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)

Jan Agha, 49, an Afghan hunter, tries to catch his crane at a field in Bagram, Parwan province, Afghanistan on April 10, 2019. As the early morning light breaks over the plain north of Kabul, bird hunter Jan Agha checks his snares as he has done for the past 30 years, hoping to catch a crane, using a tethered bird to lure others down to the nets. (Photo by Mohammad Ismail/Reuters)

Wakodahatchee wetlands, Delray Beach, Florida, US. Equipped with sinewy necks and spear-like bills, great blue herons can lunge with fearsome speed to strike their aquatic prey. Adults will also employ rapid stabbing motions as one aspect of their complex courtship displays; they’re seemingly dangerous moves, but fitting to the intensity of mating season. (Photo by Melissa Rowell/Audubon Photography Awards)

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 runner tries to get the attention of a bull, named Santon, during the “Toro de Cuerda” (Bull on Rope) festival at Plaza de Espana square in Grazalema, southern Spain, July 18, 2016. Three bulls restrained by a rope are allowed to run through the streets of the village during the annual festival. (Photo by Jon Nazca/Reuters)

Some wave over the rainbow – a splash of colour is captured in spray over the sea wall at Totland Bay on the Isle of Wight off the south coast of England on February 16, 2022. (Photo by Jamie Russell/Bournemouth News)

A Turkey-backed Syrian fighter fires a rocket-propelled grenade as he takes part in a military exercise in the countryside of the northwestern city of Afrin, in rebel-held part of Aleppo province, on May 31, 2022. (Photo by Rami al Sayed/AFP Photo)

A Sotheby's employee poses with a “Return of the Jedi” promotional C-3PO Helmet 1983, estimated at £15,000-£25,000 created by George Lucas' visual effects company during a photocall at Sotheby's in London, Britain on December 6, 2019. (Photo by Thomas Mukoya/Reuters)