Revisiting the functional response in habitat selection for large herbivores: a matter of spatial variation in resource distribution?. (20th August 2019)

• Record Type: Journal Article
• Authors: Duparc, Antoine; Garel, Mathieu; Marchand, Pascal; Dubray, Dominique; Maillard, Daniel; Loison, Anne
• Editors: Quinn, John
• Is Part Of: Behavioral ecology. Volume 30:Number 6(2019)
• Page Start: 1725
• Page End: 1733
• Publication Date: 2019-08-20
• Subjects: chamois -- foodscape -- mountain ungulate -- Rupicapra rupicapra; Animal behavior -- Periodicals; Behavior evolution -- Periodicals; Ecology -- Periodicals; Psychology, Comparative -- Periodicals; 591.5
• DOI: 10.1093/beheco/arz141
• Languages: English
• ISSNs: 1045-2249

Abstract

Abstract: Most habitats are distributed heterogeneously in space, forcing animals to move according to both habitat characteristics and their needs for energy and safety. Animal space use should therefore vary according to habitat characteristics, a process known as the "functional response" in habitat selection. This response has often been tested vis-à-vis the proportion of a habitat category within areas available to individuals. Measuring sought-after resources in landscape where they are continuously distributed is a challenge and we posit here that both the mean availability of a resource and its spatial variation should be measured. Accordingly, we tested for a functional response in habitat selection according to these two descriptors of the resource available for a mountain herbivore. We hypothesized that selection should decrease with mean value of resources available and increase with its spatial variation. Based on GPS data from 50 chamois females and data on the actual foodscape (i.e., distribution of edible-only biomass in the landscape), we estimated individual selection ratio (during summer months) for biomass at the home range level, comparing edible biomass in individual home ranges and the mean and standard deviation of edible biomass in their available range. Chamois being a group-living species, available accessible ranges were shared by several individuals that formed socio-spatial groups (clusters) in the population. As expected, selection ratios increased with the standard deviation of edible resources in each cluster, but unlike our prediction, was unrelated to its mean. Selection of areas richer in resources hence did not fade away when more resources were available on average, a result that may be explained by the need for this capital breeder species to accumulate fat-reserve at a high rate during summer months. Low spatial variation could limit the selection of chamois, which highlights the importance of resource distribution in the process of habitat selection. Abstract : Understanding how patterns of individual habitat selection respond to the characteristics of the habitat available is essential to predict the impact of global changes on animal distribution. While we might expect individuals to be less selective when food is abundant, we show in chamois that selectivity is not explained by average food abundance but by the spatial variability in the amount of food resources. Chamois always select the better patches, whether they live in a resource-poor or resource-rich landscape.