In this January 27, 2015 photo, penguins walk on the shore of Bahia Almirantazgo in Antarctica. Antarctica “is big and it's changing and it affects the rest of the planet and we can't afford to ignore what's going on down there”, said David Vaughan, science director of the British Antarctic Survey. (Photo by Natacha Pisarenko/AP Photo)

Men push a car stucking in the mud on a motorway in Nimba County, Liberia, 28 July 2019. Most highway roads in the rural parts of the country are unpaved. The government of President George Weah has promised to build roads to connect all big cites of Liberia. (Photo by Ahmed Jallanzo/EPA/EFE)

Texas Longhorns cheerleaders pose for photos after defeating the Iowa State Cyclones in the Big 12 Women's Basketball Tournament championship game at T-Mobile Center on March 12, 2024 in Kansas City, Missouri. (Photo by Jay Biggerstaff/Getty Images)

Big waves approach the beach of Nazare, Portugal, Tuesday, March 26, 2024. The high waves were caused by strong winds at one of the world's most popular surf spots. (Photo by Michael Probst/AP Photo)

Rose-ringed Parakeets roost in a copse in Wormwood Scrubs Park on December 6, 2011 in London, England. Approximately 2,500 parakeets roost in the copse at the centre of Wormwood Scrubs which has been designated by English Nature as an important site of natural significance. (Photo by Oli Scarff/Getty Images)

Migratory flamingos arriving from Europe are seen in Port Fouad Nature Reserve, on the outskirts of Port Said Governorate, Egypt on December 12, 2022. (Photo by Mohamed Abd El Ghany/Reuters)

The fourth annual BigPicture Natural World Photography Competition aims to celebrate the diversity of life on Earth, and encourages people to protect and conserve it. Here: “The Salmon Catchers”. Terrestrial Wildlife. To capture this view of a mother grizzly bear and her cub, photographer Peter Mather set up a camera trap on a log that he knew the bears tended to traverse while fishing for salmon, in the Yukon River watershed in Canada. (Photo by Peter Mather/BigPicture Natural World Photography Competition 2017)

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)