A chimpanzee feeding a leopard cub at Southam Park Zoo, Warwickshire. (Photo by Ian Tyas/Keystone Features/Getty Images). 1971

Two brown bear cubs born at Whipsnade Zoo. (Photo by Evening Standard/Getty Images). 1970

A tiger cub has a short chat with a chimp. (Photo by Ian Tyas/Keystone Features/Getty Images). 27th November 1979

Four-month-old fox cubs squaring up to each other in Walthamstow, England on August 7, 2015. (Photo by Greg Morgan/Barcroft Media)

The nearly four-week-old Tapir cub bathes on June 28, 2016 in Gondwanaland at the zoo in Leipzig, Saxony. (Photo by Jan Woitas/DPA)

A brown bear cub by the Khailyulya River in north-east Kamchatka, Russia on July 24, 2021. (Photo by Yuri Smityuk/TASS)

A lioness drinks after being fed by senior keeper Glynn Hennessy at ZSL London Zoo on August 10, 2016 in London, England. Today marks World Lion Day which highlights the first global campaign to celebrate the importance and plight of lions worldwide. (Photo by Carl Court/Getty Images)

A little girl takes a picture of a lion in the zoo in Frankfurt, Germany, Tuesday, September 13, 2016. (Photo by Michael Probst/AP Photo)