I shoot Prairie Dogs in the north of Chadron about 10 miles from the SD line. I would say late May and June are the best times to hunt as the pups are usually pretty dumb yet.

Unfortunately a lot of the landowners are charging to shoot these things now so they can afford to buy poison or just recoup some lost profit.

I haven't hunted them anywhere else in the state. North of Valentine may be good, it's close to the Rose Bud reservation where there are Prairie Dogs all over.

If your hunting public land check, and double check that it's not protected. The state is making an effort to increase the PD population on public lands so the farmer/rancher doesn't have to worry about them being classified as endangered.