A heat-stressed koala waits as a resident pours water on its back on December 19, 2015 in Adelaide, Australia. Adelaide is experiencing an extreme heatwave, with temperatures reaching over 40 degrees for five consecutive days. (Photo by Morne de Klerk/Getty Images)

Two stags fight in a wildlife park in Aurach near Kitzbuehel, in the Austrian province of Tyrol. (Photo by Kerstin Joensson/Associated Press)

Pedestrians look at “doll” model Lulu Hashimoto standing on the street during a photo opportunity for Reuters in Tokyo, Japan August 23, 2017. (Photo by Kim Kyung-Hoon/Reuters)

In this photo taken on Monday, January 5, 2015, a mallard duck attempts to walk on a frozen pond in Yukon, Okla. (Photo by Steve Gooch/AP Photo/The Oklahoman)

Children feed a giraffe at Pairi Daiza wildlife park, a zoo and botanical garden in Brugelette, Belgium, May 25, 2015. (Photo by Francois Lenoir/Reuters)

A cadet lies on the grass after collapsing during a promotion ceremony at a police school in Bogota December 7, 2012. (Photo by John Vizcaino/Reuters)

World's Greatest Swimming Pools: Four Seasons, Serengeti Pool, Tanzania. A show of elephants, buffalo and baboons awaits thanks to an active watering hole below the free-form infinity pool at this plush hideaway inside Serengeti National Park. Bonus: Because of infrared technology at the hole, guests can be notified on their bedroom TV when animals are approaching. When you've got word of wildlife on the horizon, catch them from your private terrace – or head back to the pool. (From $1,650). (Photo by Four Seasons)

This female orangutan was born at the zoo in the German capital of Berlin. German online users have fallen in love with Berlin Zoo's most recent addition – this newborn orangutan. The female orangutan was born in the early hours of 12th January at the zoo in the German capital of Berlin and weighed a tiny 1.8 kilograms, normally regarded as small for an orangutan baby but nevertheless the infant is healthy and strong. (Photo by Europics/Zoo Berlin)