Birds sit on the back of a zebra in the Nairobi National Park, near Nairobi, Kenya, November 21, 2018. (Photo by Baz Ratner/Reuters)

This bat gives a cheeky smile as he gobbles down his food at Singapore Zoo, on September 10, 2013. (Photo by Benny Iskander/HotSpot Media)

World War Two veteran Abla Begaliyev, 91, is seen in an undated handout picture (L), poses for a picture in Arashan (Top R) and at home in Kyrgyzstan April 14, 2015. Begaliyev served in the border guard cavalry from February 1942 until April 1947. Originally from Kyrgyzstan, he fought on the Ukrainian front and relocated to the border with Afghanistan at the end of World War Two. As the world marks the 70th anniversary of the end of World War Two, Reuters photographers the length and breadth of the former Soviet republics (CCCP) captured portraits of Red Army veterans, mostly now in their 80s and 90s, today and through archive pictures at the time. More than 20 million Soviet citizens were killed in the war. (Photo by Vladimir Pirogov/Reuters/Family handout (L))

A chicken gingerly crosses the double yellow line of a country road near Roseburg in western Oregon, USA on July 16, 2018. (Photo by Robin Loznak/ZUMA Wire/Alamy Live News)

A student falls asleep as she holds a book containing a portrait of China's late chairman Mao Zedong during a lesson at the Democracy Elementary and Middle School in Sitong town, Henan province December 3, 2013. In a remote part of central China, the day starts at the Democracy Elementary and Middle School with a pre-dawn jog, some revolutionary songs and then an activity long since forgotten at other schools: reciting quotations from Mao Zedong's famed “Little Red Book”. While the ruling Communist Party that Mao led continues to hold him in esteem as the leader of the Communist Revolution, his radical policies and teachings have been largely shelved since his death in 1976 in favour of a pro-market approach that has turned China from a backwater into the world's second biggest economy. The 120th anniversary of Mao's birth is on December 26, 2013. (Photo by Carlos Barria/Reuters)

Merit Prize Winner: “A Well Earned Rest in the Sahara”. This photo of Moussa Macher, our Tuareg guide, was taken at the summit of Tin-Merzouga, the largest dune (or erg) in the Tadrat region of the Sahara desert in southern Algeria. Moussa rested while waiting for us to finish our 45-minute struggle to the top. It only took ten minutes of rolling, running, and jumping to get back down. The Tadrat is part of the Tassili N'Ajjer National Park World Heritage area, famous for its red sand and engravings and rock paintings of cattle, elephants, giraffes, and rhinos that lived there when the climate was milder. Photo location: Summit of Tin-Merzouga, Tadrat, Tassili N'Ajjer National Park, Algeria. (Photo and caption by Evan Cole/National Geographic Photo Contest)

This handout picture taken and released by the Borneo Orangutan Survival Foundation (BOSF) on October 26, 2015 shows baby orangutans, which had previously suffered from respiratory problems, playing at a nursery in the rehabilitation centre operated by the BOSF on the outskirts of Palangkaraya in Central Kalimantan. Endangered orangutans are falling victim to a devastating haze crisis that has left them sick, malnourished and severely traumatised as fires rage through Indonesia's forests, reducing their habitat to a charred wasteland. (Photo by AFP Photo/Borneo Orangutan Survival Foundation/Indrayana)

A large Pacific sideband snail slowly crosses a rain wet road in rural Douglas County, Oregon near Elkton on Sunday, December 2, 2012. The moisture loving snail should be very content with the recent heavy rains in southwestern Oregon and northern California. (Photo by Robin Loznak)