The new magpie arrived today. This is the young bird of this year. All its behavior shows that it was raised by humans. What happened next is not clear: the bird either escaped or it was released without any preliminary training. In any case, it cannot survive on its own.
Unfortunately, I do not now have adult birds that could help it to become feral. All the magpies I raised this year are already living on their own. Thus, Mag will stay with us until spring, and perhaps forever.