Polar bear Giovanna (C) and her twin polar bears Nela and Nobby eat an ice cake with fresh fruit and cream to celebrate their first birthday in their enclosure at Tierpark Hellabrunn zoo in Munich December 9, 2014. (Photo by Michaela Rehle/Reuters)

A polar bear eats an ice cake with fresh fruit and cream to celebrate its first birthday in an enclosure at Tierpark Hellabrunn zoo in Munich December 9, 2014. (Photo by Michaela Rehle/Reuters)

Twin polar bears Nela and Nobby eat an ice cake with fresh fruit and cream to celebrate their first birthday in their enclosure at Tierpark Hellabrunn zoo in Munich December 9, 2014. (Photo by Michaela Rehle/Reuters)

A polar bear eats an ice cake with fresh fruit and cream to celebrate its first birthday in an enclosure at Tierpark Hellabrunn zoo in Munich December 9, 2014. (Photo by Michaela Rehle/Reuters)

Polar bear Giovanna (L) eats an ice cake with fresh fruit and cream next to one of her twin cubs during celebrations of the cubs' first birthday in their enclosure at Tierpark Hellabrunn zoo in Munich December 9, 2014. (Photo by Michaela Rehle/Reuters)

A polar bear plays with a pylon during celebrations marking its first birthday in an enclosure at Tierpark Hellabrunn zoo in Munich December 9, 2014. (Photo by Michaela Rehle/Reuters)

A polar bear plays with a pylon during celebrations marking its first birthday in an enclosure at Tierpark Hellabrunn zoo in Munich December 9, 2014. (Photo by Michaela Rehle/Reuters)

One year old polar bear twins Nobby and Nela and their mother enjoy a birthday ice cake during the cubs' first birthday party at the polar bears' outdoor enclosure at the Hellabrunn zoo in Munich, southern Germany, on December 9, 2014. Polar bear twins Nobby and Nela were born at the zoo of Munich on December 9, 2013. (Photo by Christof Stache/AFP Photo)