Bjorn, aged 5, smiles as he poses with a Owl butterfly during an event to launch the Sensational Butterflies exhibition at the Natural History Museum in London, Britain March 23, 2016. The exhibition opens to the public on March 24 and runs until September 11. (Photo by Dylan Martinez/Reuters)

Afghan protesters beat a policeman after a suicide attack that targeted crowds of minority Shiite Hazaras during a demonstration at the Deh Mazang Circle of Kabul on July 23, 2016. Islamic State jihadists claimed responsibility for twin explosions July 23 that ripped through crowds of Shiite Hazaras in Kabul, killing at least 61 people and wounding 207 others in apparently their deadliest attack in the Afghan capital. The bombings during a huge protest over a power transmission line could deepen sectarian divisions in a country well known for communal harmony despite decades of war. (Photo by Wakil Kohsar/AFP Photo)

Riot police clash with protesters during a rally to demand a referendum to remove Venezuela's President Nicolas Maduro in Caracas, Venezuela, September 1, 2016. (Photo by Marco Bello/Reuters)

A man and a woman both wounded by what locals say was recent shelling by Ukrainian forces, react as they sit in an ambulance in Donetsk August 23, 2014. (Photo by Maxim Shemetov/Reuters)

Tourists take pictures of straw figurines of traditional deities Shennong (R) and Zhang Wulang (L back) during China's National Day Holiday, in Xinhua county, Hunan province, October 4, 2015. (Photo by Reuters/China Daily)

Olaf Niess catches swans on the river Alster near the town hall in Hamburg, Germany, 17 November 2015. The Alster swans are moving to their ice-free winter quarters on the Eppendorf Muehlenteich millpond until spring. (Photo by Bodo Marks/EPA)

A person dressed as “bigfoot” makes their way through the strong wind and snow in the Back Bay neighborhood during a blizzard on January 27, 2015 in Boston, Massachusetts. (Photo by Kayana Szymczak/Getty Images)

Pakistani female police commandos attend a training session in Nowshera, near Peshawar Pakistan, Wednesday, February 11, 2015. Authorities formed a Special Combat Unit after Taliban militants stormed a Peshawar school on Dec. 16, 2014 and massacred 150 children and teachers. (Photo by Mohammad Sajjad/AP Photo)