A New Generation of Captive-bred Romanian Hamsters Released into the Wild

Picture: Yordan Koshev, PhD

A team from the Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences (IBER-BAS), the Bulgarian Society for the Protection of Birds (BSPB), Agrotime Ltd., and volunteers carried out the first release of nine captive-bred Romanian hamsters (Mesocricetus newtoni) in 2026 into suitable habitat near the town of Isperih, northeastern Bulgaria.

The release site had been prepared in advance by digging artificial burrows and installing temporary metal enclosures to support the animals’ initial adaptation. During the first days after the release, the hamsters were closely monitored by the team, and camera traps were installed to document their behaviour and survival.

The release site borders strips of natural vegetation protected by firebreaks. The selected habitat is a harvested wheat field where numerous wheat ears have intentionally been left behind, providing an important food source for the hamsters, alongside natural grass cover that offers shelter.

The land is owned by Agrotime Ltd., based in Isperih. The company applies environmentally friendly farming practices that support biodiversity. The fields are managed using no-till farming, cover and catch crops, and without the use of herbicides or pesticides. These practices help preserve biodiversity, maintain surface vegetation, improve soil fertility and moisture, protect the soil microbiome, and reduce soil erosion.

The Romanian hamster (Mesocricetus newtoni) is an extremely rare mammal whose distribution is restricted to parts of Bulgaria and Romania. Surveys carried out within the project indicate that only a single population is likely to remain in Central Northern Bulgaria. The project’s goal is to establish a captive-breeding population and release animals into the wild to support the recovery of this threatened species.

These activities are part of the project “Ensuring the Recovery of the Endangered Saker Falcon in Bulgaria and Southern Romania” (LIFE20 NAT/BG/001162), funded by the European Union’s LIFE Programme.