Beyond the individual: multisite population‐level consequences of road mortality on a declining mammal

Moore, Lauren J., Petrovan, Silviu O., Bates, Adam J., Hicks, Helen L., Baker, Philip J., Perkins, Sarah E. ORCID: https://orcid.org/0000-0002-7457-2699, Wembridge, David E. and Yarnell, Richard W. 2026. Beyond the individual: multisite population‐level consequences of road mortality on a declining mammal. Animal Conservation 10.1111/acv.70082

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Abstract

Understanding the impact of road mortality on the size, structure and persistence of wildlife populations is an increasingly important topic in conservation. However, data on demographic rates that accompany road mortality counts are rare, limiting our understanding of population-level impacts. We used a comparative study design to quantify population densities, structure, survival, cause-specific mortality and female productivity in four West-European hedgehog (Erinaceus europaeus) populations, and to forecast the impact of road mortality on population viability. In total, 269 roadkill surveys were conducted in each study site and 838.20 km of walked transects were completed. Road mortality killed 15.3%–28.6% of the local populations annually and contributed 37.7%–41.0% of total recorded mortality. Losses to road mortality were offset by juvenile recruitment and survival in relatively large (> 36 individuals) populations, but not in smaller (< 15 individuals) populations. Population viability was unaffected by current road mortality rates in the largest populations. In contrast, simulations of current road mortality in the two smallest populations halved their population sizes in five years and accelerated the time to extinction by up to 18 years compared to baseline scenarios with no roadmortality. However, simulations of 40% annual proportional loss catalysed declines in even the largest populations. This study demonstrates that the level of road mortality that local populations can endure is dependent on population size,reproductive rates and juvenile survival. Of note is that even low road mortality rates may have detrimental effects for small populations with low per-capita growth. Future studies should gather demographic context to roadkill to accurately interpret population-level impacts. Whilst reducing roadkill remains a valuable tool for conservation, focusing on habitat connectivity is also important to encourage immigration into small populations and promote landscape-scale species occupancy.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Biosciences
Publisher:	Wiley
ISSN:	1367-9430
Date of First Compliant Deposit:	6 August 2026
Date of Acceptance:	3 June 2026
Last Modified:	06 Aug 2026 10:00
URI:	https://orca.cardiff.ac.uk/id/eprint/188758

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