Berlin (dpa) - Fans mourned Sunday the death of Germany's best-loved and biggest animal star, the polar bear Knut, while animal rights activists blamed his death on the Berlin zoo where he was born and raised in captivity. Visitors to the zoo left flowers and condolence messages, including, 'Goodbye, Knut,' 'We loved you sooo much!' and 'We will miss you, Knut!' 'We had all taken the polar bear into our hearts. He was the star of the Berlin zoo,' said the city's mayor Klaus Wowereit.