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)

The extremely rare Kelvin-Helmholtz cloud formation lurking in the skies over Northumberland in North East England on December 5, 2023. The distinctive formation gets its name from scientists Lord Kelvin and Hermann von Helmholtz who studied the physics behind the rare cloud. (Photo by Ian Davison/South West News Service)

Divers wearing mermaid costumes take part in the first Chinese Mermaid Performance Contest at Atlantis resort on December 21, 2021 in Sanya, Hainan Province of China. (Photo by Luo Yunfei/China News Service via Getty Images)

A rickshaw puller transports passengers through a water-logged street after heavy rain in Kolkata, India on June 26, 2018. (Photo by Rupak De Chowdhuri/Reuters)

Children play near an apartment complex on the outskirts of Yangon, Myanmar on July 29, 2019. (Photo by Sai Aung Main/AFP Photo)

Indian Christians take part in Christmas prayers at the Infant Jesus church in Bangalore, India, 25 December 2020. Most Christians celebrate Christmas on 25 December to commemorate the birth of Jesus, the central figure of Christianity. (Photo by Jagadeesh N.V./EPA/EFE)

Germany's Laura Siegemund celebrates with France's Edouard Roger-Vasselin after winning the mixed doubles final against Britain's Neal Skupski and Desirae Krawczyk of the U.S. at the French Open in Paris on June 6, 2024. (Photo by Yves Herman/Reuters)

Members of the LGBT community kiss during a Kissathon to celebrate International Day Against Homophobia, outside Bellas Artes museum in Mexico City, Mexico, May 17, 2016. (Photo by Edgard Garrido/Reuters)