American bison, Yellowstone National Park, Wyoming, USA

© Gerald Corsi/Getty Image

American bison

American bison are the largest terrestrial animals in the Americas and living symbols of Yellowstone National Park, home to the duo seen in our image today. Yellowstone is the only place in the US where bison have roamed continuously since prehistoric times. There were around 60 million of these animals in the late 1700s as vast herds covered the grasslands of the continent. But they were driven to near extinction in the 19th century by hunting and disease. Conservation efforts have brought their numbers in the wild up to about 31,000 today.