When European settlers arrived in the “New World”, there were 30 to 60 million bison roaming the land from the East all the way to California. After Westward expansion, that number fell to only 300 total, with 25 of them being in Yellowstone. Now, the bison population is rebounding and they are reshaping their world.
According to new research published in PNAS, bison grazing follows what is known as the Green Wave, which is the idea that herbivores will follow grass as it grows in Spring to higher elevations. This part has been known for some time. However, the migrating patterns of buffalo and how they eat actually helps that grass grow. So much so, that it is visible from space.
The reason for this is that bison graze in large herds, sometimes up to thousands of individuals grazing at the same time. As they eat the grass, their hooves are constantly disturbing the top level of soil and pushing grass seed back into the ground, making that land more fertile as a result.
After studying the grass itself, they found it to be more nutritious, containing more nitrogen and carbon. This could have profound results on how we understand North American ecology.
According to the team:
We’ve been studying bison in Yellowstone for over a century, but this idea that bison set the terms of springtime, through their movements and grazing, was something that’s never been confirmed before in Yellowstone—or anywhere elseChris Geremia – Lead Bison Researcher at Yellowstone National Park
Indeed, the effect is so profound that the team believes that the behavior evolved so that the bison are actually producing their own food through their grazing habits.
Since the 19th century, bison have rebounded considerably, going from about 300 individuals to 500,000 now. Efforts are being made everywhere to preserve their space and re-introduce them to spaces they have not been in a long time. Just this month, they were brought back to Badlands National Park where they have 22,000 acres to roam.