14 week-old twin polar bear cubs play during their first presentation to the media in Hellabrunn zoo on March 19, 2014 in Munich, Germany. The male and female twins were born on December 9, 2013 in the zoo. (Photo by Alexandra Beier/Getty Images)

This picture taken on December 17, 2013 shows people taking photos of a pole dancer (R) practising after it snowed in Tianjin during a promotional event by members of China's national pole dancing team and students of the sport. China set up its first national pole dancing team in Tianjin in 2012 in order to compete in the World Pole Dancing Championships. (Photo by AFP Photo)

Miners carry a goats head for burial in the crater as part of an annual offering ceremony on the Ijen volcano on December 17, 2013 in Yogyakarta, Indonesia. The ritual is performed by the sulfur miners of Mount Ijen who slaughter a goat and then bury the head in the crater of mount Ijenn. The sacrifice is performed to ward off potential disasters for the next year. (Photo by Ulet Ifansasti/Getty Images)

A cow, which escaped from a truck, attacks a farmer trying to catch it in Liangdun village of Nangang township, Anhui province December 15, 2013. The 700 kilogram (1,543 lb) cow attacked several farmers before being shot dead by policemen, local media reported. (Photo by Reuters/China Daily)

Paramilitary policemen carry seized crystal meth at Boshe village, Lufeng, Guangdong province, December 29, 2013. Police in the southern Chinese province of Guangdong have seized nearly three tonnes of the drug crystal methamphetamine and arrested 182 people in raids on a village notorious for producing narcotics. (Photo by Reuters/Stringer)

A goose sits atop eggs in a flower bed on the Wisconsin Ave. bridge, Friday, April 19, 2013, feathers ruffled in the cold blowing wind and snowflakes. The goose is near to the statues dedicated to Gertie the duck who made international news when she built her nest next to the same bridge in 1945 and captured the attention of Milwaukee at the end of the war. A statue commemorating “Gertie the Duck” sits on the other side of the bridge. The goose has several eggs she is sitting on. (Photo by Mike De Sisti)

A house built on a rock on the river Drina is seen near the western Serbian town of Bajina Basta, about 160km (99 miles) from the capital Belgrade May 22, 2013. The house was built in 1968 by a group of young men who decided that the rock on the river was an ideal place for a tiny shelter, according to the house's co-owner, who was among those involved in its construction. (Photo by Marko Djurica/Reuters)

The sign above the door of restaurant and hotel “Am Paulusbogen” is partially submerged in the flooded centre of the Bavarian town of Passau, about 200 km (124 miles) north-east of Munich June 3, 2013. (Photo by Michaela Rehle/Reuters)