Numerical and dietary responses of a predator community in a temperate zone of Europe

Abstract

International audienceThe generalist predation hypothesis predicts that the functional responses of generalist predator species should be quicker than those of specialist predators and have a regulating effect on vole populations. New interpretations of their role in temperate ecosystems have, however, reactivated a debate suggesting generalist predators may have a destabilizing effect under certain conditions (e.g. landscape homogeneity, low prey diversity, temporary dominance of 1 prey species associated with a high degree of dietary specialization). We studied a rich predator community dominated by generalist carnivores (Martes spp., Vulpes vulpes, Felis catus) over a 6 yr period in farmland and woodland in France. The most frequent prey were small rodents (mostly Microtus arvalis, a grassland species, and Apodemus spp., a woodland species). Alternative prey were diverse and dominated by lagomorphs (Oryctolagus cuniculus, Lepus europeus). We detected a numerical response among specialist carnivores but not among generalist predators. The dietary responses of generalist predators were fairly complex and most often dependent on variation in density of at least 1 prey species. These results support the generalist predation hypothesis. We document a switch to alternative prey, an increase of diet diversity, and a decrease of diet overlap between small and medium-sized generalists during the low density phase of M. arvalis. In this ecosystem, the high density phases of small mammal species are synchronous and cause a temporary specializing of several generalist predator species. This rapid functional response may indicate the predominant role of generalists in low amplitude population cycles of voles observed in some temperate areas

Native forest replacement by exotic plantations triggers changes in prey selection of mesocarnivores

“…Small mammal species represent a significant amount of animal biomass available for mesocarnivores in natural forest ecosystems (Carey and Johnson, 1995;Hanski et al, 2001;Korpimaki et al, 2005;Dupuy et al, 2009). Although small mammals could be abundant in productive land, such as forest plantations, due to their habitat generalism or large mammal extirpation (e.g., Muñoz-Predreros et al, 1990;Lindenmayer and Hobbs, 2004;Saavedra and Simonetti, 2005;Lantschner et al, 2011;Young et al, 2015), the overall density of small mammals tends to decrease as native habitat is disturbed.…”

Predator dietary response to prey density variation and consequences for cestode transmission

“…A response of the fox diet to Microtus sp. density variations was observed in France and Belarus, but in every case, the species was fluctuating, A. terrestris was constantly at a low density, and other resources, such as forest rodents, birds or lagomorphs, were available (Sidorovich et al 2006;Guislain et al 2008;Dupuy et al 2009). In northern Europe where M. agrestis is a fluctuating species, its contribution to the fox diet was correlated to its density in the field, and (2) 104 The number of occurrences (number of faeces in which the food item occurred) is given in parentheses a Faeces collected in winter 1 were not analysed LL Maximised log-likelihood, K number of estimated parameters, N/K number of observations/K, AICc second-order Akaike index criterion, dAICc difference between AICc and the lowest value of AICc, w ic Akaike weights a Asymptotic and logistic models did not converge foxes had access to other prey when M. agrestis density was low (O'Mahony et al 1999;Dell'Arte et al 2007).…”

“…Bartel and Knowlton 2005;Gilg et al 2006;Delibes-Mateos et al 2008;Dupuy et al 2009). However, functional responses have not been studied from a parasitological perspective to understand the influence of intermediate host density variations on the definitive host predation behaviour and its consequence on parasite transmission.…”

“…It is generally described as a generalist and opportunistic predator taking its prey as a function of its availability; rodents, lagomorphs, birds, carrion, insects and fruits are its main food resources but their contribution to the diet is dependent on season, habitat composition, and the composition of the regional prey community (Ferrari and Weber 1995;Sidorovich et al 2006;Dell'Arte et al 2007). The fox predation response to prey density variation has been described in various ecological contexts (Dell'Arte et al 2007;Delibes-Mateos et al 2008;Dupuy et al 2009), but the consequences of its functional response on E. multilocularis transmission remain unexplored. In China, France and Alaska, relationships were established at the regional scale between the regular high density of some small mammal species in a community and intensive transmission in foxes and humans (see Giraudoux et al 2003 for a review).…”

Evaluating the influence of diet‐related variables on breeding performance and home range behaviour of a top predator

“…However, the relationships between prey abundance and other life-history traits are not always direct and simple to interpret. For example, in food-specialist species, variations in prey abundance may not alter feeding ecology (detected mostly by changes in diet composition), yet change the parameters related to reproductive performance and home range and movement behaviour, often resulting in a numerical response reflected in the predator's density (Korpimäki and Norrdahl 1991;Dupuy et al 2009;Terraube et al 2011). In food-generalist species, variations in prey abundance may frequently cause a functional response, with changes in dietary characteristics, such as prey frequency and diversity Norrdahl 1989, 1991;Dupuy et al 2009;Moleón et al 2012).…”