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)

David Yeo’s photography places naturally small species alongside animals that have been selectively bred to be tiny and cute. Here: “The most difficult aspect of this shoot was to get each African pygmy dormouse – also known as micro squirrels – on to a separate camera. Once in place, they needed to remain still long enough to get them both in the frame and looking at me. Often solitary, they naturally wanted to move away”. (Photo by David Yeo/Leica Studio Mayfair/The Guardian)

Goats climb on students during a yoga class with eight students and five goats at Jenness Farm in Nottingham, New Hampshire, U.S. on May 18, 2017. Tucked away in a wooded corner of southern New Hampshire, Jenness Farm is the latest small U.S. agricultural operation to cash in on the social media-driven trend, in which yoga enthusiasts practice moves like the cat pose and bridge pose while goats climb around and sometimes on them. (Photo by Brian Snyder/Reuters)

Girls take a selfie at the haze shrouded Batanghari River bridge in Jambi, Indonesia Sumatra island, September 14, 2015. Indonesian islands are blanketed in the so-called “haze”, caused by slash-and-burn clearances on the islands of Sumatra and Borneo, which makes thousands sick, delays flights and pushes air quality to unhealthy levels in neighboring Singapore and Malaysia. (Photo by Reuters/Beawiharta)

National Police members disinfect Venezuelan citizens returning to the country from Colombia, as a preventive measure against the spread of the coronavirus –COVID19- at the Simon Boliviar International Bridge, in Cucuta, Colombia-Venezuela border, on April 4, 2020. Since the first case of COVID-19 was detected last March 6, Colombia has reported 1,406 people infected and 32 dead. (Photo by Schneyder Mendoza/AFP Photo)

Fiona McGarva holds one of the sculptures from the art installation Gratitude at The Forth Bridge at North Queensferry on September 15, 2021, ahead of going on display just outside of Edinburgh at Newhailes House and Gardens from Friday 17th September. The public art installation pays tribute to NHS staff and all key workers for their ongoing courage and dedication during the Covid-19 pandemic. (Photo by Andrew Milligan/PA Images via Getty Images)