The enormous bull, an animal weighing close to a ton, found a wallow, rolled on the ground, and stirred clouds of dust. He continued dusting as I moved within 100 feet and set up my tripod and camera.

I cast a cautious glance at him again and found him on his feet now, but still not aggressive . . . or so it seemed. I put my eye to the camera's viewfinder, zoomed in on his massive head and snapped a picture.

When I look at that photograph now, it terrifies me. That old bull, a gigantic shaggy animal with an enormous bearded head, had his eyes locked on me. And although I perceived him to be quite docile when I took the photograph, now I can see he probably had rage in his heart.

In the brief time since I approached him, something in him had clicked -- some blood instinct, primitive and wild. But I failed to notice that.

And when I snapped the camera's shutter, the bull snapped as well.

Only a second after taking that photograph, I looked up again. To my horror, the bull was almost upon me. In less time than it takes to tell it, he'd covered half the distance between us.

I thought I was dead.

I veered sharply just as the bull crashed through my camera gear. The bison seemed momentarily surprised and slowed a bit, giving me time to scramble up on top of our truck.

I shouted to Josh: "Go, son! Go!" But all I could hear was the grinding of gears and hysterical laughter.

I turned to see the bull standing in front of the pickup, pawing huge clods of earth from the ground and shaking his head like El Toro in a bullfight. I feared he would charge again and turn our truck into a heap of scrap metal.

Yet Josh found the scene strangely funny. He took much longer than I thought necessary to regain his composure and back the pickup a safe distance away.

To a 16-year-old, I suppose it was humorous, watching his fat old dad run in wide-eyed terror as a hump-backed bull the size of a van chased him on top of the truck like a hound treeing a squirrel. When it was over, I laughed a bit myself.

But such episodes don't always end in laughter.

Consider, for example, the case of Jacques Dumont. Were he still alive, this 21-year old Frenchman might tell you how foolhardy it can be to approach a bison.

Dumont was in Yellowstone National Park, standing six feet from a solitary bull. As friends took his photograph, the bull charged.

Dumont was gored and tossed 10 feet in the air.

If Marvin Schrader were still alive, he might explain the danger one faces when photographing these symbols of the American frontier. Schrader, his wife and their three children, were near Old Faithful when they spotted a bull in a meadow. Schrader was 20 feet from the bison, taking photos, when the animal charged and gored him to death.