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)

Colombia fans celebrate a goal during the World Cup Group C soccer match between Colombia and Greece, at a park in Bogota June 14, 2014. (Photo by John Vizcaino/Reuters)

Framed by the setting sun, an American Bison grazes at the Tallgrass Prairie National Preserve on Tuesday, April 28, 2015, near Strong City, Kan. The buffalo herd at Tallgrass is one of the few herds of wild bison left in the United States. (Photo by Travis Heying/The Wichita Eagle via AP Photo)

Josef Stalin's head is left in a Budapest street after a statue to the communist dictator was torn from its plinth during the Hungarian Revolution in 1956. (Photo by Robert Hofbauer/Radio Free Europe/Radio Liberty)

Greece's Maria Sakkari reacts during her women's singles quarter-final tennis match against Poland's Iga Swiatekon Day 11 of The Roland Garros 2021 French Open tennis tournament in Paris on June 9, 2021. (Photo by Gonzalo Fuentes/Reuters)

American actress and model Megan Fox stuns in a lace crop top and matching stockings in Manhattan, New York as she strolled to a business meeting on September 12, 2021. (Photo by Rex Features/Shutterstock)

Wassailing celebrations get under way in Wedmore, Somerset on January 12, 2021. The tradition of the orchard-visiting wassail dates back hundreds of years with the custom of visiting orchards in cider-producing regions of England, reciting incantations and singing to the trees to promote a good harvest for the coming year. (Photo by Apex News)

British sprinter Dina Asher-Smith arrives at The Fashion Awards 2018 In Partnership With Swarovski at Royal Albert Hall on December 10, 2018 in London, England. (Photo by Mike Marsland/BFC/Mike Marsland/Getty Images)