I have been raising chickens for about 4 years and I thought I had this all figured out but I need to get some input from some other minds on this one. I have had many many chicks raised here by broodies, by incubation, and by purchase and I have never had this kind of mortality. I am not sure when a chick becomes a chicken, but these birds are about 3-4 months old. They were hatched and raised by three broody hens. I captured moms and the chicks to "keep them safe", but this isn't working well. These chickens are living in a 10 x 10 covered dog run, they now have a heat lamp just to be sure, but still losing the young chickens. I know it is not predators as they have an electric fence around them and no sign of any damage on the dead birds. Sometimes they are dead on the ground, and sometimes in the cage they sleep in. There are now only about 6 young chickens left in this pen, but about 8 mature chickens live in there as well. Over the last 12 weeks I have lost probably 10 out of 16 chicks. The first 4 were young, less than a month and I figured it was them getting beat up or stepped on by a grown chicken, or maybe just bad genetics. At first they were with thier mom and she was keeping them warm at night so I know it wasn't cold. I brought the last 2 of those 4 inside as they didn't look well, but lost them anyways. When I started losing chicks from another hen I started to get worried, and then from yet another hen. It would be one or two a day and then none for a week and then another, no pattern, and only the young ones. My first thought was coccidia so I treated for that in the water for 5 days, two different times. Still lost birds. Next thought was the bird that was growing up to be a big rooster, so I moved him out into the goat pen. Next thought was too cold, even though CA isn't really cold and the birds are way beyond fully feathered and have a cage with a perch that they get in and on. So DH gave them a heat lamp. They also had their moms to keep them warm, even though they were big birds. Next thought was mites or lice as I found one on a chick that is in the house with wry neck. So I treated the entire pen, birds and ground with poultry dust. I had 3 young chickens living in my house as a last ditch effort to stop this dying streak. One of them developed wry neck so I have been treating that and it is getting better. The other two seemed fine and I decided that they needed to go back to the coop. They were in there 2 days and I found one dead tonight. This morning it was fine.I have been watching this group closely for tell tale signs and I usually I see nothing. The one with wry neck was a little "off" before the neck thing started, but other than that I have no clues. What the heck. I just moved 12 more chicks into that pen out of desperation tonight. They are 6 weeks old and fully feathered. This weekend I am moving all the adult chickens out (it was supposed to be a temp. breeding pen and now it is a nursery). I had to move chicks out of the garage as tomorrow I will need thier pen and heat lamp for some unexpected arrivals. I had a broody desert her eggs and they are hatching in my incubator right now. My other incubator has eggs set for the New year day hatch, and my Eco-Glow warmer is in getting repaired. I was not counting on these chicks from the broody. I also have to move the wry neck chick out of the guest bathtub. Luckily Christmas guests will only be my 2 sons and they are the ones that started my chicken addiction. Any ideas, thoughts, suggestions? I am all ears.