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)

An aerial view shows people touring between the large-scale ice sculptures at the 18th Harbin Ice and Snow World during its trial run opening to public in Harbin city, Heilongjiang province, China, 21 December 2016. Some 180,000 cubic meters of ice and 150,000 cubic meters of snow were used to build the 800,000-square-meter ice wonderland. The 33rd Harbin International Ice and Snow Festival will kick off on 05 January 2017 that will last about three months. (Photo by Tian Weitao/EPA)

Guests arrive for the Arlo Guthrie concert at the Bethel Woods Center for the Arts, the original site of the Woodstock Festival, on the 50th anniversary in Bethel, New York, U.S. August 15, 2019. (Photo by Brendan McDermid/Reuters)

A lenticular cloud is seen during sunrise from Gokmen Aerospace Training Center (GUHEM) in Bursa, Turkiye on January 19, 2023. (Photo by Halit Mirahmetoglu/Anadolu Agency via Getty Images)

Australian ballet dancer Marilyn Rowe prepares to perform Swan Lake with the Australian Ballet at the Canberra Theatre in 1978. Rowe was appointed director of the Australian Ballet School in 1999. (Photo by John Crowther/The Guardian)

A drag queen waves a rainbow flag during an LGBT rights demonstration in front of the Hungarian Parliament building in Budapest, Hungary on June 14, 2021. During the protest human rights activists called on lawmakers in Hungary to reject legislation banning any content portraying or promoting homosexuality or sеx reassignment to anyone under 18. The bills, aiming at fighting pedophilia, have various amendments which would outlaw any depiction or discussion of different gender identities to youth in the public sphere. (Photo by Bela Szandelszky/AP Photo)

A diver in a pool at the Army 2021 International Military and Technical Forum, at the Patriot military park in Moscow Region, Russia on August 22, 2021. (Photo by Sergei Karpukhin/TASS/Alamy Live News)