extinction

The extinction at the end of the Cretaceous period is Earth's greatest murder mystery. 66 million years ago, something killed about 75 percent of all animals, including the dinosaurs.

Historically, coyotes roamed a broad expanse, as far east as the Mississippi and as far west as the Pacific, north into Canada and south into Mexico, but since 1900 they’ve extended their range into every corner of the US

There is reason to worry about the future of birds in North America. A large team of researchers published a study showing that the bird population of North America has dropped by 29 percent since 1970. That's about three billion fewer birds