Participants run through the streets of the Back Bay during the 16th annual Santa Speedo Run in Boston, Massachusetts, December 12, 2015. (Photo by Brian Snyder/Reuters)

A tomtit bird flies past a squirrel running on a fence after a snowfall in a park in Almaty, Kazakhstan, January 12, 2016. (Photo by Shamil Zhumatov/Reuters)

Fighters from the Democratic Forces of Syria prepare their weapons in the southwestern countryside of Hasaka, Syria February 17, 2016. Picture taken February 17, 2016. (Photo by Rodi Said/Reuters)

A Chinese bus ushers jump as she pose for a photograph on Tiananmen Square during a plenary session of the National People's Congress held at the Great Hall of the People in Beijing, Wednesday, March 9, 2016. (Photo by Andy Wong/AP Photo)

A partial solar eclipse is seen as a labourer works at a construction site in Phnom Penh, Cambodia, March 9, 2016. (Photo by Samrang Pring/Reuters)

Mohammad, a 13-year-old fighter from the “Free Syrian Army”, plays with a cat in Aleppo's Bustan al-Basha district, Syria October 28, 2013. Mohammad joined the Free Syrian Army after his father died during clashes with the Syrian regime. The gun he is using was his father's. (Photo by Molhem Barakat/Reuters)

Framed by the setting sun, an American Bison grazes at the Tallgrass Prairie National Preserve on Tuesday, April 28, 2015, near Strong City, Kan. The buffalo herd at Tallgrass is one of the few herds of wild bison left in the United States. (Photo by Travis Heying/The Wichita Eagle via AP Photo)

A child plays with a soap bubble on the city hall plaza on March 14, 2015 in Paris. (Photo by Dominique Faget/AFP Photo)