Fireworks explode over a floating Christmas tree in Lagoa Lake in Rio de Janeiro. (Photo by Victor R. Caivano/Associated Press)

A Palestinian youth demonstrates his parkour skills on a street in Gaza City, January 15, 2016. (Photo by Suhaib Salem/Reuters)

Thor, Virginia Tech College of Engineering, Robotics and Mechanisms Laboratory, tries to connect the hose to a firehose connection during the hose task at the Homestead-Miami Speedway, Friday, December 20, 2013, in Homestead, Fla. (Photo by Alan Diaz/AP Photo)

A competitor reacts as she emerges from the water during the Tough Guy event in Perton, central England, January 26, 2014. The annual Tough Guy race – “the toughest race in the world” – at Perton in Staffordshire. Tough Guy claims to be the world’s most demanding one-day survival ordeal. First staged in 1987, the Tough Guy Challenge has been widely described as one of the hardest races of it’s type with up to one-third of the starters failing to finish in a typical year. (Photo by Darren Staples/Reuters)

Young Buddhist novice monks play at a Tibetan nomadic summer grazing area on July 24, 2015 on the Tibetan Plateau in Yushu County, Qinghai, China. Tibetan nomads face many challenges to their traditional way of life including political pressures, forced resettlement by China's government, climate change and rapid modernization. The Tibetan Plateau, often called “The Roof of the World”, is the world's highest and largest plateau. (Photo by Kevin Frayer/Getty Images)

Golden-crowned Kinglets boldly bear their flashy lemon-yellow crest and a black eyebrow stripe. Taking a good look at them might be rather challenging, since they spend most of their time in the dense fir foliage or spruce. However, if you’re patient enough to find them, listen for their shrill, thin song. Though these “little Kings” are only a tad bit larger than a hummingbird, they can survive easily extreme cold by huddling close together. They breed in montane west and the far north and only visit North America during winter.

Hikers walk to reach the top of Naqba Rum area in South Sinai, Egypt, November 20, 2015. Bedouins in the "Sinai is Safe" group guided more than 100 hikers over a 25 km (15 mile) trek over the trails of the White Canyon and the Closed Canyon. The NGO aims to challenge mainstream perceptions of the area by encouraging Nile Valley residents to explore the untamed wilderness with the Bedouin tribes. (Photo by Asmaa Waguih/Reuters)

Baka pygmies in their forest home preparing food in, Sangha Forest, Central African Republic, February 2016. Here, in their forest home, traditional life continues in the face of multiplying challenges ranging from poachers, to ill health. Deep in the rainforests of central Africa lives one of the world’s most mysterious tribes. (Photo by Susan Schulman/Barcroft Images)