Disentangling landscape features and vegetation composition effects on wild ungulate use of hay meadows in high Pyrenees

Abstract

Wild ungulates seek out food resources at the bottom of mountain valleys in winter and spring, where their high density can negatively impact the production of hay meadows. This study determines the factors that explain the meadow use of four sympatric species: red-, roe-, and fallow-deer, and wild boar. In 2017, we counted the individuals of each species in 94 meadows for eight nights, between March and June, and estimated the frequency of meadow use as the proportion of positive censuses over the total censuses per meadow. We also recorded the presence of domestic ungulates. We inventoried the floristic composition in June. Species tended to use different meadows but only fallow- and roe-deer significantly segregated, indicated by the negative C-score index. As the ungulate frequency was skewed to 0, we used a generalized additive model (GAMLSS) to simultaneously simulate the probability of animals being absent and the frequency of positive censuses. Landscape features contributed to explaining the absence probability, while plant richness and legume cover explained the frequency of meadow use. The presence of domestic ungulates did not affect wild ungulate behavior. All studied species, except roe-deer, avoided exposed spots, preferentially using large meadows close to the forest. At meadow level, each species seemed to have different forage requirements. The frequency of fallow deer increased with the meadow forage quality, indicating a more grasses-based diet than the other two deer, and probably displacing roe-deer to suboptimum meadows. Red-deer used less plant-rich meadows, suggesting flexibility in their dietary choices.