We hatched 4 of our own chicks a couple months back.... One died in my arms and one had a hard struggle with curly toes and being smaller. We gave him vitamins and sugar water and nursed him back to strength, made him little booties and his feet straightened out and we named him peeps cause he peeped so much. Andy way they were doing very well so DH has been introducing them slowly to the rest of the flock (16 Red Sussex Cross)..... always being in the coop with them to protect them.... Well the other day he put them in the pen and just was going to do a couple of things and come back and see how they were doing..... he forgot about them. 2 hours later we came back, peeps was dead and the other two were bleeding and very in shock. The weird thing was that peeps had no wounds like the other ones. he must have just had a heart attack. We felt so horrible. We both had sick stomachs and wanted to crawl under a rock. The kids were sad. Lesson learned. do Not leave your chicks alone with grown up hens!!!! the two that survived we weren't sure they were going to make it but we gave them vitamins and made sure their heat lamp was nice and hot, prayed their wounds with colloidal silver and they made it through the night. And the next day so we dared to hope that they would be okay and they seem to be doing good now again.
It's good to lean some boards and other things around your coop so the chicks have somewhere to hide. It's also a good idea to let them be pretty close in size before introduction. I'm sorry to hear that this happened.
