It’s always a good idea to open the barby lid before firing the burners: sometimes unexpected things appear:

The mouse being out and about at the time, I dumped the nest (which was just a foundation) over the patio railing into the flower garden, burned out the remainder at full throttle, and continued the mission.
A week later, the mouse had not only returned, but finished off a substantial nest in the same spot, topped with a jaunty bird feather. The entrance tunnel is on the right, opening into a comfy mouse-sized pocket inside:

Once again, I dumped the nest over the railing, burned out the rest, and continued the mission.
As of three weeks later, the mouse hasn’t returned; I trust it found a hollow log somewhere out back.
As nearly as I can tell, the mouse climbed up a square steel leg, scampered through the grease catch pan, leaped up through the drain hole, wriggled through three layers of crossed bars, and then deposited a single mouthful of building material.
I really need a critter camera…
















