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Modeling connectivity to identify current and future anthropogenic barriers to movement of large carnivores: A case study in the American Southwest

19 Apr 2017

Abstract

This study sought to identify critical areas for puma (Puma concolor) movement across the state of Arizona in the American Southwest and to identify those most likely to be impacted by current and future human land uses, particularly expanding urban development and associated increases in traffic volume. Human populations in this region are expanding rapidly, with the potential for urban centers and busy roads to increasingly act as barriers to demographic and genetic connectivity of large-bodied, wide-ranging carnivores such as pumas, whose long-distance movements are likely to bring them into contact with human land uses and whose low tolerance both for and from humans may put them at risk unless opportunities for safe passage through or around human-modified landscapes are present. Brownian bridge movement models based on global positioning system collar data collected during bouts of active movement and linear mixed models were used to model habitat quality for puma movement; then, a wall-to-wall application of circuit theory models was used to produce a continuous statewide estimate of connectivity for puma movement and to identify pinch points, or bottlenecks, that may be most at risk of impacts from current and future traffic volume and expanding development. Rugged, shrub- and scrub-dominated regions were highlighted as those offering high quality movement habitat for pumas, and pinch points with the greatest potential impacts from expanding development and traffic, although widely distributed, were particularly prominent to the north and east of the city of Phoenix and along interstate highways in the western portion of the state. These pinch points likely constitute important conservation opportunities, where barriers to movement may cause disproportionate loss of connectivity, but also where actions such as placement of wildlife crossing structures or conservation easements could enhance connectivity and prevent detrimental impacts before they occur.

We identify important conservation opportunities for maintaining population-level puma (Puma concolor) connectivity through human-modified landscapes in one of the fastest growing areas of the United States. We fit Brownian bridge movement models to GPS collar data collected from puma during bouts of active movement and then relate probability of movement to characteristics of the landscape, including degree of human modification, to estimate habitat quality for puma movement. We use the resulting map and a wall-to-wall application of circuit theory models to predict important connectivity “pinch points,” or bottlenecks, across Arizona, and identify those most likely to be impacted by current and future highway traffic and expanding urban development.

Click here to view the full article which appeared in Ecology and Evolution

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