The toll of the automobile: A landmark study in road ecology
AI-generated summary
April 14th, 2025
Cars on the road in the 1950s. Licensed under CC BY 4.0
Summary
In 1925, Dayton Stoner, with the help of his wife Lillian, conducted what we believe was the first systematic investigation into the ecological impacts of roads. His article, The Toll of the Automobile (published in Science) offers a historical glimpse into the origins of road ecology, a field that continues to grow in importance a century later.
Stoner’s groundbreaking study: A road trip through Iowa
Stoner’s research began with a simple yet profound observation during a summer road trip in 1924. Over the course of 632 miles through Iowa’s farming communities and surrounding prairies, marshes, and woodlands, Stoner and his wife documented the freshly killed animals they encountered on or near roads. Driving at a modest 25 miles per hour, they identified and recorded 225 roadkill casualties spanning 29 vertebrate species.
Red-headed woodpecker. Licensed under CC BY 4.0
Key findings: The cost to wildlife
Stoner’s statistics were shocking, especially given the relatively low number of vehicles on the roads at the time. Birds suffered the greatest losses, with 142 individuals recorded as roadkill. Among them, the red-headed woodpecker was particularly hard-hit, accounting for 53 casualties. Stoner speculated that the species’ roadside feeding habits and slower escape responses made them especially vulnerable. Mammals and reptiles were also heavily impacted, with 43 and 40 observations, respectively.
Importantly, Stoner’s route included both gravel and dirt roads, which provided additional data on how road types influenced wildlife mortality. Stoner observed that gravel roads, which allowed for higher vehicle speeds, seemed to result in greater wildlife mortality than dirt roads.
The automobile: An unchecked ecological force
Stoner recognized that the speed of movement facilitated by the automobile was not only a safety risk to humans, but also to wildlife. He likened the automobile’s impact on wildlife to that of diseases such as typhoid or influenza on human populations. To him, the car was an unchecked force, killing animals at a rate that demanded serious attention.
At the time of Stoner’s study, mitigation measures like underpasses and overpasses, wildlife fencing, reduced speed zones, or roadside vegetation management were unheard of. His research was groundbreaking in suggesting that roads and vehicles were not just tools of transportation but transformative forces altering ecosystems in profound and often destructive ways. Stoner continued to study wildlife-vehicle interactions, with at least another six publications on the topic in peer-reviewed journals between 1925 and 1943 (see Snyder 1945).
The fact remains a century on
Stoner’s 1925 study is significant not only for its grim statistics but also for its role as a precursor to modern field of transport ecology. His research underscores the value of small, focused studies in identifying and addressing systemic issues that might otherwise go unnoticed and 100 years later, his observations remain profoundly relevant. His core concern was wildlife mortality caused by cars and the potential repercussions of these deaths on wildlife populations. We now know that his concerns were wholly justified, and that the impacts of roads on wildlife extend far beyond roadkill.
Habitat fragmentation, pollution, and the struggle for species to navigate human-altered landscapes are just some of the consequences of road infrastructure and vehicles. These impacts are even more pronounced in our modern time where cars and roads are far more widespread and the pace of human activity even faster than at the time of the Stoner’s road trip.
Stoner’s early work serves as a foundation for understanding these challenges and underscores the importance of addressing these and other unintended consequences of technological progress.
Looking forward: Lessons from the past
Even as roads and automobiles became hallmarks of modernity and convenience during the time of the Stoner’s observations, they also emerged as significant threats to wildlife survival. Stoner’s journey—both literal and scientific—highlights the need for continuous innovation in mitigating the ecological impacts of infrastructure. From wildlife crossings and speed restrictions to improved road design and habitat restoration, there is much to be learned and applied from his early insights. The observations outlined in this study remind us that true progress is measured not just by what we build but by how well we protect the natural world in the process.
The toll of the automobile may have been first quantified nearly a century ago, but the challenges it poses remain urgent to this day.
Author information
Dr. Dayton Stoner (1883–1944)
Source citation
Stoner, D. (1925). The toll of the automobile. Science, 61(1568), 56-57. DOI: https://www.science.org/doi/abs/10.1126/science.61.1568.56
Additional reading
Snyder, L. L. (1945). Dayton Stoner—1883 to 1944. Journal of Mammalogy, 26(2), 111-113. DOI: https://doi.org/10.2307/1375082
Author: Chat GPT
Editor: Christopher Johnson
Review: Rachel Pidgen
Cite this summary:
Chat GPT. (2025). The toll of the automobile: A landmark study in road ecology. Edited by Johnson, C. and reviewed by Pidgen, R. TransportEcology.info, Accessed at: https://transportecology.info/research/toll-of-the-automobile