Amani, a two-year-old female, relaxes at the Conservation Biology Institute. Cheetahs are the world’s fastest land mammal, adapted for brief but intense bursts of speed. They can reach 45 miles per hour within two-and-a-half seconds, with a top speed of 64 miles per hour. The cheetah population has declined dramatically over the last century mostly due to hunting. An estimated 12,000 to 15,000 cheetahs remain in the wild.