Preheat oven to 350 F. Sprinkle salt and pepper on outsides of birds. If they have been skinned, place bacon strips over them. Bake in a covered roasting pan in 1/2 inch of water for 1 to 1 1/2 hours. You want the meat to fall from the bones.
Cool: remove all meat and put through the fine blade of a meat grinder or use metal blade of food processor to mince finely. Add 1 tablespoon grated onion, egg and butter. Mix in sour cream to thoroughly moisten mixture and make it spreadable.
Add salt and pepper; mix well and pack in tightly closed jars and refrigerate or freeze.