Life in the fast lane: roadkill risk along an urban–rural gradient

Abstract

Wildlife-vehicle collisions are a major cause of mortality in animal populations and can cause significant population-level effects. Urban areas are typically associated with higher road densities and unique wildlife communities in comparison to rural areas, and therefore have the potential to be associated with high numbers of collisions, and roadkill risk. Here, we use a citizen science database of wildlife roadkill and species distribution models to assess how roadkill risk (probability of roadkill observation per km2) varied along an urban–rural gradient for British wildlife. Roadkill risk was positively associated with road density, until around 5000 m/km2, a value representing villages or the outskirts of towns and cities. Beyond 5000 m/km2, risk remained high for some species (hedgehog, fox, pigeons and gulls) but reduced for other species (badger, rabbit, pheasant). Roadkill risk was a function of live species distribution for badger, hedgehog and rabbit, with significant overlap between spatial patterns of roadkill risk and the species’ live distribution. This was not the case for fox, pheasant, pigeons and gulls. Fox roadkill risk was underrepresented in rural areas, possibly due to low road density, while pheasant risk was overrepresented. For pigeons and gulls—well-known urban exploiters—roadkill risk was overrepresented in urban areas given their live distributions, possibly due to risks associated with foraging, particularly roadkill scavenging by gulls. Our results highlight the dangers of the UK’s dense road networks to wildlife, even to species considered adapted to urban environments and human disturbance.