Patterns of coexistence between two mesocarnivores in northern Patagonia
Coexisting species often exhibit similar adaptations in shared environments, while at the same time differing in other traits reducing competition. Coexistence usually requires ecological differentiation, and an observed strategy among some mammalian carnivore guilds is coexistence by behavioral mechanisms. Patagonia is a unique region with distinctive carnivore assemblages, offering an irreplaceable context to study intraguild interactions. We analyzed coexistence patterns between two similar-sized mesocarnivores, Geoffroy’s cat (Leopardus geoffroyi) and culpeo fox (Pseudalopex culpaeus), examining the influence of anthropogenic disturbances and the occurrence of a shared prey item, the invasive European hare (Lepus europaeus). Three aspects were examined: spatial (land cover, anthropogenic disturbance, and hare distribution), temporal (activity patterns), and diet (proportion of items consumed), and we predicted segregation would occur in one or more of these aspects as a mechanism for coexistence. We conducted camera trapping from January to April 2012 and 2013 in Nahuel Huapi National Park, Argentina. Using camera detections, we analyzed spatial patterns with co-occupancy modeling, and temporal patterns by fitting kernel density estimates and measuring overlap. We performed a dietary meta-analysis using available literature, and performed a discriminant function analysis to examine if the two carnivores could be distinguished by their diet.
We obtained 51 independent detections of Geoffroy’s cats and 481 of culpeo foxes in 1680 camera days, no other medium-sized carnivores were detected. Co-occupancy models revealed high spatial overlap, Geoffroy’s cats and culpeo foxes coexistence did not appear to be influenced by land cover, anthropogenic disturbance, or hare occupancy. Models assuming spatial independence between both carnivores were most supported, adding 69% of model weight. Temporal modelling showed activity patterns of both carnivores were similar and overlap coefficient was high (D=0.89). However, timing of greatest increases in activity for both Geoffroy's cats and culpeo foxes coincided with invasive hares’ greatest activity increase (between 22 and 00hs), which might be indicating that these carnivores are adjusting their activity to maximize prey encounters. The dietary meta-analysis showed that although both species consume predominantly small and medium sized mammals, Geoffroy’s cats consume more birds, reptiles and amphibians, and culpeo foxes consume more large mammals, carrion, and plant material. In contrast with findings of other similar sized sympatric carnivores in other areas, we found no evidence of temporal or spatial segregation between Geoffroy’s cats and culpeo foxes. Coexistence between these two carnivores in this Patagonic protected area would appear to be facilitated by diet segregation.