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)

Women take part in Glowork exhibition in Riyadh, Saudi Arabia on September 28, 2017. (Photo by Faisal Al Nasser/Reuters)

David Goffin of Belgium meets a koala during a promotional event for the Australian Open tennis tournament at Melbourne Park on January 17, 2018. (Photo by Fiona Hamilton/Reuters/Tennis Australia)

A Southwest Airlines jet takes off from Reagan National Airport with a thunderhead to the east on June 20, 2017 in Alexandria, VA. (Photo by Jonathan Newton/The Washington Post)

An image taken with a drone shows beach umbrellas and deck chairs as beachgoers enjoy the hot weather in Scheveningen, the Netherlands, 24 July 2019. The Royal Dutch Meteorological Institute has issued an official warning due to high temperatures affecting the country as well as Western Europe. (Photo by Sem van der Wal/EPA/EFE)

Starlings gather on power lines at dusk, Friday, October 21, 2022, in Overland Park, Kan. (Photo by Charlie Riedel/AP Photo)

People explore the ice covered pier in Port Stanley, Ontario, Canada, on December 27, 2022. The ice formations were created by a large winter storm which hit the region on over the Christmas weekend. Temperatures were expected to moderate across the eastern and midwest US on December 27, after days of freezing weather from "the blizzard of the century" left at least 49 dead and caused Christmas travel chaos. (Photo by Geoff Robins/AFP Photo)

A Ukrainian service member smokes near a frontline, amid Russia's attack on Ukraine, in Donetsk region, Ukraine on February 8, 2023. (Photo by Yevhenii Zavhorodnii/Reuters)