Roadkill in a time of pandemic: the analysis of wildlife-vehicle collisions reveals the differential impact of COVID-19 lockdown over mammal assemblages

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Boštjan Pokorny, Jacopo Cerri , Elena Bužan


Collisions with vehicles are a major anthropogenic cause of mortality for wildlife, with conservation and evolutionary implications. Due to the COVID-19 pandemic, many countries worldwide enforced lockdowns which importantly reduced traffic, and therefore had unprecedented consequences for global wildlife populations. We modeled how the two lockdown periods in spring and autumn 2020 influenced wildlife-vehicle collisions in Slovenia (central Europe), by comparing long-term (for the period 2010–2020) and high-quality time series data on road mortality of seven mammalian species: European roe deer (n = 53,259),
red fox (n = 9,889), European badger (n = 5,170), brown hare (n = 5,050), stone marten (n = 4,267), wild boar (n = 1,188), and red deer (n = 1,088). We decomposed 2010–2019 data through autoregressive Bayesian Generalized Additive Models, and then we compared 2020 data to forecasts, aiming to estimate anomalies in number of collisions during both lockdown periods. During the spring lockdown (16 March – 30 April 2020), we observed far less collisions than in the 2010–2019 average as well as in 2020 forecasts, for roe deer and badger. In the autumnal lockdown (20 October – 31 December 2020), we observed significantly less collisions for roe deer and wild boar. Traffic reduction in both lockdown periods had a major impact on roe deer, which in autumn and spring 2020 experienced 270–330 less road-related mortality cases than expected. COVID-19 lockdown reduced traffic-related mortality for the majority of studied species. In some species, this decrease reached a magnitude of biological significance, which can have long-term repercussions on both evolution and management. Obviously, large-scale sanitary policies, imposing a reduction to human mobility, can have large-scale impacts on wildlife. As pandemics may increase in the next decades, we encourage further research exploring the consequences of their enforcement over global change and wildlife conservation and evolution.



Ecology and Evolutionary Biology, Life Sciences, Other Life Sciences, Population Biology


COVID-19, lockdown, roadkill, SARS-CoV-2, traffic, wildlife-vehicle collisions


Published: 2021-07-20 14:06

Last Updated: 2021-07-21 03:32

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