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)

The Arabian mare “Jenny” curiously sniffs at the child of Raphael Wöllstein, who is on his way to the train, on her daily walk through the Fechenheim district of Frankfurt, Germany on March 8, 2019. Her owner opens the stable door for the 22-year-old horse every morning. Then the animal can decide for itself where it wants to spend the day. So that nobody thinks she's escaped, a sign with the inscription “My name is Jenny, didn't run away, just go for a walk” is on the halter. (Photo by Boris Roessler/dpa)

Tour guides wearing traditional Chinese dress practice smiling by biting chopsticks at Qingming Grand-River Park in Kaifeng, central China's Henan Province on March 2, 2017, aiming to provide better service for visitors. (Photo by IPA Asia via ZUMA Wire)

Renowned aerobatic pilots Sean D. Tucker, flying the Oracle Challenger III, and Jeff Boerboon, flying the Jack Link's Screamin' Sasquatch, take to the skies over EAA's 2015 AirVenture Oshkosh, on Monday, July 20, 2015 in Oshkosh, Wis. (Photo by Matt Ludtke/AP Images for Jack Link's)

Athlets run during the women's 3000 meter steeplechase at the International Athletics Meeting in Lucerne, Switzerland, 14 June 2016. (Photo by Alexandra Wey/EPA)

A participant poses with his laptop during the 33rd Chaos Communication Congress on its opening day on December 27, 2016 in Hamburg, Germany. The annual event is bringing together 12,000 computer hackers and activists who will meet over the next four days to share expertise and discuss topics related to the society and the digital world. (Photo by Morris MacMatzen/Getty Images)

Grand title winner: Environmental photographer of the year. The Bitter Death Of Birds by Mehdi Mohebi Pour. This photo shows the efforts of the environmental forces to collect the bodies and prevent the spread of this disease. The Miankaleh wetland is being destroyed by changes in the climate and it is my duty as a photographer to highlight these problems and create a record for history. I want to prevent the complete destruction of the wetland and the potential environmental disaster by showing the issues and threats to these beautiful natural places. (Photo by Mehdi Mohebi Pour/Environmental Photographer of the Year)

This is the incredible moment a fierce lightning bolt crashed against the Grand Canyon illuminating the steep canyon walls. Shrouded in darkness, the breath-taking landscape was shocked into life as mother nature sent the bolt storming down to Earth. As it cracked against the rocks the bright blue bolt illuminated the South Rim of the canyon, considered one of the Seven Natural Wonders of the World. With just the Desert View Watchtower in the foreground, the lightning was perfectly framed by the canyon which is located in Arizona, USA. (Photo by Travis Roe/U.S. Dept. of the Interior/Caters News)