What moves large grazers? Habitat preferences and complementing niches of large herbivores in a Danish trophic rewilding area

Large herbivores (≥45 kg) fulfill key ecological functions. Since the Late Pleistocene megafauna diversity and abundances have declined sharply, with profound consequences for ecosystems. On this background the concept of trophic rewilding has emerged and is increasingly applied to restore natural disturbance regimes and trophic interactions, ultimately aiming to recreate self-sustaining, dynamic and diverse ecosystems. Effects of such efforts (e.g., more heterogeneous habitats) are evident, but herbivore space use, and the resulting distribution of effects on vegetation remain poorly understood. Here, we examine habitat selection of semi-feral water buffalos (Bubalus bubalis), horses (Equus ferus) and cattle (Bos taurus) in a Danish rewilding area. We modelled space use with remote sensed covariates, reflecting resources (vegetation greenness, distance to water) and infrastructure (distances to fences, paths, shelter). Seasonal differences and former land use were tested separately. We found large-herbivore space use to shift seasonally, reflecting food and water availability, and to be influenced by infrastructure and former land use. Horses reacted less to vegetation greenness and water than the two bovids. Cattle selected for green vegetation in summer, while buffalos showed the strongest association with water bodies. Overall, the three semi-feral herbivore species diverged in their habitat use both spatially and seasonally. This can be expected to translate to variable and complementary ecological impacts such as grazing, physical disturbances and habitat engineering. Such variable space use likely increases habitat heterogeneity and species richness. We therefore suggest that a diverse large-herbivore guild is key, both to understanding megafauna ecology and for successful rewilding efforts.