Today I went looking for ants in Morgan Territory Regional Preserve in Contra Costa County, California. It was sunny and about 21 degrees Celsius (70 degrees Fahrenheit). I found active Formica and reclusive Messor andrei. I also saw many clusters of soil mounds that had no visible ant activity:
I dug a little to find a specimen, and I set my Huntsman Swiss Army Knife down to provide scale for the photo.
Can anyone name the ants that made these mounds?