Wild Horse Diets are Adaptable

A University of Wyoming study of wild horses on federal lands across seven Western states has found that the animals have a high ability to gain nutrition from a variety of plants and, by so doing, maintain good body condition, even in winter. Although equids are broadly categorized as obligate grazers, our recent study reveals that free-roaming horses can not only maintain—but in many cases improve—their body condition when accessing a diverse assemblage of forage species. This dietary plasticity suggests a generalist foraging strategy in wild horses, a characteristic supported by prior work showing equids’ capability to process variable plant material. For instance, research on wild and feral equids indicates that although grasses dominate their diet, forbs and shrubs can comprise a meaningful part of the forage mix. By facilitating a broader forage base, this flexibility may help explain the continued population expansion of wild‐horse herds across federally managed rangelands in the western United States. These insights have important implications for rangeland management, suggesting that the ecological resilience of wild horses may be greater than previously assumed and that forage diversity should be factored into models of herd growth and ecosystem impact. Across the majority of study sites, grasses and grass-like species comprised the dominant portion of wild horse diets; however, researchers observed that forbs and shrubs were also selected at appreciably higher levels than previously documented. This broader forage use demonstrates a flexible feeding ecology rather than strict reliance on graminoids. Notably, free-roaming horses were able to maintain favorable body condition scores across diverse habitat types and throughout variable seasonal conditions, further supporting the conclusion that their dietary plasticity contributes to strong physiological performance on western rangelands. These findings challenge longstanding assumptions about wild horse foraging limitations and underscore the adaptive capacity of equids to exploit heterogeneous plant communities on public lands.