Students feed fruit to an elephant during Thailand's National Elephant Day in the ancient Thai capital Ayutthaya March 13, 2015. Thais honoured the elephant on Friday with special fruits and Buddhist ceremonies across the country to pay homage to their national animal. (Photo by Athit Perawongmetha/Reuters)

A Common Blue Morpho butterfly lands on the arm of Garbiella as it and hundreds of other butterflies from around the world fill the bird aviary for the next month at the San Diego Zoo Safari Park in San Diego, California March 13, 2015. Called the Butterfly Jungle, the exhibit has over 30 species of butterflies. (Photo by Mike Blake/Reuters)

Bulgarian Roma women from the close-knit Kalaidjii clan attend a so-called “bride fair” in a suburb of the city of Plovdiv April 13, 2015. Each year Roma families from the close-knit Kalaidjii clan gather during what they call a “bride fair”, an event offering parents a chance to meet and to arrange marriages for their children. (Photo by Stoyan Nenov/Reuters)

A farmer tends to his field as Mount Sinabung releases pyroclastic flows in Tiga Pancur, North Sumatra, Indonesia, Saturday, June 13, 2015. The volcano, which was put on it highest alert level last week, has sporadically erupted since 2010 after being dormant for 400 years. (AP Photo/Binsar Bakkara)

Dust covered seats are pictured inside the lounge of the Jaisalmer Airport in desert state of Rajasthan, India, August 13, 2015. Two-and-a-half years after the completion of a new $17 million terminal building, the airport in Jaisalmer, a small and remote desert city in India's western Rajasthan state, stands empty. (Photo by Anindito Mukherjee/Reuters)

Storm clouds blanket the sky over Great American Ball Park as Starlin Castro #13 of the Chicago Cubs fields a ground ball in the fifth inning against the Cincinnati Reds as on July 7, 2014 in Cincinnati, Ohio. (Photo by Jamie Sabau/Getty Images)

A Syrian boy receives treatment at a hospital in the regime-held part of Aleppo on October 13, 2016. Syrian state television said four children were killed by rebel rocket fire on a school in a western regime-held neighbourhood. (Photo by George Ourfalian/AFP Photo)

Bride Duangreuthai Amnuayweroj and groom Kasemsak Jiranantiporn fly while attached to cables during a wedding ceremony ahead of Valentine's Day at a resort in Ratchaburi province, Thailand, February 13, 2016. Four Thai couples took part in the wedding ceremony arranged by the resort. (Photo by Athit Perawongmetha/Reuters)