Authors: Castellaro Giorgio, Orellana Carla Loreto, Escanilla Juan Pablo
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Understanding how horses, hares, and guanacos partition forage resources in Andean grasslands has direct relevance to grazing management and nutritional planning in mountain regions. Castellaro and colleagues used faecal microhistology to map the botanical composition and selectivity patterns of these three herbivores across two summer seasons in Chile's Coquimbo Region, revealing how each species exploits available vegetation despite dietary overlap. Horses and guanacos showed marked similarity in their reliance on wet grassland species (approximately 32–36% of diet), whilst all three herbivores derived roughly 36–48% of intake from graminoids; however, hares consumed significantly more herbaceous dicotyledons (24%) than either ungulate. Dietary overlap between horses and guanacos reached 55.7%, indicating potential for trophic competition when grazing shared pastures, yet all three species demonstrated selective foraging behaviour independent of plant abundance, preferentially consuming nutrient-dense species that form a minor proportion of standing herbage. For practitioners managing mixed-grazing systems or designing supplementary feeding programmes in extensive mountain pastures, these findings highlight that herbivores actively select for nutritional quality over convenience, and that stocking rates and species combinations must account for this selective behaviour rather than assuming consumption patterns simply reflect vegetation composition.
Read the full abstract on PubMed
Practical Takeaways
- •Horses show distinct feeding preferences from hares despite similar overall dietary diversity, suggesting different management strategies may be needed when grazing multiple herbivore species together
- •Plant selection by herbivores is driven by nutritional quality rather than abundance, so grassland management should focus on maintaining preferred forage species even if they are less prevalent
- •High dietary overlap between horses and guanacos (55.7%) indicates potential trophic competition when co-grazing, requiring careful stocking rate management
Key Findings
- •Horses and guanacos showed similar hydromorphic grass consumption (32-36%), while hares consumed significantly less (16.3%)
- •Dietary diversity was similar across all three herbivores (73-79%), with highest overlap between horses and guanacos (55.7%)
- •All three species demonstrated selective feeding behavior independent of plant abundance in grasslands, choosing species that improve diet quality
- •Herbaceous dicotyledons contributed significantly only to hare diets (23.76%), while shrubs remained negligible across all herbivores (<3%)