Sumatran tiger Jumilah is seen with one of her cubs on display at Taronga Zoo on October 25, 2011 in Sydney, Australia. The Sumatran tiger cubs, born in August to mother Jumilah, will meet the public for the first time this week. (Photo by Mark Kolbe/Getty Images)

A child looks at a polar bear swimming under a water in its enclosure on a hot summer day at Prague Zoo, Czech Republic, July 30, 2015. (Photo by David W. Cerny/Reuters)

A baby hippo swims under the water in its enclosure at Prague Zoo, Czech Republic, February 24, 2016. The baby was born on January 28, and is yet to be named. (Photo by David W. Cerny/Reuters)

Light sculptures glow in the dark at the zoo in Cologne, Germany, 04 December 2019. The artworks are on display at the zoo as part of the China Light Festival that runs until 09 January 2020 and features more than 70 light installations on the zoo grounds. (Photo by Sascha Steinbach/EPA/EFE)

Nekama, a baby North Chinese leopard, emerges from a basket at her official presentation to the media at Tierpark zoo on March 15, 2011 in Berlin, Germany. Nekama was born on January 7, 2011 and currently weighs 4.5 kg.

A newly born Indian white tiger cub yawns in its enclosure at Liberec Zoo, Czech Republic, April 25, 2016. (Photo by David W. Cerny/Reuters)

A newly-born male baby elephant, who so far does not have a name, walks with his mother Temi during his first venture outside at their enclosure at the Tierpark Hellabrun zoo on May 12, 2011 in Munich, Germany. The baby elephant was born at the zoo on May 6. (Photo by Alexander Hassenstein/Getty Images)

A baby hippopotamus lies next to its mother on the first day it was presented to the public at the Zoo Berlin zoo on November 1, 2011 in Berlin, Germany. The baby hippo was born at the zoo on October 23. (Photo by Sean Gallup/Getty Images)