Anthropogenic factors disproportionately affect the occurrence and potential population connectivity of the Neotropic’s apex predator: The jaguar at the southwestern extent of its distribution
Jaguar occurrence was strongly negatively correlated with anthropogenic factors.
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Jaguar occurrence was lower than expected given habitat and prey availability.
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Connectivity among jaguar populations in its southwestern distribution is limited.
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Illegal killing is likely a principal factor determining jaguar occurrence.
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Range-wide, jaguar populations are likely reduced or extirpated by illegal killing.
Abstract
Maintaining population connectivity is an important component of jaguar (Panthera onca) conservation. However, the effectiveness of connectivity corridors can be affected by anthropogenic factors. At the southwestern limit of the jaguar’s current distribution in the Yungas and Dry Chaco ecoregions, connectivity among jaguar populations has been compromised by extensive deforestation. The extent that jaguars and their prey are using corridors in the region, and the factors that determine their use, however, has not been evaluated. We sampled 105 sites in 7 study areas in connectivity corridors in the Yungas and Dry Chaco ecoregions of Argentina, Bolivia, and Paraguay for jaguars and six large-bodied principal prey species through interviews with inhabitants and land owners. Using a multi-species community occupancy modeling framework, we examined species occurrence in relation to forest cover and anthropogenic factors. All species were positively associated with increasing forest cover, decreasing number of homesteads, and increasing distance from roads and settlements, with jaguar occurrence most strongly negatively correlated with anthropogenic factors. Mean conditional occupancy of jaguars was high (>75%) in only two study areas, while only two study areas had mean conditional occupancy estimates of jaguars that were consistent with prey occurrence, with other sites having lower jaguar occurrence than expected. Despite high levels of forest cover and sufficient prey availability, the lower than expected jaguar occurrence in most study areas suggests that illegal killing is likely a principal factor determining jaguar occurrence. The probability of site use by jaguars in most study areas was low, and consequently, functional connectivity is reduced in those areas and likely throughout the region. Our findings have range-wide implications for jaguar conservation since we show that despite sufficient habitat and prey availability, jaguar populations are likely reduced or extirpated by illegal killing driven by jaguar-ranching conflict, cultural norms, or fear.
