That sucks Clint .
I would think fox . We have Hawks ( birds of prey ) and they usually hit the head first .
Are you around next Monday or Tuesday ? The boat leaves port Wednesday

It happens in the middle of the day so that probably eliminates most.  Not a bird I can say that for sure as no bird will kill 8. Coons are slowish and at night and again a coon would not kill 8 birds in a 2 hour window.  Weasel or fox is my guess and I am leaning towards weasel.
 

During the day your for sure on the right track saying weasel. Possibly a mink if you have them in your area.

We had weasels get in our club's pheasant pen and they would kill a dozen or so birds. They'd eat out the throats than go after the base of the skulls. It took awhile to get rid of them with trapping and poison. The poison had to be supervised by the game warden.

Well the fence is up, I will build some weasel boxes tomorrow.  Could be a mink as there is a small trickle of a stream within 100 feet, but had the same massacre when we kept them in the barn last year and that is 1/4 mile away.   

You could try some sand or soft dirt around the perimeter of the run to show footprints, my guess would be the predator returns regularly now looking for a weak point in your defenses. 
Weasel would be highly on my list of suspects but don't forget the possibility of feral dogs...they can be pretty brazen. 

Or even a fisher or a martin 'round Parish

I'm putting my chips on foxies

Look at the upside Clint, you at least have a good supply of feathers for tying flies.

I think you have a weasel problem,I saw a Mink yesterday while walking my best friend in a city park,that was cool to see.