It’s still some distance away but he can definitely make it out and stands slowly to see where it is coming from. He can see them as they travel towards the town along the narrow country road from the direction of the hump back bridge and consciously changes the focus of his hearing to listen for the sounds of marching. They’d surely be drawn to this racket.
But there is nothing. Total silence… At least from the main body of drones, wherever it was.
The smaller groups have heard it though and the closest of them can be heard yapping and grumbling as they become agitated and alerted to the sound of the approaching engine. They can’t see it yet but it would only be a matter of seconds before they give them a target to home in on.