In PA it could be any conceivable predator, i.e. raccoon, opossum, mink, coyote, fox, even bear, etc. One predator will often kill all the birds, consume what it can and plan to come back for the rest. Other animals will clean up what it doesn't consume if they are around.
Based on your coop dimensions you should go with 6-8 birds, You can add more later so start with less. Eight birds supply more than enough eggs for our family of 4. In fact, I sell some of the eggs making enough to cover the cost of feed and nesting material.
Our coop is a 5x6 and our run is...
I just wanted to chime in on this with my experience.
I am in City of Columbus proper (43209 near Bexley), not connected with any other corporation or city limit. In 2018 we received our permit for chickens. The experience was not much different than what the original poster indicated. The...