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)

White lioness Azira lies in the cage with her three white cubs, on February 4, 2014. Zoo owner Andrzej Pabich says white lions often have defects that prevent giving birth, or the mother rejects her cubs, but Azira has been patiently feeding and caring for her little ones. (Photo by Czarek Sokolowski/Associated Press)

Reflected in an ornament, a reporter takes a photo of the White House Christmas Tree in the Blue Room during a media preview of the holiday decor at the White House in Washington, U.S., November 29, 2016. (Photo by Kevin Lamarque/Reuters)

Protester Nadine Wolf demonstrates against the proposed Stop Online Piracy Act (SOPA) and Protect IP Act (PIPA) outside the offices of U.S. Sen. Charles Schumer (D-NY) and U.S. Sen. Kirsten Gillibrand (D-NY) on January 18, 2012 in New York City. (Photo by Mario Tama/Getty Images)

The arctic hare, or polar rabbit, is a species of hare which is adapted largely to polar and mountainous habitats. The arctic hare survives with a thick coat of fur and usually digs holes in the ground or under snow to keep warm and sleep. Arctic hares look like rabbits but have shorter ears, are taller when standing, and, unlike rabbits, can thrive in cold climates. They can travel together with many other hares, sometimes huddling with dozens or more, but are usually found alone, taking, in some cases, more than one partner. The arctic hare can run up to 60 kilometres per hour (40 mph). Its predators include the arctic wolf, arctic fox, and ermine.

A woman falls to the beach after she was attacked by three white women segregationists, when she attempted a wade-in with several African American and white desegregationist demonstrators, June 23, 1964, St. Augustine Beach, Fla. The people in the photo are unidentified. (Photo by AP Photo/JK)