A Siberian tiger cub is seen at the Hengdaohezi Breeding Center for Felidae on October 26, 2007 in Harbin of Heilongjiang Province, China. Established in 1986, the breeding center is one of the world's largest captive breeding base for Siberian tigers. Distributed throughout northeastern China, far eastern Russia and North Korea, over 400 Siberian tigers exist in the wild, approximately 20 in China. (Photo by China Photos/Getty Images)

Moonlight illuminates sandstone buttes in the Valley of the Gods in the proposed Bear Ears National Monument near Mexican Hat, Utah, USA, 12 November 2016. In October 2015, a coalition of five Indian nations, including the Hopi, Ute, and Navajo, formally proposed the monument, attempting to preserve the parcel's 100,000 archeological sites from ongoing looting and grave robbing. Less than two months before handing over the White House to President Elect Trump, President Obama must decide if it's worth the political capital to designate Bear Ears a national monument. (Photo by Jim Lo Scalzo/EPA)

People in an illuminated cycle rickshaw look at a light installation at the Old Royal Library during the opening day of the "Festival of Light" show in Berlin, Germany, October 9, 2015. (Photo by Hannibal Hanschke/Reuters)

The CBRE Urban Photographer of the Year competition – now in its ninth year – encourages professional and amateur photographers to capture cities at work. Here: Dog Walker – 15:00. The competition allows photographers to enter up to 24 images, one representing each hour of the day. (Photo by Johanna Siegmann)

A tale of two foxes. Surprising behaviour, witnessed in Wapusk national park, on Hudson Bay, Canada, in early winter. Red foxes don’t actively hunt Arctic foxes, but where the ranges of two predators overlap, there can be conflict. Though the light was poor, the snow-covered tundra provided the backdrop for the moment that the red fox paused with the smaller fox in its mouth in a grim pose. (Photo by Don Gutoski/2015 Wildlife Photographer of the Year)

Workers attempt to bring a tranquillised black rhino to the ground before dehorning in an effort to deter the poaching of one of the world's endangered species, at a farm outside Klerksdorp, in the north west province, South Africa, February 24, 2016. (Photo by Siphiwe Sibeko/Reuters)

A tourist stands at an edge of the singing sand, the 150-metre-high by three-kilometre-long dune that generates a low-pitched, organ-like rumble in dry weather, in Altyn-Emel national park in Almaty region, Kazakhstan, May 12, 2016. (Photo by Shamil Zhumatov/Reuters)

Cosplayers attend Day 3 of WonderCon 2017 at Anaheim Convention Center on April 2, 2017 in Anaheim, California. (Photo by Justin Baker/FilmMagic)