An armed man herds his cattle close to the village of Nimini in northern South Sudan, February 8, 2017. In the chaos of South Sudan's civil war, it took three years for Nyagonga Machul to find her lost children. Machul had traveled from her village to the capital when President Salva Kiir, an ethnic Dinka, fired his deputy Riek Machar, a Nuer, in 2013. (Photo by Siegfried Modola/Reuters)

A model falls over on the runway in a design by Victoria Bliss during the Project NextGen show at Mercedes-Benz Fashion Week Resort 18 Collections at Carriageworks on May 16, 2017 in Sydney, Australia. (Photo by Stefan Gosatti/Getty Images)

People feed the birds in Battery Park in the Manhattan borough of New York, December 18, 2014. Hart has been feeding the birds three times a week for the last three years. (Photo by Carlo Allegri/Reuters)

A rebel fighter carries his weapon as he moves through a hole in a wall in the old city of Aleppo near the frontline against forces loyal to Syria's President Bashar al-Assad December 28, 2014. (Photo by Jalal Al-Mamo/Reuters)

A mechanical horse-dragon made of wood and steel is presented to the public in Nantes, western France on August 26, 2014. This horse-dragon, created by the French artist Francois Delaroziere of “Les Machines de l'île” (The Machines of the Isle), is the hero of the show "Long Ma" which will be presented in Beijing on October 17, 2014 as part of the fiftieth anniversary of the relationship between France and China. (Photo by Jean-Sebastien Evrard/AFP Photo)

A five-week-old orphaned Southern Sea Otter pup rests on a rubber mat after arriving at the Shedd Aquarium's Abbott Oceanarium in Chicago, Illinois October 28, 2014 in this handout photo provided to Reuters on November 5, 2014. The stranded pup was found on September 30 on Coastways Beach in California and was rescued the next day to be brought back to health at the Monterey Bay Aquarium. Southern sea otters were listed as “threatened” under the U.S. Endangered Species Act in 1977. (Photo by Brenna Hernandez/Reuters/Shedd Aquarium)

Storm clouds blanket the sky over Great American Ball Park as Starlin Castro #13 of the Chicago Cubs fields a ground ball in the fifth inning against the Cincinnati Reds as on July 7, 2014 in Cincinnati, Ohio. (Photo by Jamie Sabau/Getty Images)

Dead leaf or almost by Guilhem Duvot. Taken in Nován Stráž, Slovakia. Describe what is pictured? A dead leaf grasshopper. How does this image fit with the theme of the competition? The perfect camouflage – nature is amazing. I saw the grasshopper only because it jumped. (Photo by Guilhem Duvot/Royal Society of Biology)