The Return
The bison, North America’s largest mammal, provides one of the last evolutionary links to the Pleistocene era, a period (1.8 million to 11,550 years ago) when huge mammals dominated the landscape. Just two centuries ago, between 30 and 60 million bison roamed the continent’s grassy, shrubby plains and prairies, and their range extended from Mexico to central Canada. In the late nineteenth century, sport-hunting and mass slaughters of this mammal brought the species to the brink of extinction. In 1906, less than 1,000 bison, wild and captive, remained in North America.
Since then—with much thanks to strong conservation efforts that mobilized in the early 1900s—the continent’s bison population was able to grow to about 450,000. But fewer than 20,000 of these animals range freely and many contain genes from cattle or other bison subspecies. The vast majority of today’s bison are raised as domestic livestock. When wild bison numbered in the millions, and large herds migrated across the open grasslands, their ability to travel freely across vast expanses also meant they grazed across the region, coexisting with prairie dogs, ferrets, burrowing owls, and other grassland animals. These iconic American herbivores shaped the vegetation and landscape as they fed on and dispersed the seeds of grasses, sedges, and forbs. Several bird species adapted to or co-evolved with types of grasses and vegetation structures that had been, for millennia, grazed by millions of free-ranging bison.
One of the major problem that bison face today is the genetic bottleneck that has been caused by the very small number of bison that survived their near extinction event. The term “Bottleneck Effect” is the entry of genes from domestic cattle into the bison population through hybridization. In response to a public outcry, the U.S congress released some captive bison into Yellowstone National Park to rebuild a wild herd. So now, more than 100 years later, efforts are underway to repopulate the species, as the American Buffalo fight back! Today, nearly 2,500 wild buffalo make their home in Yellowstone Park. It’s one of the greatest comeback stories in conservation history! The bison are fighting back!