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)

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 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.

Slovenian photographer Peter Gedei started caving 25 years ago and has carried a camera with him on every trip getting stunning pictures from his travels, capturing the ice formations, tight chambers and beautiful halls. Photo: The Ice Cave in Postojna, Slovenia. (Photo by Peter Gedei/Caters News)

Members of the Pontifical Swiss Guard stand by at St. Peter's Square before Pope Francis delivers his traditional Christmas Day Urbi et Orbi speech to the city and the world from the main balcony of St. Peter's Basilica at the Vatican, December 25, 2021. (Photo by Yara Nardi/Reuters)

A lone male cheetah is set upon by a pack of African wild dogs. Peter Haygarth had been following the dogs as they hunted in Zimanga Private Game Reserve in KwaZulu-Natal, South Africa. On first encountering the cheetah, the dogs were wary, but as the rest of the pack arrived, their confidence grew and they began to encircle the cat. Peter kept his focus on the cat’s face. In a few minutes the spat was over as the cheetah fled. (Behaviour: mammals category). (Photo by Peter Haygarth)

Kerry Katona carries Peter McDonagh's flag before he faces Peter Krame during their Super welterweight bout at the Bolton Whites Hotel, Bolton, United Kingdom on May 12, 2018. (Photo by Lee Smith/Action Images via Reuters)