Did you have the led closed? The only time I've seen dead birds in a tote is when the led was closed. It's because of lack of oxygen. In fact, the led should never be closed.I have tried to brood a total of 60 chicks (20 at a time) in plastic sterilile tubs, you know... the ones you get at wal mart. All three broods died completeley. I am trying to find out if the plastic is bad for the chicks. On the other hand I have a really crappy Post office that lets the chicks stay overnite before they call me to come pick them up. This was on all three broods. Is it the plastic or is it the fact that the chicks were in the shipping box without food & water for 96 hours (4 days)
If you didn't have the led closed, then I'll assume that it was something else. Dehydration, too cold, etc.