Mesocarnivore activity patterns in the semiarid Caatinga: limited by the harsh environment or affected by interspecific interactions?

Activity patterns reflect adaptations to local biological and physical conditions. We estimated the activity patterns of 3 mesocarnivore species in a semiarid environment in northeastern Brazil: the ocelot (Leopardus pardalis), crab-eating fox (Cerdocyon thous), and oncilla (Leopardus tigrinus). We compared the overlap of daily activity among these species and to apex predators. We also estimated nighttime activity of these mesocarnivores during 2 years and compared activity peaks with those of apex predators and potential prey. All 3 mesocarnivores were nocturnal, with ocelots having only 1 record during daytime. Coefficients of overlap with larger predators were high (Delta(1) > 0.7) for all pairwise comparisons, since all species were very nocturnal. Nighttime-only activity comparisons (Kolmogorov-Smirnov tests) showed that activity of oncillas differed from that of both larger mesocarnivores and jaguar activity, suggesting temporal segregation. Contrary to our expectations, rodent activity was dissimilar from that of ocelots and crab-eating foxes, but activity of rodents and oncillas was relatively synchronous. Activity of both cat species seems limited to the cooler nighttime, and nocturnal behavior of oncillas more likely reflects activity of potential prey rather than regulation by intraguild predators. Future studies in arid regions should consider climatic factors when estimating activity patterns.