These bison were off by themselves, leading me to believe they represent the “elders.” The bulls, as they grow older, become solitary hermits, wandering the hills in ones and twos, away from the groups of cows, calves and competitive younger males.

Tatanka is the Lakota word for “bull bison” (they are also known as buffalo but are really bison). Tatanka was considered sacred by the plains tribes, and a critical source of food for many tribes. In the Oglala Lakota heritage center, there is is a chilling photo of a mountain of bison skulls, from a processing center in Detroit.  At one time, it is estimated that N. American bison herds numbered over 30 million. They were quite systematically exterminated: for hides, furs, trophy heads. Often they were shot from trains (“hunting specials” — men shooting at the herds from open train windows).  An adult bison weighs in at 1-2 tons, but sometimes only their tongue, considered a delicacy, was cut out by these hunters;  the rest was left to rot.

Badlands National Park has approximately 600 bison, and tries to maintain that number, for reasons of sustainability. See: http://www.nps.gov/badl/parknews/badlands-bison-roundup.htm

See also:  “Buffalo skulls in a pile” (Detroit processing center).  Photo from the Detroit Public Library (Burton Historical Collection).
http://ww2.glenbow.org/dbimages/arc4/t/na-2242-2.jpg