A gold mine worker displays gold in a local mine in Al-Ibedia locality at River Nile State, July 30, 2013. (Photo by Mohamed Nureldin Abdallah/Reuters)

A hot air-balloon flies during the International Lorraine Mondial Air Balloons Festival, in Chambley-Bussieres, eastern France, Friday, July 26, 2013. (Photo by Mathieu Cugnot/AP Photo)

Marenda Schipper and Patrick Boelsterli show of their bee beards at an annual competition at Clovermead Adventure Farm, Saturday August 10, 2013 in Aylmer, Ontario, Canada. (Photo by Dave Chidley/AP Photo/The Canadian Press)

Takehiko Yagi is a rising star in Japanese photography, and his vibrant pictures of the Hindu spring festival of Holi won the Grand Prize at the fourth annual Nikkei National Geographic Photo Prize. Diving into the Colors of Holi is his first exhibition in the US, on show at Foto Care Gallery in New York until 28 September, 2016. Here: Jaipur, India, 2013, (Photo by Takehiko Yagi/The Guardian)

An employee at Christie's auction house examines a complete sub-fossilised elephant bird egg on March 27, 2013 in London, England. The elephant bird egg is expected to fetch 30,000 GBP when it features in Christie's “Travel, Science and Natural History” sale, which is to be held on April 24, 2013 in London. (Photo by Oli Scarff)

Riot police stand guard behind a fire as refinery workers hold a blockade of the oil depot of Douchy-Les-Mines to protest against the government's proposed labour reforms, on May 25, 2016. Refinery workers stepped up strikes that threaten to paralyse France weeks ahead of the Euro 2016 tournament as the government moved to break their blockades, escalating a three-month tug-of-war over labour reforms. (Photo by François L.O./AFP Photo)

A tourist poses next to a tiger before officials start moving tigers from Thailand's controversial Tiger Temple, a popular tourist destination which has come under fire in recent years over the welfare of its big cats in Kanchanaburi province, west of Bangkok, Thailand, May 30, 2016. Wildlife authorities raid a Buddhist temple that has more than 100 tigers, taking away three cats and vowing to confiscate scores more in response to global pressure over wildlife trafficking. (Photo by Chaiwat Subprasom/Reuters)