Ever notice how you watch out for other people's children (sometimes muttering "what's wrong with the mother???") ... once you're a parent, it's (ahem) apparent that you can't turn off the mothering/parenting instinct.
Once you're a mother, you're a mother to the world.
You can't help it. You notice things. You can't *not* notice things. If you see a child wandering toward a street, and the child's mother happens to glance another direction and doesn't notice the wandering child, you don't *not* do something. You either rush forward to stop the child (if you're not worried about someone screaming "STRANGER!!!" .... followed by "POLICE!!!") or you yell to the mother to get her to notice what's going on.
You don't let harm come to children .. no matter what age.
Once you're a mother, you're a mother to the world ... and apparently it's not limited to humans, either.