Successful restoration of heathlands and grasslands associated with long-term habitat preferences of cattle and horses: Insights from GPS tracking

Long-term, year-round grazing by large herbivores is increasingly used to restore degraded temperate heathlands and grasslands, yet the behavioral mechanisms of grazers underlying restoration remain insufficiently understood. We combined over 13 years of high-resolution GPS-tracking data of free-ranging Heck cattle and Konik horses with repeated vegetation surveys across various habitat types (encroachment-derived Calamagrostis epigejos stands, dry sandy grasslands, dry heaths, and pioneer forests) in Central Germany. We quantified how habitat preference and vegetation structure co-develop under low-intensity, year-round grazing following abandonment. Habitat preference differed among habitat types and showed clear seasonal patterns. Preference values were consistently higher in summer than in winter for both grazer species, reflecting selective use of productive regrowth. Winter preferences were weak, indicating low selectivity and homogeneous space use that facilitated grazing in habitats otherwise avoided during the growing season, including dry heaths and pioneer forests. Across the study period, we detected long-term shifts in habitat preference that corresponded with vegetation changes associated with the restoration of dry heaths and sandy grasslands. As standing biomass declined, C. epigejos and grass litter decreased, open soil increased, and Calluna vulgaris advanced into the optimal phase. These structural improvements reduced forage-quality contrasts among habitats, resulting in progressively weaker preference patterns and a more even distribution of habitat use across the landscape. Our results provide rare long-term empirical evidence linking grazer behavior and vegetation dynamics in conservation grazing systems and highlight that year-round extensive grazing, rather than summer-only grazing, is required to achieve stable long-term restoration outcomes.