Natural Cavity Nester?

I’ve been observing this pair of House Wrens that chose to build their nest and raise their chicks in a hole that is located in an old fence post. The cavity was created when the gate hardware fell out of the post years ago.

I posted about it back in late April: Long Stick – Small Hole

They are feeding chicks, now. Based on the size of the meals, the chicks must be fairly large, now.

It’s hard to decide whether this nest site would be considered a “natural cavity” or a “human offered house.”

What would you say?