Wildlife Population Plummeted Since 1970

This is Scientific American 60-Second Earth. I'm David Biello. Your minute begins now.
The river animals have it worst.
Thanks to water extraction, dam building and other river-changing pursuits, more than three-quarters of river amphibians, fish and mammals have disappeared since 1970.
That's not three-quarters of species, mind you, it's three-quarters of the individuals in a given population.
And it's not just the rivers.
Nearly 40 percent of both land and sea animals, from sardines to elephants, have disappeared over the same time span.
The numbers are from a new report from the conservation group World Wildlife Fund.
These lost animals have been replaced by either people or our domesticated animals--chickens, cows and pigs, among others.
Farms to feed people displace forests that feed wildlife.
And people also eat wildlife directly, from fish to bushmeat.
As a result, the survey finds fewer and fewer individuals among more than 3,000 species and 10,000 populations surveyed.
But there is hope.
The vast majority of these beleaguered species are not extinct.
And in rich regions like the U.S., Europe and Japan, wildlife numbers are actually increasing: coyote, deer, turkey and other forest animals, for example, as the forest regrows along the east coast of North America.
Exporting that trend could help stave off the gathering sixth mass extinction.
Your minute is up, for Scientific American 60-Second Earth. I'm David Biello.