Smithsonian National Zoo biologist Leigh Pitsko releases a male lion cub for its swim test in the zoo habitat moat, in Washington May 6, 2014. Four, unnamed ten-week old lion cubs were tested today for their ability to swim and remove themselves from their zoo habitat moat. (Photo by Gary Cameron/Reuters)

Austrian alpine skiers (LtoR) Georg Streitberger, Klaus Kroell, Max Franz, Joachim Puchner, Romed Baumann pose in the Olympic Rings on February 4, 2014 at the Mountain Olympic Village at the Rosa Khutor Alpine centre, four days prior to the start of the 2014 Sochi Winter Olympic Games. (Photo by Fabrice Coffrini/AFP Photo)

An anti-government protester sits on the ground in front of police during a demonstration in Sarajevo February 6, 2014. Hundreds of people turned out in solidarity in the capital Sarajevo, with teenagers throwing eggs and stones at a government building and fought with police. Four officers were taken to hospital, officials said. (Photo by Dado Ruvic/Reuters)

This photo released by the Cleveland Animal Protective League shows Lurleen, the nursing mother and Noland the puppy snuggling up Wednesday, June 19, 2013, in Cleveland. Lurleen already is caring for four newborn kittens and now is nursing the orphaned week-old pit bull puppy in Cleveland. (Photo by AP Photo/Cleveland Animal Protective League)

A tourist crosses flooded St. Mark's Square in Venice, Italy on November 11, 2012. Flooding is common this time of year and Sunday's level that reached a peak of 58.66 inches was below the 63 inches recorded four years ago in the worst flooding in decades. (Photo by Luigi Costantini/Associated Press)

A dachshund portraying a racehorse, trots down Duval Street in Key West, Florida, December 31, 2014. About 175 dachshunds and other dogs participated in the event that preludes four warm-weather takeoffs on New York City's Times Square ball drop. (Photo by Steve Panariello/Reuters/Florida Keys News Bureau)

A view of a Van Gogh-inspired hot air balloon being inflated during the Philippine International Hot Air Balloon Fiesta at Clark Freeport Zone in Pampanga province, north of Manila February 12, 2015. According to the organizer, a total of 32 hot air balloons are part of the four-day event. (Photo by Erik De Castro/Reuters)

Participants demonstrate for the media before the role play event at Czocha Castle in Sucha, west southern Poland April 9, 2015. Harry Potter enthusiasts from all over the world are attending a four-day live action role play event at the medieval castle made into a close imitation of the “College of Wizardry”. (Photo by Kacper Pempel/Reuters)