My Orpingtons did better in the heat than my Brahmas, Colt. In fact, when my late friend, Ladyhawk (Cetawin on BYC) lost most of her flock one day when the heat index where she lived in Kentucky soared to 114*, the ones who survived were her big Blue Orp rooster, Lancelot, a red Cochin and two or three Orp hens, one a humongous one that, as far as I know, was still alive a few months ago at 12 years old. Her Delaware hens, daughters of my late Isaac, both perished. They were all outside, dustbathing under her big front porch, fans blowing on them and had just given the entire bunch chilled watermelon, but soon realized something was wrong and went under there, began pulling out dead and dying birds. I think she lost 14 birds in one afternoon, much smaller bodied than those big Orps. My Brahmas wouldn't have made it, I'm sure. Delawares are not as heat tolerant as folks think. Brahmas pant at 70*, the wusses.
Betsy is probably on her way out at just 6 years old. She is sitting, won't eat, won't even go outside with her flock. I can't do a thing for her, unfortunately, except push food out of her crop and move it along, but it's not the main issue. Something else is wrong inside, I have no doubt.