The effects of ungulates on pine invasions are variable across studies: some studies suggest that they promoted the invasion 22, 24-26 and others suggest that they hinder the pine invasion 27-30. For example, it was proposed that sheep and cows could favor the Pinus sylvestris and Pinus mugo invasion process in Spain, while Abies alba could be controlled by these ungulates in the same areas, possibly, because of its higher sensitivity to herbivory damage 31. Other studies observed that exotic invasive deer preferred native species over the exotic Pinaceae species Pseudotsuga menziesii and Pinus ponderosa in Argentina 22, 24. Lastly, in another study, it was observed that feral horses could have promoted the establishment of Pinus halepensis seedlings after a long period of grazing in Argentinean Pampean grasslands 26. Among the studies that suggest that ungulates could be controlling pine invasions; it was observed that semi-feral cattle and sheep prevent the regeneration of Pinus nigra and Pinus sylvestris in France 28, 29. Finally, it was suggested that exotic vertebrates herbivores negatively affected Pinus radiata survival in Mediterranean areas of Chile 30. These opposing results may be due to distinctive characteristics of ungulates; such as its behavior, physiology, habits, and origin; as well as intrinsic characteristics of the plant such as phenology, plant morphology, and palatability 32-36. Regarding plant palatability, the plant nutritional quality (e.g. proportion of fiber and water content), its physical characteristics (e.g. leaf toughness and trichomes), and their secondary metabolites (e.g. alkaloids and monoterpenes) are important traits that affect the ungulate preference 32-34, 37. Particularly for mammalian herbivores, in several studies, the preference between conifer species was related to the type and concentrations of secondary compounds 38-44. For example, total foliar monoterpenes concentration influenced negatively the browsing behavior of Red deer (Cervus elaphus) 38 and Black-tailed deer (Odocoileus hemionus columbianus) 39. However, chemical defenses vary greatly between different conifer species and even between genotypes within a species, causing palatability to differ 45, 46. Among ungulates, it is known that sheep exhibit high plasticity in feeding preference, and even though they are considered grazers herbivores, they have been used to successfully control weeds because they can consume plants with higher fiber content than can other domestic ungulates 47. Although studies are scarce, it has been suggested that regular sheep browsing could limit the spread of species in the Pinaceae family. Ledgard 48 observed that in New Zealand, even low stocking rates of sheep reduced the successful establishment of Pinus contorta seedlings younger than two years old. However, for efficient control, it is necessary more intensive browsing to impede the establishment of new seedlings 49. Crozier and Ledgard 50 assessed the palatability of seven pine species to sheep in New Zealand. They foun...