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)

Hooded demonstrators vandalise a shop window in Mexico City, during the commemoration of the 50th anniversary of the 1968 Tlatelolco student massacre, on October 2, 2018. Fifty years ago, Mexican troops opened fire on student demonstrators, killing hundreds just days before Mexico City hosted the 1968 Olympics – one of the darkest episodes in a year of global turbulence. (Photo by Ronaldo Schemidt/AFP Photo)

A child covered in mud on Lake Chokrak near the village of Kurortnoye, Leninsky District of Crimea in Russia on July 4, 2019. (Photo by Sergei Malgavko/TASS)

Firefighters extinguish a fire in Kampar, Riau province on Indonesia's Sumatra island on August 13, 2019. Indonesian authorities are deploying thousands of extra personnel to prevent a repeat of the 2015 fires, which were the worst for two decades and choked the region in haze for weeks. (Photo by Wahyudi/AFP Photo)

A combine harvester drives over a field of cut grass and threshes lawn seeds from the dried plants in Hanshagen, Germany, Thursday, June 30, 2022. In Mecklenburg-Western Pomerania, the harvest has started earlier than usual due to the heat. (Photo by Jens Büttner/dpa via AP Photo)

Workers inflate and secure giant helium balloons which will be a featured part of tomorrow's 97th annual Macy's Thanksgiving Day Parade in New York, New York, USA, 22 November 2023. The annual parade will feature 16 giant character helium balloons which will be lead down the street by teams of people. (Photo by Justin Lane/EPA)

People attend in costume the 2022 New York Comic Con, at the Jacob Javits Convention Center in Manhattan in New York City, New York, U.S., October 6, 2022. (Photo by Brendan McDermid/Reuters)

Chinese butchers catch a pig to slaughter on January 31, 2005 in Jinzhai County, Anhui Province, China. (Photo by Cancan Chu/GettyImages)