I saw several ground squirrels using these burrows while my softball team was warming up in the grass. We even saw a few of these squirrels run onto the grass between innings.
The squirrels do not show up in the photo, but I know at least one is somewhere in the photo, and my coworker (Miguel Ordenana) said he can tell that these are ground squirrel burrows.
In Los Alamitos, California
Caspian or Royal?