A rescue helicopter is shown at the Mount Everest south base camp in Nepal a day after a huge earthquake-caused avalanche killed at least 17 people, in this photo courtesy of 6summitschallenge.com taken on April 26, 2015 and released on April 27, 2015. Rescue teams, helped by clear weather, used helicopters to airlift scores of people stranded at higher altitudes, two at a time. (Photo by Reuters/6summitschallenge.com)

Lilly Caron, 8, of Bridgeton, Maine, Jason Homchick, of San Diego, and Lilly's father Jason Caron, (obscured), ride the Sky Swing at Seacoast Adventure, Thursday, July 14, 2016, in Wyndham, Maine. The 100-foot-tall swing gives riders the combined thrills of sky diving and hang gliding. (Photo by Robert F. Bukaty/AP Photo)

Ary Borges feeds his tiger named Dan at his home in Maringa, Brazil, Thursday, September 26, 2013. Borges is in a legal battle with federal wildlife officials to keep his endangered animals from undergoing vasectomies and being taken away from him. He defends his right to breed the animals and says he gives them a better home than they might find elsewhere in Brazil. (Photo by Renata Brito/AP Photo)

A Pakistani feeds his goat wearing the words “Eid Mubarak” or “Eid Greeting”, to be slaughtered on the Muslim holiday of Eid al-Adha, or “Feast of Sacrifice”, in Islamabad, Pakistan on Tuesday, October 15, 2013. Muslims all over the world are celebrating Eid al-Adha by sacrificing sheep, goats, cows and camels, to commemorate the Prophet Abraham's readiness to sacrifice his son, Ismail, on God's command. (Photo by Anjum Naveed/AP Photo)

The Northern Lights glow green in a spectacular light show above a field of trees frozen solid with snow. (Photo by Jaak Sarv/Solent News & Photo Agency)

Western lowland gorilla Kijivu holds her newborn baby at the Prague Zoo in the Czech Republic. (Photo by Isifa/Getty Images)

A goose has terrorized students at the University of Warwick, Coventry, UK, on May 22, 2013. The bird built its nest near a block of student apartments and attacks anyone who goes near the nest. (Photo by Caters News/The Grosby Group)

Iranian worshippers chant slogans during a protest after their Friday prayer, as part of widespread anger across the Muslim world about a film ridiculing Islam's Prophet Muhammad on September 14, 2012. (Photo by Vahid Salemi/Associated Press)