We didn't see any either when we were there a couple of weeks ago. It's an enormous place so you might get lucky, you might not. Still disappointing not to see them. I was there several years ago and saw a lot of them on the driving loop. This time on the 2 mile hike, we saw a herd of deer close up and a wild turkey and a couple of snakes and a lot of birds.
39,000 acres. 2,500 bison. Might be hard to see bison. Better chance when cooler.
Last week, 5/23/20, they were everywhere. Crossing the road as we were driving through, along the road, literally everywhere. I am shocked you didnt see any. We could have reached out the window to touch them.
When I went a few weeks ago they were up near the visitors center
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