Three one-month-old lioness cubs are held by a keeper as they take their first outing on February 21, 2010 at the Ramat Gan Safari Park near Tel Aviv, Israel. The still unnamed cubs are the first triplet females to be born at the safari park and officials say their birth will ensure the continuity of the park's pride of lions. (Photo by David Silverman/Getty Images)

Hundreds of green bicycles are prepared as 960 of them await riders for the new year gala at the Temple of Heaven Park on December 29, 2011 in Beijing, China. Annual New Year countdown ceremony will be held at the park on December 31. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

An indigenous girl carries a monkey inside her house in their village at Xingu national park in Mato Grosso, Brazil, October 2, 2015. The Kamayura tribe consists of around 300 people, and is one of the 16 ethnic groups living in the indigenous Xingu national park. (Photo by Paulo Whitaker/Reuters)

A couple chats at a park during sunset in Chihuahua November 15, 2014. (Photo by Jose Luis Gonzalez/Reuters)

Cambodian children sleep on a pavement at a park in Phnom Penh on July 8, 2016. (Photo by Tang Chhin Sothy/AFP Photo)

Girls enjoy nice weather at a park in front of the Pothonggang Department Store in central Pyongyang October 11, 2015. (Photo by Damir Sagolj/Reuters)

A tomtit bird flies past a squirrel running on a fence after a snowfall in a park in Almaty, Kazakhstan, January 12, 2016. (Photo by Shamil Zhumatov/Reuters)

A women sits on the south rim of Grand Canyon National Park in northern Arizona, April 12, 2015. (Photo by Jim Urquhart/Reuters)