Modeling the effects of deforestation on the connectivity of jaguar Panthera onca populations at the southern extent of the species’ range

Abstract

We employed least-cost and circuit theory modeling to model the connectivity among previously defined Jaguar Conservation Units (JCUs) at the southern limit of the jaguar's range in Argentina, Bolivia, Brazil and Paraguay, in order to assess the effects of deforestation and land use change between 2000 and 2014. Due to uncertainty about possible limitations to jaguar dispersal, we examined connectivity where linkages were not cost-limited and limited to 1000 km cost-weighted distance. When linkage length was not cost-limited, total linkage area decreased by 9%, and mean least-cost distance and mean effective resistance increased by 6 and 31%, respectively, from 2000 to 2014. Limiting linkages to 1000 km cost-weighted distance indicated that the southern-and eastern-most JCUs were isolated as early as 2000 and that the number of linkages between the other JCUs decreased between 2000 and 2014, causing the linkage area to decrease by 27% while the least-cost distance of the remaining linkages increased by a mean of 4% and effective resistance increased on average by 44%. By limiting linkages to a plausible costweighted distance, we demonstrated that JCUs in the Atlantic Forest, Argentine Chaco and the Argentine/Bolivian Yungas have been isolated since at least 2000, and that there has been a loss of connectivity through eastern Bolivia, increased resistance in the remaining linkages and a constriction of all but one linkage to a minimum width of < 8 km. Our results are consistent with an observed loss of genetic diversity in jaguar populations within portions of our study area and indicate a need for further research to better quantify jaguar dispersal.

Habitat loss and overhunting synergistically drive the extirpation of jaguars from the Gran Chaco

“…Furthermore, jaguars in the Chaco exhibit some of the lowest densities and largest home ranges in the Americas (Giordano, ; McBride & Thompson, ; Noss et al., ; Quiroga et al., ). Our results therefore highlight the urgency of managing jaguars in the Chaco as a single population, by protecting the remaining core area patches and ensuring their connectivity along corridors which are currently dominated by hunting threats, particularly between the central and northern Chaco patches (Quiroga et al., ; Thompson & Velilla, ).…”

“…Two Jaguar Conservation Units (JCU), the Gran Chaco JCU in the north and the Chaco JCU in the centre, and corridors to connect them, have been proposed for the Chaco to protect important jaguar populations, (Rabinowitz & Zeller, ; Zeller, ). Land use change, however, is increasingly reducing habitat inside and connectivity among them (Piquer‐Rodríguez et al., ; Thompson & Velilla, ).…”

Sustainability Agenda for the Pantanal Wetland: Perspectives on a Collaborative Interface for Science, Policy, and Decision-Making

“…This intensification has led to the replacement of native vegetation and grasses with exotic, African grass species (Miranda et al, 2018). The result is an increasing simplification of the landscape, with loss, fragmentation, and degradation of natural habitats and severe negative impacts on biodiversity and ecosystem services (e.g., Barbosa da Silva, Arieira, Parolin, Nunes da Cunha, & Junk, 2016;Dorado-Rodrigues, Layme, Silva, Nunes da Cunha, & Stru¨ssmann, 2015;Nunes, 2015;Silveira, Tomas, Fischer, & Bordignon, 2018;Thompson & Velilla, 2017;Tomas, 2017;Tomas, Freitas, & Pereira, 2013).…”

Beyond fangs: beef and soybean trade drive jaguar extinction

“…Furthermore, jaguars in the Chaco exhibit some of the lowest densities and largest home ranges in the Americas (Noss et al 2012;Quiroga et al 2014;Giordano 2015;McBride & Thompson 2018). Our results therefore highlight the urgency of managing jaguars in the Chaco as a single population, by protecting the remaining core area patches and ensuring their connectivity along corridors which are currently dominated by hunting threats, particularly between the central and northern Chaco patches (Quiroga et al 2014;Thompson & Velilla 2017).…”

“…Two Jaguar Conservation Units (JCU), the Gran Chaco JCU in the north and the Chaco JCU in the centre, and corridors to connect them, have been proposed for the Chaco to protect important jaguar populations, (Zeller 2007;Rabinowitz & Zeller 2010). Land-use change, however, is increasingly reducing habitat inside and connectivity among them (Piquer-Rodríguez et al 2015;Thompson & Velilla 2017).…”