In this Tuesday, April 26, 2016 photo provided by the San Diego Zoo Safari Park, adult Sumatran tiger Joanne and her cub make a public debut in the maternity exhibit at Tull Family Tiger Trail at San Diego Zoo Safari Park in Escondido, Calif. Visitors got their first glimpses Tuesday of multiple cubs as they romped and munched on plants in their habitat. (Photo by Ken Bohn/San Diego Zoo Safari Park via AP Photo)





Water is sprayed on a tiger to keep it cool by at the Nehru Zoological park in Hyderabad, India, Tuesday, April 26, 2016. Weeks of sweltering temperatures have caused scores of deaths across India and the met department has warned that any relief from monsoon rains was still likely weeks away. (Photo by Mahesh Kumar A./AP Photo)





An elephant breastfeeds its young one at the Amboseli National Park, southeast of Kenya's capital Nairobi, April 25, 2016. (Photo by Thomas Mukoya/Reuters)





An elephant soils its body as it walks in the Amboseli National Park, southeast of Kenya's capital Nairobi, April 25, 2016. (Photo by Thomas Mukoya/Reuters)





A baby elephant walks behind its mother as they graze in the Amboseli National Park, southeast of Kenya's capital Nairobi, April 25, 2016. (Photo by Thomas Mukoya/Reuters)





Elephants graze in the open field within the Amboseli National Park, southeast of Kenya's capital Nairobi, April 25, 2016. (Photo by Thomas Mukoya/Reuters)





A bird flies over a family of elephants walking in the Amboseli National Park, southeast of Kenya's capital Nairobi, April 25, 2016. (Photo by Thomas Mukoya/Reuters)





An elephant walks in the open field within the Amboseli National Park, southeast of Kenya's capital Nairobi, April 25, 2016. (Photo by Thomas Mukoya/Reuters)





An elephant grazes in the open field within the Amboseli National Park, southeast of Kenya's capital Nairobi, April 25, 2016. (Photo by Thomas Mukoya/Reuters)





A 23-day-old hamadryas baboon plays with a stuffed toy at Sri Chamarajendra Zoological Gardens after the baboon, according to a zoo doctor, was abandoned by its mother after its birth on April 4, in the southern city of Mysuru, India, April 28, 2016. (Photo by Abhishek N. Chinnappa/Reuters)





A 23-day-old hamadryas baboon plays with a stuffed toy at Sri Chamarajendra Zoological Gardens after the baboon, according to a zoo doctor, was abandoned by its mother after its birth on April 4, in the southern city of Mysuru, India, April 28, 2016. (Photo by Abhishek N. Chinnappa/Reuters)





A 23-day-old hamadryas baboon plays with a stuffed toy at Sri Chamarajendra Zoological Gardens after the baboon, according to a zoo doctor, was abandoned by its mother after its birth on April 4, in the southern city of Mysuru, India, April 28, 2016. (Photo by Abhishek N. Chinnappa/Reuters)





A 23-day-old hamadryas baboon plays with a stuffed toy at Sri Chamarajendra Zoological Gardens after the baboon, according to a zoo doctor, was abandoned by its mother after its birth on April 4, in the southern city of Mysuru, India, April 28, 2016. (Photo by Abhishek N. Chinnappa/Reuters)





A squirrel eats a nut in a park in Lviv, Ukraine, April 29, 2016. (Photo by Gleb Garanich/Reuters)





A squirrel eats a nut in a park in Lviv, Ukraine, April 29, 2016. (Photo by Gleb Garanich/Reuters)





A former circus lion looks from inside his cage, in the outskirts of Lima, Peru, Tuesday, April 26, 2016. Thirty-three lions rescued from circuses in Peru and Colombia are heading back to their homeland to live out the rest of their lives in a private sanctuary in South Africa. The largest ever airlift of lions will take place Friday and was organized and paid for by Animal Defenders International. (Photo by Martin Mejia/AP Photo)





A photo made available on 27 April 2016 shows a fishing squacco heron near Pusztaszer, some 140 kms southeast of Budapest, Hungary 26 April 2016. (Photo by Attila Kovacs/EPA)





