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)

A protestor confronts police and National Guard troops near the Wauwatosa City Hal on October 09, 2020 in Wauwatosa, Wisconsin. The city has faced three days of demonstrations, prompting a 7 PM curfew, after District Attorney John Chisholm refused to press charges against Wauwatosa Police Officer Joseph Mensah for the Feb. 2 fatal shooting of 17-year-old Alvin Cole. (Photo by Scott Olson/Getty Images)

Gentoo penguins watching Christmas films at the Sea Life London aquarium on November 30, 2020. The attraction has installed two TVs, showing festive films, outside the penguin enclosure to prepare them for the stimulation of guests returning on Wednesday after the UK’s lockdown is lifted. (Photo by Yui Mok/PA Images via Getty Images)

Revellers of street parties known as blocos, dance during a protest against restrictions by city officials in Rio de Janeiro, Brazil, Wednesday, April 13, 2022. City Hall has banned the street parties during Carnival celebrations, which were delayed by almost two months due to the pandemic. (Photo by Silvia Izquierdo/AP Photo)

Qian Hao's imported Pekingese dog, Mixiu, runs in a park in Beijing, China, February 8, 2018. (Photo by Thomas Peter/Reuters)

The Knights of Middle England equestrian stunt display team perform ahead of the first match on July 13, 2024. The British Beach Polo Championships, or “sand polo”, returns to the exclusive Sandbanks peninsula near Poole, Dorset. Spectators can appreciate the horsemanship, speed and gladiatorial nature of polo at the largest beach polo event in the world. (Photo by Max Willcock/Bournemouth News)

An officer from the California Department of Fish and Wildlife gets ready to tranquillize a bear in Pasadena, California, U.S., August 20, 2021. (Photo by Mario Anzuoni/Reuters)

North Koreans who signed up to join the army train in the midst of political tension with South Korea, in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang August 23, 2015. Top aides to the leaders of North and South Korea resumed talks on Sunday after negotiating through the night in a bid to ease tensions involving an exchange of artillery fire that brought the peninsula to the brink of armed conflict. (Photo by Reuters/KCNA)