Leo, an orphaned Sumatran orangutan, is taken to the Sumatran Orangutan Conservation Programme rehabilitation centre. Leo will join other orangutans who have been reintroduced to the Pinus Jantho nature reserve. The SOCP has gradually formed a completely new wild population of species that have been threatened with extinction. (Photo by Sutanta Aditya/Barcroft Images)

A zoo keeper carries a pelican to move it to its winter enclosure at Dvur Kralove Zoo in Dvur Kralove nad Labem, Czech Republic on November 5, 2019. (Photo by David W. Cerny/Reuters)

A camel calf is seen among a herd in the desert near Dakhla in Morocco-administered Western Sahara, on October 13, 2019. In the Oued Eddahab desert in Western Sahara, Habiboullah Dlimi raises dairy and racing camels just like his ancestors used to, but with a little help from modern technology. While his animals roam free and are milked traditionally, by hand, at dawn and dusk, they are watched over by hired herders and Dlimi follows GPS coordinates across the desert in a 4X4 vehicle to reach them. (Photo by Fadel Senna/AFP Photo)

People take pictures of deer in the Phoenix Park in Dublin, Ireland December 5, 2016. (Photo by Clodagh Kilcoyne/Reuters)

A wild leopard runs on the stairs as it tries to escape from a compound of a house in Kathmandu, Nepal June 1, 2016. (Photo by Navesh Chitrakar/Reuters)

Solo, a rare baby tapir, makes his debut at Chester zoo, UK on July 18, 2016. The Malayan tapir is an endangered species and Solo is the first ever calf born at the zoo. (Photo by Chester Zoo/Rex Features/Shutterstock)

A male deer barks at dawn during the annual deer rutting season at Richmond Park in London, Britain, October 9, 2016. (Photo by Toby Melville/Reuters)

“This grey adult male seal enjoys a good grin while lying on the beach”. (Photo by Michael Hutch/SplashdownDirect via Rex USA)