Winter migration for Yellowstone National Park's American bison (Bison bison) has begun, as captured by a tourist filming the event from the inside of their parked car, reports Hannah Osborne for Newsweek. The video, uploaded to YouTube, shows a herd of 150 bison walking in between traffic at the park's west entrance road for a total of ten minutes.
Park officials also shared a post on Facebook warning visitors to keep their distance from migrating bison. They write: "Remember to drive cautiously, give them room - at least 100 yards (91 meters) from bears or wolves, and at least 25 yards (23 meters) from bison, elk, and other wildlife - and use a zoom lens!"
Bison, also known as buffalo, are native to North America, live in small groups, and undergo short-season migrations. Once the snow begins to fall and accumulate, bison migrate to lower elevations in search of food and will often be seen walking along the park's roads. Bighorn sheep, elk, pronghorn, and mule deer also migrate to lower elevations when winter settles in. These mammals eventually return to higher elevation grasslands during the summer, per the Yellowstone National Park website on bison management.
Bison are essential to Yellowstone's ecosystem because their migration patterns can influence the landscape through how intensely they graze in grasslands. Considered ecosystem engineers, their eating patterns help prompt rapid growth earlier in spring and keep plants growing longer, as evidenced by NASA satellite images of grazed and non-grazed areas, per Yellowstone National Park.
The National Park Service last counted 4,680 bison residing in Yellowstone in 2020, reports Newsweek. Yellowstone is one of few areas where bison can roam freely. Efforts to conserve their population numbers were put in place as the species neared extinction in 1900. During the Western expansion, bison were intentionally slaughtered to remove a major food source for Indigenous people, reported J. Weston Phippen for the Atlantic in 2016.
Before Europeans arrived, it is estimated that 50 million bison roamed the North American continent, and the animals were the backbone of the Indigenous people's economy. Often regarded as a sacred symbol, bison flesh, hides, fur and bones were used for food, shelter, tools, clothing and more. In recent years, the National Wildlife Federation has partnered with tribal governments to return bison to native lands.
Yellowstone officials advise against approaching wildlife to take photos. If anyone encounters bison on the park's roads, they should stay inside their vehicles, Newsweek reports.
"Bison are wild animals that respond to threats by displaying aggressive behaviors like pawing the ground, snorting, bobbing their head, bellowing, and raising their tail. If that doesn't make the threat (in this instance, it was a person) move away, a threatened bison may charge," Chris Geremia, a bison biologist, tells Newsweek. "To be safe around bison, stay at least 25 yards away, move away if they approach, and run away or find cover if they charge."