When visiting the bison at Blue Mounds State Park in southwest Minnesota, watching them graze on the plentiful prairie grass, be sure to keep one eye on their tails.

A tail that hangs down means a bison is relaxed; a tail extending out means the animal is a little agitated. And if it’s sticking straight up? “You should be somewhere else,” recommend those in the know.

But don’t bother trying to make a run for it — bison can hit speeds of over 30 mph, and not many fences will stop a speeding 2,000-pound bull if he has a mind to get through it. So certainly come visit these majestic prairie giants but don’t poke at ’em. The fences are really there more to keep you out, than the bison in.

Founded in 1937, Blue Mounds State Park acquired its first three bison in 1961 from the Niobrara National Wildlife Refuge in Nebraska; today they maintain around 100 animals in a 500-acre range that is the centerpiece of the 1,800-acre park.

There are a lot of great reasons to visit Blue Mounds — rock climbing the Sioux quartzite cliffs, birdwatching for blue grosbeaks, stepping around prickly pear cactus — but you’d best go see the bison first.

You wouldn’t want to make them angry.

For more information, log on to www.dnr.state.mn.us/state_parks/blue_mounds or call (507) 283-1307. Blue Mounds State Park is located four miles north of Luverne off of Minnesota Highway 75.