Biogeographical patterns in the diet of an opportunistic predator: the red fox Vulpes vulpes in the Iberian Peninsula

Abstract

Biogeographical diversity is central to the trophic ecology of predators. Understanding the biogeographical trophic patterns of generalist predators, such as the red fox Vulpes vulpes, is particularly challenging because of their wide distributions, broad trophic spectra and high ecological plasticity, which often generate conflicts with humans. We reviewed 55 studies from the Iberian Peninsula concerning the diet of the red fox to describe its trophic patterns from a biogeographical perspective. We considered the frequency of occurrence of seven food groups and characterized each study site according to environmental variables. We tested relationships between geographical variables and each food group independently, and assessed the consumption of lagomorphs in relation to the other food groups. We also tested the relationships between trophic diversity, the main food groups, latitude and altitude, and finally investigated changes in the consumption of all food groups in relation to habitat type and seasonality. We found a latitudinal pattern in the diet of the red fox, which was characterized by a greater consumption of lagomorphs and invertebrates in southern areas, and a higher intake of small mammals and fruits/seeds in northern regions. Additionally, the consumption of invertebrates increased from east to west, while fruit/seed consumption increased from west to east. Consumption of lagomorphs decreased, and of small mammals increased, with altitude. Trophic diversity was not associated with geographical variables. The intake of lagomorphs and small mammals was greatest in Mediterranean scrub and forest, respectively. Reptiles and invertebrates were consumed mostly during summer; fruits/seeds in autumn. Iberian red foxes show variation in their feeding habits associated with environmental variables, which are in turn associated with the availability of their main prey. Foxes select rabbits where they are abundant, and feed on small mammals and fruits/seeds where lagomorphs are scarce.

Biogeographical patterns of the diet of Palearctic badger: Is badger an earthworm specialist predator?

“…For example, wildcats mainly eat rodents at northern latitudes but prey on rabbits at southern latitudes [2]. The same pattern of rabbit intake has been shown for red fox [4]. Martens shift from preying on mammals to eating fruit when fruit is abundant [3].…”

“…There are also obvious latitudinal gradients in the dietary compositions of wildcat (Felis silvestris) [2], martens (Martes spp.) [3] and red fox (Vulpes vulpes) [4]. Wildcats eat more rabbits in lower latitude but more rodents in higher latitude [2].…”

“…Red fox preys on more lagomorphs and invertebrates in southern areas but eats more small mammals and fruits in northern areas. Additionally, red fox eats more lagomorphs in lower elevation but more small mammals in higher elevation [4]. Environmental variables also play important roles in the feeding ecology of animals.…”

Factors affecting the diet of the red fox (Vulpes vulpes) in a heterogeneousMediterranean landscape

“…Their increased consumption during spring is possibly due to the increased activity of cold-blooded vertebrates in April and May (Cavallini and Lovari, 1991). On the other hand, their decreased consumption in summer, when they are still active (Díaz-Ruiz et al, 2013), is not easily explained. It could probably be due to the ending of late summer mating season (Bartelt et al, 2010).…”

“…of individual species for different environmental factors (Díaz-Ruiz et al, 2013), and in a landscape context, this variation can be ordered along 1, 2, or 3 imaginary axes. Sometimes these axes are identified with a specific studied environmental condition.…”