Elephants are pictured on May 21, 2014 in their outdoor enclosure at the zoo in Magdeburg. (Photo by Jens Wolf/AFP Photo/DPA)

A pig is stranded on a roof during heavy floods in Vojskova, May 19, 2014. More than a quarter of Bosnia's four million people have been affected by the worst floods to hit the Balkans in more than a century, the government said on Monday, warning of “terrifying” destruction comparable to the country's 1992-95 war. (Photo by Srdjan Zivulovic/Reuters)

An European bison (Bison bonasus) rubs its face in dirt after being relocated to Armenis, Tarcu Mountains, southwestern Romania, May 17, 2014. The bison, Europe's largest living wild land mammal, has been extinct in the area for 200 years. Seventeen bison were brought here from Sweden, Germany, Italy, Belgium and Romania, in the biggest-ever bison transportation and reintroduction to have taken place in Europe, according to the World Wide Fund for Nature (WWF) and Rewilding Europe environmental organisations. It is hoped that the animal will serve as a regional tourism attraction, with a Bison Visitor Centre to be established in the future. (Photo by Bogdan Cristel/Reuters)

A man climbs on the roof of a house to feed pigs they rescued during heavy floods in the village of Vojskova, on May 19, 2014. (Photo by Srdjan Zivulovic/Reuters)

Two young male Sumatran tigers play in a new $19.5 million tiger habitat at the San Diego Zoo's Wild Animal Park in San Diego's San Pasqual Valley May 21, 2014. The soon to open exhibit will house six tigers and features waterfall feed ponds, rocks for climbing and tall crass for catnaps. (Photo by Mike Blake/Reuters)

A Dwarf crocodile is reflected in a pond at Colombo's Zoological Gardens May 22,2014. (Photo by Dinuka Liyanawatte/Reuters)

A picture made available 18 May 2014 shows a one-year-old Barbary ape chewing grass on Monkey Hill in Salem, Baden-Wuerttemberg, Germany, 17 May 2014. (Photo by Felix Kaestle/EPA)

Baby pygmy hippopotamus “Lani” eats a salad on May 17, 2014 at the Basel Zoo. It has been 14 years since a baby pygmy hippopotamus was last born at Basel Zoo. Lani came into the world on March 18, when it was still a little cold for her outside. Now, she joins her mother in the outdoor enclosure on warm, sunny days. Lani is one around 135 pygmy hippopotamuses in the European Endangered Species Programme. (Photo by Fabrice Coffrini/AFP Photo)

Undated handout photo issued by Woburn Safari Park of one of the youngest Joeys (approx three-weeks-old) poking its head out of its mother's pouch to enjoy the sunshine as Woburn Safari Park has enjoyed a recent baby boom, including baby Red River hoglets, baby Joeys and baby Ring Tailed lemurs. (Photo by Daniel Davies/Woburn Safari Park/PA Wire)

Undated handout photo issued by the Wildfowl & Wetlands Trust (WWT) of a crane chick with one of its parents at the Slimbridge Wetland Centre in Gloucestershire, one of two crane chicks to be hatched by Slimbridge cranes – Monty and Chris and the first in the west of Britain for 400 years. (Photo by Graham Hann/PA Wire/WWT)

Undated handout photo issued by Chester Zoo of one of the five baby meerkats, born one month ago at the Zoo, who have taken their first steps outside. Keepers have yet to give them names as they don't know if they're male or female. The tiny newcomers made their first public appearances after being hidden away in burrows by their parents since being born on April 20. (Photo by Steve Rawlins/PA Wire/Chester Zoo)

Biologist Rodrigo Cerqueira holds an armadillo, named Ana Botafogo in honor of the Brazilian dancer, at the Rio Zoo in Rio de Janeiro, Brazil, Wednesday, May 21, 2014. The three-banded armadillo is in danger of extinction, largely because of deforestation and hunting in its habitat in the shrub lands of northeastern Brazil. Those risks in large part are why the armadillo was chosen as the World Cup mascot. Another is that when it's frightened, it rolls up into a ball small enough to fit into one hand, looking like a tan soccer ball. (Photo by Silvia Izquierdo/AP Photo)

Biologist Rodrigo Cerqueira touches an armadillo, named Ana Botafogo in honor of the Brazilian dancer, at the Rio Zoo in Rio de Janeiro, Brazil, Wednesday, May 21, 2014. A Brazilian environmental group has launched an effort to save the endangered three-banded armadillo, the mascot for the World Cup that starts next month. The armadillo is in danger of extinction, largely because of deforestation and hunting in its habitat in the shrub lands of northeastern Brazil, according to the Caatinga Association. Those risks in large part are why the armadillo was chosen as World Cup mascot. Another is that when it's frightened, it rolls up into a ball small enough to fit into one hand, looking like a tan soccer ball. (Photo by Silvia Izquierdo/AP Photo)

