I got lucky and one of the alphas led his harem near where I was sitting as they headed to bed down for the evening. after making myself very small and invisible, because he looked like he might grind me or anything else to dust given half a provocation, I watched the cows trail along behind.
this mother stopped to give her calf from this spring some dinner. after maybe 30-60 seconds here comes her yearling from last year... without hesitation he trotted right up to mom and butted her right in the... well, butt. He finally butted his head between her hind legs and got some love. she was patient and tolerated the intrusion even though she had a look of, "oh damn it, not you too!" on her face.
I thought it a cool curiosity. this yearling is in for a hard lesson later this summer when mom kicks him halfway into next week for trying the same.
american bison - wichita mountains wildlife preserve.