Andy Goldfarb, a staff biologist at the Point Defiance Zoo & Aquarium, plays with one of the four clouded leopard cubs currently at the zoo Friday, June 5, 2015 in Tacoma, Wash. The quadruplets were born on May 12, 2015 and now weigh about 1.7 lbs. each. Friday was their first official day on display for public viewing, usually during their every-four-hours bottle-feeding sessions, which were started after the cubs' mother did not show enough interest in continuing to nurse them. (AP Photo/Ted S. Warren)

This photo released Saturday March 22, 2014 by Stichting Ambulance Wens or Ambulance Wish Foundation shows a giraffe at Blijdorp Zoo in Rotterdam giving a lick to terminally ill Mario Eijs on Wednesday March 19, 2014. The Stichting Ambulancewens “Ambulance Wish Foundation” offers transport for terminally ill patients who cannot walk to help fulfill a last wish, in Eijs' case to be taken to the Blijdorp Zoo in Rotterdam where he worked doing odd jobs for 25 years. Eijs, who has a mental handicap, is dying of a brain tumor and has difficulty walking or speaking. (Photo by AP Photo/Stichting Ambulance Wens)

Stumpy the lemur has just turned 27 and is believed to be the oldest ring-tailed lemur in the world. He's still loving life, according to Zoo keepers. (Photo by Hemedia/Swns Group)

Female Siberian tiger Dasha yawns in the new enclosure at the zoo in Duisburg, Germany, 30 March 2016. The new facility is three times larger than the old one and will be opened to the public on the same day. (Photo by Roland Weihrauch/EPA)

A newly born Sitatunga calf seen at ZSL Whipsnade Zoo on November 24, 2016 in Whipsnade, England. The swamp-dwelling species, also known as a marshbuck, is Africa's only true amphibious antelope. It was snuggled up in the leaves and almost perfectly camouflaged as it mother tended it. (Photo by Tony Margiocchi/Barcroft Images)

Giant panda Mei Xiang discovers a birthday cake meant for her cub Bei Bei (NP) who turns one at the Smithsonian National Zoo in Washington, DC on August 20, 2016. (Photo by Linda Davidson/The Washington Post)

Baby giraffe of Niger (Giraffa Camelopardalis) “Kenai” (R), born on August 25, 2016, kisses his mother “Dioni” on August 31, 2016 at the zoo of La Fleche, northwestern France. (Photo by Jean-Francois Monier/AFP Photo)

Alpacas peek out of their box in Kielnarowa, Poland, June 11, 2014. A total of 35 female and 3 male alpacas were imported from Chile by the Rzeszow University of Information Technology and Management Center Zoo to be used for the therapy of children. Alpacas also provide one of the most expensive wools. (Photo by Darek Demanowicz/EPA)