A road to conservation: understanding the dynamics of road-effects and road-effect mitigation
Date
2019-05-30
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Globally, roads are one of the most ubiquitous forms of human infrastructure, and have
been identified as a serious conservation concern. Though roads impact wildlife in a variety of
ways, their effects are often negative. Perhaps the most concerning threats are habitat
fragmentation and mortality via wildlife-vehicle collisions. Attempts to manage the negative
effects of roads have had mixed results, and major gaps in our understanding of how roads affect
wildlife populations and the effectiveness of strategies to mitigate road-effects remain. Many
factors contribute to these gaps, particularly the logistical constraints associated with road-effect
monitoring and weak study designs that inhibit strong inferences crucial for effective
management. To this end, I approached road-effect mitigation in a holistic way. First, I
documented and analyzed the local-scale population and spatial ecologies of large mammals
around a newly twinned highway. I found that highway twinning, a common strategy to
accommodate increased traffic volume, had little effect on large mammals. Second, I focused on
the optimization and evaluation of road-effect mitigation (i.e., exclusion fencing and roadcrossing structures). I developed a procedure for identifying ideal locations for mitigation
features by comparing road monitoring data to landscape resistance models for both large
mammals and herpetofauna. Using this approach, I designed a mitigation plan for reptiles and
amphibians, which I evaluated using a robust 6-year Before-After-Control-Impact design that
included road surveys, trapping, and two methods of monitoring tunnel usage: trail cameras and
PIT tag scanners. I found that exclusion fencing was effective for turtles and amphibians but had
no impact on the number of snakes detected on the road. Crossing tunnels were well used by
reptiles and amphibians and I demonstrated that for turtles, tunnels effectively facilitated
connectivity at the population-level. Finally, I investigated the value of outreach as a long-term
conservation strategy in the context of road ecology. I demonstrated that outreach programs
significantly increase the perceptions of youth concerning their own likelihood to participate in
conservation. Further, using a mixed-methods approach, I identified the aspects of outreach that
were most effective at eliciting this change, creating broadly applicable guidelines to optimize
future outreach endeavors. By addressing knowledge gaps pertaining to each phase of road-effect
mitigation, I have provided a structural framework from which the field of road ecology can
continue to flourish. My findings have serious implications for wildlife management and
conservation because they increase our understanding of road-effects and importantly, how to
increase the success of road-effect mitigation.
Description
Keywords
roads, highways, road-effects, road-effect mitigation