A small monkey sits atop the head of a woman in the Tatuyo indigenous community near Manaus, Brazil, Monday, May 19, 2014. Manaus is one of the host cities for the 2014 World Cup in Brazil. (Photo by Felipe Dana/AP Photo)

A polar bear jumps into the water in its new enclosure during warm and sunny weather at the Schoenbrunn Zoo in Vienna, Austria, on Thursday, May 22, 2014. The Austrian capital expects temperatures up to 28 degrees Celsius (82,4 Fahrenheit) for Thursday. (Photo by Ronald Zak/AP Photo)

Rafael Lopez holds up his carpet python during a demonstration by the owners of exotic pets outside the Capitol in San Juan, Puerto Rico, Wednesday, May 21, 2014. Exotic pet owners oppose proposed amendments to the “New Wildlife Act of Puerto Rico” law because it creates a list of “harmful and poisonous species” which would make it unlawful to continue to have their exotic pets at home. (Photo by Ricardo Arduengo/AP Photo)

A dog called Denise jumps through the water as it chases a ball in a lake in Duisburg, Germany, Tuesday, May 20, 2014. Temperatures in Germany reached 29 Celcius (84F), the hottest day of the year so far. (Photo by Frank Augstein/AP Photo)

Three of the five baby meerkats play with their mother at the Chester Zoo, on May 23, 2014. (Photo by Steve Rawlins/PA Wire/Chester Zoo)

A woman leads her painted buffalo onto a stage during a buffalo bodypainting competition in Jiangcheng county, Yunnan province May 18, 2014. Artists from eight countries painted on buffalos to compete for a 100,000 yuan ($16,042) prize reward during the competition on Sunday, according to local media. (Photo by Wong Campion/Reuters)

Mammoth researcher Professor Adrian Lister poses for photographs looking at Lyuba, a baby woolly mammoth considered to be the most complete example of the species ever found, at the Natural History Museum in London, Monday, May 19, 2014. Lyuba, her name taken from the word for love in Russian, was discovered frozen in clay and mud in Russia's Yamal Peninsula of Siberia in 2007 and is estimated to have died around 42,000 years ago at one month old. She is 85cm tall and 130 cm long, and is on loan from Russia's Shemanovsky Museum to feature in the exhibition “Mammoths: Ice Age Giants”, which runs from March 23 to September 7. (Photo by Matt Dunham/AP Photo)

A baby Yemen chameleon (Chamaleo calyptratus) crawls on the fingers of veterinarian Lidija Stanisic at her house in the outskirts of Zagreb, Croatia, 19 May 2014. (Photo by Antonio Bat/EPA)

A Yemen chameleon (Chamaleo calyptratus) crawls on the hand of veterinarian Lidija Stanisic at her house in the outskirts of Zagreb, Croatia, 19 May 2014. (Photo by Antonio Bat/EPA)

A baby Yemen chameleon (Chamaleo calyptratus) crawls on the fingers of veterinarian Lidija Stanisic at her house in the outskirts of Zagreb, Croatia, May 19, 2014. Eight baby chameleons came into the world at the veterinarian house a few weeks ago. (Photo by Antonio Bat/EPA)

A polar bear sticks its face into a heap of snow to cool down from the sweltering heat in the zoo in Moscow, Russia, 20 May 2014. The temperatures in Moscow are around 30 degrees Celsius. (Photo by Yuri Kochetkov/EPA)

A white-faced saki is pictured in its enclosure at the Tierpark zoo in Berlin on May 20, 2014. In the wild, the animals are native to parts of South America. (Photo by Hauke-Christian Dittrich/AFP Photo/DPA)

A white-faced saki is pictured in its enclosure at the Tierpark zoo in Berlin on May 20, 2014. (Photo by Hauke-Christian Dittrich/AFP Photo/DPA)

In this undated photo released by Damien Hirst and Science Ltd., British artist Damien Hirst's latest piece entitled “Gone but Not Forgotten”, which features the gilded skeleton of a woolly mammoth in a steel and glass vitrine, is displayed. Famed British artist Damien Hirst has created a gilded woolly mammoth skeleton encased in a gold tank to be auctioned off at the annual amfAR Cinema Against AIDS gala in Cap d'Antibes, southern France, on Thursday, May 22, 2014. (Photo by AP Photo/Prudence Cuming Associates)

