Impact of hunting on large vertebrates in the Mbaracayu Reserve, Paraguay

Over 1,400,000 m of line transect data were collected in collaboration with Ache Indians to determine encounter rates with all large vertebrates in the Mbaracayu Reserve Paraguay. The data were analyzed using logistic regression in order to determine the impact of human hunting on animal encounter rates in the reserve. The method controlled for effects of season, weather, time of day, and habitat in order to statistically isolate the human predation effect. Encounters with the animals themselves as well as fresh signs of their activity allowed us to determine whether lower encounter rates in hunted zones are simply due to increased wariness by target species. Our results show that areas near hunters are hunted more frequently, and that Dasypus novemcinctus, Cebus apella, Tapirus terrestris, and Mazama spp. are all encountered at lower rates in those areas than in unhunted zones. We were unable to show that encounter rates with other important game species have been affected by human hunting Demonstration of local depletion by central place foragers is expected, however, and cannot be used to conclude that prey species are in danger of regional extirpation.