Shoot. An almost perfect quartering away shot. Just behind his shoulder with either a bow or firearm. That spot is partially concealed by the prairie grass but that won't affect the arrow or bullet at all at that distance.
Shoot, just behind the shoulder.
I see white patch under the chin. That is where I'd aim with a firearm. Left side of the patch, catching the spine.
I would have to pass on it with a bow. Too much grass in the way and my Martin compound shoots very flat making it impossible to arch the arrow in the bread basket. I'd be tempted with my old recurve with wooden shafts but I still call it a pass up.
With a rifle or revolver, directly below the eye where the white hair starts and he would probably drop right there for an easy recovery. Like Tom, I would not feel comfortable firing with a bow, for fear of not hitting him with a decent kill shot and therefore the necessity of a prolonged tracking session in difficult tracking vegetation. None of my choice good kill shot locations on his body are visible. Probably an easy enough shot with a bow slightly down into the grass line, but I would pass. Even an arrow can occasionally not leave enough of a blood trail for a short distance or short period of time and a deer can certainly dissappear into that tall grass easily making recovery very tedious. But, if I had him dead to rights at 25 yards with a full draw, I might be tempted to place the arrow in that same white spot directly below the eye line.