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)

Commended. In late May, about a quarter of a million snow geese arrive from North America to nest on Wrangel Island, in northeastern Russia. They form the world's largest breeding colony of snow geese. Photographer Sergey Gorshkov spent two months on the remote island photographing the unfolding dramas. Arctic foxes take advantage of the abundance of eggs, caching surplus eggs for leaner times. But a goose (here the gander) is easily a match for a fox, which must rely on speed and guile to steal eggs. “The battles were fairly equal”, notes Sergey, “and I only saw a fox succeed in grabbing an egg on a couple of occasions, despite many attempts”. Surprisingly, “the geese lacked any sense of community spirit”, he adds, “and never reacted when a fox harassed a neighboring pair nesting close by”. (Photo by Sergey Gorshkov/Veolia Environnement Wildlife Photographer)

A rare white kiwi chick is seen only days after being hatched on May 22, 2011 in Wellington, New Zealand. The all-white kiwi, named “Manukura” is suspected to be the first white chick born in captivity. The chick is the thirteenth of fourteen baby kiwis hatched at the wildlife centre this season. (Photo by Mike Heydon/Jet Productions NZ Limited via Getty Images)

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)

Looking for love by Tony Wu, USA. Highly commended, Animal Portraits. “Accentuating his mature appearance with pastel colours, protruding lips and an outstanding pink forehead, this Asian sheepshead wrasse sets out to impress females and see off rivals, which he will head-butt and bite, near Japan’s remote Sado Island. Individuals start out as females, and when they reach a certain age and size – up to a metre (more than 3 feet) long – can transform into males. Long-lived and slow-growing, the species is intrinsically vulnerable to overfishing”. (Photo by Tony Wu/2018 Wildlife Photographer of the Year)

Singer Rihanna performs onstage during the 2011 Billboard Music Awards at the MGM Grand Garden Arena May 22, 2011 in Las Vegas, Nevada. (Photo by Ethan Miller/Getty Images for ABC)

Actors Justin Timberlake (L) and Mila Kunis present an award onstage during the 2011 MTV Movie Awards at Universal Studios' Gibson Amphitheatre on June 5, 2011 in Universal City, California. (Photo by Kevin Winter/Getty Images)