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 hot air balloon competition called “Grudziadzkie Zawody Balonowe” is held in Lisie Katy, central-northern Poland, 14 May 2021. The compe​tition is held for the eighteenth time. (Photo by Tytus Zmijewski/EPA/EFE)

In this photograph taken on June 28, 2015, a hiker in Hong Kong takes a picture of the city from a walking trail. The southern Chinese territory is crisscrossed by more than 180 miles of designated hiking trails. (Photo by Alex Ogle/AFP Photo)

Germany's Darja Varfolomeev competes in the individual all-around final of the Olympic qualifier 40th FIG Rhythmic Gymnastics World Championships in Valencia on August 26, 2023. (Photo by Jose Jordan/AFP Photo)

Muslim pilgrims pray around the holy Kaaba at the Grand Mosque, during the annual haj pilgrimage in Mecca September 30, 2014. (Photo by Muhammad Hamed/Reuters)

Mourning woman. (Photo by Rich Legg/Getty Images/iStockphoto)

In an observance of Epiphany, Russian Orthodox believers swim in an icy pond outside Nizhny Novgorod, Russia. (Photo by Olga “Zwezdochka”)

Audrey Lu and Misha Mitrofanov of the United States compete in the Pairs Short Program during day 1 of the ISU Grand Prix of Figure Skating Rostelecom Cup at Megasport Arena on November 15, 2019 in Moscow, Russia. (Photo by Maxim Shemetov/Reuters)