Intra- and Interspecific Differences in Diet Quality and Composition in a Large Herbivore Community

Abstract

Species diversity in large herbivore communities is often explained by niche segregation allowed by differences in body mass and digestive morphophysiological features. Based on large number of gut samples in fall and winter, we analysed the temporal dynamics of diet composition, quality and interspecific overlap of 4 coexisting mountain herbivores. We tested whether the relative consumption of grass and browse differed among species of different rumen types (moose-type and intermediate-type), whether diet was of lower quality for the largest species, whether we could identify plant species which determined diet quality, and whether these plants, which could be “key-food-resources” were similar for all herbivores. Our analyses revealed that (1) body mass and rumen types were overall poor predictors of diet composition and quality, although the roe deer, a species with a moose-type rumen was confirmed as an “obligatory non grazer”, while red deer, the largest species, had the most lignified diet; (2) diet overlap among herbivores was well predicted by rumen type (high among species of intermediate types only), when measured over broad plant groups, (3) the relationship between diet composition and quality differed among herbivore species, and the actual plant species used during winter which determined the diet quality, was herbivore species-specific. Even if diets overlapped to a great extent, the species-specific relationships between diet composition and quality suggest that herbivores may select different plant species within similar plant group types, or different plant parts and that this, along with other behavioural mechanisms of ecological niche segregation, may contribute to the coexistence of large herbivores of relatively similar body mass, as observed in mountain ecosystems.

Multivariate calibration of near infrared spectra for predicting nutrient concentrations of solid moose rumen contents

“…Our results are comparable with the only available study on application of NIRS for determining the chemical composition of solid rumen contents by Redjadj et al (2014).…”

“…The performance of our prediction models of NDF and ADF are comparable to previous studies on solid rumen content samples (Redjadj et al 2014), liquid rumen samples (Jean et al 2016) of herbivores, a wide range of feeds for ruminants (Belanche et al 2014) and meadow herbage (Andrés et al 2005). For the prediction of microbial-N (R 2 = 0.81; RMSEP = 1.25; RPD = 2.32) and lignin (R 2 = 0.84; RMSEP = 1.05; RPD = 2.57), the model performance was comparably lower than that of protein and NDF.…”

“…NIRS has also proven its utility for nutritive evaluation of forage and diets in a wide range of applications (Andrés et al 2005;Belanche et al 2014;Foskolos et al 2015). However, direct analyses of rumen contents by NIRS are largely missing (Redjadj et al 2014;Jean et al 2016).…”

Upscaling the niche variation hypothesis from the intra- to the inter-specific level

“…Mouflon overlap with chamois in spring and summer in alpine pastures (Darmon et al 2012) and shift to forest during November when snow comes (Duparc et al 2012). Roe deer mostly use forests (Redjadj 2010;Redjadj et al 2014).…”

“…Here, we tested NVH (at the intra-and inter-specific levels) and SH (at the inter-specific level) by collecting data on the diet of three species of large mountain herbivores ranked from solitary to highly gregarious [respectively: roe deer Capreolus capreolus (Dzieciolowski 1979), chamois Rupicapra rupicapra (Boschi and Nievergelt 2003), and mouflon Ovis gmelini (Cransac et al 1998)] and with contrasting diets (Bertolino et al 2009;Redjadj et al 2014). Large herbivores in general feed on a large number of plant items, but until recently, it remained difficult to assess the variety of plant species consumed in the wild (Rayé et al 2011).…”