Animals are dying off in the wild at a pace as great as the extinction that wiped out the dinosaurs about 65 million years ago because of human activity and climate change.

Current extinction rates are at least 12 times faster than normal because people kill them for food, money or destroy their habitat, said Anthony Barnosky, a biology professor at the University of California-Berkeley.

"If that rate continues unchanged, the Earth's sixth mass extinction is a certainty," Barnosky said. "Within about 200 to 300 years, three out of every four species we're familiar with would be gone."