The polar bears in the picture are actually Aalborg Zoo's. They stayed in Duisburg in 1998 while Aalborg Zoo (Denmark) built a brand new exhibit for them.
The only condition that Duisburg Zoo had was that the very old female from Duisburg would follow the other polar bears back to their new enclosure in Denmark when their "vacation" was over. She was the last polar bear in Duisburg. She died in Aalborg of old age about 1 year after the transport.