A Montagu's Harrier (Circus pygargus) carries a lizard over a meadow near Mallnow, Germany, 20 May 2014. (Photo by Patrick Pleul/EPA)

Red howler monkey Taima plays in the enclosure in the zoo in Berlin, Germany, Tuesday May 20, 2014. (Photo by Hauke-Christian Dittrich/AP Photo/DPA)

A cayman is seen after falling from a car nearby the Court of Amazonas in Aleixo district, South-Central zone of Manaus, Amazonas, Brazil on May 15th, 2014. The animal was carried to “Refugio de Vida Silvestre Sauim Castanheiras”, a conservation area. (Photo by Raphael Alves/AFP Photo)

Lauryn Zepeda, one of the 10 horse trainers chosen to participate in LOPES Rescues competition, works with Gringo, a mustang, in Bolivia, N.C., Friday, May 216, 2014. Zepeda utilizes the clicker tool method that disciplines animals through positive reinforcement. (Photo by Mike Spencer/AP Photo/The Star-News)

A pair of 20-year-old Galápagos tortoises raise their heads as they wander through their new home at The Pittsburgh Zoo & PPG Aquarium on Thursday, May 22, 2014, in Pittsburgh. The zoo invited media inside the habitat to photograph the new additions to their exhibits. (Photo by Keith Srakocic/AP Photo)

A little monkey sits on the foot of a zoo worker while she cleaning the cage at the zoo in Moscow, Russia, 20 May 2014. The temperatures in Moscow are around 30 degrees Celsius. (Photo by Yuri Kochetkov/EPA)

A porcupine looks down from a tree inside of Ricketts Glen State Park, Monday, May 19, 2014 in Benton, Pa. (Photo by Andrew Krech/AP Photo/ Citizens' Voice)

Tropical Blue-and-gold Macaws are seen at Bronte Beach on May 23, 2014 in Sydney, Australia. Sydney is experiencing it's hottest May on record, already recording it's hottest week for this time of year in over 150 years. (Photo by Ryan Pierse/Getty Images)

A young golden monkey (fifteen days old) rests in his mother's breast in South Korea's largest amusement park Everland in Youngin, Gyeonggi-province, South Korea, 20 May 2014. The golden monkey, admired for its golden fur, is one of the first-class national protected animals in China. (Photo by Jeon Heon-Kyun/EPA)

A young golden monkey (fifteen days old) rests in his mother's arms in South Korea's largest amusement park Everland in Youngin, Gyeonggi-province, South Korea, 20 May 2014. (Photo by Jeon Heon-Kyun/EPA)

Lucifer, a 30-stone male Asian lion, is surrounded by ZSL London Zoo's team of vets and keepers as they carry out a health check ahead of him moving home. The 11-year-old lion moves to another breeding group next week as the Zoological Society of London (ZSL) launches its Lions400 campaign – an ambitious public fundraising campaign designed to raise £5.7m for the endangered Asian lion. The campaign will include the building of a new state-of-the-art lion breeding centre and visitor experience, as well as the extension of vital conservation work in the field where only 400 Asian lions are left in the wild. Lucifer's female cubs will remain with the Zoo to begin a new breeding group, which visitors will be able to see when the new exhibit opens in 2016. Lucifer, named after his studbook number of 666, has been given a clean bill of health and is due to move later this week. (Photo by Jeff Moore/Splash News)

An Adult White-tailed Eagle hunting for fish for her young chicks, on May 20, 2014. (Photo by Valerie O'Sullivan/Golden Eagle Trust)

A worker cleans a hippo's teeth at Qingdao Forest Wildlife Park on May 22, 2014 in Qingdao, Shandong Province of China. Workers at the park clean hippos' teeth twice a week in summer. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

A Green Garden Lizard or Pala Katussa in Sinhalese changing its colour when threatened in the hills of Kadugannawa 99 kilometres from Colombo, Sri lanka, 22 May 2014. Common among home gardens as well in shrub jungles island-wide its green acts as camouflage among the foliage. When threatened or agitated it changes colour around its upper body. It is mostly left unharmed by humans. (Photo by M. A. Pushpa Kumara/EPA)

A sloth peeks out from behind a door on a floating house in the “Lago do Janauari” near Manaus, Brazil, Tuesday, May 20, 2014. Manaus is one of the host cities for the 2014 World Cup in Brazil. (Photo by Felipe Dana/AP Photo)

Surya licks her one of Sumatran tiger cubs Mentari and Kuasa, who are in the grass for the first time in their enclosure, at Flamingo Land, Malton, North Yorkshire, on May 21, 2014. (Photo by Lynne Cameron/PA Wire)