National Geographic, August 2, 2016: William J. Ripple is an ecologist at Oregon State University who has been studying gray wolves, cougars, and other top predators for decades. Last year, he and his colleagues reviewed the status of the planet’s 31 largest carnivores—a list that includes lions, tigers, and bears, but also sea otters, dingoes, and lynxes. They found that 24 of these animals are in decline, and 17 have been confined to less than half of their original ranges. “They are some of the world’s most admired mammals and, ironically, some of the most imperilled,” the team wrote.