I don’t think it’s in an animal’s instincts to make a lot of noise when they are guarding young out in the wild. That can attract the wrong kind of attention.
I was going to mention the same thing. Folks do not often consider the pack instinctive mentality of the family dog. To them, we are simply their "pack". That pack has a hierarchy that they understand completely (at least in their mind). There is an Alpha and they have their place as well. It is ingrained in their instinct, once the bonds are established, to be with, protect and support the pack. We have a terrific lab. For some time, when my son was younger and she was a pup, she had some issues competing for dominance over my son (this was a bit of a problem at times). She played a little rough with him. She is a great watch dog and alerts whenever someone comes on the property. She doesn't like strangers at the door unless me or my wife acknowledges them.
She does have one particular behavior that we have not been able to fully explain. When I (the pack alpha male) is around, she mostly ignores or at least tolerates other dogs. If I am not around, she can be nasty to other dogs when they approach, especially in her yard or with my kids. These are the neighbor's pets I'm talking about. We joke that in our neighborhood, she is the dog bully.
I love a good dog.