Ecological correlates of the spatial co-occurrence of sympatric mammalian carnivores worldwide
Our goal was to investigate co-occurrence within the order Carnivora and determine which ecological traits influence the spatial distributions of sympatric species (i.e. the overlap or avoidance of two species in habitat use). To accomplish this goal, we used a dataset consisting of remote camera trap data from surveys in 13 study areas in 12 countries, which included observations of 86 mammalian carnivore species in four of the five major biomes worldwide.
Locations of the 13 study areas, which include remote camera trap surveys conducted in 12 countries, spanning 5 continents and 4 of the 5 major biomes worldwide. Examples of co-occurring species pairs include: (a) Nasua nasua (South American coati) and Eira barabara (tayra) in Argentina, © M. Di Bitetti; (b) Puma concolor (puma) and Panthera onca (jaguar) in Belize, © Belize Jaguar Project/Virginia Tech; (c) Urocyon cinereoargenteus (grey fox) and Martes pennanti (fisher) in United States, © J. Tucker/US Forest Service; (d) Ursus arctos (grizzly bear) and Canis lupus (grey wolf) in Canada, © Park Canada; (e) Gulo gulo (wolverine) and Vulpes vulpes (red fox) in Norway, © S. Killengreen; (f) Acinonyx jubatus venaticus (Asiatic cheetah) and Canis lupus (grey wolf) in Iran, © Iranian Cheetah Society/CACP/DoE/Panthera; (g) Leptailurus serval (Serval) and Panthera leo (lion) in Senegal, © M. Kane; (h) Panthera pardus (leopard) and Vulpes chama (cape fox) in South Africa, © Q. Martins/Cape Leopard Trust; (i) Proteles cristata (aardwolf) and Otocyon megalotis (bat-eared fox) in Botswana, © L. Rich/Panthera; (j) Eupleres goudotii (falanouc) and Cryptoprocta ferox (fosa) in Madagascar, © Z. Farris; (k) Hemigalus derbyanus (banded palm civet) and Paradoxurus hermaphroditus (common palm civet) in Sumatra, © F. Widodo/WWF; (l) Panthera tigris tigris (Bengal tiger) and Pantherus pardus fusca (Indian leopard) in Nepal, © K. Thapa/WWF.
We approached the analysis as a two-step process. First, we analysed these data using a pair-wise cooccurrence estimator to quantify relative co-occurrence of sympatric species while accounting for imperfect detection. We then used estimates of co-occurrence (i.e. species interaction factor) to determine how shared ecological traits, including diet, body size, temporal activity patterns, social structure and phylogenetic proximity, correlated with cooccurrence probabilities.
Overall, mammalian carnivores tended to overlap spatially, but there was wide heterogeneity across species pairs with some showing large spatial overlap and others showing large spatial avoidance. Specifically, we found that body size, temporal activity patterns and dietary habits were related to co-occurrence patterns, where species that shared similar ecological traits generally had greater overlap in site use.
We found a different pattern with respect to body size, with species tending to have a lower co-occurrence when paired with a larger car- nivore. These results suggest that top-down processes may also be important in structuring carnivore communities.
These results suggest that at the spatial scale of our study, shared ecological traits are not leading to competitive exclusion, but are rather causing species to select sites where resource availability is likely similar, and thus tend to co-occur. Our study provides an important first step in understanding the drivers of carnivore co-occurrence at a global scale, and a foundation from which future studies interested in more fine-scale assessments of species-pair relationships can build.