Road networks fragment habitat and cause direct mortality in reptiles and amphibians at a scale that contributes significantly to population declines across Europe and North America.
Animals killed on roads die traumatically — collision injuries cause acute pain and death that may not be immediate. Frogs attempting to cross roads during breeding migrations face vehicle traffic in high numbers, with survivorship in some locations near zero without intervention. Snakes warming on road surfaces — thermoregulating on the heat-absorbing tarmac — are struck repeatedly. Tortoises killed by road traffic represent decades of individual life and slow reproduction impossible to recover quickly. Road mortality disrupts population genetics by selectively removing individuals attempting gene flow between fragments.