Bull bison in fall grass

A big bull, coat already darkening for winter, caught mid-chew with a mouthful of grass still hanging from his beard. Yellowstone’s bison are the most genetically pure and continuously wild bison population in the country — they were never crossbred with cattle the way many other herds were during the species’ near-collapse.

Why it matters

Yellowstone is home to the largest bison population on public land in the United States, descended in part from a small group of wild bison that survived poaching in the park’s remote interior in the late 1800s, when the species was reduced to just a few hundred animals continent-wide.

Getting the shot

A fairly close, direct encounter along a roadside — bison here are habituated to vehicles but not to people on foot, so I stayed in place and let the long lens do the work rather than approaching. The muted fall grass colors kept the bull’s dark coat from getting lost in the frame.