We just got back from a dogging trip out west. One of my main tools with research was google earth. Yes, when zoomed you can see circles without vegetation around the holes. I correlated with older prairie dog colony maps then looked at land ownership. I got us thick into dogs that may not if been shot at all this year. That is judging by activity, and lack of recent vehicle traffic with any roads.
One we walked in about two miles, no closer access. We found doggy nirvana, the son used up all his ammo. Of course traveling light, shooting sticks and a bipod were used, no tables or elaborate rests.
Google earth gets updated periodically, not sure how often that is.