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)

Budgies feed on seeds from a local visitor's hands at Ocean Park in metro Manila, Philippines September 10, 2016. (Photo by Romeo Ranoco/Reuters)

A participant, riding a horse and dressed as a knight, presents flowers to women during an event marking Valentine's Day in central Moscow, Russia, February 14, 2016. (Photo by Maxim Zmeyev/Reuters)

A Sri Lankan leopard is pictured at a zoo in Dehiwala near Colombo on March 3, 2016, on World Wildlife Day. (Photo by Ishara S. Kodikara/AFP Photo)

Women take part in a rally called “March of Whores” to protest against discrimination and violence against women on International Women's Day in Bogota, Colombia, March 8, 2016. (Photo by John Vizcaino/Reuters)

Pro-government fighters stand next to a tank destroyed during recent fighting in Yemen's southwestern city of Taiz March 14, 2016. (Photo by Anees Mahyoub/Reuters)

A white Bengal tiger cub born in captivity is seen during a press presentation at Huachipa's private zoo in Lima, Peru, March 16, 2016. (Photo by Mariana Bazo/Reuters)

The sun rises beside St Mary's Lighthouse in Whitley Bay, Tyne and Wear, as the unseasonably cool weather continues on Thursday, April 28, 2016. (Photo by Owen Humphreys/PA Wire)