Murder Mystery

I made a gruesome discovery yesterday morning.   The half-devoured body a barred Rock hen lay out in the open in the chicken pen.  How could this have possibly happened?  With no hiding places, I could not have missed her the night before and left her outside in danger.  Opening the doors to let the others out (after removing the remains), I found the crime scene inside.  Over time, the big door had warped, leaving a gap at the bottom; a gap not so big I was worried about the chickens getting out, but evidently big enough to allow a small or thin predator in.  Feathers on the floor told the tale.  When chickens sleep, they sleep deep.  I doubt they raised an alarm when the murderer entered, made its choice, and struck.  The flock had obliterated any footprints, so I have no idea what could have climbed the fence (nothing had dug under), squeezed through the opening and then dragged the prey outside.  The killer remains unknown and at large.  Last night I jammed a board up against the door, effectively closing the gap after the little kids were tucked inside.  I'd rather read a murder mystery than find one.