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 white whale wears a wreath at the Hakkeijima Sea Paradise aquarium-amusement park complex in Yokohama, Japan, on October 3, 2012. (Photo by Associated Press)

A man jokingly poses with a new installation of British graffiti artist Banksy's art in New York, October 20, 2013. (Photo by Carlo Allegri/Reuters)

A crow attacks a passerby, in a series of crow attacks on residents at a neighbourhood in Singapore on February 14, 2023. (Photo by Leonard Phuah/Shin Min Daily/Singapore Press Holding Media Trust via Reuters)

A participant at London Pride 2022 parade takes a mocking selfie next to Christian extremists protesting the parade in Piccadilly on July 2, 2022. (Photo by Vuk Valcic/ZUMA Press Wire/Rex Features/Shutterstock)

A seal infront of a passing cruise ship on the shore between Sandhaven village and Fraserburgh in Scotland in August 2023. (Photo by Mark Grant/Caters News Agency)

A reveller drinks wine while waiting for the launch of the “Chupinazo” rocket, to mark the official opening of the 2023 San Fermín fiestas in Pamplona, Spain, Thursday, July 6, 2023. (Photo by Alvaro Barrientos/AP Photo)

Macro or Micro? Scientists’ pictures baffle our sense of scale. It began when Stephen Young, a geography professor at Salem State University in Massachusetts, tricked his biologist colleague Paul Kelly into thinking a satellite image was one of his electron microscope scans. Can you guess whether they are close-up or very far away? (Photo by Paul Kelly)