Electric wire around and heavy-duty poultry netting over the run would not be overly expensive, and would keep your birds in and most predators out.
Free ranging birds are simply too attractive to not get noticed sooner or later by predators. Remember that if they do not hunt and kill, they do not eat - it is perfectly natural for them to look for easy game. It is not personal or malicious on their part, just a matter of survival. And no matter how many you kill, there will always be more, so killing whatever happens by your house is not an efficient means of protecting your birds. Some folks figure they will loose some birds and can tolerate that in exchange for letting their birds roam at large, and that is fine too.
Free ranging birds are simply too attractive to not get noticed sooner or later by predators. Remember that if they do not hunt and kill, they do not eat - it is perfectly natural for them to look for easy game. It is not personal or malicious on their part, just a matter of survival. And no matter how many you kill, there will always be more, so killing whatever happens by your house is not an efficient means of protecting your birds. Some folks figure they will loose some birds and can tolerate that in exchange for letting their birds roam at large, and that is fine too.