In this undated photo made available by journal Nature on January 15, 2014, a northern bald ibis (Geronticus eremita) flies in Tuscany, Italy. A new study released Wednesday, January 15, 2014 says the birds choreograph the flapping of their wings, getting a boost from an updraft of air in the wake of the flapping wings by flying behind the first bird and off to the side. When a flock of birds take advantage of these aerodynamics, they form a V. (Photo by Markus Unsöld/AP Photo)

Liu Chunxia, a supporter of Xu Zhiyong, one of China's most prominent rights advocates, is detained by policemen while she gathers with other supporters nearby a court where Xu's trial is being held in Beijing January 22, 2014. When dozens of activists unfurled banners across the country last March and April calling for officials to disclose their assets, they did so at the urging of one of China's most prominent rights advocates, Xu Zhiyong. Xu, 40, stands trial on Wednesday on a charge of “gathering a crowd to disturb public order” punishable by up to five years in prison. His case will almost certainly spark fresh criticism from Western governments over Beijing's crackdown on dissent. (Photo by Kim Kyung-Hoon/Reuters)

A visitor holds an Israeli-made rifle during the 8th International Land and Naval Defense system exhibition, in New Delhi, India, on February 6, 2014. (Photo by Anindito Mukherjee/Reuters)

A member of the Brotherhood of Gentlemen Legionnaires of Asturias feeds its mascot after the governing body of the “Estudiantes” brotherhood decided that penance could not be carried out in the streets due to rain on Palm Sunday in Oviedo, northern Spain, March 20, 2016. (Photo by Eloy Alonso/Reuters)

This photo released by North Korea's official Korean Central News Agency (KCNA) on June 7, 2012 shows North Korean leader Kim Jong-Un (C) surrounded by members of the Korean Children's Union (KCU) organizations during a joint national meeting to celebrate the 66th anniversary of the KCU organizations at Kim Il-Sung Stadium in Pyongyang on June 6, 2012. (Photo by AFP Photo/KCNA via KNS)

Beachgoers watch the detonation of a 500 pound British bomb on the beach on May 19, 2014 in Wassenaar, Netherlands. The bomb was dropped by the British allied forces during the second world war over nearby Leiden where it was found on a building site. (Photo by Michel Porro/Getty Images)

A fisherman carries a sailfish on his head to the fish market in Hamarweyne near the port of Mogadishu on April, 4, 2016. (Photo by Mohamed Abdiwahab/AFP Photo)

A performer presents a creation from the Haute Coiffure Fall-Winter 2014/15 collection by French designer Charlie Le Mindu during the Paris Fashion Week, in Paris, France, July 7, 2014. The presentation of the Haute Couture collections runs from 06 to 10 July. (Photo by Etienne Laurent/EPA)