We studied the annual and seasonal food habits of sympatric grey fox (Lycalopex griseus) and culpeo fox (Lycalopex culpaeus) in a protected area, in southeastern Argentine Patagonia, to test the hypothesis that both foxes partition prey. Grey foxes consumed a larger proportion of rodents than culpeos (66.1% versus 37. % of occurrences in feces, respectively), and culpeos consumed a larger proportion of the introduced European hare (Lepus europaeus) (32.8% versus 7.1%, respectively). Additionally, arthropods made up a significant portion of the diet of the grey fox, and occurred in the 95.5% of the analyzed feces. Despite the great differences in size of culpeo and grey foxes, the former being significantly larger, both species consumed the same type of prey, and no significant differences in the mean weight of vertebrate prey were detected in their diets. Culpeo and grey foxes diets differed during spring – summer with low values of mean diet overlap (31%). But in autumn – winter, when prey diversity is lower in Patagonia, diet was more similar and diet overlap (73%) increased. An exploratory analysis of habitat use by culpeo and grey foxes suggested that both species utilize habitat in a similar way. Our data agree with generalizations about competitive interactions between the large and the small canid in an assemblage. Although both foxes can potentially consume the same type of prey, through interference the larger culpeo would exclude the smaller grey fox from habitats with high-quality prey, resulting in prey partitioning. The possibility that both foxes partition habitat at a finer scale in our study area should be explored.

Peer reviewed