The role of the southern water vole Arvicola sapidus in the diet of predators: a review

Abstract

Abstract For the recovery and conservation of endangered species such as the southern water vole Arvicola sapidus, it is important to understand the effects of predation on their populations. The impact of a predator on a prey species depends on the dynamics and structure of their populations, the abundance of both species and their relationships with other species. When considering broad geographic areas, the analysis of the trophic dimension can provide an estimate of the effect of predatory pressure on the prey. To determine the potential impact of predators on the southern water vole, we used information provided in 74 studies concerning the diet of predators in the geographical range of the prey species. The trophic spectrum was determined based on faeces, stomach contents or pellets in which the arvicoline was present. Based on the percentage of biomass consumed in each of nine trophic categories, the potential impact posed by predators was linked with dietary profile, trophic diversity, intensity of southern water vole consumption and availability of preferred prey. In the localities studied, southern water voles are not the preferred prey of any of the predators we considered, but represent an alternative prey for some of them, especially when their main prey species are scarce. The predators with the greatest potential impact on southern water vole populations are Lutra lutra and Ardea cinerea; those with a moderate impact are some mesocarnivores (Felis silvestris, Genetta genetta, Neovison vison, Vulpes vulpes and Martes foina), a bird frequenting aquatic environments (Ciconia ciconia), and the raptors Aquila fasciatus and Hieraaetus pennatus. The results obtained may be useful in the planning of measures for the conservation of the southern water vole, such as translocations or reintroductions, and in the design of strategies to reduce predatory pressure with the aim of promoting the success of these programmes.