Most likely a Racoon, or Possum, they both love eggs, and will kill and carry off most small birds. Multiples if they can during one night. I have discovered that Fox have an increadable odor problem. They smell like a Skunk, and will mark territory, where a skunk will usually spray in defense. At any rate, Racoons will upset your plans, as they will enter anything that is open. We lockdown every night, and stil,l some gets under a fence or in a yard, with the resulting loss. The very next thread will show some results for trapping, and one pirate just before being shot.
The losses of our 'pet' and favored birds, hardens our heart somwhat. So we have to learn to tighten up security. Nature, the Mother, is in tune for making a surplus, that all her shildren enjoy. When I lose 4 girls in one night, at $10 a pop, its not so nice, not seeing them greet me.
I have a flight of Red tailed Hawks , and midwest turkey vultures , that patrol constantly. I must defend in a non lethatl way, They are Raptores, and are protected by law, as are the seabirds, ( seagulls, ) that rob my feed, and carry Who knows what infections.
I see no problem in trapping marauding coons, They are tasty if you have the stomach for bare knuckles living, but destroying, or relocating works too. My little Foxy- fox, got trapped with a 1/2 pound chick carcus, and got a ride to the south some 20 miles, to a new habitat. Any relocation has to be a good distance, and not interfere with others.
Bottom line, chickens tend to be escape artists, and Racoons breakin artists, that expidite the smallest chinks in your thinking. Good luck keeping them at bay.