Welcome to Backyard Chickens! We are glad you joined the flock! BYC is a helpful site providing all of the information you need to know about poultry. There is always space for more members on the BYC roost! In what condition are your chickens in when you find them dead? A predator would leave obvious signs of wounds, blood or a missing head. A contagious disease is also a possibility. Hope you enjoy it here as much as we all do!
Sorry for your losses. It would be best if you discussed them at "Emergencies, diseases, injuries, cures,"thread." You can assist them by providing all the symptoms you have observed.