Penguins swim in the Detroit Zoo's new Polk Penguin Conservation Center, Wednesday, April 13, 2016, in Royal Oak, Mich. The new penguin habitat that the zoo calls the world's largest such facility offers its 80-plus residents new rocks for climbing, waves, snow and better ice conditions, while allowing visitors to come nose-to-beak with the stately birds. (Photo by Carlos Osorio/AP Photo)





A white Bengal tiger cub plays with its sister, a golden Bengal tiger cub, at the Circo de Renato (Renato Circus) in Ciudad Sandino, Nicaragua April 6, 2016. (Photo by Oswaldo Rivas/Reuters)





This undated image provided by The National Aquarium of New Zealand shows Inky the octopus swimming in a tank at the National Aquarium of New Zealand in Napier, New Zealand. Inky the octopus escaped the National Aquarium of New Zealand for the Pacific Ocean. (Photo by The National Aquarium of New Zealand via AP Photo)





Pelicans fly above agricultural fields near the southern Israeli city of Netivot, April 11, 2016. (Photo by Amir Cohen/Reuters)





Tian Tian, a giant panda eats bamboo in the outdoor enclosure at Edinburgh Zoo ,Scotland April 12, 2016. The Royal Zoological Society of Scotland and Royal Botanic Garden Edinburgh will perform research into the complexity of the panda diet. (Photo by Russell Cheyne/Reuters)





The world second-oldest gorilla “Fatou” eats from a fruit birthday basket at the Berlin zoo, Germany, April 13, 2016. (Photo by Hannibal Hanschke/Reuters)





A goat feeds a tapir calf, that was abandoned by its mother, at the National Zoo in Managua, Nicaragua April 14, 2016. (Photo by Oswaldo Rivas/Reuters)





A goat feeds a tapir calf, that was abandoned by its mother, at the National Zoo in Managua, Nicaragua April 14, 2016. (Photo by Oswaldo Rivas/Reuters)





A goat feeds a tapir calf, that was abandoned by its mother, at the National Zoo in Managua, Nicaragua April 14, 2016. (Photo by Oswaldo Rivas/Reuters)





A white stork brings branches to its nest situated on a cell phone tower near Don Benito, Spain, April 13, 2016. (Photo by Paul Hanna/Reuters)





A white stork brings branches to its nest situated on a cell phone tower near Don Benito, Spain, April 13, 2016. (Photo by Paul Hanna/Reuters)





In this November 1, 2013 file photo, tourists on an elephant watch a one-horned rhinoceros inside the Kaziranga national park, about 250 kilometers (155 miles) east of Gauhati, India. With the Duke and Duchess of Cambridge set to visit the world's largest one-horn rhino park in remote northeastern India, conservationists hope the British royals can help raise global alarms about how black-market demand for rhino horns and other animal parts is fueling illegal poaching and pushing species to the brink. (Photo by Anupam Nath/AP Photo)





A Hippopotamus cools off in a pond at the National Zoological Park on April 14, 2016 in New Delhi, India. The advent of summer across the Indian subcontinent has already brought heat-wave like conditions with significantly higher than normal temperatures being recorded across West, Central and especially North India. New Delhi has already experienced 40 degree Celsius plus days, with maximum and minimum temperatures 5-6 degrees higher being recorded in other parts of the country. (Photo by Shams Qari/Barcroft India)





A newborn reticulated giraffe baby is seen with its mother in their enclosure in the Debrecen Zoological and Botanical Garden in Debrecen, Hungary, 11 April 2016. The baby is the very first of its kind since the foundation of the Debrecen Zoo. (Photo by Szolt Czegledi/EPA)





The three little fox cubs Allan, Albertina and Alina were found abandoned at a construction site outside Stockholm, Sweden on April 10, 2016. Now they live with animal caretaker Emma Karlsson awaiting a new home in a zoo. (Photo by Aftonbladet/IBL via ZUMA Wire)





The white boar “Bruno” stands in his enclosure in the Wildpark Schloss Ortenburg zoo in Ortenburg, Germany, 13 April 2016. Caretakers discovered a white boar among the six newborns, born one week ago. (Photo by Armin Weigel/DPA via ZUMA Press)





Baboons play together at Berlin Zoo in Berlin, Germany on April 14, 2016. (Photo by Theo Heimann/Startraksphoto.com)





Miniature pig “Nueffel” is walked in a park in Hanover, Germany, 14 April 2016. (Photo by Sebastian Gollnow/EPA)





Miniature pig “Nueffel” is walked in a park in Hanover, Germany, 14 April 2016. (Photo by Sebastian Gollnow/EPA)





A one-month-old wallaby peeks out of its mother's pouch at the Amneville zoo on April 5, 2016. (Photo by Jean-Christophe Verhaegen/AFP Photo)





Marnie the Dog attends the “Second Chance Dogs” Screening In Honor Of ASPCA's 150th Anniversary at The House of Vans on April 10, 2016 in the Brooklyn borough of New York City. (Photo by Jemal Countess/Getty Images)





These rare clouded leopard cubs are the pride and joy of staff at Tampa's Lowry Park Zoo in Florida. The adorable felines are currently being hand reared after their mother became anxious and stopped caring for them. Named “Aiya” and “Shigu” the six-week-old fur balls are of the very vulnerable “big cat” species native to Southeast Asia. Clouded leopard numbers are dwindling rapidly due to poaching and the destruction of their rainforest habitat for palm oil plantations. Animal conservationists advise the boycott of all palm oil products. (Photo by CaitlinChase/Splash News)