Abstract
We present the first estimates of home range and core area size for jaguar (Panthera onca) in western Paraguay in the Dry Chaco, Humid Chaco and Pantanal. Using an autocorrelated kernel density estimator we estimated mean home range sizes of 818 km2 (95% CI:425-1981) in the Dry Chaco and 237 km2 (95% CI:90-427) in the Humid Chaco/Pantanal. The home range estimates for the Dry Chaco are the largest recorded for jaguar. Core areas, defined as the home range area where use was equal to expected use, was consistent across sexes and systems on average represented by the 59% utility distribution isopleth (range:56-64%). Males had a higher probability of larger home ranges and more directional and greater daily movements than females collectively and within systems. The large home ranges in the Dry Chaco are attributable to the relatively low productivity of that semi-arid ecosystem and high heterogeneity in resource distribution while the larger than expected home ranges in the Humid Chaco/Pantanal compared to home range estimates from the Brazilian Pantanal may be due to differences in geomorphology and hydrological cycle. Known mortality of study jaguars from persecution was high (∼75%) and consequently we do not rule out the possibility that the observed large home ranges are partially a function of reduced densities. The large home ranges of jaguars in western Paraguay and a low proportional area of protected areas in the region demonstrate the importance of private ranchland for the long-term conservation of the species which, given the high mortality from persecution, highlight a crucial need to incorporate the livestock production sector in conservation decision making, including region-wide efforts to mitigate jaguar-livestock conflict.