Trophic niche partitioning between two native and two exotic carnivores in SW Portugal

Abstract

Abstract. The introduction of exotic species is one of the most pervasive consequences of the increased human mobility. The most known negative effects are the decrease or extinction of natives. The common-genet, Genetta genetta, and the Egyptian mongoose, Herpestes ichneumon, were introduced in the Iberian Peninsula in the 15th and 19th centuries, respectively. The competitive exclusion principle defines that two ecologically similar species cannot coexist. Thus, some degree of partitioning has to occur in species realized niche, which can occur at the trophic level. To test this hypothesis of partitioning we compared the diet of these two exotic species with that of two native species (stone marten, Martes foina, and red fox, Vulpes vulpes). The results show a high degree of overlap (>45%) between the diets of species similar in their feeding strategies (arboreal and ground feeding). Nonetheless, at the finer scale of prey consumed at the species level some differences are found between the native and exotic species. These results suggest that if coexistence is due to trophic niche partitioning it only occurs at the level of the consumed species. However, coexistence may also be due to a combination of different strategies (home-range size, time and space use) that structured the different realized niches of each species.

Unusual findings on host-tick interactions through carnivore scat analysis

“…badgers-Neal and Cheeseman 1996), several studies aiming the feeding ecology of carnivores in western Portugal did not detect ticks in scats (e.g. badgers- Rosalino et al 2005;otters-Freitas et al 2007; common-genets, Egyptian mongooses, stone-martens and red foxes- Santos et al 2007). Moreover, when grooming is focused on parasite-defense, it frequently also involves fur ingestion (Mooring et al 2004), which was not detected in our scat samples.…”

Does riparian habitat condition influence mammalian carnivore abundance in Mediterranean ecosystems?

“…The common genet has also shown an important association with riparian habitats in both seasons and with forested areas. This can be attributable to its preference for hollow trees as resting sites (Palomares and Delibes 1994;Santos-Reis et al 2004) and where the genet can find the wood mouse (Apodemus sylvaticus), its main prey (Palomares and Delibes 1994;Rosalino and Santos-Reis 2002;Virgós and Casanovas 1997) as well as cray-fish in the summer (Santos et al 2007). It also showed a strong association with streams embedded in cork oak woodland in the wet season, which may be attributable to the small mammal abundance peak verified in this period in riparian areas, with the forested area offering plenty of their favourite refuges (Palomares and Delibes 1994;Santos-Reis et al 2004).…”

Spatio-temporal variation of predator diet in a rural habitat: stone martens in the villages of Białowieża forest

“…This may relate to differential hunting microhabitat selection by these predators (barns and stables by stone marten and open areas by tawny owls), but it also may indicate that stone marten prefer rats over other species of the rodent community inhabiting the village. Interestingly, in Portugal rats were not preyed upon by stone marten despite the fact that the red fox (Vulpes vulpes) and the Egyptian mongoose (Herpestes ichneumon) consumed rats frequently (Santos et al 2007). In other regions, rats were also consumed in small proportions (Lode 1994;Lanszki 2003) or were not found at all in the stone marten diet (Serafini and Lovari 1993;Martinoli and Preatoni 1995;Pedrini et al 1995;Carvalho and Gomes 2004;Barrientos and Virgos 2006).…”