm and gentle (my children, and now my granddaughter, made lap pets of them), they handle both free ranging and confinement well, and they are the best layers of the standard, brown egg laying breeds. A Black Australorp holds the brown egg laying record with 364 eggs in 365 days, and while none of mine have ever reached that kind of production (and likely never will), I've still had some of them lay more than 300 eggs in a year. Whatever breeds you decide to go with, good luck with your flock.