Abstract
BackgroundTwo coexisting species with similar ecological requirements avoid or reduce competition by changing the extent of their use of a given resource. Numerous coexistence mechanisms have been proposed, but species interactions can also be aggressive; thus, generally a subordinate species modifies its realized niche to limit the probability of direct encounters with the dominant species. We studied niche partitioning between two sympatric wild canids in north-eastern Italy: the golden jackal and the red fox, which, based on competition theories, have a high potential for competition. We considered four main niche dimensions: space, habitat, time, and diet.ResultsWe investigated three study areas monitoring target species populations from March 2017 to November 2018 using non-invasive monitoring techniques. Red fox presence was ascertained in every study area, while golden jackal presence was not ascertained in one study area, where we collected data regarding wolf presence. Considering the two target species, we observed partial diet partitioning based on prey size, with the golden jackal mainly feeding on wild ungulates and the red fox mainly feeding on small mammals. The two canids had an extensive temporal overlap along the diel cycle, having both predominant crepuscular and nocturnal activity patterns, but marked spatial partitioning and differential use of habitats. The golden jackal proved to be specialist concerning the habitat dimension, while the red fox resulted completely generalist: the former selected less human-modified habitats and avoided intensively cultivated lands, while the latter was present in all habitats, including intensively cultivated lands.ConclusionsThe observed partitioning might be due partially to some ecological adaptations (e.g. specialist vs. generalist use of resources) and specific behaviours (e.g. cooperative vs. solitary hunting) and partially to the avoidance response of the red fox aimed at reducing the probability of direct encounters with the golden jackal.
Highlights
Sympatric species with similar ecological requirements can either coexist or competitively exclude each other depending on resources availability: the strength of the competition between them generally decreases with increased differentiated resources use ([1] and references therein)
We carried out an integrated research in which we considered golden jackal and red fox resource partitioning along different niche dimensions: (i) space, (ii) habitat, (iii) time, and (iv) diet
Considering the first study period (March 2017–February 2018), most of the records were collected in Goritian Karst study area (n = 105), while a few were collected in Tagliamento Valley study area (n = 18); no record was collected in Magredi study area (Table 2 and Additional file 1: Fig. 1 in S2)
Summary
Sympatric species with similar ecological requirements can either coexist or competitively exclude each other depending on resources availability: the strength of the competition between them generally decreases with increased differentiated resources use ([1] and references therein). Torretta et al BMC Ecol Evo (2021) 21:129 structuring the guild; the magnitude of interspecific aggressive behaviours is generally driven by relative differences in body sizes (i.e. aggressive behaviours are more frequent when the body mass ratio of the contenders ranges between 2 and 5.4), dietary overlap, predatory habits, and taxonomic similarity (i.e. aggressive behaviours are more frequent between species of the same family) [4, 5] Because these interactions are generally asymmetric (subordinate vs dominant), generally the subordinate species modify its realized niches by changing the extent of its use of resources. We considered four main niche dimensions: space, habitat, time, and diet
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