I have holes like this all over my yard. This area is worse than most of the yard. This is near the base of a full grown tree. I know I have lots of gray squirrels and chipmunks. Any ideas on what is making the holes, and how to get rid of whatever it is?

Those holes are probably from chipmunks. Here's a guide to some common holes: http://www.icwdm.org/Inspectio...

What a cool site you linked Tee!

Thanks, Ann.

Thanks for the link. The holes in my yard look identical to the I picture of the chipmunk holes. Any ideas for getting rid of them?

Havahart brand makes a humane trap for trapping and releasing them elsewhere. Sometimes it's easier to have a professional do that though.