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 truck creates a wake as its driver tries to navigate a severely flooded street as heavy rains pour down Monday, September 8, 2014, in Phoenix. Storms that flooded several Phoenix-area freeways and numerous local streets during the Monday morning commute set an all-time record for rainfall in Phoenix in a single day. (Photo by Ross D. Franklin/AP Photo)

Star trails form over the Memorial House of the Bulgarian Communist Party on mount Buzludzha in this long exposure picture taken on September 12, 2014. The monument was officially opened in 1981 by the Bulgarian Communist regime to mark 100 years of the set up of an organised Socialist movement, a predecessor of the Bulgarian Communist Party. The monument, no longer maintained by the Bulgarian government after the fall of the Communist regime in 1989, is now abandoned and vandalized. (Photo by Stoyan Nenov/Reuters)

Indian authorities hold a tiger skin as they set fire to a stockpile of illegal wildlife parts at the Delhi Zoo in New Delhi, India, Sunday, November 2, 2014. A stockpile of tiger skins, elephant tusks, rhino horns and other illegal animal parts were burned Sunday in an effort to discourage wildlife smuggling in South Asia. (Photo by Tsering Topgyal/AP Photo)

Workers from the South Florida Science Center and Aquarium and Imagine Exhibitions put together an animatronic spinosaurus outside the science center in West Palm Beach, Fla., Tuesday, October 27, 2015. The giant spinosaurus is part of the Dinosaurs Around the World exhibit, set to open on November 1. (Photo by Maria Lorenzino/South Florida Sun-Sentinel via AP Photo)

A man stands next to the body of a migrant child washed up on a beach in Canakkale's Bademli district on January 30, 2016 after at least 37 migrants drowned when their boat sank in the Aegean Sea while trying to cross from Turkey to Greece, Turkey's state-run Anatolia news agency reported. The migrants, who included those from Myanmar, Afghanistan and Syria, set sail from the Canakkale province to reach the nearby Greek island of Lesbos, Anatolia said. (Photo by Ozan Kose/AFP Photo)

In this photo provided by the Karenni Nationalities Defense Force (KNDF), smokes and flames billow from vehicles in Hpruso township, Kayah state, Myanmar, Friday, December 24, 2021. Myanmar government troops rounded up villagers, some believed to be women and children, fatally shot more than 30 and set the bodies on fire, a witness and other reports said Saturday. (Photo by KNDF via AP Photo)

Commuters travel in an overcrowded train near a railway station at Loni town in India's state of Uttar Pradesh on April 24, 2023. India is set to overtake China as the world's most populous country by the end of June, UN estimates showed on April 19, posing huge challenges to a nation with creaking infrastructure and insufficient jobs for millions of young people. (Photo by Arun Sankar/AFP Photo)