Spatial distribution and habitat selection in coexisting species of mountain ungulates

Abstract

One of the main objectives of community ecology is to understand the conditions allowing species to coexist, which requires identifying how co‐occurring species use and share space and resources. Species of the same trophic level, such as large herbivores, are of fundamental interest in that context because competition for resources is likely. Segregation in space or on some axes of the ecological niche are processes allowing coexistence, yet, both are seldom studied jointly. Based on annual spring censuses collected for 11 yr, we analysed the degree of overlap in spatial distribution among chamois Rupicapra rupicapra and mouflon Ovis gmelini musimon, 2 species of similar size that coexist on the same alpine pastures. We further investigated whether they differed in terms of habitat selection processes, and identified which environmental factors led to species being aggregated or segregated. The areas of intensive use for 2 species were more spatially aggregated than expected by chance. Habitat selection was studied using multivariate methods based on the niche concept, considering the presence of 1 species as an environmental variable for the other. Despite a large overlap in niches (88%), segregation was significant as chamois preferred meadows dominated by Sesleria and Carex sempervirens while mouflon selected meadows dominated by Carex ferruginea and avoided being close to areas affected by human activities. Importantly, habitat selection within each species was not affected by the presence of the other species. Coexistence between these 2 species and spatial overlap may be permitted because resource partitioning occurs at a fine temporal and/or spatial scale. We underscore that joint approaches of spatial and ecological processes are necessary to disclose the type of interaction (neutral, facilitation or competition) at play within a community.

Estimating herbaceous plant biomass in mountain grasslands: a comparative study using three different methods

“…Therefore, depending on the question of interest, this approach may lead to irrelevant measure of biomass. For example, in mountainous landscapes composed of heterogeneous communities and where screes are important habitats for ungulates (Calenge 2007, Darmon et al 2012, it is of prime importance to accurately estimate the amount of resources they can find in such habitat. Using plate meter is obviously not advisable in such environments to address the question of resource availability to herbivores.…”

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

“…Three herbivore species coexist in the game reserve: chamois, mouflon and roe deer. Their population sizes are, respectively, about 2000, 500, and 250 (Darmon et al 2012). Chamois are at a high density in subalpine pastures and lower density in forests (Redjadj 2010).…”

“…Chamois are at a high density in subalpine pastures and lower density in forests (Redjadj 2010). 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).…”

Empirical evaluation of the strength of interspecific competition in shaping small mammal communities in fragmented landscapes

“…As an example, microhabitat or temporal segregation (e.g. Buesching et al 2008;Darmon et al 2012;Abu Baker and Brown 2014) may be used by individuals as a response to competitors to minimize the amount of interspecific interference. As a support to this, we found that multiple simultaneous captures in a same trap were much more frequent between individuals of the same species than between individuals of different species, possibly indicating their propensity to avoid direct interspecific contacts.…”