This February, five-year-old polar bear Wolodja was relocated to Zoo Berlin to allow for renovation work on the Tierpark’s polar bear habitat. After two months’ absence, he is now returning home. His son, five-month-old Fritz, died unexpectedly on 6 March from multiple organ failure caused by liver damage. Since then, numerous experts at various institutions – including biologists, pathologists, veterinarians and even doctors of human medicine – have been looking for the cause of little Fritz’s tragic death, taking samples of tissue, blood, urine and faeces and conducting microbiological, virological and toxicological examinations. Although most of the analyses have now been completed, the cause of death has still not been determined.
Prof. Alex Greenwood, head of the Department of Wildlife Diseases at the Leibniz Institute for Zoo and Wildlife Research, has been working on the virological diagnostic investigation with Prof. Nikolaus Osterrieder of Freie Universität Berlin. Greenwood says that their complex analyses of more than 600 million DNA sequences will still take several weeks to complete. “Thus far, we have not discovered any evidence of a viral disease. This case is rather baffling.”
As Fritz’s mum Tonja (aged seven) continues to live at the Tierpark without any sign of illness and there are no indications that Wolodja is at risk, the experts agree that there is no reason why Wolodja should not return to the Tierpark. And there are good reasons for reuniting the pair: “Tonja needs a sparring partner,” says Zoo and Tierpark Director Dr Andreas Knieriem. “Wolodja and Tonja are a good match, so they should be brought back together as soon as possible.” Wolodja returns to Tierpark Berlin on 22 April and will be given plenty of time to reacquaint himself with his old stomping ground.
If Wolodja settles back in quickly enough, he may be able to enjoy a dip in the bears’ outdoor area as early as this Sunday. He will then be reintroduced to Tonja at the start of next week.
Background
Tonja gave birth to her first offspring at Tierpark Berlin on 3 November 2016. Fritz was the first baby polar bear at Tierpark Berlin in 22 years and initially developed very well. It was therefore a great shock when, on the evening of 6 March, he suddenly fell ill and died from multiple organ failure.
