Friends visiting here this week have many interesting stories. They are retired college professors, a botanist and a zoologist.

Here is one of the stories:

In South Dakota they were studying the effect of grass fires on the ecosystem so they were having a controlled burn. A herd of bison was trapped on a grassy knoll, surrounded by the fire. They stood up there looking around, and as the flames got nearer, they all lined up behind one of the cows, even though there were mature bulls in the herd of 30 or 40 animals, a cow was the leader.

In single file the bison started down the side of the knoll toward the flames. The leader cow turned her head from side to side as she looked for the best spot, and the line of bison zig zagged a little as they tried to decide where to cross through. Finally, they ran through the flames to the burned area on the other side.

This was the thing to do because they couldn't out run the fire, but they went to where it had already been, and it wouldn't turn back on them.

They were very close together, and this contributed to the only fatality: one of the animals broke its neck when it collided with the rear of the one in front of it. It fell to the ground and the ones behind it went around it and continued their escape, and it was consumed by the fire that overtook the grassy knoll.

When the fire was out and cooled, the bison returned to that area and ate the ashes. There must have been some nutrient in the ashes that they craved.

They came back to area to eat the emerging vegetation for the next three years, but not after that. They chose certain plants to eat that were in particular stages of growth. For example, the first time they came, they ate only sedges and newly emerging grasses, but the next time they came the sedges and those particular grasses were maturing and forming seeds so the bison ate different plants that were just starting to emerge, giving the sedges etc. the chance to have a second growth cycle. And the next time they moved to different plants, letting the second set mature and re-seed themselves.

This is not how cows eat - they are bred to eat pretty much everything in the field, so points up the difference between natural grazing and bringing in non-indigenous livestock.