When you go to Custer State Park, they tell you to keep a safe distance from the bison. -- the lumbering beasts that walk the roads with that "leave-me-alone" demeanor. It's easy to see why.
But they don't tell you to keep your distance from the park's roaming herd of burros. I'm not sure it's possible to keep your distance from these guys. To say the burros are friendly would be an understatement. Not only do they come running when a car pulls over, but they also poke their enormous heads right in the window. One woman told me once that a burro actually tried to climb into her minivan.
Why so friendly? They love to beg for food -- an apple, carrot, muffin, corn chips, whatever. They're not fussy.
The begging burros are one of the most popular attractions in Custer State Park. Children love feeding them. Parents do, too. If you search Google Images for Custer State Park, you're likely to see as many burro pictures and bison photos.
Most places discourage feeding wildlife, but the begging burros are an exception. For one thing, they are not wildlife in the strictest sense. They descended from pack animals once used in the park. I've heard they were used for treks to the summit of Harney Peak, At some point, the animals' owner simply let them go, and they've been roaming the park ever since.