Holes appearing in yard!
I have recently noticed holes appearing in my yard. The first was
discovered when digging our pond. There was a perfectly round hole,
several inches in diameter, quite deep, nearly the length of a shovel
handle. It looked as if were machine made, it was smooth and perfect.
The next hole occurred near the rear of the house, a bench collapsed
into it! Today I noticed another, around the corner from the last one,
through the gravel in the side yard. I am in the middle of Los Angeles,
the only "wildlife" I have are birds, squirrels, feral cats and rats.
What could be causing these?