cornish rock cross dying

[carriagemasters]

I have 51/2 old Cornish rock crosses. I came home yesterday and one was dead upside down on his back. Wasn't sure if it was the heat....it was88 degrees, but I have a swamp cooler blowing on them all the time. The rest of them seemed fine, not too hot with plenty of food and water all day. Last night the temp was around 60 and this am another one dead, again upside down on his back. I think it might be "flip" something I found on a thread here. Any ideas or help??

 

[Robinsonpoultry]

It may be the birds can't move quick enough. Surprisingly the other birds will trample them to death. Just another Possibility.