Before European settlers came to North America, bison migrations were essential to the annual renewal of shortgrass prairie ecosystems, says EarthWatch chief scientist Cristina Eisenberg. By nipping off grasses, fixing nitrogen in the soil, and churning up the earth, their passage kept grasslands across parts of Montana, Wyoming, Colorado and Idaho functioning smoothly.
Audacious as such dispersals may seem, these peripatetic carnivores can’t help making them. This behavior is imprinted in their DNA, in the shape of their bodies, and in how their minds work. Moreover, they do it with casual grace, as if such heroic dispersals amounted to just another day in their lives.