Rewilding European cattle: insights from the feral cattle in the Chornobyl Radiation and Ecological Biosphere Reserve

Truly feral cattle populations are rare in Europe, limiting our understanding of how domestic cattle function under wild conditions. We document the development and ecology of an accidentally feral herd in the Chornobyl Radiation and Ecological Biosphere Reserve, northern Ukraine. After the last owner passed away in 2016, a group of seven Ukrainian black-and-white dairy cattle became free-living near the abandoned village of Lubyanka. Between 2016 and 2024, opportunistic field observations and camera-trap records documented herd size, habitat use, diet, social structure, and anti-predator behaviour. The herd increased steadily to 20 individuals by 2022, demonstrating successful adaptation to free-living conditions, but declined to 12 animals by 2025, most likely due to war-related mortality rather than ecological constraints. The cattle used a compact home area of approximately 12 km², showed no evidence of seasonal migration, grazed palatable meadow graminoids during the growing season, and shifted to woody browse in winter. They exhibited cohesive social organisation, alarm calls, and coordinated group responses to wolves and bears. These findings show that domestic cattle can rapidly re-establish key wild-ungulate traits and function as a large herbivore under minimal human influence. At the same time, the small and isolated population remains demographically vulnerable, underscoring the potential need for reinforcement if such feral herds are to persist and contribute to rewilding efforts in Europe.