An elephant from Earl's Court Circus with a man in its mouth, 1928. P.S. All pictures are presented in high resolution.

Global wildlife populations will decline by 67% by 2020 unless urgent action is taken to reduce human impact on species and ecosystems, warns the biennial Living Planet Index report from WWF (World Wide Fund for Nature) and ZSL (Zoological Society of London). From elephants to eels, here are some of the wildlife populations most affected by human activity. Here: The maned wolf is among the large mammals in the Brazilian Cerrado that are threatened by the increasing conversion of grasslands into farmland for grazing and growing crops. (Photo by Ben Cranke/Nature Picture Library/Alamy Stock Photo)

A Southwest Airlines jet takes off from Reagan National Airport with a thunderhead to the east on June 20, 2017 in Alexandria, VA. (Photo by Jonathan Newton/The Washington Post)

Hailee Steinfeld performs at the American Music Awards at the Microsoft Theater on Sunday, November 19, 2017, in Los Angeles. (Photo by Matt Sayles/Invision/AP Photo)

A protester gestures as he holds a dog before a burning barricade during protests in Harare, Zimbabwe on January 15, 2019. (Photo by Philimon Bulawayo/Reuters)

Australian ballet dancers rehearse their moves on Whitehaven Beach on June 11, 2010 on Hamilton Island, Australia. (Photo by James Morgan/Hamilton Island via Getty Images)