Food niche segregation between sympatric golden jackals and red foxes in central Bulgaria

In Europe, the range of the golden jackal (Canis aureus) has expanded since the mid-twentieth century, but little is known about how it interacts with other sympatric carnivores. Among European countries, Bulgaria has the largest population of golden jackals and jackal numbers have increased around two-fold during the past two decades, particularly in lowland habitats. Larger canids often competitively exclude, or even kill, smaller sympatric ones, especially when guild dynamics are in flux due to population re-establishment. We therefore investigate whether trophic niche segregation occurs between golden jackals and red foxes (Vulpes vulpes) in central Bulgaria, where both species are sympatric. Because jackals are more abundant in lowland than in upland Bulgaria, we further investigate whether habitat elevation affects the strength of trophic competition. From the analysis of stomach contents of both species, collected from lowland and upland areas during hunting seasons between 1997 and 2009, we found no significant food niche overlap, and no effect of elevation on trophic interactions. In lowland habitat, golden jackals mainly scavenged carcasses of domestic animals, whereas in upland habitat they consumed mostly carcasses of wild ungulates. In contrast, red foxes predominantly and consistently predated rodents in both habitats. This suggests that trophic segregation facilitates the coexistence of these canids under these prevailing population conditions. Nevertheless, we stress that as golden jackals colonize Eastern Europe, impacts on red foxes, and consequences for ecological communities, should be monitored carefully, especially in regions with less carrion available to support jackals

vertebrate scavenging communities

A scavenger is an animal that feeds on the carcass or remains of any dead animal which it did not participate in its killing. Scavenging is pervasive across the animal kingdom and almost all predator species use carrion to a certain extent in both terrestrial and aquatic ecosystems. There is a group of animals, the obligate scavengers, which rely (almost) entirely on carrion. Among vertebrates, only birds have evolved into obligate scavengers, namely vultures, which suggests that the costs of adaptation to obligate scavenging are high. Obligate and facultative scavengers exhibit a wide array of adaptations to locate and exploit carrion across systems, including inexpensive locomotion to find the unpredictable carrion on savannas, caching carrion in cold tundra or chemotaxis in aquatic systems. Traditionally viewed as an opportunistic process, particularly for facultative scavengers, carrion consumption by vertebrates often follows complex and structured patterns and is crucial in maintaining the stability and structure of food webs.Peer reviewe