No,I did have a Guinea wander up once,but the dogs injured it and it only lived a week.I would check and see if your neighbors are missing any chickens.Are you quarantining these chickens before adding them to your flock?
Probably belongs to one of your neighbors. Ask around and let them know to keep their birds contained, some neighbors may not be so welcoming. My old neighbors shot my rooster for his trespassing lol.