I'm in San Diego. I have (had) 13 hens and one rooster. I just lost my second hen to unknown causes. The birds all seem healthy and active, can it be over feeding? I left for three days five days ago and for the first time ever I put out a large quantity of feed. These chickens usually get out into a large yard every day.
I came back to find one dead in the coop. The rest of the flock seemed fine. Still a huge amount of Lay pellets in the feeder, plenty of water. I put them up last night and all seemed fine especially my favorite little mixed breed that hops up on to my shoulder to ride to the coop in the afternoon. She was dead this morning.
That's two in a couple of days and I'm worried now that I'll lose the rest.
Update: Two more losses over the next week. I took the last to a specialist Vet. He told me it wasn't Bird Flu or Newcastle. Not a parasite or respiratory infection.
He advised sending it off for a full necropsy. ($400, out of the question, sorry) It's been a month or so with no more deaths. I switched to organic feed, probably no connection.