Shortlisted for the 2024 Southwood Prize

Kylie Soanes details how, alongside colleagues, they analysed 313 studies to determine whether wildlife crossing structures mitigate the barrier effect of roads on wildlife movement.

About the research

Overview

Wildlife crossing structures are a common tool to help animals cross roads safely. While there’s clear evidence that these structures are used by wildlife, we wanted to dig deeper into the evidence of their effect on animal movement. Do they prevent new roads from becoming a barrier or restore movement pathways across existing roads? Are they better than taking no action at all? Despite hundreds of published studies of wildlife crossing structures from all over the globe, it turns out we still don’t have a good answer – we found just 14% of studies were capable of addressing these questions.

© Kylie Soanes

The few that did show that we can definitely improve the animal movement across roads, but it’s rarely enough to prevent a negative impact from occurring. Our work shows that we need to dramatically improve the effectiveness of our mitigation measures, but also our evaluation, so that we have robust evidence to guide how those improvements should be made.

Challenges

The main challenge was finding a way to draw together evidence from so many different sources, without excluding studies that were small or within the grey literature. We had to develop a conceptual framework that struck the right balance between being comprehensive and being rigorous, and that reflected the varying contexts in which crossing structures are used so that the work was relevant to practice.

Next steps and broader implications

We hope to see a move towards including benchmark comparisons in any evaluation as a standard approach.

© Kylie Soanes

Our work has provided a critical stocktake for the field of road ecology – an opportunity to examine the evidence collected to date and carefully consider the complexities of evaluation in a way that reflects the realities of practice. From here, we are better placed to progress research and action based on the best available evidence, rather than a handful of popular case studies. 

About the author

Current position

I am a research fellow in urban biodiversity at the Melbourne Centre for Cities and School of Agriculture, Food and Ecosystem Sciences at the University of Melbourne.

© Kylie Soanes

Getting involved in ecology

I’ve always been a nature noticer – even from an early age I was rescuing wayward lizards from roadsides or looking for ways to care for nature in our neighbourhood. I feel very lucky to have found a career that allows me to do this professionally!

Current research focus

I still enjoy thinking about complex problems, synthesising information, and evaluating conservation actions. Now though, my focus is largely in urban environments where I work to support practitioners and decision makers to find creative ways of making space for nature in cities.  

Advice for fellow ecologists

Don’t ignore complexity. It makes things more difficult and uncomfortable but if you can find a way to deal with it your work will be all the richer and more relevant for it.

Read the full article “Do wildlife crossing structures mitigate the barrier effect of roads on animal movement? A global assessment” in Journal of Applied Ecology.

Find the other early career researchers and their articles that have been shortlisted for the 2024 Southwood Prize here!