"Everything was completely normal before the apparent "attack". No signs of stress, they are pretty happy birds free ranging during the daylight hours. No symptoms were noticed, and we observe them quite frequently. After the event, I was looking all over for her and figured she was snatched by a hawk. That's when my friend said she was hiding in between a sheet of OSB and the fence (a tight spot), but that had been more than 2 hours ago. I fished her out and she immediately ran to another hiding spot. That's when I separated her from the others."
The behavior described is VERY indicative of an attack, but not a chicken attack by flock mates she knows and is familiar with. It is indicative of a predator encounter and most likely a hawk. Most birds, chickens and pigeons in particular, have an instinctive and indescribably intense terror of "the shadow". Once chased by a large Coopers or similar hawk...and they will follow them right inside the building sometimes...the bird can be in a state of near shock. This could cause it to react strangely and make it a target of others. Hawks can harm the bird without it being obvious. Small punctures that become readily infected due to the filthy nature of the predators claws. Your bird could be stressed by an attack, followed by infection which may or may not lead to a latent disease coming forth.
Our old dog, bless him, was the greatest flock master that lived. A huge dope of a dog who could go from 0-30 mph in about 3 seconds from a sound sleep and launch himself in the air high enough to scare a large Coopers into dropping a shrieking Silkie hen. He nearly caught that hawk, but it is the chicken you need to hear about. She ran for cover like a rabbit. When I found her she would not move and only huddled. She ate and drank sporadically for 3 days and then abruptly died. Something to consider even if it is a bit of a stretch. Still....sounds like a near miss by a predator.
