I think we are pretty close to being on the same page. My electric fences work to keep the birds in as well as dogs and predators out.
The shoot em method does have that serious flaw. Even if I am willing to shoot whatever comes around, that requires that I be there at the time, and on alert, locked and loaded and ready and willing to shoot. In the past, I was once startled to see a strange dog on my front porch........I'm on 10 acres, and 100 yards from the road.....but there it was. German Shorthair pointer on my front porch.....no more than 100 feet from where the birds were hanging out in the back yard. Dog's owner was a nice young lady who was riding her horse down the road and letting her dog......that dog......run around with her on her ride. It wasn't loose....it was running with her...out on a nice walk. Yet it chose to leave her side and ranged out to my doorstep. So I could have been faced with the choice.......get up.....get my shotgun, keep an eye on it and if it crossed the fence and started after the birds.......gun it down......then explain to the young lady about consequences and all that. She could have done nothing to stop it in time and she was right there......as was I. What stood in it's way was an electric fence.....so I never budged or gave it any worry. It left, unharmed, as was the case with the birds.....unharmed. But death was that close.
I have seen other dogs who have gone after the birds, then tangle with the fence and they leave in a hurry....still very much alive......and never come back. That was with me there to witness the event. No telling how many times that scenario has repeated itself that I don't even know about. I think of that really hot electric fence as being like the goats blood over my doorway. It is what allows death to pass me by. More like encourages death in it's many predatory forms to leave the birds alone.