The loss of large animals such as wolves and sharks has far-reaching implications, a new study says.
American Bison American bison join the morning commute on Hwy. 89 in Yellowstone National Park in Wyoming. In the early 1800s, about 65 million buffalo roamed North America, but hunting and poaching had a devastating effect on their population. By 1890, fewer than 1,000 remained. Today there are about 4,000 at Yellowstone. The decline of such large such predators is causing prey animals to swell in population and throw food chains out of balance, a new report says. Mark Ralston/AFP/Getty Images Buy Photo