Young and old elephants play with a Christmas trees before eating them at the zoo in Prague, Czech Republic, Monday, January 12, 2015. The animals at Prague Zoological Garden enjoy Christmas trees donated to the zoo by vendors who could not sell them before the holidays. (Photo by Vit Simanek/AP Photo/CTK)

A young girl watches a river dolphin swimming by at the aquarium of the Zoo in Duisburg, Germany, Wednesday, January 14, 2015. Every year the Zoo counts its animals, size and weight in an inventory. 4,237 animals in 356 species live in this western German Zoo. (Photo by Frank Augstein/AP Photo)

This undated image provided by the U.S. Fish and Wildlife Service shows a black-footed ferret at the Vermejo Park Ranch in northern New Mexico. The agency is working with landowners such as media mogul Ted Turner, who owns the ranch, to recover the endangered species across 12 western states. (Photo by Kimberly Fraser/AP Photo/U.S. Fish and Wildlife Service)

A giant panda plays on a swing after snowfall at a wildlife park in Kunming, Yunnan province January 10, 2015. (Photo by Wong Campion/Reuters)

A tortoise rests on a scale watched by keeper Alexander Nolte during an inventory at the Zoo in Duisburg, Germany, Wednesday, January 14, 2015. Every year the Zoo counts its' animals, size and weight. 4,237 animals in 356 species live in this western German Zoo. (Photo by Frank Augstein/AP Photo)

A black swan swims in a partly frozen pond at Kugulu Park in Ankara January 10, 2015. (Photo by Umit Bektas/Reuters)

A wild macaque eats a tangerine left by visitors on a tree branch, in rain at a wildlife park on Qianling Mountain, in Guiyang, Guizhou province January 9, 2015. (Photo by Reuters/Stringer)

Second Chance, a four-year-old boxer, wears sunglasses due to sensitive eyes as it takes a walk with its owner along the beach in Oceanside, California January 13, 2015. (Photo by Mike Blake/Reuters)

Second Chance, a four-year-old boxer, wears sunglasses due to sensitive eyes greets another dog during a walk with its owner along the beach in Oceanside, California January 13, 2015. (Photo by Mike Blake/Reuters)

A polar bear rests in its enclosure at Munich's Hellabrunn Zoo January 14, 2015. (Photo by Michael Dalder/Reuters)

Northern rockhopper penguins stands in its enclosure at Munich's Hellabrunn Zoo January 14, 2015. (Photo by Michael Dalder/Reuters)

A panda bear sits on a logs in a zoo on January 15, 2015 in Hangzhou, China. (Photo by Feature China/Barcroft Media)

A chimpanzee tastes an ice cream bar received from a zookeeper to help endure the intense summer heat at the Zoo in Rio de Janeiro, Brazil, on January 13, 2015. (Photo by Yasuyoshi Chiba/AFP Photo)

A woman throws a ball for her springer spaniel dog on the west strand Portrush on January 14, 2015 in Antrim, Northern Ireland. The province experienced heavy snowfall as a cold weather front hit the northern part of the United Kingdom today causing major traffic disruption and school closures. (Photo by Charles McQuillan/Getty Images)

A male Orangutan climbs in its enclosure at the San Diego Zoo, California on January 13, 2015. Orangutans, native to the rainforests of Indonesia and Malaysia, are considered among the most intelligent primates. (Photo by Mark Ralston/AFP Photo)

A corn snake sits on a rule during an animal inventory at the zoo in Duisburg, western Germany, on January 14, 2015. (Photo by Rolf Vennenbernd/AFP Photo/DPA)

Capybaras rests inside their enclosure at the San Diego Zoo, California on January 13, 2015. Capybaras are native to South America, are excellent swimmers and also the worlds largest rodent. (Photo by Mark Ralston/AFP Photo)

A Tasmanian Devil named Conrad inside its enclosure at the San Diego Zoo, California on January 13, 2015. Tasmanian Devils are native to Australia and are a carnivorous marsupial. (Photo by Mark Ralston/AFP Photo)

A Chinese shepherd leads his flock in the haze in a Beijing suburb on January 15, 2015 in Beijing, China. The PM2.5 Air Quality Index (AQI) reached more than 500 in Beijing city, resulting in a smog hitting Beijing from Tuesday. (Photo by Lintao Zhang/Getty Images)

A Southwest African Meerkat keeps warm inside its enclosure at the San Diego Zoo, California on January 13, 2015. The Meerkat is native to Southern Africa. (Photo by Mark Ralston/AFP Photo)

A lion tries to catch a box at the Santa Fe zoo in Medellin, Antioquia department, Colombia on January 10, 2015. The animals received, as gifts, boxes with their favourite foods as part of “Three Kings arrived at the Zoo”. (Photo by Raul Arboleda/AFP Photo)

A Persian cat during the International Cat Show 2015 at Shah Alam, Malaysia, January 11, 2015. Management of International Cat Show 2015 will hold a Corporate Social Responsibility (CSR) project by holding a charity bazaar to gather funds to fill the “Flood Disaster Fund”. (Photo by Fazry Ismail/EPA)

Undated handout photo issued by Chester Zoo of a Cinnamon Frog Nyctixalus Pictus, as the rare frogs found in the forests of South East Asia have bred for the first time at Chester Zoo – a European first. Issue date: Thursday January 15, 2015. (Photo by Steve Rawlins/PA Wire/Chester Zoo)

An undated handout picture made available by the Taronga Conservation Society Australia on 16 January 2015 shows koala joeys Bai'yali and Holly, at Taronga Zoo in Sydney, Australia. The poor eyesight of koalas has led to the species evolving to greet through nose touching and is a common way for koalas to determine if they're encountering a friend or a foe. (Photo by EPA/Taronga Conservation Society Australia)

A common green mamba is pictured in its enclosure at Munich's Hellabrunn Zoo January 14, 2015. (Photo by Michael Dalder/Reuters)

An albino roe deer (Capreolus capreolus) stands in its enclosure at the Protected Animal Rehabilitation Centre in Przemysl, South-eastern Poland, 16 January 2015. The albino deer was found near Korytniki village by residents. Albinism is very rare among wild animals. (Photo by Darek Delmanowicz/EPA)

A goosander holds a fish in its beak in a stream in Gangneung, Gangwon Province, South Korea, 14 January 2015. (Photo by EPA/Yonhap)

A bison plays with a Christmas tree at the zoo in Prague, Czech Republic, Monday, January 12, 2015. (Photo by Vit Simanek/AP Photo/CTK)

A hippopotamus also known as the common hippo swims in its enclosure at the San Diego Zoo, California on January 13, 2015. The name hippopotamus comes from the ancient Greek for “river horse”. Hippos can be very aggressive towards humans. (Photo by Mark Ralston/AFP Photo)

Bearded collie “Paddy” has his hair streaming in the wind on January 10, 2015 in Lengenfeld, southern Germany. Meteorologists forecast storm front “Felix” to sweep over wide parts of the country. (Photo by Nicolas Armer/AFP Photo)

Undated handout photo issued by Whipsnade Zoo of a baby pygmy hippo who was born at the zoo on Boxing Day, January 15, 2015. PThe Zoo's keepers say they are especially proud of the baby's mum, 28-year-old Flora, who has been battling cancer. (Photo by Whipsnade Zoo/PA Wire)

A fox runs past the door of 10 Downing Street on Janurary 13, 2015. (Photo by Justin Tallis/AFP Photo)