The three-month old Kamchatka brown bear cub enjoys fresh air in the zoo in Brno, Czech Republic, April 28, 2016. Cub´s mother Kamchatka and her partner Jelizar are orphans, once caught in the nature of Russia. (Photo by Vaclav Salek/CTK via ZUMA Press)





This handout photo made available by Tierpark Nordhorn on April 26, 2016 shows a male vulture brooding an abandoned egg at Tierpark Nordhorn Zoo, in Lower Saxony, Germany, on April 26, 2016. A pair of gay vultures in a German zoo have adopted an egg abandoned by its mother and started to incubate it in a nest they built. Animal keepers had collected the egg in the muddy ground under a tree where it had been dropped by a griffon vulture called “Lisa”, said national news agency DPA. (Photo by Franz Frieling/AFP Photo/DPA)





An undated handout picture made available on 29 April 2016 by the Toronga Zoo shows a baby echidna making a remarkable recovery after being attacked by chickens in a family's backyard at the Taronga Zoo in Sydney, Australia. (Photo by EPA/Taronga Zoo)





In this June 24, 2015, photo released by Wildlife Conservation Society, a Cambodian Royal Turtle walks on the sand of Sre Ambel river bank, in Koh Kong province, in western Phnom Penh, Cambodia. Cambodia's Royal Turtle is nearly extinct, with fewer than 10 left in the wild, because increased sand dredging and illegal clearance of flooded forest have shrunk its habitat, a conservationist group warned Monday, April 25, 2016. (Photo by Wildlife Conservation Society via AP Photo)





Resident nursery dog Blakely rests with a cheetah cub in the nursery at the Cincinnati Zoo & Botanical Gardens, Friday, April 29, 2016, in Cincinnati. Three of the zoo's four cubs were born prematurely on March 8 as part of a breeding program for the endangered big cats, requiring round-the-clock care and hand feeding. The fourth is an orphan from Oregon who's mother could not produce enough milk to feed him. (Photo by John Minchillo/AP Photo)





Dachshunds compete in the19th Annual Buda Wiener Dog Races on Sunday April 24, 2016 in Austin, Texas. (Photo by Erika Rich/American-Statesman)





A pelican looks into the camera at the zoo in Frankfurt, central Germany, Thursday, April 28, 2016. (Photo by Frank Rumpenhorst/DPA via AP Photo)





Hippopotamus and Pelicans at Lake Nakuru in Kenya on April 27, 2016. (Photo by Action Press/Startraksphoto.Com)





A photo made available on 27 April 2016 shows a preening grey egret near Pusztaszer, some 140 kms southeast of Budapest, Hungary 25 April 2016. (Photo by Attila Kovacs/EPA)





A red panda feeds on bamboo in the sunshine at Bristol Zoo Gardens, England on April 29, 2016. (Photo by Ben Birchall/PA Images/Startraksphoto.com)





These rare clouded leopard cubs, born on the leap day of February 29, 2016 are making great progress. “Our leap year leopards are developing in leaps and bounds”, joked Rachel Nelson, a spokesperson for Tampa's Lowry Park Zoo in Florida, USA. The adorable cubs are named Aiya and Shigu. Their species of big cat is known to be shy and reclusive, dwelling mostly in the forests of Southeast Asia. Palm oil plantations plus high levels of hunting and poaching have driven them dangerously close extinction. (Photo by Chase/TLPZ/Splash News)





A picture made available 26 April 2016 shows a tiger playing in the water at the Tiger Temple in Kanchanaburi province, Thailand, 24 April 2016. The site known in Thai as “Wat Pa Luangta Maha Bua Yannasampanno” has been the focus of a dispute with the Department of National Parks, Wildlife and Plant Conservation (DNP) after the DNP asked in 2015 that the temple hands over its 147 tigers since it was not licensed to keep them. The temple has requested for a zoo license according to its managing director. (Photo by Diego Azubel/EPA)





In this Tuesday, April 26, 2016 photo, an elephant opens its mouth while being sprayed water to cool off at Dusit Zoo in Bangkok, Thailand. Authorities are telling people to stay out of the blazing sun to avoid heat stroke. April in Thailand is typically hot and sweaty but his year's scorching weather has set a record for the longest heat wave in at least 65 years. (Photo by Sakchai Lalit/AP Photo)