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)

Nose to Nose; Human/Nature winner. “Doug Gimesy was documenting work at the Joey and Bat Sanctuary near Melbourne when he met a wombat (Vombatus ursinus) whose mother had been killed by a car. Gimesy watched as a young veterinary student bottle-fed the orphaned joey, then touched her nose to the joey’s in a tender moment of interspecies bonding”. (Photo by Doug Gimesy/BigPicture)

The Euro sculpture is partially reflected in a puddle on a cobblestone pavement in front of the headquarters of the European Central Bank in Frankfurt on Jan. 21. (Kai Pfaffenbach/Reuters)