A three month old white Bengal female tiger cub looks around her enclosure at the Buenos Aires Zoo, Argentina, Wednesday, April 16, 2014. Cleo, a captive Bengal white tiger at the zoo, gave birth to two females and one male white tiger cubs on January 16, 2014. (Photo by Natacha Pisarenko/AP Photo)

An activist kicks the shields of the military police officers during a demonstration in the military zone of the 27th infantry battalion in Iguala, Guerrero, January 12, 2015. Activists and relatives of the 43 missing trainee teachers from Ayotzinapa's teacher training college broke into the military zone, located less than a mile from where the students went missing, in an attempt to look for the missing students.The remains of only one of the 43 students has been identified so far. (Photo by Jorge Dan Lopez/Reuters)

A pro-Russian activist aims a pistol at supporters of the Kiev government during clashes in the streets of Odessa May 2, 2014. Police said a man was shot dead in clashes between a crowd backing Kiev and pro-Russian activists in the largely Russian-speaking southern port of Odessa, which lies west of Crimea, annexed by Moscow in March. (Photo by Yevgeny Volokin/Reuters)

Two female soldiers have their picture taken by an army colleague at Mangyongdae. (Photo by Gavin John/Mediadrumworld.com)

Full length portrait of female skier, Sierra Nevada Mountains in California, USA. (Photo by Anatoliy Gleb/Getty Images)

Young female Ibex on the fork of Disteis (2,200 m), near the top of the Jof di Montasio (Friuli, Italy). (Photo by Stefano Zocca)

A Palestinian social activist working for the International South South Cooperation (Cooperazione Internazionale Sud Sud, or CISS) entertain children who are patients inside a hospital in Gaza City August 31, 2015. Activists working for the Italian non-profit NGO use entertainment and humour to help bring treatment to children suffering from psychological trauma in the Gaza Strip. (Photo by Mohammed Salem/Reuters)

Ukrainian police detain activists of women's rights group Femen as they protest against homophobia outside the parliament building in Kiev, Ukraine, November 12, 2015. Femen and gay rights activists are pushing parliament to adopt bills, including one that would ban discrimination in the workplace based on sexuality, which is included in a package of laws to liberalise Ukraine's visa regime with the EU. (Photo by Gleb Garanich/Reuters)