A Sikh warrior, wearing a huge turban attends the annual fair of “Hola Mohalla” in Anandpur Sahib, in the northern Indian state of Punjab, Monday, March 17, 2014. Believers from various parts of northern India collect at the religious fair to celebrate the festival of Holi in a tradition set by the tenth Sikh guru Guru Gobind Singh in the seventeenth century. Nihangs, or Sikh warriors, display their martial skills and attire during the fair, believed to be maintained in the exact tradition as set by the Guru. (Photo by Altaf Qadri/AP Photo)

“Himalayan Dog”. This dog just appeared out of nowhere and followed us for an entire week during our trekking trip in the Himalayan outback. He always used to sleep in front of our tent and guarded us in the nights. When I decided to get up at 4 a.m. to climb the next 5000 m peak for sunrise he accompanied me as well. On the top he was sitting for the entire 30 minutes on this place looking straight into the countryside. Photo location: Ladakh, India. (Photo and caption by Sebastian Wahlhuetter/National Geographic Photo Contest)

An Indian labourer sifts coloured powder, known as “gulal”, to be used during the forthcoming spring festival of Holi, inside a factory at Fulbari village on the outskirts of Siliguri on March 6, 2017. Holi, the popular Hindu spring festival of colours is observed in India at the end of the winter season on the last full moon of the lunar month, and will be celebrated on March 13 this year. (Photo by Diptendu Dutta/AFP Photo)

A devotee with his body painted poses as he waits to perform during a ritual as part of the annual Shiva Gajan religious festival at Sona Palasi village, in West Bengal, India, April 11, 2016. Devotees offer sacrifices and perform acts of devotion during the festival in the hopes of winning the favour of Hindu god Shiva and ensuring the fulfillment of their wishes, and also to mark the end of the Bengali calendar year. (Photo by Rupak De Chowdhuri/Reuters)

Indian underprivileged and specially abled grooms and brides in traditional marriage attire arrives to take part in a mass marriage ceremony in Mumbai, India, 29 May 2016. Around 51 couples got married during the ceremony which was organized by Narayan Seva Sansthan, for the underprivileged and specially abled people. From this 51 couples, both the partners are physically disabled in 22 couples, one partner is physically disabled in seven couples and 22 couples are from underprivileged circumstances. (Photo by Divyakant Solanki/EPA)

An astonishing set of snaps of a thrill-seeker's sky-high catwalk show on the edge of some of the world's tallest buildings has turned her into a social media sensation. Daredevil Angelina Nikolau, 23, from Russia, has spent weeks travelling around China and Hong Kong posing for jaw-dropping skyscraper selfies hundreds of feet above the ground. Her vertigo inducing results – uploaded to Instagram – have made her an instant star on the internet. (Photo by Kirill Oreshkin/CEN)

In this Thursday, December 1, 2016 photo, Cat Bigney, part of the Oglala Native American tribe, waits on the shore of the Cannonball river for travelers to arrive by canoe at the Oceti Sakowin camp where people have gathered to protest the Dakota Access oil pipeline in Cannon Ball, N.D. So far, those at the camp have shrugged off the heavy snow, icy winds and frigid temperatures. But if they defy next week's government deadline to abandon the camp, demonstrators know the real deep freeze lies ahead. Life-threatening wind chills and towering snow drifts could mean the greatest challenge is simple survival. (Photo by David Goldman/AP Photo)

The National Geographic Photo Ark is a travelling exhibition of photographer Joel Sartore’s quest to create a photo archive of biodiversity around the world. So far, Sartore has captured studio portraits of more than 6,000 species – a number that he hopes to double. On 1 July, the ark will open at Melbourne zoo – the first time it has been exhibited in the southern hemisphere. More than 50 portraits will be on display, including many of Australian endangered animals being protected by programs at the zoo itself. These captions have been edited from text supplied by Melbourne zoo. Here: Barking owl. (Photo by Joel Sartore/National Geographic Photo Ark/The Guardian)