I had 4 out of 24 dead the morning after a thunderstorm. Weird. They all were in the same corner of the tractor, out from under the tarp. We only got 1/2 inch of rain, so they didn't drown in standing water. This happened about a week ago when they were about 4-5 weeks old. Any ideas? We are expecting more thunderstorms this week and I don't want to lose any more if there is something I can do.