In 2020 the common hamster Cricetus cricetus was recategorized from Least Concern to Critically Endangered on the IUCN Red List. This rodent species originally lived on the Eurasian Steppe but has adapted to the large-scale transformation of its original habitat to agricultural land. The increasing intensification of agricultural practices has, however, brought new challenges.

In 2020, contrary to the global trend, hamster populations appeared to be stable in central Europe. Within this area, the Pannonian region, with Hungary in its centre, hosts the largest population, and this population has displayed decade-long fluctuations. In 2020 there was a peak in population size, followed by a rapid decline, and the hamster population in Hungary has now reached an all-time low.

It is unclear whether the population will recover, as the hamster faces a paradoxical conservation status in Hungary. Although protected, farmers have the right to exterminate populations at the first signs of any unfolding population increase, without the need for permission. Although this practice is intended to safeguard farmers' legitimate interests, emerging evidence suggest it may jeopardize hamster populations regionally.

Female common hamster Cricetus cricetus at her burrow. Photo: V. Nyíri.

Adding to the complexity of the situation, during the last population increase in Hungary the hamster started to utilize village gardens. Contrary to expectations, these semi-urban populations have thrived even as rural populations have declined. Although this suggests a potential novel way for the species to survive, it raises new challenges and underscores the need for innovative conservation.

We launched a detailed population genomics study in 2023, within the Biodiversity Genomics Europe project, to investigate the intricate genetics of the Pannonian hamster population. As part of this, field surveys uncovered a significant decline in numbers. However, there was a noticeable contrast either side of the Danube River, with a decline in the east and an upward trajectory in the west. The first results from RADseq-based conservation genomic research in February 2024 identified that the Danube, the largest river in the Pannonian Basin, has shaped the current regional genetic structure. Of even greater concern was the discovery of alarmingly low levels of genetic diversity, potentially lower than those observed in the rarest mammals.

These findings shed light on the discord between existing legislation and the population trends of the hamster in Hungary. Although data on crop losses as a result of hamster population increases are scarce, the absence of significant reports from farmers suggests losses may not be as substantial as perceived. The future of the Pannonian hamster depends on collaboration between conservationists and farmers to balance conservation with agricultural interests.