Yes I know what you mean, it is hard to tell exactly but we’ve lost two birds in what appears to be the same way. We have a mix of sized hens - no bantams but our Croad Langshan hens are large, sweet, a bit clumsy and I’ve seen them tread on the others so she may have been sat on too. Either way, my husband is constructing a different perch system as we speak which we believe will be much safer for all of them. At least if one sits on another they’ll just drop off and not kill each other. Who knows... Hens can surprise us all the time can’t they?