This region has ground squirrels. Their holes in the ground can range from 8-10 inches up to a two foot hole in the ground.
I am unable to get a ruling by the book as squirrels are not included , when my ball lands in a furrow or den of these pests.
A close friend was playing a qualifying round in Sacramento and one player of the foursome would not concede it was a bouroughing animal home, when in fact it was a ground squirrels home, citing the rule book "Squirrels do not count"!
It cost him a qualifying spot and while the local rules cover the ground squirrel hole, USGA rules do not.
Has anyone seen a newer rule to cover ground squirrels? These little critters run up to 25-30 per colonly on hills on courses!