Any idea what's causing these circles in my gravel driveway?

[oosik]

That's probably about the best answer sixdogs. The quail and doves pick my driveway clean - of the small stuff.

 

[jc42.2]

Attached are two pics of circular clean spots in my gravel driveway. I have about seven of them. All that happens is the gravel is brushed away from the base material. Almost all are nearly round and I've seen them for a couple years and almost always in the fall.

These two areas in the driveway are maybe 30 ft apart.

View attachment 722870 . View attachment 722871

My first thought is a bird was doing this in order to get smaller grit to eat for their gullet that grinds up food. I don't know. We are also frequented by possums and coons and an occasional red fox. A couple housecats as well and a rabbit.

Anyone have a guess what these are or what is causing them?

Those are made by worms, Few worms. They usually have a small pile in center which covers the worm hole. At night the worm comes up and pulls a rock or twig to the hole. I think it is some sort protection adaptation.

 

[jc42.2]

Those are made by worms, Few worms. They usually have a small pile in center which covers the worm hole. At night the worm comes up and pulls a rock or twig to the hole. I think it is some sort protection adaptation.

That should read 'Dew worms'.

 

[newbury]

That should read 'Dew worms'.

Also known as nightcrawlers, here's a link
linky
Spent many a summer evening picking them out of the lawn for fishing trips.