Targeted killings needed to limit ageing zoo populations, study warns

Geneva (dpa) – Zoos are facing ageing populations that threaten the conservation of endangered species, and targeted culls may be needed to make room for young animals, the team led by Marcus Clauss at the University of Zurich has warned. "If I could constantly build new enclosures, this measure would probably not be necessary," Clauss told dpa. "But if I keep all animals into old age in a world with limited enclosure space, I have no room for the next generation." The researchers examined 774 mammal populations, from hoofed animals to primates and carnivores, in European and North American zoos over 53 years. Across species, they found more populations with older than younger animals. They said the average age has steadily risen. The proportion of species with females still reproducing has fallen to 69% in Europe and 49% in North America. An ageing population is less resilient to, for example, animal diseases, the experts warned. Smaller groups with fewer than 150 animals and little reproduction could disappear entirely in the event of an outbreak. "The danger is not that all zoo animals will be gone in ten years," Clauss said. "But the trend is so striking that you need a new strategy." He said more must be done to make targeted culls socially acceptable for the sake of the next generation. In Germany there were protests in summer 2025 after 12 baboons were killed at Nuremberg Zoo due to lack of space. Zurich Zoo said the first option is always to place older animals elsewhere, but places are limited. "Culls are always carried out in accordance with the law, with animal welfare in mind and after thorough consideration of all options." The following information is not intended for publication dpa oe xxde coh

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