A zookeeper feeds a hippopotamus with a watermelon in its enclosure in Belgrade's zoo, Serbia, July 20, 2015. Temperatures in Serbia have risen up to 40 degrees Celsius (104 degrees Fahrenheit), according to official meteorological data. (Photo by Marko Djurica/Reuters)

A boy runs past one of the exhibits during the Dinosaurs exhibition in Belgrade, Serbia, Thursday, August 21, 2014. “Dino Park” has opened at Belgrade's Kalemegdan Fortress. (Photo by Darko Vojinovic/AP Photo)

The Dora the Explorer balloon moves through Times Square during the Macy's Thanksgiving Day parade Thursday, November 23, 2006 in New York. (Photo by Frank Franklin II/AP Photo)

“A Mothers Tail”. A baby cub pulls on his mother's tail to get attention. Photo location: Masai Mara, Kenya. (Photo and caption by Tori Marsh/National Geographic Photo Contest)

Boys eat at a rubbish dump where they are collecting recyclable waste outside Yemen's Red Sea port city of Houdieda January 20, 2016. (Photo by Abduljabbar Zeyad/Reuters)

A boy works on a car in Babi Kouakou's car repair garage in Bouake, Ivory Coast February 9, 2016. Babi specialises in restoring old cars. (Photo by Thierry Gouegnon/Reuters)

South Korea's Black Eagles aerobatics team perform a maneuver during a preview of the Singapore Airshow at Changi exhibition center in Singapore February 14, 2016. The Airshow will take place from February 16-21. (Photo by Edgar Su/Reuters)

A model wears a creation for Yves Saint Laurent's Fall-Winter 2016-2017 ready to wear fashion collection presented Monday, March 7, 2016 in Paris. (Photo by Thibault Camus/AP Photo)