Study: Yellowstone bison mow, fertilize their own grass

Bison in Yellowstone National Park, Wyo. (Wikimedia Commons)

MISSOULA, Mont. (AP) - A Yellowstone National Park grazing study found bison essentially mow and fertilize their own food, allowing them to graze in one area for two to three months during the spring and summer while other ungulates have to keep moving to higher elevations to follow new plant growth.

When hundreds of bison graze in an area, it greens up earlier and faster and the grass stays greener for a much longer time.

The grassland dynamics were observable by sensors on NASA satellites.

Research found that large numbers of bison grazing in one area actually stimulate the growth of nutritious grasses, in part because the grass is fertilized by their waste.

The research was published this week in the Proceedings of the National Academy of Sciences.

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