Photographs of newborn animals from zoos create the impression that breeding in captivity is going well.
However, scientific data shows a different picture. Most mammal populations in zoos are rapidly aging, which raises doubts about their contribution to biodiversity conservation. This conclusion was reached by the authors of a study published in the journal PNAS.
The researchers analyzed data on 774 mammal populations housed in zoos in Europe and North America. The sample included data from the period between 1970 and 2023. The analysis showed that in many cases, the population structure is skewed towards adults and elderly individuals, while the number of young animals is decreasing. Such an age ratio is considered unfavorable and increases the risk of population extinction.
Researchers were additionally alarmed by the sharp decline in the number of females participating in reproduction. This means that even with adult animals present, the potential for population renewal remains limited.
The authors of the study link these developments to two factors. On one hand, the conditions in zoos have significantly improved over the past decades, leading to increased lifespans for animals. On the other hand, many zoos are facing space shortages, making it difficult to accommodate offspring.
As one of the researchers, M. Klaus, emphasizes, zoos will only be able to fulfill their conservation function if they can maintain stable, self-sustaining populations, rather than merely prolonging the lives of individual animals.
