Marty’s photo of the day #4817: Prairie dogs are a keystone species. If you don’t pay close attention, it’s easy to assume that every animal atop a mound in a prairie dog town is a prairie dog, but you’d be wrong. Using the same holes are burrowing owls and rabbits. Also, if you reach deep into a hole, you just might find a rattlesnake. This is a desert cottontail, photographed earlier this month, in the American Prairie (formerly the American Prairie Reserve), Montana.