Modeling the indirect effects of road networks on the foraging activities of bats

• Published in: Landscape ecology 2013-05, Vol.28 (5), p.979-991
• Main Authors: Bennett, Victoria J., Sparks, Dale W., Zollner, Patrick A.
• Format: Article
• Language: English
• Subjects: Animal populations; Bats; Biomedical and Life Sciences; Ecological models; Ecology; Environmental Management; Foraging behavior; Habitat availability; Habitats; Historical ecology; Human influences; Landscape Ecology; Landscape/Regional and Urban Planning; Life Sciences; Nature Conservation; Research Article; Roads; Roads & highways; Sustainable design; Sustainable Development; Wildlife
• ISSN: 0921-2973; 1572-9761
• DOI: 10.1007/s10980-013-9874-0

Negative impacts of road networks on wildlife are of global concern. While direct mortality of wildlife via roads has been well-documented, we know little about indirect effects of roads. Using a simulation model parameterized from empirical data, we explored how roads in proximity to maternity roosts influenced foraging activities of the endangered Indiana bat. First, we conducted manipulated landscape simulations to identify characteristics (such as traffic volume, foraging habitat availability, etc.) that influenced landscape permeability. We used a classification and regression tree procedure to assess which landscape and road-related variables, alone or in combination, influenced bat movement. We determined that roads did act as filters (>10 vehicles/5 min) or barriers (>200 vehicles/5 min) to movement. However, it is a combination of the proportion of foraging habitat accessible without crossing a road, and roost-to-road distance that dictated whether the barrier and filter effects of roads hindered the bats’ foraging abilities. We then simulated movement patterns and foraging success of Indiana bats at 32 existing maternity roosts to identify conditions under which colonies currently persist. We established a foraging success threshold, above which Indiana bats currently persist. The value represents the time virtual bats spend in foraging habitat during the simulation period. Finally, simulations from these landscapes around known maternity roosts demonstrate that the road network and landscape configuration are critical to foraging success. This modeling approach and threshold value are beneficial to road developers and represent an invaluable tool in the ecological design of transportation infrastructures.