I had a radio on at night in my barn because my game camera died. Not sure if there were any predators came around then or not. I have since replaced it.Sounds like a fox. They watch, and knew you were gone. They kill as many birds as they can at once then take them away, and will keep coming back until they're all gone. They leave little trace of what happened.
As @dotporter said, a radio turned on will keep predators away. They won't come around human noises and activities. As well as electric fencing.