Predicting hedgehog mortality risks on British roads using habitat suitability modelling

Road vehicle collisions are likely to be an important contributory factor
in the decline of the European hedgehog (Erinaceus europaeus) in
Britain. Here, a collaborative roadkill dataset collected from multiple
projects across Britain was used to assess when, where and why hedgehog
roadkill are more likely to occur. Seasonal trends were assessed using a
Generalized Additive Model (GAM). There were few casualties in winter —
the hibernation season for hedgehogs — with a gradual increase from
February that reached a peak in July before declining thereafter. A
sequential multi-level Habitat Suitability Modelling (HSM) framework was
then used to identify areas showing a high probability of hedgehog
roadkill occurrence throughout the entire British road network (~ 400,000
km) based on multi-scale environmental determinants. The HSM predicted
that grassland and urban habitat coverage were important in predicting the
probability of roadkill at a national scale. Probabilities peaked at
approximately 50% urban cover at a 1 km scale and increased linearly with
grassland cover (improved and rough grassland). Areas predicted to
experience high probabilities of hedgehog roadkill occurrence were
therefore in urban and suburban environments, i.e. where a mix of urban
and grassland habitats occur. These areas covered 9% of the total area
within the national British road network. Used alongside evidence on the
persistence with which hedgehog roadkill are recorded in a given location
over time, the HSM framework can help to identify priority areas for
mitigation measures.