Killing multiple birds during the day?

I hate this to be my introduction to the forum, but I've encountered a bizarre pattern of predation with my chickens. This spring we received 7 older birds from a friend. They soon became a part of my daily routine. As I am home all day, the chickens quickly became free range birds. They never left our property and normally could be found around our back porch or following my two German Shepherds around.

Last week something came in and killed 2 of our birds between 7-8 AM. I noticed something was wrong when I saw the chickens in our neighbor's yard. I found the first pile of feathers by the milkhouse, and quickly identified them as coming from my barred rock. I followed the feather trail and discovered her partially consumed corpse under some brush. My dogs then alerted to another pile of feathers, which had come from my leghorn. We tracked the trail via scent and feathers from my back yard, to the front yard where there was another pile of feathers, and I could see another puff of feathers across the street in the neighbors yard. I called my other chickens back to their pen and locked them in. I had my husband remove the body for burial and we bated a trap. That night we caught an opossum. From what I saw I guessed that the attacker was either a fox or a coyote. The fact that the animal would leave a partially eaten bird to attack another is extremely perplexing.

The other chickens were kept in their pen and run until today as I was going to be outdoors most of the day. I went inside for lunch around noon and at 1PM went back outside. I noticed one of my wyandottes lying on the ground near their dusting location which is 10 feet from my back door. Upon closer inspection I saw that she was dead from a broken neck. She was still warm and there was no saliva on her feathers, nor blood on her body. All feathers were intact. I have searched all over and cannot find my other chickens. Nor have they come home to roost. I have not found any feathers either. The dogs never barked (they were inside), nor did my chickens make any alert nose. I am devastated, angry and confused. My husband bated the trap with her body in the hope that the predator will come back and be caught.

I have lived with free range birds my entire life and cannot figure out what predator would do this. This attack happened in the middle of the day, 10 feet from my house, multiple birds disappeared, and nothing made a noise. Further nothing has shown up on our game camera which we keep pointed at the coop. Does anyone have an idea of what this predator may be?

 

3 Birds returned to the coop. I'm glad that they are safe.