Back in July I had a rooster that I had hatched out in March. We were out of town and my son was chicken sitting. He called me and said that roo was dead, on the ground with some of his feathers plucked off his back. I posted here from my phone wondering what in the world it could be. I thought maybe he just dropped dead from the heat and the others were pecking/plucking him. He was a very large for his age roo. Consensus was that it was possible that something got into the run. Problem was, there was no blood, no marks, no injuries and it was very fresh. Before then, and until this day I've never had anything get into the run. I still don't know what happened to him. After my little frizzle roo died from Mareks I would've liked to have had a necropsy done on that other one, but my son disposed of him right away. That still wouldn't have explained the bald patch on his back.
I know how it is to feel stumped, for sure! I just can't think of anything that would take 2 in one night, even heat.