Palestinian schoolboys sit in the trunk of a car as they go to school on a rainy day in Khan Younis, in the southern Gaza Strip, October 7, 2015. (Photo by Ibraheem Abu Mustafa/Reuters)

People stroll alongside one of the hills of the Tio Pio park in Madrid, Monday, January 25, 2016. The park is a high viewpoint frequented mostly by locals due to its view of the Spanish capital skyline. (Photo by Francisco Seco/AP Photo)

Refugee children play with a stuffed toy at a muddy makeshift camp at the Greek-Macedonian border, near the village of Idomeni, Greece March 15, 2016. (Photo by Alexandros Avramidis/Reuters)

Veteran racehorse Morestead models the world's first authentic Harris Tweed suit designed for a racing horse, which has been specially commissioned by William Hill to celebrate the opening of this year's Cheltenham Festival on March 15, 2016 in the U.K. (Photo by Joe Pepler/Rex Features/Shutterstock)

Schoolchildren play music to entertain and inspire people on their way home from work Tuesday, March 29, 2016 in Pyongyang, North Korea. North Korea has called a 70-day loyalty drive areas of a major congress of the ruling party scheduled for early May and everyone from students to coal miners have been mobilized nationwide to demonstrate their devotion to the leadership. (Photo by Eric Talmadge/AP Photo)

Lowry Park Zoo elephants Matjeka, 23, and her 1-year-old daughter, Mavi, apply a liberal coating of “sunscreen” to themselves in a clay mud wallow at the park Tuesday, August 12, 2014, in Tampa, Fla., on the park's first observation of World Elephant Day to raise awareness of the wild African elephant crisis. “Elephants are prone to being sunburned”, said associate curator Chris Massaro. “What they need is lot of mud or clay to roll around in and cover up their skin so it will protect it from the sun”. (Photo by Cherie Diez/AP Photo/The Tampa Bay Times)

In this Friday, February 6, 2015 photo, sandhill cranes begin to stir after resting for the night at a roosting location along their winter migration route in Cecilia, Ky. According to counts made by biologists with the Kentucky Fish and Wildlife Resources, about 12,000 of the birds have stopped in Cecilia this week during their winter northward migration on their way to their nesting grounds in the Great Lakes region. (Photo by David Stephenson/AP Photo)

A man poses with a hyena along a street in Lagos, Nigeria November 4, 2008. (Photo by Akintunde Akinleye/Reuters)